Are Scooter LG 36V 4.4AH battery packs good for Ebike?

General Discussion about electric bicycles.
docw009   10 kW

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by docw009 » Jul 12 2018 9:31am

robocam wrote:
Jul 11 2018 4:23pm
When I measure the voltage at the XT-60 connector, it reads zero volts but when I measure on the circuit board, it reads 34.9V. Does this mean that the BMS has cut off the power? I'm going to try charging one of them with my ebike 36V charger to see what happens.
I bought six working packs from alarmhookup. I wish they were still available. I found them dependable. THey're stored in an old grill outside for the summer.

But to your problem, the BMS is powered off one or more cell groups and has likely run then down below the 2.5V cutoff. Unplug the white connector with the 10 balance wires and carefully measure the cell groups. If you see one or two under 2.5V, that's why the battery is shut off. They shouldn't charge if this is true.

Can they be recovered? It will depend on how low they went and your appetite for risk, Read up on what happens when you run lithium too low, Scary stuff. If they are not too low, and you want to recover them, you would have to charge the low groups separately and you have to bring them to the same level as the others. These boards have no balance circuits so this is the only time you can get them equal. You must monitor the voltage for bakance. Another option, if the cells were deemed unsafe, is to break up a battery and replace the dead cells with charged ones. Either way, be safe.

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by jcool3 » Jul 12 2018 11:38am

docw009 wrote:
Jul 12 2018 9:31am
robocam wrote:
Jul 11 2018 4:23pm
When I measure the voltage at the XT-60 connector, it reads zero volts but when I measure on the circuit board, it reads 34.9V. Does this mean that the BMS has cut off the power? I'm going to try charging one of them with my ebike 36V charger to see what happens.
I bought six working packs from alarmhookup. I wish they were still available. I found them dependable. THey're stored in an old grill outside for the summer.

But to your problem, the BMS is powered off one or more cell groups and has likely run then down below the 2.5V cutoff. Unplug the white connector with the 10 balance wires and carefully measure the cell groups. If you see one or two under 2.5V, that's why the battery is shut off. They shouldn't charge if this is true.

Can they be recovered? It will depend on how low they went and your appetite for risk, Read up on what happens when you run lithium too low, Scary stuff. If they are not too low, and you want to recover them, you would have to charge the low groups separately and you have to bring them to the same level as the others. These boards have no balance circuits so this is the only time you can get them equal. You must monitor the voltage for bakance. Another option, if the cells were deemed unsafe, is to break up a battery and replace the dead cells with charged ones. Either way, be safe.
I have the same problem. Working great until one day Zero voltage on one pack. This pack was never in storage, I was using it and charging it everyday. Does the bms need to be replaced? How can you tell if the bms is working correctly?

docw009   10 kW

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by docw009 » Jul 13 2018 1:14am

The BMS shuts down the pack if any of the cell groups are undervoltage (usually 2.5V). The cells on these packs are arranged lengthwise, so it's hard to check voltages on the series cell groups. If you look for the 10 pin plastic connector on the BMS, those pins allow you to measure each cell group. Write down the 10 voltage and that will tell you the status of the pack.

Here's a pic I took of one of the packs last year. The pads marked B1 thru B10 are opposite the 10 pin balance wire connector, and easy to access. I had to find the negative end of the battery, but on a fully charged battery, B1 is 4.2V, and B10 is 42 volts. Some of these packs will have a different style BMS, but this is the idea. On other packs, you may have to disconnect the balance wire connector and probe in there instead. Be careful. It's too easy to short a pair of pins and if you do that, you are shorting a parallel group.
A_pads.jpg
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skeetab5780   10 MW

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by skeetab5780 » Jul 13 2018 12:30pm

They don't all look like that I have two other brands that look completely different. Boards not even the same

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by wturber » Jul 13 2018 1:10pm

skeetab5780 wrote:
Jul 13 2018 12:30pm
They don't all look like that I have two other brands that look completely different. Boards not even the same
And all the connectors aren't the same. I have two different sizes. That said, probing the detached connector with thin copper wire worked fine for me when I checked the pack I had problems with. I figure that even if I shorted the thin wire probes I used, the thin wires would limit the amount of current that could flow. But I was careful and that idea was never tested or confirmed. :^)
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
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skeetab5780   10 MW

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by skeetab5780 » Jul 13 2018 1:55pm

all the packs I have, have the BMS on the very top(on the four top cells)

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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by docw009 » Jul 13 2018 7:01pm

Well, I did say they were different. The first was off an LG pack Here's another style BMS off a Panasonic pack from same seller.

If you remove the wrapping you can access these pads. Or you can scrape the glue off the 10 pin connector and pull it off. Find the negative end of the battery. Put one voltmeter probe there. The loose connector has all the balance wires. Stick a pin in each connector position, put the other probe there and write down the values from one end ti the other.

The 10th pin will read 34.9V because that's what the OP said. Taking a guess and wondering if the first pin will be 2.5V or less. These packs ship with all the cells at 3.6V. So if one went down from powering the BMS, it would likely be the first one. Anyway, the numbers add up. Nine times 3.6 is 32.4V. Add 2.5 and we have 34.9.
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Re: Are Scooter LG 36V 4.4AH battery packs good for Ebike?

Post by parabellum » Jul 14 2018 1:02am

skeetab5780 wrote:
Jul 13 2018 1:55pm
all the packs I have, have the BMS on the very top(on the four top cells)
I got packs with 3 different BMS boards, mine where samsung 22p with 2 different boards on the side and a board in between. Some packs where crushed, but got refund for. I did not found any info on those LG initially so i went Samsung route.

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