Search found 1254 matches

by rg12
Apr 29 2020 4:15am
Forum: General Discussion
Topic: Can a Hot Wire Foam Cutter Cut Paper?
Replies: 1
Views: 221

Can a Hot Wire Foam Cutter Cut Paper?

I'm considering ordering this foam cutting table: https://www.ebay.com/itm/220V-50-300-Foam-Cutting-Machine-Hot-Wire-Styrofoam-Cutter-Work-Table-Tool/143575897599?hash=item216dca55ff%3Ag%3AUTsAAOSwSw5dsYb1&LH_BIN=1 I use alot of EVA foam but all my EVA has a glue side wire paper on it to peal and st...
by rg12
Apr 28 2020 9:18am
Forum: General Discussion
Topic: How To Measure Ring Terminals?
Replies: 4
Views: 230

How To Measure Ring Terminals?

https://www.ebay.com/itm/Non-Insulated-Stud-Hole-Copper-Cable-Lug-Connecting-Terminal-SC6-6-to-SC95-12/223521174943?hash=item340ae6759f%3Am%3AmmXSSnRVX0u8mE1dUtsoIyA&LH_BIN=1 Got this link for purchasing ring terminals for wires measured in AWG (got only metric terminals at the moment that are no g...
by rg12
Apr 28 2020 9:13am
Forum: Battery Technology
Topic: BMS Testing?
Replies: 7
Views: 293

Re: BMS Testing?

Don't think enough of a market to make it worth developing such a product. An accurate DMM & ammeter, variable power supply and a dummy load or DCDC charger that also does discharging and some old batteries will do the trick These devices do exist but super expensive and professional and was wander...
by rg12
Apr 28 2020 6:39am
Forum: Battery Technology
Topic: BMS Testing?
Replies: 7
Views: 293

BMS Testing?

Was wandering if there is an affordable BMS testing device, heard it's called a battery emulator or something.
I want to test the basic functions, HVC & LVC (per cell) and balance which is a tricky one and have no idea if machines test that.
by rg12
Apr 25 2020 11:11am
Forum: Battery Technology
Topic: Lipo to ANT BMS Weird Problem
Replies: 15
Views: 505

Re: Lipo to ANT BMS Weird Problem

serious_sam wrote:
Apr 25 2020 9:53am
Have you actually checked the voltage of each cell? Multimeter? Balance charger?
It keeps perfect balance when not under load at max diff of 0.003V
Under load the only way I checked balance is through the bms app.
Tomorrow will add the deleted wires and update here.
by rg12
Apr 25 2020 9:18am
Forum: Battery Technology
Topic: Lipo to ANT BMS Weird Problem
Replies: 15
Views: 505

Re: Lipo to ANT BMS Weird Problem

I think it is the voltage drop in your main wiring between the packs that is the problem. That is the likely situation. I hope it works to add the deleated balance wires, that Is how I planned to do it. That will divide the voltage drop seen at the BMS in half, not remove it completely. The voltage...
by rg12
Apr 25 2020 5:09am
Forum: Battery Technology
Topic: Lipo to ANT BMS Weird Problem
Replies: 15
Views: 505

Re: Lipo to ANT BMS Weird Problem

You have a voltage drop of 2,5V on the pack with both cells and wiring I guess? It seems like you have a voltage drop of almost 0,2v between each pack in the wiring. It doesn't make sense since the app reads that only the first cell in packs 2 and 3 is affected and not the whole pack. I will hopefu...
by rg12
Apr 24 2020 8:48am
Forum: Battery Technology
Topic: Lipo to ANT BMS Weird Problem
Replies: 15
Views: 505

Re: Lipo to ANT BMS Weird Problem

j bjork wrote:
Apr 24 2020 8:45am
I think it is the voltage drop in your main wiring between the packs that is the problem.
There is a normal voltage drop there, in total it's about 2.5V for 120A, the problem is that the negative wire of cell 8 and 15 is going through the main wires thus making the read not true.
by rg12
Apr 24 2020 7:39am
Forum: Battery Technology
Topic: Lipo to ANT BMS Weird Problem
Replies: 15
Views: 505

Lipo to ANT BMS Weird Problem

lipo.jpg What you see in the photo is 3 (brand new) lipo packs of 7S 20Ah connected in series. 22 balance wires need to go to the BMS (21S total). Each pack has 8 balance wires so I eliminated wire number 1 in pack #2 and in pack #3 as they already exist since the main harness that connects the pac...
by rg12
Apr 23 2020 4:37am
Forum: Battery Technology
Topic: Max Voltage Sag Per Cell?
Replies: 6
Views: 257

Re: Max Voltage Sag Per Cell?

my 17s4p of 25r gets 4-5v sag at 40amps/ or 10 amps max per cell. at 50 amps or 12.5/cell it was around 7 amp sag. when I paralleled another pack that was connected with a 10 amp fuse I still had 4-5v sag and the fuse didnt blow. how are you doing your math? my pack is 68 cells / 5 volt sag is 0.07...
by rg12
Apr 22 2020 10:47am
Forum: Battery Technology
Topic: Max Voltage Sag Per Cell?
Replies: 6
Views: 257

Max Voltage Sag Per Cell?

