BMSBattery Charger Not Charging / Arcing to Metal Table

Batteries, Chargers, and Battery Management Systems.
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BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Oct 30, 2017 11:28 am

Hello All,

I have a BMSBattery bottle battery that is a couple years old. The charger doesn't seem to work anymore and I'm actually scared to even try to use it as the last time I did it arced to the table that it was on.

I'd like to get a new charger but don't want to spend a ton of money. A local eBike shop said they had one that would work but they wanted $80 for what appeared to be a laptop charger. This is basically what he had https://goo.gl/pE3A6t as far as I can tell...

This is the charger that came with my battery...

Image

Would the charger from Amazon work?

- Doug

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by docw009 » Oct 30, 2017 5:35 pm

That link shows a power supply and it's the wrong voltage. Look for a 36V lithium battery charger which will have a max voltage of 42.0 volts. Lots of them on ebay and amazon, starting at $12, but some of suspect quality.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by fechter » Oct 30, 2017 7:37 pm

The arcing is very unusual. May be the reason it doesn't work anymore. Normally the case is grounded to the AC plug and on some models, one of the output wires may also be connected to the case. Something else must be touching the table to make it arc.

If it's not working, why not take it apart and inspect the insides. Not much to lose. You might find an obvious problem.
"One test is worth a thousand opinions"

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Oct 30, 2017 9:56 pm

I just have no idea what I'm looking at once it's apart. I can take it apart and post some photos...

It wouldn't charge before the thing arced, that just happened the last time I plugged it in. It was odd, and unnerving.

It looks like this one would work... https://goo.gl/jJ2xMP

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by amberwolf » Oct 30, 2017 10:05 pm

It might have a wire that's come undone from the board inside, that normally goes up to the AC input plug, and it's touching teh case now. That would be easy to fix.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by fechter » Oct 31, 2017 2:56 pm

iamodugsebike wrote:I just have no idea what I'm looking at once it's apart. I can take it apart and post some photos...

It wouldn't charge before the thing arced, that just happened the last time I plugged it in. It was odd, and unnerving.

It looks like this one would work... https://goo.gl/jJ2xMP
Like I said, not much to lose. Often times there is something obvious.

The charger in the link looks like it would work fine, but slightly slower.
"One test is worth a thousand opinions"

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 02, 2017 11:38 am

.
It worked!! :) :)

I ordered that charger from Amazon and charged my battery last night. Took about 4 hours to charge from 1/4 power. Not sure how much range the battery has left in it and no real way to test it other than going for a ride so I guess I'll do that this weekend.

I'm still going to open the old charger up when I have a chance, I'll post pictures here if I don't see anything obvious. I did notice the fan stopped working at the same time it stopped charging.

Would be nice to have two chargers... could charge the battery at work if I did.

Thanks for the help getting the correct charger!

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 06, 2017 3:36 pm

.
I'm not 100% sure if anyone will see this or not, not sure how the notifications work.

I was wondering since Fechter said...
fechter wrote: The charger in the link looks like it would work fine, but slightly slower.
Would a 42V 4A charger like this one https://goo.gl/WZSfJB charge my battery twice as fast as the 2A charger I just bought??

Also why do you need a 42V charger for a 36V battery?

Thanks!
-Doug

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by docw009 » Nov 06, 2017 6:04 pm

If the specifications are honest, yes, a 4A rated charger could charge a battery 2X faster than a 2A rated charger. There is some point where an overly fast charge rate can damage the cells. I believe it's 1/2 the max discharge rate of the cells.

Your BMS bottle battery is certain capable of more than 8A discharge, probably more like 20A. So 4A ought to be quite safe.

Your BMS battery has 10 series groups of 18650 cells. A cell has a voltage of 4.2 volts at full charge. So 10 x 4.2 is 42 volts and that's why we have 42 volt chargers. The 36V refers to the nominal voltage on these cells when it's about 40-50% charged, the nominal level.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 18, 2017 10:59 am

.
Took the bike for a test ride over the weekend on what would be my normal commute...

Got 3 miles into a 10 mile ride and the battery cut out, totally. Never seen it like that before, usually I can turn it back on and run for a minute or at least get a battery reading from the built in light. This time nothing...

