E-bike Battery, Cell Rejuvenation
Discussion
Hi all,
Anyone on here a battery guru? The battery on my partners Halfords Subway Carrera has depleted and won’t charge back up (green light on charger only). Sometimes it will display 80% battery on button press, other times it acts completely dead.
A new battery is a shocking £490 from Halfords. However I’m pretty sure it’s just a dead battery/cluster. It’s a 36v battery, I have opened up the casing and carefully removed the BMS to expose the Li-lion batteries. With a multimeter I am getting the following
Cluster 1: 1.5v
Cluster 2: 1.67v
Cluster 3: 2.08v
Cluster 4: 2.03v
Cluster 5: 2.07v
Cluster 6: 1.65v
The individual batteries are MH12210’s which should have a nominal voltage of 3.7v (fully charged at 4.2v).
The multimeter reading from total 18.7v (36v battery). I’m pretty certain the BMS is preventing the cells from recharging as it’s protecting clusters that have fallen below a pre-set charge parameter.
I’m unable to remove the batteries easily. As they’re all spot welded and siliconed into place. I believe it can put power to the batteries to rejuvenate them.
I actually have a DC power supply that I use for testing 12v LED lamps. What settings could I use with this to provide power to the cells and recharge them enough to get them to ‘play ball’ with the regular charger?
I know I’m halfway there, just need some further direction.
Cheers,
Lund
Anyone on here a battery guru? The battery on my partners Halfords Subway Carrera has depleted and won’t charge back up (green light on charger only). Sometimes it will display 80% battery on button press, other times it acts completely dead.
A new battery is a shocking £490 from Halfords. However I’m pretty sure it’s just a dead battery/cluster. It’s a 36v battery, I have opened up the casing and carefully removed the BMS to expose the Li-lion batteries. With a multimeter I am getting the following
Cluster 1: 1.5v
Cluster 2: 1.67v
Cluster 3: 2.08v
Cluster 4: 2.03v
Cluster 5: 2.07v
Cluster 6: 1.65v
The individual batteries are MH12210’s which should have a nominal voltage of 3.7v (fully charged at 4.2v).
The multimeter reading from total 18.7v (36v battery). I’m pretty certain the BMS is preventing the cells from recharging as it’s protecting clusters that have fallen below a pre-set charge parameter.
I’m unable to remove the batteries easily. As they’re all spot welded and siliconed into place. I believe it can put power to the batteries to rejuvenate them.
I actually have a DC power supply that I use for testing 12v LED lamps. What settings could I use with this to provide power to the cells and recharge them enough to get them to ‘play ball’ with the regular charger?
I know I’m halfway there, just need some further direction.
Cheers,
Lund
I'm a model flyer and this is an issue with the lithium polymer batteries we use.
Generally a lithium ion battery charger won't try and charge a cell once it gets below about 3V. Some people have found that under-voltage lithium cells can be charged on a low current setting with a multi-type battery charger on a nickel metal hydride setting. This is done for just long enough to bring the cell back to 3.7 volts. Then the cells can be charged again on a lithium ion setting.
No charger or battery manufacturer is likely to endorse this method. If you are going to attempt this, do it outside and don't leave the batteries and charger unattended.
The likelihood is that by getting as low as they have, the cells have suffered some irreversible damage, so don't expect them to reach full capacity again.
You want a charger with a digital display. I use a Ripmax Sigma Pro Peak, but the Imax B6 is probably the most popular. The cheaper ones run off a 12 to 18v DC input, the dearer AC ones work off the mains too.
Imax B6 Charger AC/DC
Generally a lithium ion battery charger won't try and charge a cell once it gets below about 3V. Some people have found that under-voltage lithium cells can be charged on a low current setting with a multi-type battery charger on a nickel metal hydride setting. This is done for just long enough to bring the cell back to 3.7 volts. Then the cells can be charged again on a lithium ion setting.
No charger or battery manufacturer is likely to endorse this method. If you are going to attempt this, do it outside and don't leave the batteries and charger unattended.
The likelihood is that by getting as low as they have, the cells have suffered some irreversible damage, so don't expect them to reach full capacity again.
