Battery capacity drop
- Thread starter Khumarahn
- Start date
D
Deleted member 4366
Guest
Most ebike batteries these days have 18650 cells regardless of size, shape or position of the battery. Prismatic cells are more or less obsolete. Pouch cells are still used in some, but they're often glued together, which makes servicing difficult. The only easy to service batteries are ones with Headway cells, but they're relatively large and heavy for their capacity.
Bottle batteries are the hardest to repair because they're welded after assembly to the cell-holders, so you can't get the cells out. In the pod type batteries that I indicated above, the cells are welded in a block, so it's not quite so difficult. If you get a battery with branded cells, it'll probably last for years.
Bottle batteries are the hardest to repair because they're welded after assembly to the cell-holders, so you can't get the cells out. In the pod type batteries that I indicated above, the cells are welded in a block, so it's not quite so difficult. If you get a battery with branded cells, it'll probably last for years.
Many thanks to everybody for help! I wouldn't be able to do anything without your advice. I decided to try to fix the battery, and maybe buy a new one if I fail, or other cells go bad, or I need a new bms. I bought four of these: http://www.ebay.co.uk/itm/360939737464 . It will take some time for the delivery, and then I plan to spend two weeks in Russia, but when I get everything and start working on it, I will let you know how it goes.
I have disassembled the battery. I noticed that it smelled sort of burned, but I was not sure. I found some defects around 10-th cell (but not only), see my photos below:
This is frustrating...
This may have happened this way: some time ago on my way to work the battery fell off on the road. The little plastic plate that holds the lock on the attachment of the battery cracked:
and probably some vibrations helped the battery out. It was a dangerous moment, because I was on a speed of around 24mph and in traffic, and a car behind me had to do an emergency break. But the battery didn't fall high, and it rolled to a stop.
Maybe this battery design is not reliable enough for the vibrations of the road bike?
Anyway, I will try to solder cells and assemble the battery back, we'll see what it gives.
This is frustrating...
This may have happened this way: some time ago on my way to work the battery fell off on the road. The little plastic plate that holds the lock on the attachment of the battery cracked:
and probably some vibrations helped the battery out. It was a dangerous moment, because I was on a speed of around 24mph and in traffic, and a car behind me had to do an emergency break. But the battery didn't fall high, and it rolled to a stop.
Maybe this battery design is not reliable enough for the vibrations of the road bike?
Anyway, I will try to solder cells and assemble the battery back, we'll see what it gives.
D
Deleted member 4366
Guest
I had a bottle battery before and it didn't seem very secure to me. It rattled even when the lock was properly adjusted. I kept it tight and safer with a strip of velcro around it and the down tube.
D
Deleted member 4366
Guest
A piece of 1.35 copper wire, taken from the household mains cable, something like 80p per meter in Wilko.
I have been fighting rattling with soft pads between the battery and the frame, and battery and battery holder. After battery fell out, I use velcro strip too.
I complained to bmsbattery about battery falling out and later about capacity drop. They normally just do not reply to my messages, but after several attempts they got back to me. For $15 (shipping cost) they sent me a replacement for the broken plastic part. For the battery - they offered a 10% discount if I buy a new one. This is less than I would expect, but better than nothing
Thank you again for the support! I had zero knowledge about how these batteries are made, and how bms works, until I started this thread.
Thanks for the info, it's given me an idea to join a couple 18650 cells to fix a 4-cell light battery pack where 2 are ok and 2 are dud.
So I strip out a small length of the bendy copper single strand from that heavy main cable, then tin a length first, then tin the cell ends, cut a piece of the already tinned copper strand to size then melt all together?
Does that sound about right?
Any other tips. Thanks.
D
Deleted member 4366
Guest
Couldn't get the solder to stick to that piece of single copper wire even using flux also tried a flame torch, so plan-B will be to use normal type wire and try to solder along that.
Is really showed me how difficult it really is to make such a good job like Khumarahn made.
Is really showed me how difficult it really is to make such a good job like Khumarahn made.
I've made up loads of 18650 packs. For what it's worth, here's my method:
1. Tin the wire first.
2. Now apply a liitle flux to the battery, and get it clamped.
3. Get a blob of solder to flow onto the battery. Make sure it flows.
4. Place the tinned wire on top of the battery terminal, apply iron, and again ensure solder flows.
Never failed me yet.
1. Tin the wire first.
2. Now apply a liitle flux to the battery, and get it clamped.
3. Get a blob of solder to flow onto the battery. Make sure it flows.
4. Place the tinned wire on top of the battery terminal, apply iron, and again ensure solder flows.
Never failed me yet.
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