I'm going to try to take the battery apart tomorrow to see if there is any obvious broken connections inside it.

The battery is about three years old with probably 20-30 cycles on it and always stored with a partial charge. I wouldn't expect to get the full 12 Ah from it but is it unreasonable to think I'd still be able to get half that?

Does anyone know where I could get a reasonably safe 10Ah bottle battery for $250 or less? I see some on eBay, mostly DuraB, just don't know the quality.

- Doug

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by Chalo » Nov 18, 2017 1:31 pm

You might have a cell imbalance issue. Leave the thing on the charger for a few days continuously and see if the capacity improves significantly.

If not, you probably have a bunk cell or cell group in your battery.
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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by fechter » Nov 18, 2017 3:49 pm

I agree it sounds like a balance problem. If you take it apart, try to measure each cell group and look for one that's lower than the rest. Manually charging low groups with a single cell charger is the fastest way to restore the balance.
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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 18, 2017 10:10 pm

.
Isn't there a danger of the thing exploding if left on charge too long?

What equipment is needed for testing/charging individual cell groups?

-Doug

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by fechter » Nov 19, 2017 1:10 am

There are some other threads on the forum where people ran into the same thing. The pack has to be disassembled enough to reach the BMS board, then you can measure individual cell voltages along the connector. Best thing is to measure all of them and record the numbers.

If you decide you need to charge a low group, yes you need a proper charger or things can blow up. For single cell charging, I use a bench power supply dialed in to 4.2v. There are inexpensive single cell chargers made for loose 18650 cells that would work fine too. As long as the charge voltage is in the safe range, it can stay on for days without danger of setting anything on fire.
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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by Buk___ » Nov 19, 2017 1:33 am

iamodugsebike wrote:
Nov 18, 2017 10:10 pm
.
Isn't there a danger of the thing exploding if left on charge too long?

What equipment is needed for testing/charging individual cell groups?

-Doug
Take a look at my dead battery thread where the guys here talked me through reviving a new battery that wouldn't charge because the voltages had fallen below the BMS LVC cut-off.

In a nutshell, the process involved opening the pack to gain access to the BMS board connector and unplugging it. The finding an old (phone charger) wall-wart that provided an appropriate voltage at low amperage and connecting it to each parallel group of cells in turn and carefully monitoring the voltages to bring each group up to ~4V. (This takes care and patience and quite a while.)

Once done, you reconnect the BMS and connect the pack to your standard charger and it should be able to charge the pack in the normal way. (This assumes none of the cells in the pack are actually damaged.)

Read the thread for the full skinny from the experts.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by markz » Nov 19, 2017 2:41 pm

Ah yessssssss.......... cell imbalance, that is what I am working on right now. I find it funny that my "hacked" together pack is great, yet my perfectly looking pack that I thought would be the good one is all out of whack, plus one parallel group is 0V. Luckily its the end one. I was getting way less range then usual, and I am unsure as to why that group died. Luckily it didnt mess anything else up. Should be an easy fix, got nothing to do today, besides I like to e-cruise around.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 19, 2017 10:20 pm

.
So I took the battery out of the case... It looks like there are three groups of cells.

Image

One of the groups seems to have two less actual cells in it than the others, is that normal??

Image

I think I see the BMS harness which I marked with a red arrow below... I believe to test the voltage I need to stick one of each pins of the multimeter into set 1, 2 , and 3??

Image

I have no experience so don't even know how to setup the multimeter correctly to do the tests, I'll have to read more posts to get a better handle on it. I got a cheap multimeter from Harbor Freight today.

Image

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by amberwolf » Nov 19, 2017 11:47 pm

Regarding the groupings and "2 less cells" I'd venture that the layers do not equal the groups. If you open it up and look where the welds are between them, you'll probably find all parallel groups are equal numbers of cells to each other.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by Buk___ » Nov 20, 2017 10:34 am

iamodugsebike wrote:
Nov 19, 2017 10:20 pm
.
So I took the battery out of the case... It looks like there are three groups of cells.

How many batteries in total do you count?

