bluetooth BMS?

Batteries, Chargers, and Battery Management Systems.
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eee291   100 kW

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Re: bluetooth BMS?

Post by eee291 » May 17 2020 1:31pm

In my case all the BMSs that I bought from LTT could easily handle their rated current.
So you say the continuous 60A rated bms i bought from LLT, actually does only 30A for real??


What kind of bms would be appropriate for my application?
It looks like you still don't understand, it's not the fault of the BMS that the Controller is only drawing 30A.
Since the battery can supply enough current it looks like the controller is the only culprit remaining.

If you really think that the BMS is at fault you could temporarily bypass it and measure the current with a current clamp or shunt.
Spoiler alert: It'll still only show 30A

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Re: bluetooth BMS?

Post by john61ct » May 17 2020 2:36pm

Sorry, what evidence do we have that the battery can actually supply 60A for more than say ten minutes?

Without dropping too much voltage?

That should be easier to test first rather than the controller.

I agree best go take the BMS out of the current path, so long as you can still monitor cell-group voltages to help protect the battery while testing.

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Re: bluetooth BMS?

Post by eee291 » May 17 2020 3:41pm

Why would it ever need to supply 60A for ten minutes, have you ever been on an ebike?
I'd like to see the Controller pull 60A even for just a second, a 5S VTC6 pack can handle 60A without catching fire for sure.

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Re: bluetooth BMS?

Post by john61ct » May 17 2020 5:08pm


Just responding to
Wald wrote:So you say the continuous 60A rated bms i bought from LLT, actually does only 30A for real??
A 60Ah pack should not have much trouble, even made from cheap Chinese knockoff cells.

And this is a general BMS thread in the EV sub, so no we're not just talking "bikes" here.

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serious_sam   1 kW

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Re: bluetooth BMS?

Post by serious_sam » May 17 2020 6:10pm

eee291 wrote:
May 17 2020 3:41pm
a 5S VTC6 pack can handle 60A without catching fire for sure.
*5P

I regularly pull 150A from my 5P VTC6 pack. No problems (except a bit of sag). It's easily good for 75A continuous.

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Re: bluetooth BMS?

Post by agniusm » May 20 2020 4:47pm

Is there a physical difference between lipo and lifepo4 bms versions? Possible to program lifepo4 to work on lipo cells?

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Re: bluetooth BMS?

Post by john61ct » May 21 2020 6:41am

BMSs you really can't generalize, so many varieties out there from cheap Chinesium to those costing a thousand bucks.

At the cheap end, most BMSs voltage setpoint parameters are hard-coded, specific to a certain chemistry and usually to high and too low to be useful, crappy balancing too.

Better models are user-programmable, bludtooth or have a display. But the difference between LFP and other LI chemistries is so great often separate models even then.

Separate balancers dedicated to that function, as opposed to the protective ones.

What kind of "physical" differences you asking about?

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Re: bluetooth BMS?

Post by agniusm » May 22 2020 6:07am

john61ct wrote:
May 21 2020 6:41am
BMSs you really can't generalize, so many varieties out there from cheap Chinesium to those costing a thousand bucks.

At the cheap end, most BMSs voltage setpoint parameters are hard-coded, specific to a certain chemistry and usually to high and too low to be useful, crappy balancing too.

Better models are user-programmable, bludtooth or have a display. But the difference between LFP and other LI chemistries is so great often separate models even then.

Separate balancers dedicated to that function, as opposed to the protective ones.

What kind of "physical" differences you asking about?
Well, sure i am asking on the bms'es that are discussed here, bluetooth bms with xiaoxiang app. They sell them as lipo or lifepo4 but they are programmable so i vander if they are compatible. I bought lifepo4 and old cells i had died. Now i got nissan leaf cells and wandering if i can use lifepo4 bluetooth bms on them.
I know energus tinyBMS works on both chemistries but i dont know if this one does

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Re: bluetooth BMS?

Post by agniusm » May 22 2020 6:08am

john61ct wrote:
May 21 2020 6:41am
BMSs you really can't generalize, so many varieties out there from cheap Chinesium to those costing a thousand bucks.

