Ebike Battery stored for a long time

Batteries, Chargers, and Battery Management Systems.
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jawzay   100 µW

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Ebike Battery stored for a long time

Post by jawzay » Apr 28 2021 4:44pm

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?

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Chalo   100 GW

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Re: Ebike Battery stored for a long tome

Post by Chalo » Apr 28 2021 4:54pm

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.
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Re: Ebike Battery stored for a long tome

Post by jawzay » May 03 2021 5:06pm

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?

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Chalo   100 GW

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Re: Ebike Battery stored for a long tome

Post by Chalo » May 03 2021 10:32pm

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.
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Re: Ebike Battery stored for a long tome

Post by amberwolf » May 04 2021 12:06am

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.

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Chalo   100 GW

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Re: Ebike Battery stored for a long tome

Post by Chalo » May 04 2021 1:07am

amberwolf wrote:
May 04 2021 12:06am
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.
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Re: Ebike Battery stored for a long tome

Post by rick_p » May 04 2021 2:24pm

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?

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Re: Ebike Battery stored for a long tome

Post by rick_p » May 04 2021 11:40pm

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.

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Re: Ebike Battery stored for a long tome

Post by Chalo » May 06 2021 11:54am

rick_p wrote:
May 04 2021 2:24pm
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.
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Re: Ebike Battery stored for a long tome

Post by rick_p » May 06 2021 2:01pm

Chalo wrote:
May 06 2021 11:54am
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?

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Re: Ebike Battery stored for a long tome

Post by Chalo » May 06 2021 2:54pm

rick_p wrote:
May 06 2021 2:01pm
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.
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Re: Ebike Battery stored for a long tome

Post by goatman » May 06 2021 3:30pm

rick_p wrote:
May 06 2021 2:01pm
Chalo wrote:
May 06 2021 11:54am
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

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Re: Ebike Battery stored for a long tome

Post by rick_p » May 06 2021 6:08pm

goatman wrote:
May 06 2021 3:30pm
tried the pickling salt, didnt work and the truck smelt like dill pickles
:lol:

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flippy   100 MW

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Re: Ebike Battery stored for a long tome

Post by flippy » May 06 2021 6:19pm

distilled water only works if the battery was cooked.
The bitterness of low quality remains long after the sweetness of low price is forgotten

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Re: Ebike Battery stored for a long tome

Post by rick_p » May 06 2021 10:23pm

flippy wrote:
May 06 2021 6:19pm
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.

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Re: Ebike Battery stored for a long tome

Post by flippy » May 07 2021 3:05am

rick_p wrote:
May 06 2021 10:23pm
flippy wrote:
May 06 2021 6:19pm
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.
The bitterness of low quality remains long after the sweetness of low price is forgotten

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Re: Ebike Battery stored for a long tome

Post by rick_p » May 07 2021 1:58pm

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.

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Re: Ebike Battery stored for a long tome

Post by Hillhater » May 07 2021 4:56pm

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:
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Re: Ebike Battery stored for a long tome

Post by rick_p » May 08 2021 11:41am

Hillhater wrote:
May 07 2021 4:56pm
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.

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Re: Ebike Battery stored for a long tome

Post by Hillhater » May 08 2021 11:03pm

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.
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Re: Ebike Battery stored for a long tome

Post by rick_p » May 09 2021 11:35am

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?

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Re: Ebike Battery stored for a long tome

Post by rick_p » May 10 2021 9:55am

Hillhater wrote:
May 07 2021 4:56pm
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?

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Re: Ebike Battery stored for a long tome

Post by Chalo » May 10 2021 2:29pm

rick_p wrote:
May 10 2021 9:55am
Hillhater wrote:
May 07 2021 4:56pm
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.
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Re: Ebike Battery stored for a long tome

Post by rick_p » May 10 2021 3:09pm

Chalo wrote:
May 10 2021 2:29pm
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 wrote:
May 10 2021 2:29pm
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 wrote:
May 10 2021 2:29pm
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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