Lipo failure

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neptronix   100 GW

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Re: Lipo failure

Post by neptronix » Jul 02 2015 10:20pm

Nope, 9 packs out of 10 arrive basically perfect.
I know this because i've ordered about 32 of them over the course of 5 years, and have the cycle graphs to prove it.
This is also the experience of many longtime lipo users.

If they were random rejects, the packs would not look nearly as nice and have a uniform construction of cells.

Also, my 5 year old packs wouldn't still be running, delivering far more cycles than promised.

A cycle graph tells you all you need to know about a pack. The only reason i haven't had my house burn down is because i cycle graphed every battery i own upon arrival and never use the packs with dud/underperforming cells in them. I follow all of the safety advice i was given long ago and found it to be legit. I treat 18650's and other chemistries just the same. That is why i believe, for me, that RC Lipo is safe.
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Alan B   100 GW

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Re: Lipo failure

Post by Alan B » Jul 02 2015 11:22pm

Single cells can burst into flame if overcharged, or charged after being overdischarged, or if shorted or mechanically damaged. Using single cells does not solve the problem.

Laptops use multi-cell lipos. The pack I'm looking at is 2S2P. The cells are in a frame that doesn't protect them much at all, and is labelled with various warnings about mishandling causing fire, etc. There are a LOT of these on every airplane flying around the world every minute of every day, they even get charged onboard those airplanes quite frequently. They have figured out how to make lipos safe, just as many members of ES have logged tens of thousands of miles on their own packs without conflagration.

On what do you base this claim that the HK cells are rejects? Wild guessing? Where is the data to back that up? Sounds like baseless speculation.

There aren't enough discards for companies like Hobbyking to make their manufacturing requirements, I have a lot of HK lipos and the vast majority of them have perfect cells with better balance than the A123 cylindrical cells that I have in commercial packs. I have had very few that didn't balance perfectly, and zero that have burst into flames. When a cell is "off normal" it needs to be culled. Anyone who uses a cell without testing is asking for fireworks.

Hobby Lipos are getting better all the time, just like the commercial cells and packs. They are all in the same industry and are learning from the same processes. None of them are perfect, even big names like Sony, Apple and Dell have had major fires and recalls (even with cylindrical cells). Clearly the big names have better QC and better systems management, so they will have lower failure rates. But there are many "low end" vendors making commercial ebike packs. I suspect that these are not better than the best packs that ES members make.

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Re: Lipo failure

Post by Syonyk » Jul 03 2015 10:44am

neptronix wrote:Nope, 9 packs out of 10 arrive basically perfect.
I know this because i've ordered about 32 of them over the course of 5 years, and have the cycle graphs to prove it.
This is also the experience of many longtime lipo users.
That 10% of the packs arrive in some way faulty does not back your argument that they're all high quality cells... if I had a 10% failure rate on new 18650s, I'd be returning the whole shipment in a heartbeat. I'd be very cranky at a 1% failure rate...

I'm basing my statements on liveforphysics' post here: http://www.endless-sphere.com/forums/vi ... 50#p401772
I've visited the nano-tech (and other) factory in China, visited (for business reasons unrelated to ebikes) some other LiPo factories in Korea, and spent a few days with the owner of hobbyking in Hong Kong and in China.