Is there a rule of thumb for that?
I know that I don't like more than a 5-6V sag on a 20S pack which means about 0.28V per cell.
About that it feels like abuse to me.
Can that rule be enforced on all lithium ion and lipo cells?
by rg12
Apr 22 2020 10:24am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

Thank for all the info :) About figuring out capacity in 15m, it can't be that accurate but if a ballpark is what you are looking for then that's a different story. About measuring mOh with a multimeter, of course it's not it's range, I use a specific device to measure IR that goes to these resoluti...
by rg12
Apr 18 2020 8:23am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

It does change the measurement. I'm not saying every time in all conditions. And it takes very accurate equipment as well as precisely replicated conditions to get comparable results. I'm getting the impression you aren't too concerned with accuracy and precision though, so in that case it doesn't ...
by rg12
Apr 17 2020 4:58am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

Isn't the capacity "changing" with different currents happen because the voltage sags to cutoff sooner? No, two completely different mechanisms that happen to overlap in their result. Yet again: A battery literally holds a different amount of energy depending on the discharge rate. Very frustrating...
by rg12
Apr 16 2020 12:36pm
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

No you won't. A battery literally holds a different amount of energy depending on the discharge rate. Kind of like testing MPG driving at different speeds, and sometimes with an extra 1000lbs sometimes not. Look up Peukert's Law. One more time. An accurate battery capacity test requires a precisely...
by rg12
Apr 11 2020 4:37am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

What if I start at let's say 4C and avoiding hitting the cutoff by lowering up to 0.2C so the discharge will end at 0.2C Will that produce the same amount of Ah? Let's assume that there is no heat produced... Sorry I wasn't more clear. If accuracy in your benchmarking is desired, pick one rate and ...
by rg12
Apr 10 2020 11:56am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

Bahaha. If you aint cycling @ 0.5C, or 1C, and/ or 2C, you just dumb, or happy with inaccurate results.. Some bring out the old 0.2C rate too.. but that's just wimpy. LOl of course you check the charge efficiency. I dont know what dataloggeer you use.. but I absolutely cycle for accuracy. How would...
by rg12
Apr 10 2020 11:44am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

Yes for lead standard is the 20-hour rate 0.05C, some vendors publish a dozen different rates. Talking discharge of course, CEF is a bit higher than with LI. If you want a standard for LI 0.2C or lower will align better than faster with vendor specs. Anything over 0.4C will reduce cycle lifetime fo...
by rg12
Apr 10 2020 8:57am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Re: Why Measure Capacity by Discharge and not by Charge?

Thanks for all the info guys (aside from two of you who insisted on contributing your information in the lowest form possible "LOL, DUHH, JESUS!!" what a bunch of dumb amateurs). Anyway, I get that Ah put in isn't perfectly aligned with Ah put out but what I meant to say is that this difference is v...
by rg12
Apr 10 2020 8:32am
Forum: Battery Technology
Topic: Parallel Internal Resistance Measuring?
Replies: 4
Views: 174

Re: Parallel Internal Resistance Measuring?

Thanks, will test and report :)
by rg12
Apr 08 2020 5:25am
Forum: Battery Technology
Topic: Why Measure Capacity by Discharge and not by Charge?
Replies: 33
Views: 1025

Why Measure Capacity by Discharge and not by Charge?

Measuring in discharge is affected by sag which changes with different currents so you reach the cutoff from different voltages and get a different result for the same battery. Why not discharge to about 2.8V at whatever discharge rate needed to get it there and then charge it at whatever current al...
by rg12
Apr 08 2020 5:17am
Forum: Battery Technology
Topic: Parallel Internal Resistance Measuring?
Replies: 4
Views: 174

Parallel Internal Resistance Measuring?

If I have 10 brand new cells in parallel that each has 12mOh IR, will measuring the whole group paralleled show 1.2mOh or the calculation isn't so linear and simple?
by rg12
Mar 04 2020 7:36am
Forum: General Discussion
Topic: Trying To Track ANT BMS Factory
Replies: 1
Views: 878

Re: Trying To Track ANT BMS Factory

Anyone?
by rg12
Feb 26 2020 3:33pm
Forum: General Discussion
Topic: Trying To Track ANT BMS Factory
Replies: 1
Views: 878

Trying To Track ANT BMS Factory

Any ideas how to get to them?
I use their bms regularly and the resellers I buy from order one by one by request straight from their factory meaning that they do sell low quantities so why should I buy through a reseller.
Any ideas?
by rg12
Feb 25 2020 6:42am
Forum: General Discussion
Topic: Total Installed 16" (motorcycle) Tire Diameter?
Replies: 17
Views: 1433

Re: Total Installed 16" (motorcycle) Tire Diameter?

It's for a low torque setup and with short spokes radial is going to be fine, I just wanted to see how far are the spoke holes of the motor from the inner rim on a 14" moto rim but I see that there is no problem.
Thanks :)