>one or 2 bad cells ruining the pack
very likely, the shutdown initiates on voltage threshold detecting battery as discharged, while it's just cell/s dead with subnormal voltage
take apart, measure each cell, replace
just don't puncture any cell
>is there any risk of electrocution?
no, only burns if you frick up
you dont need spot welder, if you have good solder station, crank up the temp, and you can solder the battery before overheating it
if you are fast you wont damage the cell
just make sure twice before connecting anything, making a short with that power can deliver hurting
If you don't have a specific question, do not frick around with lithium sausages. again.
DO NOT FRICK AROUND WITH LITHIUM SAUSAGES.
It is toast. If BMS thinks that it should turn off the scooter, there is a reason why. And cell replacement never works because cells have different parameters from the factory, and now you're trying to use used cells with new ones which have all sorts of different ESR and capacity which will just fail soon enough shortly after.
https://i.imgur.com/UoD2dI3.png
I don't have any equipment beside a multimeter and a soldering iron. And the pack seems to be glued.
I'll buy a spot welder and a li ion charger/tester. Hopefully it's just a few cells and not the entire pack.
Also, is there any risk of electrocution?
Also it seems to use chinky cells so good luck finding replacement cells.
Best you can do is replacing BMS with one that has balancing.
could be down to insulator buildup within the electrolyte, which stems the flow of lithium ions between the electrodes. try whacking a nail into a few of the cells and if that's the problem it should drain out and start working as normal. if not report back here
I'd find something with vaguely similar ratings that has the same form factor and buy that, chinks sell similar batteries for around $100-$150. Swap over the BMS or get a new one if the battery doesn't have it. You can probably sell these batteries to a recycler for $50.
Unless you get lucky and find the culprit getting hot or something...you will have to take it completely apart and rebuild it.
You can try to match the battery and a self balancing BMS should still get the pack running.
But idk also that price is definitely too much.
I've seen 48v 15ah for 200$
Measure individual cell voltages. If any cell is <2.4V it's dead. You could try replacing the dead cell, but you'll need to know what type of 18650 cell it is. Prob LFP, but could be NMC. They have different nominal voltages - and you can't mix them. Maybe check if you can see a part number printed on one of the cells. But yeah, if it's NMC and you frick up and short or puncture a cell you'll cause thermal runaway and an unstoppable fire.
>how much of a Li-ion battery's original capacity can you expect to recover by reconditioning it?
idk probably will hold for another year or so, i'm gonna buy the tools to build battery packs because i want to convert my bicycle too and it's probably cheaper this way
Why not buy some holders for the 18650s and make your own pack?
Then, if one of them goes wrong, you can just replace that cell easily.
I have several old packs and I keep them in hopes that one day I’ll get to take on this project for myself.
I think it’s crazy how these are made to the point where it’s a scam.
Chinese 18650s and 'pouch' cells are notorious for extremely poor life. Individual cells don't fail often, it's almost always that the cells are just worn out.
For instance, if original capacity was 20 amp-hours, it will lose capacity quickly until it's less than half. So, voltage will sag under load and runtime will be greatly reduced. In my experience, chinese lithium cells often are trash within 1-2 years while Jap/Korean 18650s will last 5-10x longer while imperceptibly losing capacity. Chinese cells, by contrast, work well for a year or so then very quickly lose most of their capacity.
You can look how they're wired in series and measure the voltage across each cell without disassembling the pack to check for failed cells, but with that many cells it wouldn't be that significant. Also, there's miliohm testers to better check how worn a cell is internally and can be bought cheap on amazon.
It's way better to buy lightly used 'name brand' batteries (Samsung, Sanyo, Sony, Panasonic, etc) than generic chinese cells as EVERY chinese battery is at best like 80% as good in initial capacity but last 20% as long.
If you're disassembling, first discharge the pack to the minimum (2.5v per cell), be careful not to short anything (watch metal touching metal where it wasn't) and you can easily pop off the tabs on the end of the cells with a small flathead screwdriver or similar prying device. Li-on batteries are almost impossible to make dangerous if they're at low charge and not dead shorted. You can even use a regular $30 pistol soldering iron instead of a spot welder if you heat the ends just breifly with not much solder needed at all.
Lipo 'pouch' cells are the ones that are more dangerous but the cylindrical ones are near impossible to set on fire, especially if they're not fully charged.
The voltage sags from 54V to 44V and then the scooter shuts off. I wonder if it's just one or 2 bad cells ruining the pack.
>one or 2 bad cells ruining the pack
very likely, the shutdown initiates on voltage threshold detecting battery as discharged, while it's just cell/s dead with subnormal voltage
take apart, measure each cell, replace
just don't puncture any cell
I don't have any equipment beside a multimeter and a soldering iron. And the pack seems to be glued.
I'll buy a spot welder and a li ion charger/tester. Hopefully it's just a few cells and not the entire pack.
Also, is there any risk of electrocution?
>is there any risk of electrocution?
no, only burns if you frick up
you dont need spot welder, if you have good solder station, crank up the temp, and you can solder the battery before overheating it
if you are fast you wont damage the cell
just make sure twice before connecting anything, making a short with that power can deliver hurting
If you don't have a specific question, do not frick around with lithium sausages. again.