To get some things straight:
#1 He had no idea people were running ebikes on RC Lipo.
#2 All our ebike Lipo sales for the last 5 years wouldn't keep his factory busy for more than an hour.
#3 All of us combined are a statistically insignificant part of his battery businesses that means nothing to him.
#4 HobbyKing has still only lost money (and he is fine with that, his money comes from other industry, he runs hobbyking for fun, and has said the moment its not fun anymore he will close it down),
#5 The whole RC battery division is just a side-gig as something to do with OEM mfg left overs and surplus, excess supplies from OEM contracts etc. This is why supply/stock consistency is so random.
#6 He absolutely hates the thought of people charging these large Lipo packs in there garages and homes.
#7 After showing him vids of high-power ebikes (which he didn't know existed) he thinks ebikes should use LiFePO4, and thinks RC Lipo should only be used for racing (loves the idea of racing ebikes) or by experts in charging and charged outside somewhere safe.
#8 Ebike battery sales (in the form of RC packs) don't matter to him, and he would rather discourage than encourage them.
Also, my 5 year old packs wouldn't still be running, delivering far more cycles than promised.
You got high quality cells. Not everything coming off as seconds failed QA - it can be, as posted above, left overs and surplus. Some of the cells are good. Others seem to be not-so-good.
A cycle graph tells you all you need to know about a pack. The only reason i haven't had my house burn down is because i cycle graphed every battery i own upon arrival and never use the packs with dud/underperforming cells in them. I follow all of the safety advice i was given long ago and found it to be legit. I treat 18650's and other chemistries just the same. That is why i believe, for me, that RC Lipo is safe.
Ok. And the cost of the equipment to cycle graph your cells is significant. It's fine if geeking out with lipo packs is your hobby, but they still are not a good power source for a general use electric bike.
Alan B wrote:Single cells can burst into flame if overcharged, or charged after being overdischarged, or if shorted or mechanically damaged. Using single cells does not solve the problem.
It is much, much harder to overcharge/overdischarge a single cell with a basic BMS installed, because there's only one voltage to monitor. Keep it between the lines of about 3.0v and 4.2v, and there's no way to damage the cell electrically. Cell phones/tablets/etc all do this. This is radically safer than having a series pack with no per-cell level monitoring, as is commonly done.
On what do you base this claim that the HK cells are rejects? Wild guessing? Where is the data to back that up? Sounds like baseless speculation.
See above. "Factory overstocks" is probably a better term, though the random sampling of cells appears to be accurate.
There aren't enough discards for companies like Hobbyking to make their manufacturing requirements, I have a lot of HK lipos and the vast majority of them have perfect cells with better balance than the A123 cylindrical cells that I have in commercial packs. I have had very few that didn't balance perfectly, and zero that have burst into flames. When a cell is "off normal" it needs to be culled. Anyone who uses a cell without testing is asking for fireworks.
That people consider the HK failure rate acceptable boggles my mind.
I suspect that these are not better than the best packs that ES members make.
Perhaps. I don't have a problem with people who deeply understand the quirks and hazards of lipo packs using them. I do have a problem with lipo builds being the default recommendation for anyone who asks about a battery, because this means a large group of people who do not have the equipment, knowledge, or expertise to safely use large lipo packs are building and using them. Fires are the result. And as I've said repeatedly, the difference between a home built lipo pack that burns down a building and a professionally built Samsung 18650 pack with a full BMS, as discussed in the news, is nothing. Zero. They are both "ebike battery packs."

I like ebikes. I think they're a great way to get around. I think that the consistent suggestion of building lipo packs for new riders is actively harmful to the long term acceptance of ebikes due to their somewhat frequent exits from the world in a fireball.
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Re: Lipo failure

Post by dnmun » Jul 03 2015 12:02pm

in that paper you offered, they talked specifically about how it is now standard practice in these pouch manufacturing facilities to immediately scrap any and all product that is damaged in any way. dropped, scratched or bent, and they are discarded.

there is a discussion of the numerous battery fires in aircraft shipping and manufacturing facilities at the end of that paper. some of the factory losses were significant. they do not tolerate any abuse or allow an abused pouch to remain in the production process. it is scrapped.

ps, all the air freight battery fires were attributed to shorts of the battery in the shipping container or improper handling or shipping practice.

there was no spontaneous combustion that everyone here likes to assume.

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Re: Lipo failure

Post by gensem » Jul 03 2015 12:46pm

I recently got 45x 4s 5000mah hardcase lipo from HK... I tested 23 out 45 already and none were bad till now.
IR 1.9 to 2.5.
All packs have over 3800mah from 4.05v to 3.55v but they do tend to unbalance a little below 3.65v-3.60v
Im posting this just to say that quality is quite consistent over all cells.
Either way I dont recommend and will not use all that lipo in an ebike without monitoring.
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Re: Lipo failure

Post by dnmun » Jul 03 2015 1:59pm

i was able to store 5100 mAh in my lipoly after i had cycled them several times when i got them so i am surprised you got less than 80% from your packs.

i never bot a bad lipoly. i got free a lipoly 6S pack that had been bulk charged and several pouches were 0V and several were at 5.5V but that was entirely from use without a BMS to protect them.

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Re: Lipo failure

Post by Syonyk » Jul 03 2015 3:25pm

dnmun wrote:in that paper you offered, they talked specifically about how it is now standard practice in these pouch manufacturing facilities to immediately scrap any and all product that is damaged in any way. dropped, scratched or bent, and they are discarded.
I agree. And that's one theory. I question if this is done as consistently as asserted.
ps, all the air freight battery fires were attributed to shorts of the battery in the shipping container or improper handling or shipping practice.

there was no spontaneous combustion that everyone here likes to assume.
Without knowing a lot more about the incidents, I can't comment on that, but to assert that a set of batteries must have shorted in shipping is a pretty safe assertion if the packaging is substandard. It may or may not be the case all the time.
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Re: Lipo failure

Post by Alan B » Jul 03 2015 3:32pm

I don't think the quality of prime RC cells is as bad as you say. I do avoid the cheapest packs and move a little up the quality ladder. Buying the absolute lowest priced product is generally not a good QC plan. But once you get off the "bottom" of the market the quality has been quite good, and it has improved markedly over time as they learn how to make better product.

