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

[docw009]

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.

 

[jcool3]

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]

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.

 

[skeetab5780]

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

 

[wturber]

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. :^)

 

[skeetab5780]

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

 

[docw009]

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.

 

[parabellum]

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.

 

[GIGATT]

Greetings what is the maximum amperage you guys would charge these packs at?

Does 7 amps at 39 volts sound like too much or should I just charge and keep an eye out for heat?

Thanks

 

[docw009]

Max charge rate will depend on which cells are in your packs. You probably have to peel back any shrink wrap and look. I think mine are Samsung 22P. which has a max charge rate of 2.1A per cell or 4.2A per pack. Your charger would be too big for my packs.

By the way, I am still using mine after 20 months. I think they are at least 80% of original.

 

[wturber]

For the LGs that had the MF1 cells the standard charge rate is 1.075 amps per cell. The maximum is double that at 2.150 amp per cell. The pack are 2P, so you can double that rate for one cell. So you should probably not exceed 2 amp per pack for the sake of long cell life, but it isn't dangerous to double that.

Charge voltage is 4.2V

The cells output is rated at a standard discharge of 430 mA while the maximum discharge rate is 2 amps. Again, since the cells are in 2P configuration, your real world use can be double those values per pack.

I run 8 of these packs in parallel. That means that when I pull more than 6.88 amps, I can expect less than the full rated capacity from the cells. I typically pull about double the standard discharge rate which is still well under the maximum discharge rate.

I charge 8 packs at just under 8amps and 42 volts. That means I'm charging at about about half the standard charge rate.

These packs have been holding up well over more than 18 months and getting close to 8000 miles. I just bought five more so I can add an auxiliary pack for some longer trips.

 

[GIGATT]

Greetings what is the maximum amperage you guys would charge these packs at?

Does 7 amps at 39 volts sound like too much or should I just charge and keep an eye out for heat?

Thanks

Thanks, I should have clarified that I have 10 of these packs = 200 cells/ in parallel charging at 7 amps and 39 volts they are Samsung cells.

Sometimes I run at 36v and sometimes at 72v

 

[wturber]

Thanks, I should have clarified that I have 10 of these packs = 200 cells/ in parallel charging at 7 amps and 39 volts they are Samsung cells.

Sometimes I run at 36v and sometimes at 72v

I'm not sure why you are charging at 39 volts, but you certainly aren't charging at too high of an amperage level.

 

[GIGATT]

I made a rather bootleg charger out of two laptop chargers
They are 19ish volts each.

What is the highest amperage that you would charge 10 of these packs?

 

[wturber]

I made a rather bootleg charger out of two laptop chargers
They are 19ish volts each.

What is the highest amperage that you would charge 10 of these packs?

Per the cell specification, about 20 amps ( 2 amps per pack, 1 amp per cell) would be the max I'd charge that pack - since long service life is important to me. But you could double that if you were willing to shorten the service life of the cells a bit. For instance, maybe mostly you charge at the lower rate, but on a long distance tour you charge at a higher rate at stops for convenience.

As it is, I charge at around 1 amp per pack which is about half the standard rate simply because high rate chargers tend to be expensive and heavy. The Meanwell HLG-320H-42A that I use weighs in at 4.2 lbs - which is actually heavier than I'd like for a charger that is always attached to the bike. But it is robust and fast enough for my needs. It is also adjustable to different charge rates and different maximum voltages and because the electronics are potted is well suited to staying attached to the bike. BTW, it isn't a charger per se, but is an LED power supply. It usually costs about $80. Well worth it for me.

BTW, charging to 39 volts probably isn't hurting anything by itself. My concern would be that because you aren't getting very close to a full charge you may run them closer to empty more often. But maybe not if you are running 10 in parallel. If you max charge to 41 volts and don't run them low, they could last a very long time. I charge to 42 volts, but never leave them at that level for more than a few minutes. My understanding is that the 42 volts alone isn't the problem. What matters most is how long the batteries sit at that voltage. I partially charge at night and then top off the batteries before I head out to work. But given my reduced capacity needs of late, I may change my charge voltage to 41 volts just in case that helps longevity a bit more. I'll probably do that this weekend.

 

[Quinc]

Everyone still happy with these? I am running 4 in parallel in my razor mx650 and charging them in parallel through the controller with the stock razor charger. So far so good. I am thinking about running 8 of them at 72v 17.6ah on a 48v 1800w motor next.

 

[docw009]

One of my remaining five 10S-2P hoverboard packs failed this month. At first I thought it was because I had let the BMS run the cells down from not using it since last summer. Two groups had zero volt cells, whike the eight were at 4.1V.

I changed out those two cell groups using Samsung cells from a pack I had taken apart. All seemed well, and it charged. The next day, I could feel heat coming from the BMS. I re-opened it and found the two cell groups I had replaced were down to 3.8V. My theory is that the BMS had two stuck or leaking balance circuits. By the way, this was not the original BMS. I had replaced with a BMS with balance circuits..

So I replaced my replacement BMS with another one like it. Man those two BMS cost me more than the pack and one failed.

 

[jcool3]

Anyone thinking of building a diy kit battery might compare the cost of joining several of these in parallel.
They are way cheaper.