Ebike Battery stored for a long time

jawzay

1 mW
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Apr 19, 2021
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15
Hi All,

I bought an ebike from someone who claims it has not been used for years. I assumed the battery is dead as the seller claimed that.

After I charged the battery (Giant twist 26V) with my own charger it just started charging and indicated 29.3volt when it was fully loaded. Tested with a dummy load and there is still a capacity of 8.8ampere in the battery.

Strange, or is this possible even though the bicycle / battery has not been used for years?
 
Batteries can sit for years and still be usable, as long as they were disconnected from any load. The main risk with bike battery packs as we know them is that the BMS can completely drain one or more cell groups (to run the basic functions of the BMS) if left unattended for a long time.

It would be a good fault check to do on your battery, to open it up and check the voltage of each cell group individually. This is usually easiest to do by probing the multi-pin connector that plugs into the BMS.
 
Thank you very much! Fully charged the battery is 29.3Volts. Is measuring the resistance also a good way to give some information about the health of the battery and is there a good way to measure the resistance?
 
The best way to check the health of the battery is to charge it up, open it, and check the voltage of each individual cell group. Then run it down somewhat, and check the cell group voltages again. If they're pretty much the same overall, that's good. If there's one or more group that has different voltage, that's bad.

If they're balanced after being charged fully, but imbalanced after discharging, that's also bad.
 
Some of the old Giant bikes used 24v (about 29v full) NiCd or NiMH batteries, which don't typically have a BMS. These may drain down to completely empty and still be able to recharge fully (though over time they do lose capacity, and/or current-delivery-capability.

If the battery gets warm or even hot at / after end of charge, then it is probably NiXX chemistry.
 
amberwolf said:
Some of the old Giant bikes used 24v (about 29v full) NiCd or NiMH batteries, which don't typically have a BMS.

That's a good point. I associate this chemistry only with LaFree bikes made by Giant, but surely there were others.

If you open the pack and find the cells are in a series of 20 or 21 groups, then that's what you have.

The first e-bike I ever built used Sanyo NiCd D cells, so I should have thought of that.
 
I don't want to commandeer the thread but I have a similar situation and a similar question. I also bought an ebike from someone who claims it had not been used for years, but the difference between the OP's situation and mine is, the 24 volt battery is compromised of two 12 volt 10amh SLA batteries.

When I charged it for the first time after bringing it home, it reached full charge a lot faster than I expected. I mounted it and went for a ride, I'd estimate I got around 12 miles on mostly flat terrain with mild pedal assist before it got pretty weak. This seems low on the mileage and confirms why the batteries charged so quickly. Is there anything that can be done to rejuvenate the batteries or is it time to replace them?
 
A quick follow up to my last post. I rode the bike again after the second time it was charged in two days, and I think I got a little more distance out of it. It may just be a coincidence, but it seems like the performance is increasing now that it's getting used again.
 
rick_p said:
I don't want to commandeer the thread but I have a similar situation and a similar question. I also bought an ebike from someone who claims it had not been used for years, but the difference between the OP's situation and mine is, the 24 volt battery is compromised of two 12 volt 10amh SLA batteries.

When I charged it for the first time after bringing it home, it reached full charge a lot faster than I expected. I mounted it and went for a ride, I'd estimate I got around 12 miles on mostly flat terrain with mild pedal assist before it got pretty weak. This seems low on the mileage and confirms why the batteries charged so quickly. Is there anything that can be done to rejuvenate the batteries or is it time to replace them?

Lead-acid batteries don't tolerate years of disuse without trickle charging. They're done. They were never much good to begin with, anyway. I recommend replacing them with some kind of lithium battery and charger in the 30V range.
 
Chalo said:
Lead-acid batteries don't tolerate years of disuse without trickle charging. They're done. They were never much good to begin with, anyway. I recommend replacing them with some kind of lithium battery and charger in the 30V range.
I had a sneaky suspicion that might be the case. I will likely do as you said and upgrade them, but I can't help but ask about these revival methods I've seen on YouTube where folks open them, fill the cells with distilled water, and then trickle charge them with constant current/low amperage chargers. Does that actually work?
 
rick_p said:
I can't help but ask about these revival methods I've seen on YouTube where folks open them, fill the cells with distilled water, and then trickle charge them with constant current/low amperage chargers. Does that actually work?