The failure rate is nothing like 10%. A pack has 6 or so cells, so a shipment of 13 packs has almost 80 cells, and zero were bad in my CroBorg's Multistar order, as an example. The out of the box balance voltages were much better matched than I see on new prime A123 cells, for another example.

My average orders are 50-100 cells, and there have been less than one bad cell per order on average. So my lipo bad cell rate has been well under 1%. People who mention numbers like 9 of 10 are not being precise. It is just part of the philosophy to buy a few extra cells to insure a complete pack's worth of good cells are available during the build in the rare case that some are bad.

Every ebike shop that has a welder is making packs, and increasingly home enthusiasts are doing it too. Are those the same quality as commercial factory quality?

Just like the cheapest lipo, there is the cheapest 18650. I've had those burst and corrode in flashlights, and have poor life. Good or Bad Quality is not reserved for any particular cell type.

I think the problem here is "low quality homebuilt (or commercially built) packs", not "lipo". Lipo is attractive for many reasons, but dangerous packs are built out of many cell types. Headway LiFePO4 packs with a BMS have burned just fine as well.

If lipos are inherently dangerous how can they be used in so many commercial products?

For lipos to be safe in cellphones and tablets requires electronics that works correctly. Laptop series parallel packs also requires balancing that works properly. Clearly the electronics can be done correctly, or these phones and laptops would be burning up regularly, like they used to.tor

Manual Monitoring various lipo packs that I have built, I see they require balancing less than once per year with hundreds of cycles per year. I'd like to have a reliable BMS but the high vibration environment of eBikes is hard on electronics, and BMS failures are common. The experience for many has been that BMS's kill more packs than manual monitoring.

We need better quality packs and better quality BMS's at prices sensible for the eBike market. The low quality BMS's on most eBike packs don't meet commercial BMS standards for redundant self checking. A BMS that doesn't self check is not really any better than manual testing. Most failure modes result in the BMS indicating all OK. If it fails you think you are protected, but you are not.

As others have mentioned, many failures come from shorts. These are irrespective of cell type.

Many failures come from charging a damaged pack. In many or most cases the operator knows the pack is damaged and charges it anyway, hoping it will recover. A functioning BMS or a proper manual check would prevent this. A broken BMS may provide a false sense of security and lead to a fire.

There are differences between cell types and between chemistries. But all the other important factors cannot be ignored. Choosing one factor and ignoring all others doesn't provide a balanced view of the risks.

Keeping safe requires understanding the factors, making considered plans and taking appropriate actions, not fixating on one issue and ignoring other more important ones.

Stay safe on this fourth of July weekend, and have a good one. We want our fireworks to burn safely and our ebikes to avoid burning. :)

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Re: Lipo failure

Post by Syonyk » Jul 03 2015 3:56pm

Alan B wrote:I do avoid the cheapest packs and move a little up the quality ladder. Buying the absolute lowest priced product is generally not a good QC plan. But once you get off the "bottom" of the market the quality has been quite good, and it has improved markedly over time as they learn how to make better product.

The failure rate is nothing like 10%. A pack has 6 or so cells, so a shipment of 13 packs has almost 80 cells, and zero were bad in my CroBorg's Multistar order, as an example. The out of the box balance voltages were much better matched than I see on new prime A123 cells, for another example.

My average orders are 50-100 cells, and there have been less than one bad cell per order on average. So my lipo bad cell rate has been well under 1%. People who mention numbers like 9 of 10 are not being precise. It is just part of the philosophy to buy a few extra cells to insure a complete pack's worth of good cells are available during the build in the rare case that some are bad.
You start by saying you don't buy the cheapest cells available, and then immediately spin into "And the failure rate of these not-the-cheapest cells isn't very bad!" Which is what I would expect. I assume high end lipo batteries are well tested and have a very low failure rate, but nobody seems to be spending the money on those for ebike packs.

My main problem is the view, disturbingly common here, that buying the cheapest lipo packs you can find and then stringing them together is a great way to make a high power ebike battery. It's not. It's not a safe way to build a pack, and the fires are showing this.
Every ebike shop that has a welder is making packs, and increasingly home enthusiasts are doing it too. Are those the same quality as commercial factory quality?
No idea. If it's being built by people who build a lot of packs, have a high quality BMS in it, and are using brand new cells, it's pretty much comparable to commercial factory builds. If it's a BMS-free build of recycled whatever-you-can-find 18650s (or Ultrafires, which are the same difference), no, it's not.