At the cheap end, most BMSs voltage setpoint parameters are hard-coded, specific to a certain chemistry and usually to high and too low to be useful, crappy balancing too.

Better models are user-programmable, bludtooth or have a display. But the difference between LFP and other LI chemistries is so great often separate models even then.

Separate balancers dedicated to that function, as opposed to the protective ones.

What kind of "physical" differences you asking about?
Well, sure i am asking on the bms'es that are discussed here, bluetooth bms with xiaoxiang app. They sell them as lipo or lifepo4 but they are programmable so i vander if they are compatible. I bought lifepo4 and old cells i had died. Now i got nissan leaf cells and wandering if i can use lifepo4 bluetooth bms on them.
I know energus tinyBMS works on both chemistries but i dont know if this one does

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Re: bluetooth BMS?

Post by john61ct » May 22 2020 10:17am

FYI, there are literally dozens of completely different units discussed in this thread.

Many have proposed coming up with a standard way of referring to specific types, but so far the one category you mention

as opposed to ANT type is as good as I can make out.

I suggest finding a specific model from a specific supplier, post the URL, that's IMO the only way to be sure we're talking the same unit.

And if that source happens to offer decent documentation - and I would not buy from one that didn't - then you may / should be able to tell from the min/max voltage ranges.

But right up front on 99% of listings, they list the intended chemistries, the most flexible include LTO as well as "lithium-ion" to indicate the 3.6-3.7Vnominal chemistries, with 3.2-3.3V LFP falling in between.

But I believe most just specify the one, and the min/max range is too narrow to work with more than one.



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Re: bluetooth BMS?

Post by john61ct » May 22 2020 10:22am

LLT / JBD are related companies, good to start there I think.

Xiaoxiang type
Jiabaida Technology
Dongguan Jiabaida Electronic Technology Co., Ltd.

I believe SZLLT is also a relevant search string.

Less sure about RJXZS.

They seem to make separate units for "Li ion" as opposed to LFP, no idea about LTO.

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Re: bluetooth BMS?

Post by tmho » May 22 2020 1:20pm

agniusm wrote:
May 20 2020 4:47pm
Is there a physical difference between lipo and lifepo4 bms versions? Possible to program lifepo4 to work on lipo cells?
I am using the "ANT" bluetooth bms. For ANT, all versions can be used for all chemistry. Just choose the versions matching the no. of S group. And you set the voltages you like for your chemistry.

See one of the post for details.
https://de.aliexpress.com/item/32826820 ... .subject_1

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Re: bluetooth BMS?

Post by serious_sam » May 22 2020 7:02pm

agniusm wrote:
May 22 2020 6:08am
bluetooth bms with xiaoxiang app.
You can program all the parameters like LVC HVC etc on cell level and pack level, so you can use them with whatever lithium cells you want.

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Re: bluetooth BMS?

Post by john61ct » May 23 2020 12:39am

So why do they sell separate models by chemistry/

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Re: bluetooth BMS?

Post by serious_sam » May 23 2020 3:50am

john61ct wrote:
May 23 2020 12:39am
So why do they sell separate models by chemistry/
No idea. Maybe so they can target specific needs of their customes (specific chemistry), but just stock the one product. Then they can just load the appropriate settings into the BMS before shipping.

Similar situation with the current rating. You can program a 50A unit to allow 100A. It'd just get hotter quicker. They're all the same fundamental product. From what I've seen, the higher current rated ones just have more mosfets, and sometimes more shunts and more/longer copper strips added on top of the tracks. For example, I bought a 40A unit, replaced the mosfets with more/better parts, added more copper, tripled the shunts, and changed the limit to 200A. I run 150A though it all the time, no problems.

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Re: bluetooth BMS?

Post by agniusm » May 23 2020 4:48am

john61ct wrote:
May 22 2020 10:22am
LLT / JBD are related companies, good to start there I think.

Xiaoxiang type
Jiabaida Technology
Dongguan Jiabaida Electronic Technology Co., Ltd.

I believe SZLLT is also a relevant search string.

Less sure about RJXZS.

