10S BMS balance wiring

hburtonr

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Aug 10, 2024
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Hi I thought i would try something and connected the battery to the bike and powered it on, with the single flashing power light i tested the battery with my multi meter to see if there was a voltage drop, as i used a battery bag to mount the battery and still had access to the cells, but there wasn't, so im thinking maybe controller ??
 

saneagle

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Oct 10, 2010
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This was their representative that i spoke to
It's possible that you got scammed. Without proper test equipment, it's not possible to be conclusive. If you live anywhere near Telford, you can bring them to my house, and I'll test them.

The next question is how many amps does your controller take from them. Look at the label on it and tell us the maximum current.
 

hburtonr

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Aug 10, 2024
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That's kind of you but i'm down in cornwall. I don't know if i have been scammed but the batteries have EVE on them, albeit covered with another label. I bought a couple of range extenders from them also, so i will see what they are like when they turn up, just thought it was weird that im still getting 42V even connected to the bike and switched on. The controller is 15amp but will pull it apart again to be sure
Thanks
 

saneagle

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Oct 10, 2010
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That's kind of you but i'm down in cornwall. I don't know if i have been scammed but the batteries have EVE on them, albeit covered with another label. I bought a couple of range extenders from them also, so i will see what they are like when they turn up, just thought it was weird that im still getting 42V even connected to the bike and switched on. The controller is 15amp but will pull it apart again to be sure
Thanks
When you have a 36v battery running with a 15A controller, it's not unusual to get a bit of voltage sag at maximum power, which you would see as the display going down one segment, then recovering when you stop taking power.

Regarding your post #8, I have several comments: Firstly, the battery should give around 42.0v when fully charged. If it's much less than that, you need to balance the cells. Unbalanced cells would give the symptoms you describe. Secondly, your meter might be giving the incorrect result. You can test it by measuring the charger output, which should also be 42.0v. Thirdly. if the cells are bad (say recycled ones), they'll sag a lot and give the sort of symptoms you describe.
 

Nealh

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Aug 7, 2014
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40.5v is low for 10s, cells might crap or the pack unbalanced .
What cell rating ?
How have you welded the cells ?
Are there some bad /poor welds?
Which Buss material is used ?


Below is a genuine Eve 25P 20A Cell.

60604
 
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saneagle

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Oct 10, 2010
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Yeah thats weird as mine are defo blue, what is the difference between INR 18650 and ICR 18650 ?? and mine are 2.55ah
I didn't notice that before. ICR batteries are for laptops. They need more sophisticated control systems than your average ebike type BMS because they tend to overheat and catch fire. Also, they're not really suitable for the higher current that ebikes require, which is probably the cause of your problem. It might be dangerous to continue using them for your ebike, so definitely don't charge them in your house or bring your bike in.

This is why I was asking you to tell us which cells you had!
 
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Nealh

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The different names are the chemical make of the cells cathode.
LCR = lithium cobalt oxide cells .
LNR = lithium nickel manganese cells.

Most modern cells tend to be LNR cells which have higher discharge /current ratings.
 

hburtonr

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Aug 10, 2024
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40.5v is low for 10s, cells might crap or the pack unbalanced .
What cell rating ?
How have you welded the cells ?
Are there some bad /poor welds?
Which Buss material is used ?


Below is a genuine Eve 25P 20A Cell.

View attachment 60604
Hiya,
it was 40.5v but after charging the battery was reading 42.2v, The cells are rated C. I used a spot welder to weld the cells, 6 spots on each cell, using pure nickel 0.15 x 8mm strips
This is what i used
 

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hburtonr

Pedelecer
Aug 10, 2024
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I didn't notice that before. ICR batteries are for laptops. They need more sophisticated control systems than your average ebike type BMS because they tend to overheat and catch fire. Also, they're not really suitable for the higher current that ebikes require, which is probably the cause of your problem. It might be dangerous to continue using them for your ebike, so definitely don't charge them in your house or bring your bike in.

This is why I was asking you to tell us which cells you had!
Ahh Thank you for clarifying that, when i purchased these cells i told her that it was for e-bike battery
 

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saneagle

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Oct 10, 2010
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Here's some data from Nkon, a trusted supplier. They list it as 7.65A max. My experience says that cells work fairly well up to 50% of their maximum discharge rate, so a 4P pack should be OK at 15 amps. In other words, if your cells are full quality ones, your pack should be OK for the application you have, other than the slightly higher fire risk.