Also, where are you finding these ebike shops that make packs? I've yet to tear down a pack that the ebike vendor could tell me much about. BionX doesn't make their own packs, iZip doesn't make their own packs... they're buying pre-built packs from other people. Talking to a few local ebike shops in the Seattle area, none of them are building their own packs either, and couldn't point me to anyone who rebuilds packs in the area.
I think the problem here is "low quality homebuilt (or commercially built) packs", not "lipo". Lipo is attractive for many reasons, but dangerous packs are built out of many cell types. Headway LiFePO4 packs with a BMS have burned just fine as well.
Sure. That's fair. You can build a junk 18650 pack that will have problems as well, but the bulk of the cheap packs people are building on ES seem to be lipo based, and I still hold the strong opinion that a lipo pack, as is commonly built, is not safe for ebike use. By the time you start adding firewalls and BMS boards, the cost advantage of lipo goes away over other options.
If lipos are inherently dangerous how can they be used in so many commercial products?
Because they're using higher quality cells than are used for RC hobby packs, are using a single cell (most of the time), have a competent BMS on them, and aren't managed by unplugging the pack and plugging it into a charger regularly. Do that with an ebike battery pack, and you'll probably be just fine, even with pouch type batteries. Very few people are doing that.
Manual Monitoring various lipo packs that I have built, I see they require balancing less than once per year with hundreds of cycles per year. I'd like to have a reliable BMS but the high vibration environment of eBikes is hard on electronics, and BMS failures are common. The experience for many has been that BMS's kill more packs than manual monitoring.
If you're manually monitoring the cell voltages every single charge, and discard any cells that are below the cutoff voltage, then you're probably fine. Again, the vast majority of people don't seem to be taking this care with their packs, and I would argue strongly that you shouldn't have to. For an electric bike to be a useful vehicle, it should have roughly the maintenance requirements of a normal bicycle or car, which doesn't look like careful manual pack monitoring every single day. If you're building a high power mountain racer, absolutely, run BMS-free and manually monitor the pack. For a daily commuter vehicle, this is an absurd requirement for safe operation, but it's required for safe lipo pack operation.
We need better quality packs and better quality BMS's at prices sensible for the eBike market. The low quality BMS's on most eBike packs don't meet commercial BMS standards for redundant self checking. A BMS that doesn't self check is not really any better than manual testing. Most failure modes result in the BMS indicating all OK. If it fails you think you are protected, but you are not.
No arguments here.
As others have mentioned, many failures come from shorts. These are irrespective of cell type.
A good BMS will block output current above the rated output by cutting the pack off from a short. If the rest of the pack is well sealed and insulated, an internal short is unlikely. And some chemistries are safer in the face of a short than others - LiMn cells don't seem to have particularly bad shorted cell behavior, though they're significantly less energy dense than LiCo.
Many failures come from charging a damaged pack. In many or most cases the operator knows the pack is damaged and charges it anyway, hoping it will recover. A functioning BMS or a proper manual check would prevent this. A broken BMS may provide a false sense of security and lead to a fire.
True. But having to pair a broken BMS and a damaged pack reduces the chances of a damaged pack being charged. If someone is going to be an idiot and charge a fully drained lipo cell hoping it recovers, I can't help that, but I can certainly encourage people to not be idiots.
Keeping safe requires understanding the factors, making considered plans and taking appropriate actions, not fixating on one issue and ignoring other more important ones.
Sure - but stopping recommending new ebike builders use a DIY BMS-less lipo pack is a good start down this road.
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Re: Lipo failure

Post by neptronix » Jul 03 2015 4:14pm

Syonyk wrote: That 10% of the packs arrive in some way faulty does not back your argument that they're all high quality cells... if I had a 10% failure rate on new 18650s, I'd be returning the whole shipment in a heartbeat. I'd be very cranky at a 1% failure rate...
When i say faulty, i mean that there is an underperforming cell ( different IR, less capacity, etc ) in 1 out of 10 packs.
So, out of 50 cells in total, you're going to get 1 or 2 underperforming cells. You can cycle graph it, send the data to hobby king, and get a refund for the pack.

This is not a problem to me because the packs are so much cheaper than many other lithium chemistries and all the labor of wiring cells in series and installing balance taps is a huge bonus in my eyes.