They seem to make separate units for "Li ion" as opposed to LFP, no idea about LTO.
Yes, have llt one with xiaoxiang app. Here is the one: https://www.lithiumbatterypcb.com/produ ... -function/

Original post is on these BMS'es so i dont specify exactly as i am posting on original subject.
My thinking was the same, if HVC and LVC is programmable there should be no difference but they listed it as li-ion and lifepo4 and i got thinking that there might be a different range for LVC and HVC hence i asked before getting into wiring the wrong bms

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Re: bluetooth BMS?

Post by thundercamel » May 24 2020 12:26pm

I know my JBD BMS with the Xiaoxiang app has limits of how high and low you can set the parameters, and those limits have changed a bit with the newer version of Xiaoxiang this year. The PC app either doesn't have any limits, or they're so loose I never had a problem setting what I wanted.
My Ebike builds - Existing bikes, affordable motor kits, self built 14s6p batteries - Now with more recumbent!

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Re: bluetooth BMS?

Post by quamau » May 24 2020 12:39pm

Agniusm,

I can confirm JBD-type boards do work for LiIon as well as for LiFe. Not only I am using two of them, one for 14s LiIon and the other with 17s LiFe. But when getting the 14s board by mistake I bought the LiFe version. It's only the default parameter values which are different: you just reprogram the correct cell/battery limits.

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Re: bluetooth BMS?

Post by agniusm » May 25 2020 1:51am

quamau wrote:
May 24 2020 12:39pm
Agniusm,

I can confirm JBD-type boards do work for LiIon as well as for LiFe. Not only I am using two of them, one for 14s LiIon and the other with 17s LiFe. But when getting the 14s board by mistake I bought the LiFe version. It's only the default parameter values which are different: you just reprogram the correct cell/battery limits.
Great, thank you. Wont be stuck then waiting for a new one.
Thanks everyone for help

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Re: bluetooth BMS?

Post by 999zip999 » May 25 2020 2:08am

Thank you as your talk makes E.S. yes the both of you. Thanks

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Re: bluetooth BMS?

Post by hussman » May 30 2020 7:20am

Does anyone have an ANT BMS 300A 20s for sale in Australia? Rather than buying it from overseas.

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Re: bluetooth BMS?

Post by agniusm » May 31 2020 3:51am

Got another question :)
I bought 16S bms but i ha e to go with 15S due to controller capping. Which contacts should i short to go lower to 15S? Its already down from 20S
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Re: bluetooth BMS?

Post by qfade » Jun 02 2020 4:31am

Hello.
I have a problem with my BMS. shows bad cell voltages. The wiring is ok. My BMS has been in operation for 26 days and it will break down after connecting the charger.
One photo shows how BMS worked.
Does anyone know how to fix it?
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Re: bluetooth BMS?

Post by Shazzy » Jun 05 2020 7:24pm

I have a 13s 60A JBD BMS.

Cells were fully charged and balanced before and after the the battery pack was made. I left it overnight and noticed that Cell 1 (next to battery pack negative) kept discharging down to 3.2. Pack is made of x11 cells per parallel group.

When I charge it cell 1 doesn't seem to pick up in line with the rest of the cells.

Checked my wiring three times. Pack negative goes to B- along with black balance cable. First white balance cable goes to the positive of cell 1 (the cell that keeps discharging). Then all subsequent balance cables go to + of next cell group.

Anyone know why Cell 1 keeps discharging?
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Re: bluetooth BMS?

Post by serious_sam » Jun 05 2020 7:40pm

1. Disconnect the BMS from the pack completely.
2. Fully charge the pack. Note: If one cell group is more than about 0.1V lower than the rest (like in your case), it will take forever for the BMS to balance the pack. You need to charge that group individually using a hobby charger or appropriate power supply.
3. Confirm all cell groups are charged to 4.2V using a multimeter (not the BMS app).
4. Wait 24 hours.
5. Check all cell group voltages (multimeter).
6. Conclude if the problem is in the BMS or the cell group.
A) If cell group, disassemble, and repeat process for all 11 cells individually to find which cell(s) are bad.
B) If BMS, discard.
7. Report back here with findings.

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