You want a charger with a digital display. I use a Ripmax Sigma Pro Peak, but the Imax B6 is probably the most popular. The cheaper ones run off a 12 to 18v DC input, the dearer AC ones work off the mains too.
Imax B6 Charger AC/DC
Edited by GliderRider on Friday 3rd November 01:30
GliderRider said:
I'm a model flyer and this is a issue with the lithium polymer batteries we use.
Generally a lithium ion battery charger won't try and charge a cell once it gets below about 3V. Some people have found that under-voltage lithium cells can be charged on a low current setting with a multi-type battery charger on a nickel metal hydride setting. This is done for just long enough to bring the cell back to 3.7 volts. Then the cells can be charged again on a lithium ion setting.
No charger or battery manufacturer is likely to endorse this method. If you are going to attempt this, do it outside and don't leave the batteries and charger unattended.
The likelihood is that by getting as low as they have, the cells have suffered some irreversible damage, so don't expect them to reach full capacity again.
You want a charger with a digital display. I use a Ripmax Sigma Pro Peak, but the Imax B6 is probably the most popular. The cheaper ones run off a 12 to 18v DC input, the dearer AC ones work off the mains too.
Imax B6 Charger AC/DC
Thanks for your reply. Yes, I have this power supply which I think can do just that; Generally a lithium ion battery charger won't try and charge a cell once it gets below about 3V. Some people have found that under-voltage lithium cells can be charged on a low current setting with a multi-type battery charger on a nickel metal hydride setting. This is done for just long enough to bring the cell back to 3.7 volts. Then the cells can be charged again on a lithium ion setting.
No charger or battery manufacturer is likely to endorse this method. If you are going to attempt this, do it outside and don't leave the batteries and charger unattended.
The likelihood is that by getting as low as they have, the cells have suffered some irreversible damage, so don't expect them to reach full capacity again.
You want a charger with a digital display. I use a Ripmax Sigma Pro Peak, but the Imax B6 is probably the most popular. The cheaper ones run off a 12 to 18v DC input, the dearer AC ones work off the mains too.
Imax B6 Charger AC/DC
https://amzn.eu/d/c051kG6
I’m hoping to bring them up to around 3v and then use the main charger to bring them back upto spec, or as good as can be!
Model: NCR18650
Standard Capacity: 3400mAh
Standard charge: 1.25A, 4.2V, CCCV, 100mA deadline
Quick charge: 4A, 4.2 ± 0.05V, CCCV, 100mA deadline
Charging time; Standard charge 4hours/100mA deadline
Quick charge: 2hours/100mA deadline (25 °C)
If I supply 4A / 4.2v to the full pack positive negative so you think that would do it? Obviously keep an eye on the temps and how it’s responding.
Edited by Lund on Thursday 2nd November 20:04
I would advise identifying which cells are at low voltage and trying to charge them individually. With your whole pack at 18.7 volts, I very much doubt that putting 4.2v across the whole pack will do anything. That is the sort of voltage I would be putting across a single cell.
A charging current greater than 1C with suspect cells is asking for trouble, I would start at about 1/3C (standard capacity = 1C charge rate).
Here is some more info: Recovering over discharged lipos
What you have is a power supply, not a smart charger. A smart charger looks at the cell voltage and adjusts the charge accordingly (when set to the appropriate cell type). It may well work to bring the flattened cells up to a voltage at which the proper lithium ion charger will work, but that's it.
I'm no battery expert. Do have a search on RC Groups for what people say there about Li-ion recovery.
A charging current greater than 1C with suspect cells is asking for trouble, I would start at about 1/3C (standard capacity = 1C charge rate).
Here is some more info: Recovering over discharged lipos
What you have is a power supply, not a smart charger. A smart charger looks at the cell voltage and adjusts the charge accordingly (when set to the appropriate cell type). It may well work to bring the flattened cells up to a voltage at which the proper lithium ion charger will work, but that's it.
I'm no battery expert. Do have a search on RC Groups for what people say there about Li-ion recovery.
I have managed to charge each cell to circa 3.3v (3.6 is nominal). They’re all there or thereabouts. The total power of the pack is now at 31.7v, but still it doesn’t want to charge with the mains charger. Just shows solid green light. The battery is however responding each time I press the button now which wasn’t before. Shows 3 out of 4 bars charge. Each cluster measured voltage is different by 1.01 > 1.08. Would the BMS Still view this as out of balance?