If you order some cheap BMSed chinese pack from any other vendor, you're gonna get approx. the same dud rate. The difference is that you can't send part of the battery back to the factory and get another part back and then proceed to hook it up to the rest of your pack without doing tab welding or soldering with some weird type of solder you've never dealt with before.
You got high quality cells. Not everything coming off as seconds failed QA - it can be, as posted above, left overs and surplus. Some of the cells are good. Others seem to be not-so-good.
I made 4 orders over 5 years and every time, i got high quality packs with an occasional pack that wasn't up to par. I don't have better luck than anyone else. I think icecube57 is the biggest user of lipos and has had the same wonky pack rate as me.
Ok. And the cost of the equipment to cycle graph your cells is significant. It's fine if geeking out with lipo packs is your hobby, but they still are not a good power source for a general use electric bike.
$100 for an iCharger 1010b+ is a significant cost? not when you're dealing with $1000 of battery cells whose condition is unknown to you. It replaces a BMS. What would a totally solid, reliable, well built 100A capable 12S BMS cost? prolly the same price if not more.

Shoot, i have used the iCharger for tons of things - reconditioning lifepo4 packs that went below LVC, bringing car batteries back to life from 3 volts... having this equipment on hand has paid for itself. If i was constructing 18650 batteries, i'd still be using it to cycle graph every cell to weed out any duds recieved.

PS. Even commercially packs come with dud cells from time to time. Even still, most commercial BMSes give you ZERO information about your battery. I've used my RC Balancing setup to diagnose pack issues for many people who had BMSes. Some of these BMSes even drain one or two cells in series and eventually kill the pack as a result. I call those types of BMSes 'battery murdering systems'..
I simply do not trust BMSes, unless they tell me exactly what's going on. I'd run one on a EV car with a graphical display, but not on a bike..
That people consider the HK failure rate acceptable boggles my mind.
I can buy a 12S 16AH 160A rated ( happy to do 40A continuous all day long without making more than 1-2F of ambient heat and hold steady voltage under load ) at battery for <$250 from hobbyking. Having to send the occasional dud pack back to the factory more than makes up for the price. The value of these packs is great. That's why it's worth the hassle.
Fires are the result. And as I've said repeatedly, the difference between a home built lipo pack that burns down a building and a professionally built Samsung 18650 pack with a full BMS, as discussed in the news, is nothing. Zero. They are both "ebike battery packs."
Many people do not own many professionally built samsung packs in the first place.
Em3ev is one of the cheaper sources of these packs. To get my 12S 16AH $250 hobbyking RC Lipo equivalent pack, i'm gonna hand over $700 + shipping from China.. and then, i will have a battery that costs 3 times as much delivered that is capable of about 1/3rd of the amp output of what the lipo is.

Why do i buy lipos? higher power output, good energy density ( 190whrs/kg in the 10C multistars is excellent ), and economics. The unstated cost is that i need to spend a little time occasionally looking over the pack with a fine tooth comb and be prepared for a potential fire if i goof up really bad. I don't goof up really bad because i know what i'm doing.

If you don't know what you're doing ( usually due to not understanding the danger ), your cost is potentially your life or property. That's a high cost.
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Re: Lipo failure

Post by neptronix » Jul 03 2015 4:31pm

Syonyk wrote:Sure - but stopping recommending new ebike builders use a DIY BMS-less lipo pack is a good start down this road.
I'm glad someone ( mwkeefer ) recommended that i start out with lipo as a total newb. :lol:
I think he understood that i was a computer programmer and DIYer of other things before.
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I used to rewire synthesis chips, timing/sequencing circuits, and sample bank ROMs in vintage consumer keyboards just to hear the obscene tortured sounds they'd output afterwards as a hobby before i got into ebikes. I figured out how to do this without killing the chips by measuring voltages, amperages etc. coming in and out of them.

If you don't have some kind of nerdy electronics/computer science fetish already, non-BMSed lipo is indeed, probably not for you. How about that?
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
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Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Lipo failure

Post by Syonyk » Jul 03 2015 4:36pm

neptronix wrote:
Syonyk wrote:Sure - but stopping recommending new ebike builders use a DIY BMS-less lipo pack is a good start down this road.
If you don't have some kind of nerdy electronics/computer science fetish already, non-BMSed lipo is indeed, probably not for you. How about that?
That's fine. If someone really wants to be bothered by all the hassle of keeping a non-BMS lipo pack healthy, go for it. I'm not going to argue.

But for the vast majority of people interested in ebikes, a non-BMS lipo pack is a disaster looking for a place to happen.
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Re: Lipo failure

Post by neptronix » Jul 03 2015 4:48pm

Syonyk wrote:That's fine. If someone really wants to be bothered by all the hassle of keeping a non-BMS lipo pack healthy, go for it. I'm not going to argue.