DO NOT FRICK AROUND WITH LITHIUM SAUSAGES.
It is toast. If BMS thinks that it should turn off the scooter, there is a reason why. And cell replacement never works because cells have different parameters from the factory, and now you're trying to use used cells with new ones which have all sorts of different ESR and capacity which will just fail soon enough shortly after.
Also it seems to use chinky cells so good luck finding replacement cells.
Best you can do is replacing BMS with one that has balancing.
he's here guys
could be down to insulator buildup within the electrolyte, which stems the flow of lithium ions between the electrodes. try whacking a nail into a few of the cells and if that's the problem it should drain out and start working as normal. if not report back here
is this the actual battery that came with the scooter or a hackjob?
Why do they build them like this? It's so hard to diagnose and repair.
They're not meant to be serviceable. It's easier to salvage the cells and buy a new battery than to repair it.
a new battery is 500$, i'd rather just buy the tools to fix this one for this price
How many amp-hours is the battery, that it's so expensive? A 100ah cell pack with a BMS etc is under $1250 these days.
Those don't look like more than 10-15 ah per set of 3.7v cells.
Ah duh there it is. 13ah.
I'd find something with vaguely similar ratings that has the same form factor and buy that, chinks sell similar batteries for around $100-$150. Swap over the BMS or get a new one if the battery doesn't have it. You can probably sell these batteries to a recycler for $50.
these things are stupid dangerous and moronic. shoulda just stuck with the good ol icu, dummy.
i bet you fell for the 'green energy' angle, lol.
How should i go about disassembling without shorting or causing a fire?
Very carefully.
just be yourself bro
great advice
you should watch a lot of videos, especially the ones where the batteries blow up, and you can't put the fire out.
for detailed questions ask in /rcg they are the local battery experts.
all cells are chinky
/rcg?
Unless you get lucky and find the culprit getting hot or something...you will have to take it completely apart and rebuild it.
You can try to match the battery and a self balancing BMS should still get the pack running.
But idk also that price is definitely too much.
I've seen 48v 15ah for 200$
Measure individual cell voltages. If any cell is <2.4V it's dead. You could try replacing the dead cell, but you'll need to know what type of 18650 cell it is. Prob LFP, but could be NMC. They have different nominal voltages - and you can't mix them. Maybe check if you can see a part number printed on one of the cells. But yeah, if it's NMC and you frick up and short or puncture a cell you'll cause thermal runaway and an unstoppable fire.
i think it's a BAK cell of 2500mA
>I need help sucking dick
In a best case scenario, how much of a Li-ion battery's original capacity can you expect to recover by reconditioning it?
>how much of a Li-ion battery's original capacity can you expect to recover by reconditioning it?
idk probably will hold for another year or so, i'm gonna buy the tools to build battery packs because i want to convert my bicycle too and it's probably cheaper this way
Why not buy some holders for the 18650s and make your own pack?
Then, if one of them goes wrong, you can just replace that cell easily.
I have several old packs and I keep them in hopes that one day I’ll get to take on this project for myself.
I think it’s crazy how these are made to the point where it’s a scam.
why do they keep soldering/welding them then? it's stupid
Probably takes a bit more room and materials compared to just taping the cells together.
Contact resistance is usually awful. Look at your pix that looks like 22g interconnect wire LOL
Chinese 18650s and 'pouch' cells are notorious for extremely poor life. Individual cells don't fail often, it's almost always that the cells are just worn out.
For instance, if original capacity was 20 amp-hours, it will lose capacity quickly until it's less than half. So, voltage will sag under load and runtime will be greatly reduced. In my experience, chinese lithium cells often are trash within 1-2 years while Jap/Korean 18650s will last 5-10x longer while imperceptibly losing capacity. Chinese cells, by contrast, work well for a year or so then very quickly lose most of their capacity.
You can look how they're wired in series and measure the voltage across each cell without disassembling the pack to check for failed cells, but with that many cells it wouldn't be that significant. Also, there's miliohm testers to better check how worn a cell is internally and can be bought cheap on amazon.
It's way better to buy lightly used 'name brand' batteries (Samsung, Sanyo, Sony, Panasonic, etc) than generic chinese cells as EVERY chinese battery is at best like 80% as good in initial capacity but last 20% as long.
If you're disassembling, first discharge the pack to the minimum (2.5v per cell), be careful not to short anything (watch metal touching metal where it wasn't) and you can easily pop off the tabs on the end of the cells with a small flathead screwdriver or similar prying device. Li-on batteries are almost impossible to make dangerous if they're at low charge and not dead shorted. You can even use a regular $30 pistol soldering iron instead of a spot welder if you heat the ends just breifly with not much solder needed at all.
Lipo 'pouch' cells are the ones that are more dangerous but the cylindrical ones are near impossible to set on fire, especially if they're not fully charged.
escoot
ive always suspected its these homosexuals dicking with their batteries then crashing on the trail as a cause of all these forest fires...
those are environmental activists
i saw a guy riding a super73 and the controller caught on fire under the seat...wasnt even the battery