Edited by Lund on Friday 3rd November 16:45
How many cells do you have there?
Each cell is nominal 3.7V
Are they in series/parallel groups?
This is the cell:
https://www.batteriesplus.co.uk/acatalog/Panasonic...
so standard charge is 1.25A constant current, until the volts rise to 4.2V, then constant voltage of 4.2V until the current drops to 100mA
I only had 3 cells, so it wasn't too tedious to charge each cell, then discharge it a bit with a resistor, then recharge it. I'm told a few cycles can help.
Bit tedious when you've got 18 cells? but maybe you can work on series groups?
A year on, the drill in question is working well with a good run time, so it's worth persevering IMHO.
If you don't have resistors or current limiting supplies at hand, a 12V light bulb in series with a 12/13/14/15V supply will limit the current according to its wattage. Worst case you pop a few bulbs.
Each cell is nominal 3.7V
Are they in series/parallel groups?
This is the cell:
https://www.batteriesplus.co.uk/acatalog/Panasonic...
so standard charge is 1.25A constant current, until the volts rise to 4.2V, then constant voltage of 4.2V until the current drops to 100mA
I only had 3 cells, so it wasn't too tedious to charge each cell, then discharge it a bit with a resistor, then recharge it. I'm told a few cycles can help.
Bit tedious when you've got 18 cells? but maybe you can work on series groups?
A year on, the drill in question is working well with a good run time, so it's worth persevering IMHO.
If you don't have resistors or current limiting supplies at hand, a 12V light bulb in series with a 12/13/14/15V supply will limit the current according to its wattage. Worst case you pop a few bulbs.
Thanks for your reply. I have 5 clusters of 6 individual batteries. (30 batteries in total).
I am charging the clusters. When I put the multimeter to each cluster, I generally see 3v’s now.
Each cluster I am currently bringing up to 3.7v, with a steady 4.05v charge (it’s taken some time).
Sadly I can’t remove each battery individually, they’re siliconed in and spot welded in series and even the clusters are non-removable in the plastic casing.
When I test the full battery capacity I now see 33v.
When I plug-in the mains charger I get a reading of 42.2v on the battery charge terminals (charger is working). However the BMS still preventing the battery from being charged.
Am I missing something obvious here?
I am charging the clusters. When I put the multimeter to each cluster, I generally see 3v’s now.
Each cluster I am currently bringing up to 3.7v, with a steady 4.05v charge (it’s taken some time).
Sadly I can’t remove each battery individually, they’re siliconed in and spot welded in series and even the clusters are non-removable in the plastic casing.
When I test the full battery capacity I now see 33v.
When I plug-in the mains charger I get a reading of 42.2v on the battery charge terminals (charger is working). However the BMS still preventing the battery from being charged.
Am I missing something obvious here?
Hi, yes it’s essentially been left discharged for a long time. I’m trying to wake up the cells. It’s responded positively so far, in the beginning when the power button was depressed (to indicate the battery charge) it wouldn’t always light up, it might do three times and then not work for several days. Now the power button is consistently working since the ongoing recharge.
peterperkins said:
If you value your house/garage bin them and buy some new ones.
Over discharged Lithium are not to be trifled with especially if they are LiPo.
For the sake of £450 just buy a new OEM pack. I have a dead Fazua pack (German engineering appears to be mainly marketing vs real quality), have thought about taking it apart, but will just depose of it.Over discharged Lithium are not to be trifled with especially if they are LiPo.
RC community must have good advice on how to risk mitigate etc, but if the eBike is just another tool, why risk it and wasted time faffing for such a small cost. I can see how battery managment is an essential part of RC 'fun', but no one can surely find trying to repair a Halfords eBike battery interesting or worthwhile.
The Lithium chemistry in Tesla cells is more volatile than eBike stuff, but I have little interest in dealing with something like this is the garage/house from charging a DIY bodged eBike battery pack.
https://youtu.be/WdDi1haA71Q?si=bRkvWwnxbIGjeRmn
Edited by gangzoom on Saturday 4th November 09:09
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