You have 10 connections in total in your balance connectors, which would usually mean that you have 9 serial groups (my 10S BMS has 11 connections); but as yours are split between 2 connectors, two of them (1 per connector) are probably a common connection, which would leave you with an 8S pack.

If your total number of batteries equally divides by 8, that would be a fairly strong indication of the S count.

Do you remember/have record of the battery rating? Can you get a clear shot of the information written on the sides of the battery?

eg. Mine was described as 36V10.4Ah and contains 40 18650 cells; and the writing on the batteries is: "Samsung ICR18650-26H". The 26H stands for 2600mAh, so 10.4Ah / 2.6Ah = 4, so 4 bateries per parallel group and 10 parallel groups i series gives 10*3.6V = 36V nominal.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 20, 2017 6:08 pm

.
I reassembled the pack and am in the process of doing as Chalo suggested leaving it on the charger for an extended period of time. The charging block went green within twenty minutes of being put on the charger which would supposedly indicate a full charge. I'm hoping to leave it on the charger for about six hours today and then as many hours as I can tomorrow. I'm not comfortable leaving it on the charger when I'm sleeping.

I'm charging it outside my house and it's currently 45 degrees in Philly, will that have any ill effects on it?

I went that route because the whole pack is soldered up pretty tightly, it seems to me if I start to take it apart more than I already had I'm going to find myself in a situation where I'm rebuilding the pack which I'm not confident I can actually do. I figured I'd try the easier way first and it that doesn't work then I'll have nothing to lose.

Was thinking it would be neat to build a pack with fresh cells... I found these on eBay and if they are real Samsung cells they seem like a good deal... https://www.ebay.com/itm/172648851568?ul_noapp=true

If I bought two of those would combining them into one pack result in a 36V 8.8Ah pack? Would it be possible just to wire them in parallel (or series?) to get that that or would I need to completely rebuild it?

- Doug
Last edited by iamodugsebike on Nov 20, 2017 6:15 pm, edited 1 time in total.

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 20, 2017 6:14 pm

.
I also don't have that much info on the battery. BMSBattery just listed it as a 36V Battery with integrated SP06 controller.

If I end up really taking the battery apart I'll post better photos of the cells and any details I can find about them.

Thanks everyone for the help!
- Doug

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by docw009 » Nov 20, 2017 6:17 pm

Even though we only see 10 balance wires in his photo, this is for sure a 36V battery with 10 groups.

The 10 balance wires for 9 of those groups are in those two white plugs. The 11th balance wire is either the negative end or the positive end of the battery. It''s easy to figure out the wire sequence by measuring a few pins, but it's also easy to short circuit those wires while doing the measurement. Then you might melt a probe, damage the BMS or even spatter hot metal into your face, so I'll leave that alone wile the OP does some more recharging.
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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by 999zip999 » Nov 20, 2017 9:04 pm

Yes those cells can be used as 8.08 ah but better off with 12 or 13 ah is best 3 groups. Than you could get the lego style snap together blocks with a bms.. But get reading first.where do you live ?

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 22, 2017 5:07 pm

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I live just outside of Philadelphia Pennsylvania

Was curious about those VRUZEND bricks. Have you ever used them before?

I just went on a test ride after leaving the battery on charge for about 48 hours. It was dark so I only got in 8 miles however the entire time I was on maximum pedal assist and not really putting much effort in myself. When I was done the LCD said I still had half a charge! :o :D

So why did that work? Does the BMS send power to the cells that need it and not to the ones that are already fully charged? Is there a certain way of charging to avoid that happening again? How many more test rides should I do before I depend on the battery for a commute?

I still want to learn more about batteries because I hate they are such a black box. This battery was never able to go further than 15 miles with considerable assist from me. I'd like to build a larger battery to get more range but don't have a ton of cash to pour into it. Probably the wrong hobby to pursue... :roll:

- Doug

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Re: BMSBattery Charger Not Charging / Arcing to Metal Table

Post by iamodugsebike » Nov 25, 2017 7:34 pm

.
Another test ride got 10.8 miles on level 5 assist then 3 on level 3 assist... Seems pretty decent for a couple year old battery?

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