You should try again with them fully charged, which should give a range of about 30 miles if you pedal with normal effort. Don't take too much notice of any LED lights on your display other than to expect cut-off when they show the battery to be empty.
 

hburtonr

Pedelecer
Aug 10, 2024
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Here's some data from Nkon, a trusted supplier. They list it as 7.65A max. My experience says that cells work fairly well up to 50% of their maximum discharge rate, so a 4P pack should be OK at 15 amps. In other words, if your cells are full quality ones, your pack should be OK for the application you have, other than the slightly higher fire risk.


You should try again with them fully charged, which should give a range of about 30 miles if you pedal with normal effort. Don't take too much notice of any LED lights on your display other than to expect cut-off when they show the battery to be empty.
Thanks for all the info, i would test the bike myself but i had a full replacement knee 3 weeks ago, so quite limited movement at the moment, but i will get my son to take it out later and see how long the battery lasts, as it is the display says 1 flashing light which means its very low
many thanks
 

saneagle

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Oct 10, 2010
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Thanks for all the info, i would test the bike myself but i had a full replacement knee 3 weeks ago, so quite limited movement at the moment, but i will get my son to take it out later and see how long the battery lasts, as it is the display says 1 flashing light which means its very low
many thanks
The display is basically a voltmeter. It should show all lights when the battery is fully charged. If you have only one light left and flashing at 40.5v, then you probably have the display set to 48v instead of 36v. What's written on the back of it?
 

hburtonr

Pedelecer
Aug 10, 2024
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The display is basically a voltmeter. It should show all lights when the battery is fully charged. If you have only one light left and flashing at 40.5v, then you probably have the display set to 48v instead of 36v. What's written on the back of it?
Thing is, it is flashing but 42.1V at the battery, when i originally connected the battery for the first time all 3 lights lit up, but then the next time i switched it on it went from 3 then 2 then 1 in quite a short time and now when i connect it, 3 lights flash then straight to 1
 

saneagle

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Oct 10, 2010
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Thing is, it is flashing but 42.1V at the battery, when i originally connected the battery for the first time all 3 lights lit up, but then the next time i switched it on it went from 3 then 2 then 1 in quite a short time and now when i connect it, 3 lights flash then straight to 1
If only you would answer questions!
 

hburtonr

Pedelecer
Aug 10, 2024
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If only you would answer questions!
my son has had the bike out today, he was riding up and down my estate for a good half hour or so approx 3-4 miles and the motor was still pulling like a train as it was when he first got on it, the flashing single light was still the same when he decided to stop and bring it in ??
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
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Telford
my son has had the bike out today, he was riding up and down my estate for a good half hour or so approx 3-4 miles and the motor was still pulling like a train as it was when he first got on it, the flashing single light was still the same when he decided to stop and bring it in ??
Here's something you could try: Disconnect the battery and switch on the display. It'll probably flash on then fade off while it drains the capacitor in the controller. Try to switch it on again just to make sure that all charge is gone, then reconnect the battery to see if the display will bounce back to normal operation. If a display is dual voltage and has automatic detection, they can sometimes choose 48v when you connect them to a fully charged 36v one at 42v because it's ambiguous what you have. the way round it is to make sure it's unambiguous when you first connect it, ideally around 36v or lower for a 36v one or higher than 44v for a 48v one.

If that doesn't work, you need to measure the battery's voltage while the display is flashing one light to see what's going on with the volatge. If the voltage is down, we need to find out why.
 

hburtonr

Pedelecer
Aug 10, 2024
29
0
Here's something you could try: Disconnect the battery and switch on the display. It'll probably flash on then fade off while it drains the capacitor in the controller. Try to switch it on again just to make sure that all charge is gone, then reconnect the battery to see if the display will bounce back to normal operation. If a display is dual voltage and has automatic detection, they can sometimes choose 48v when you connect them to a fully charged 36v one at 42v because it's ambiguous what you have. the way round it is to make sure it's unambiguous when you first connect it, ideally around 36v or lower for a 36v one or higher than 44v for a 48v one.

If that doesn't work, you need to measure the battery's voltage while the display is flashing one light to see what's going on with the volatge. If the voltage is down, we need to find out why.
Hiya Saneagle,
yeah i did that and noticed it flashed and faded away, but when connected again, it is still the same, after my son had been riding it last night, with the 1 flashing light, i measured the voltage and it was 41.2V, this is nominal i think, thanks for your help
 

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