But for the vast majority of people interested in ebikes, a non-BMS lipo pack is a disaster looking for a place to happen.
This just goes for any DIY forum, really.

I still see people installing front motors on aluminum front suspension forks here.
I still see people using RC Lipo without having a clue about what's going on.
I still see 20lb battery packs hanging off the seatpost.
I still see people not installing torque arms, or simply installing them wrong.

Oh god, we can yell time tested wisdom until we are blue in the face and people still do this stuff. Drives me up a wall :lol:

Darwin's chainsaw loves this forum. That's just the nature of DIY.. survival of the smartest :lol:
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Lipo failure

Post by Syonyk » Jul 03 2015 5:04pm

I disagree with your comparison based on the severity of the consequences.
neptronix wrote:I still see people installing front motors on aluminum front suspension forks here.
You'll break your fork, hurt, possibly severely, yourself. Very unlikely to hurt anyone else.
I still see 20lb battery packs hanging off the seatpost.
You'll break your luggage rack, and it's mostly likely to be an annoyance.
I still see people not installing torque arms, or simply installing them wrong.
Again with the "break your bike, hurt yourself" level consequences.
I still see people using RC Lipo without having a clue about what's going on.
This is a totally different range of consequences. Many people live in apartments. An aggressive thermal runaway and venting of a lithium pack that ignites will easily light a substantial structural fire, in a hurry. People charge their bikes inside apartments, because that's the option they have. Even in a detached single family house, if other people live there, you're potentially risking their life, as well as the lives of any responders to the fire.

I assure you, the first time an apartment complex gets burned down by an ebike, people will pay attention to ebikes like they never have before. And I don't want that to happen.
Darwin's chainsaw loves this forum. That's just the nature of DIY.. survival of the smartest :lol:
If you're just going to hurt yourself, absolutely. But recommending a battery pack construction style that is cheap, powerful, and downright hazardous unless treated very, very carefully, is just stupid. At best.
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

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neptronix   100 GW

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Re: Lipo failure

Post by neptronix » Jul 03 2015 5:38pm

Front motor fork snappage: prepare to suddenly be superman. I hope you have a full face helmet.
rear rack snappage: seat post and part of the frame usually comes off with the rear rack; prepare to fall backwards suddenly, and land on a battery / asphalt mixture. I hope you have a helmet because your head is probably hitting the ground first.
Rear dropout snappage: I really hope you have a helmet, otherwise landing on your head won't go so well.

I've not heard of RC Lipo taking down a building before. Usually, it's fire and smoke damage that destroy a garage or bedroom.
This has happened plenty of times with BMSed, commercial packs, too.

Any form of stored energy is dangerous. Lawnmowers, cars, other lawn tools, motorcycles, cell phones, etc burn houses down on the daily. Electrical wiring itself or appliances cause fires on the daily..

What's the benefit to risk ratio? that is very subjective. I'm happy to keep 2kwhrs of lipo in my garage because the benefit is great, in my opinion. There is no other battery out there currently that interests me, other than a few newer 18650 formulations, but i don't have the will or justification to invest in a tab welding machine and do all that manual labor.

But that's just like, my opinion, man 8)
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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nutnspecial   1.21 GW

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Re: Lipo failure

Post by nutnspecial » Jul 03 2015 8:34pm

Wow, alot has been said here. To add a little flave to the flave, the only thing I'll say is a question: how can you guys bother (to this degree) with negative nancy's like this? I guess I just don't have the energy to waste.

I think marilyn manson said it best in regards to my feelings on lipo- :twisted: User friendly.


Not sure if utube is ok with this level of '''''''''''' ? Sorry if it isn't, but i kinda like the lyric application towards lipo baby!

Ps.
But seriously, isn't lipo like the sexy black lady with the python draped over shoulder dripping wine down her leg into your mouth?? AHHAHAHAHAHAH
Last edited by nutnspecial on Jul 04 2015 1:08pm, edited 1 time in total.

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Re: Lipo failure

Post by Syonyk » Jul 03 2015 9:43pm

nutspecial wrote:But seriously, isn't lipo like the sexy black lady with the python draped over shoulder dripping wine down her leg into your mouth?? AHHAHAHAHAHAH
... sure. Not worth taking home into your house every single night.
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

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nutnspecial   1.21 GW

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Re: Lipo failure

Post by nutnspecial » Jul 03 2015 10:10pm

LOL, nice one. Omg I can't stop laughing. That sexy evil lady dripping the wine don't come in my house at all, I just like to ride her BAWAHAHA.
Last edited by nutnspecial on Jul 04 2015 1:07pm, edited 1 time in total.

