Testing battery on a used elec-bike that I want to buy

mchevrier

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Jun 19, 2022
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Hi,
I am shopping for a used e-bike.
When I visit a used e-bike owner selling his e-bike, how can I verify if the battery is still holding charge and has reasonable autonomy? The price of a new battery is so high that I want to make sure before I buy that e-bike.
Thanks,
Michel.
 
Without rigorous testing or specialized testing equipment you can't definitively ascertain the health and future longevity of a used ebike battery. Therefore, we almost always estimate the battery to be at or near its end, when making an offer on a used ebike. Unless you explicitly know all the details of the battery's age, how it was treated, and the quality of its components and workmanship.

So, sadly, you have to price the system as if it needs a replacement battery.

Many sellers, even otherwise honest ones, think that as long as the battery charges and can power the bike, it is in great condition. Don't fall for that.
The truth is, most all batteries start to degrade the minute they are built (shelf life longevity) and used.
 
mchevrier said:
When I visit a used e-bike owner selling his e-bike, how can I verify if the battery is still holding charge and has reasonable autonomy?
The "best" way is to test ride it like you would use it yourself, from a full charge until it runs out of power and turns off, to see how far it takes you under the conditions you will use it in. Then you'll know that the bike actually works as you need it to, for as far as you need it to.


Another way is to use a load tester system on just the battery, that can record the Wh, voltage sag, etc., at the amp rate (or higher) that the bike itself will use worst-case, to test the battery from full to empty to be sure it is working as it should thru the whole remaining capacity, but you'd also need to know what the wh/mile (or wh/km) usage of the bike is, to know how far the battery would take you. Since that's probably not available, all this test will do is to tell you how many wh the battery is still capable of producing.
 
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