I've never tried it. Most bike SLAs are absorbed glass mat type cells, and I doubt refilling those would be effective.
 
rick_p said:
Chalo said:
Lead-acid batteries don't tolerate years of disuse without trickle charging. They're done. They were never much good to begin with, anyway. I recommend replacing them with some kind of lithium battery and charger in the 30V range.
I had a sneaky suspicion that might be the case. I will likely do as you said and upgrade them, but I can't help but ask about these revival methods I've seen on YouTube where folks open them, fill the cells with distilled water, and then trickle charge them with constant current/low amperage chargers. Does that actually work?

ive done the baking soda trick and creek water on some like my mining truck that sat all winter, i can get another summer out of them but as soon as the cold weather starts coming they die

tried the pickling salt, didnt work and the truck smelt like dill pickles
 
distilled water only works if the battery was cooked.
 
flippy said:
distilled water only works if the battery was cooked.
Doh! Just before seeing this I had added distilled water and started the charging process. We shall see! Worse case scenario is I spun my wheels and got nowhere with my already mostly dead batteries.
 
rick_p said:
flippy said:
distilled water only works if the battery was cooked.
Doh! Just before seeing this I had added distilled water and started the charging process. We shall see! Worse case scenario is I spun my wheels and got nowhere with my already mostly dead batteries.
use a IR meter and measure the temperature of the side and see if cells get hot. often its just 1 cell that heats up. if you see that then stop charging and toss the battery.
 
Well, the experiment was a complete fail. After reassembling the two 12 volt batteries back into the case I plugged in the regular 24 volt charger to top off the charging process. One or both of the batteries boiled over and made a huge mess inside the case. I'll be dropping off the batteries to the auto parts store for recycling, they are definitely done now. Not really a loss, they were pretty much done anyway.

I'll start a new post to discuss the upgrade to a Lithium setup.
 
Hmm ?..... its a shame... 12 miles on used 24v SLAs was not a bad result ( dependig on the Ah rating , and your ride style etc)
But Lead is best forgotten anyway.
I would plan for 36 v Li to give you more capacity, range and speed. :wink:
 
Hillhater said:
Hmm ?..... its a shame... 12 miles on used 24v SLAs was not a bad result ( dependig on the Ah rating , and your ride style etc)
I miscalculated the actual distance, it was probably only 8-10 miles, but I still agree that it was a shame it didn't work, I was hoping to get some more miles out of them. In contrast though, I have two other identical battery cases that came with a different bike that uses the same Currie slide in rack. These batteries have LiFePo4 batteries inside, which are also old but must have been stored properly because in contrast to the distance I got from the SLA batteries, I charged up one of the old 24 volt 10ah LiFePo4 batteries and went on the same ride, and still had two out of the three led lights left on battery charge indicator on the throttle when I got home.

I have been hesitant to charge these LiFePo4 batteries because I don't have the original charger that came with them, I only have a 24 volt 1.8amp charger that came with my daughter's scooter, which probably has a Lithium Ion battery, and although I think it's OK to use that charger, I'm not sure if it's the "right" charger to use.
 
I say again.....
8-10 miles on used 10Ah Lead cells is about what you should expect.
Even at their best they would only have 240 Wh of capacity on a SLOW discharge, so with aging and high rate discharge, you would be lucky to get 150-200Wh from them. (Mr Pukert wants his cut also !)
so riding them normally at say 200W discharge,.. 15-20Wh per mile was not a unexpected result.
The Lfe4 cells will always give a much better result from the same quoted capacity.
 
Yep, I should have left well enough alone but the damage is done, so no looking back. Moving forward though, I sure wish I knew if the 24 volt 1.8amp charger that came with my daughter's scooter, which has a Lithium Ion battery is safe/correct to use with my LiFePo4 batteries?
 
Hillhater said:
I would plan for 36 v Li to give you more capacity, range and speed. :wink:
Would it be safe to run a 36 volt battery without upgrading the controller? And what about the fun8 hub motor?
 
rick_p said:
Hillhater said:
I would plan for 36 v Li to give you more capacity, range and speed. :wink:
Would it be safe to run a 36 volt battery without upgrading the controller? And what about the fun8 hub motor?

Most 24V controllers (but not all) can use 36V. The worst that happens is something goes "pop" inside the controller and you pedal back to base.

Hub motors don't have a specific voltage, but just a specific rpm per volt. If you feed them more voltage, they try to turn faster (which they might or might not actually do, depending on how much power they have available).

FYI, that's "8fun", not fun8. 8 = "ba" in Mandarin, so it's "ba fun" or Bafang, a very common and well known e-bike equipment manufacturer. If it's also a Bafang controller, I bet it will run fine on 36V.
 
Chalo said:
Most 24V controllers (but not all) can use 36V. The worst that happens is something goes "pop" inside the controller and you pedal back to base.
I was hoping there was a terrified emoji to use here, but no luck, just a :flame: LOL, let's say I've been :warn:

Chalo said:
Hub motors don't have a specific voltage, but just a specific rpm per volt. If you feed them more voltage, they try to turn faster (which they might or might not actually do, depending on how much power they have available).
That is really good to know, thanks for sharing that!

Chalo said:
FYI, that's "8fun", not fun8. 8 = "ba" in Mandarin, so it's "ba fun" or Bafang, a very common and well known e-bike equipment manufacturer. If it's also a Bafang controller, I bet it will run fine on 36V.
What "fun" information! The pun is intended, and it actually is cool to learn what 8fun and bafang stand for. Thanks again!
 
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