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neptronix   100 GW

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Re: Lipo failure

Post by neptronix » Jul 03 2015 10:18pm

Oldie, but goodie.. :mrgreen:
1525111_10152436438531156_5433966571089194917_n.jpg
1525111_10152436438531156_5433966571089194917_n.jpg (64.63 KiB) Viewed 2356 times
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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nutnspecial   1.21 GW

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Re: Lipo failure

Post by nutnspecial » Jul 03 2015 10:28pm

Hmmm, maybe I should try lifepo? She looks hot'n'wholesome, and makes lipo look like a dam slut?

On second look (sla, *shudders), I get that lifepo get's to be a bit much compared to my lipo lover at high draw. No room for that kinda shenanigans in my bike-life!

How does bloodhound gang put it? " no i can't be tied down with a girl, that wants me tied up!"
Last edited by nutnspecial on Jul 04 2015 1:11pm, edited 1 time in total.

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Re: Lipo failure

Post by amberwolf » Jul 04 2015 1:35am

neptronix wrote:I've not heard of RC Lipo taking down a building before. Usually, it's fire and smoke damage that destroy a garage or bedroom.
Floont?
http://www.endless-sphere.com/forums/vi ... 25#p781444

These linked in another thread:
http://www.hobbyking.com/hobbyking/foru ... ?TID=25069

http://www.kitv.com/news/hawaii/homeown ... e/24445618

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Alan B   100 GW

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Re: Lipo failure

Post by Alan B » Jul 04 2015 1:59am

In the Floont case he was reportedly reconfiguring a number of different packs together to very high voltage and bulk charging them, so the balance was poor, and not monitored or controlled. This is a particularly high risk approach to battery configuration, and I would not recommend that.

The BMS doesn't protect against shorts inside the pack, and homemade packs often don't have the proper insulators or adequate mechanical support for the cells, nor do the welded strips have the proper stress relief cuts that the commercial packs have.

For high current applications the BMS is not generally switching the high current path, it controls power to the controller logic subsystem instead, so a short will depend not on the BMS but on the overcurrent device which many builds are lacking, or which are not rated for the proper voltage. This only works if the short is downstream of the protective device. The majority of connections and opportunities for a short are inside the battery pack where the overcurrent device or BMS is not helpful.

Not many commercial packs meet the needs of high performance ebikes. They cannot deliver the current needed. Or they are too large, heavy or expensive for the application. If folks could easily and cost effectively buy packs that met their needs, they would. They just aren't very available in the configuration that fits the application.

The people on this forum don't represent the majority of ebikers. These are the folks who want to build something, not the off-the-shelf appliance operators that represent most of the population. Not too many of this crowd live in apartments, from what I've seen. If you want to address the majority of ebikers you need to find a different venue. This isn't going to reach them. This is the DIY crowd made primarily up of engineers, technicians, inventors, experimenters, modders and tinkerers.

I just reviewed my inventory of RC Lithium batteries. The only ones that appear to be going bad are the LiFePO4 packs and A123 and Headway cells. All of the iffy ones are LiFePO4. The A123 and Headway cells in particular seem to have excessively large leakage currents compared to LiPo. So much for that super life claim they make. These have never been mistreated, but all the mylar bagged LiFePO4 have swollen, and many of the cylindrical A123 and Headway cells have dropped quite low in terminal voltage. The Lipo, even the old lipo, are fine. Voltages are normal and no major swelling. The only lipo that have died on me are the ones I overdischarged. BMS's often overdischarge packs during storage, that's a common complaint around here. The BMS draws a little power from the first 2 cells of a pack, and those end up dead over the winter. Happens to lithium tool batteries too. The BMS kills them.

Quite a few folks on here make packs from discarded laptop or tool cells, or bulk purchased 18650's. Lipo isn't the only game in town.

Installing a BMS is no guarantee of either protection or safety. We've seen plenty of failures and a few fires with BMS's here on ES.

You should still monitor your cells even if you have a BMS. Like checking your oil or your tire pressures, having a sensor is no excuse for not verifying proper levels. Most BMS's fail "unsafe". I haven't seen a truly failsafe BMS design yet for eBikes.

Based on what I'm seeing here, LiFePO4 packs die much faster in storage than LiPo, and BMS's kill packs in storage as do controllers. So the user MUST take appropriate steps to manage the pack, even if they have a BMS. Expecting that everything will take care of itself leads to failed packs.

The best protection and safety is from proactive knowledgeable users who understand their batteries and take proper care of them.

Perhaps all others should just buy lead.

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Re: Lipo failure

Post by gensem » Jul 04 2015 12:11pm

dnmun wrote:i was able to store 5100 mAh in my lipoly after i had cycled them several times when i got them so i am surprised you got less than 80% from your packs.

i never bot a bad lipoly. i got free a lipoly 6S pack that had been bulk charged and several pouches were 0V and several were at 5.5V but that was entirely from use without a BMS to protect them.
Im testing from 4.05v to 3.55v. 4.2v to 3.3v would probably net me 5000mah.
Justin we really appreciate what you did!

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Re: Lipo failure

Post by dnmun » Jul 04 2015 5:37pm

yep, i think you would get the full storage if you charged to 4.2V and discharged to 3V. 4.08V is about 88% SOC from my testing.

this theory that charging to full voltage will destroy your battery has never been demonstrated. the old school thinking says that the charge has to stay within the 80%-20% window for maximum cycle life but that is more of an assumption than proven imo.

all the laptop lipo is kept charged to 4.20V and they do not explode. all of the cycle life testing is done from 100% to 0% SOC to show how many full cycles.

the biggest risk is in over discharging down below the LVC where the ability of the cell to transport ions is severely limited.

leaving the lipo on the charger 24/7 is obviously detrimental but charging to full charge and using the pack soon after is the easiest way to get maximum value from the money spent to buy the storage in your pack.

just do not over discharge and leave over discharged. very few people know when they have a cell that has over discharged.

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Re: Lipo failure

Post by ddk » Jul 04 2015 10:28pm

dnmun wrote:...
leaving the lipo on the charger 24/7 is obviously detrimental but charging to full charge and using the pack soon after is the easiest way to get maximum value from the money spent to buy the storage in your pack.
...
My 12-yr old LiCo-powered toothbrush begs to differ.
My LiCo-powered jacket also holds an opposite opinion.
My LiCo powered tools... rarely used but always plugged-in laptop computer... 5-yr old cell phone (I get/make as many as two phone calls a month), flashlights, blah blah blah... the only LiCo batteries I don't leave on a charger 24/7 are my trike batteries.
I currently operate with about 10kW of trike batteries fashioned from HK Turnigy 20C cells (and a couple of Zippy brand. see: previous post)
I initially budgeted a couple of years use from the 20C batteries. I has been gladly mistaken in my (researched) assumptions.
Summation:
...as far as I'm concerned, esp. having suffered through years of NiCad and other secondary battery chemistry failures, LiCo FTW

caveat: I possess nothing powered with other LiPo chemistries. I also use a few NiMh batteries that have to be replaced every few years and about 10kW of solar-charged flooded-cell lead acid which actually powers most my stuff, including those 'other' battery chargers. Not including hotel (A/C) and refrigeration (dumb ol' rv type inefficient fridge)

-I digress
Why haven't I had any fires?
Because I don't trust anything stated on the internet, I did my own testing of the Turnigy 20C cells.
You should too. (you = everyone else)

What I discovered was:
-imo the cells are NOT 20C/2C... closer to 10C discharge/1C charge. Hence for safe operation with a 20-30A motor controller (unmeasurable self-heating) I started with a minimum of 3 each, 5A cells in parallel operation*.
4 and 5 each 5A cells in parallel is my current 'normal' battery practice.
INFO TIME: The packs are Fused/Switched using automotive fuses and switches. Spares carried in each battery pack. Don't use automotive fuses if using over 15S of LiCoLikewise, automotive switches work fine on 10s, not so fine on 14S

-I get about the same range on my trikes charging to 'only' 4.15V per cell as 4.2V. I currently rarely discharge a pack below 3.85V per cell (avg=3.95) because:
-Discharging below 3.55 volts per cell leads to unbalanced cell conditions in a pack where I don't want to pay that much attention to batteries during 'normal operation'. My real range is likely 4x 'normal operation'.
I travel for fun and shopping, not profit. Just like using a car only different. My current trips average about 20 miles a day is all. Previously that was 50 miles with the occasional 150 miles per day carrying additional battery packs.
For Fun.
This is not a limit.
This is how I do it.


BUT
- I wouldn't trust me because I'm just another idiot stating something on the internet.
-and-
While WIKIs can be useful, they can also be very, very, very, insanely... wrong.
Not that the ES wiki is wrong. Wouldn't know. Kahs I du wut I wa-unt. -and now it's time to go watch the fireworks bye bye.


* the Multistar 16Ah battery should be able to make a bigger fire. :mrgreen:
"How can we play Hot Wheels without lighter fluid? " -Serge

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