Testing a battery

matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,862
1,346
Hi all
How do I test my battery for how much charge it has whilst its off the bike.
as on the back there are 2 x minus - and 2 x plus symbols + if you zoom in you can see them its a 36V 13Ah down tube type

https://www.yosepower.co.uk/products/36v13ah-hl-i-down-tube-lithium-ion-e-bike-battery


View attachment 50648
Usually the outer connections are connected as + and -, often the middle two are not. If they are it is just to share the load.

So with multimeter if the probes are thin enough, just touch them on the outer connections, with the battery switch turned on.

Fully charged should say 42V give or take a few tenths.
 

billyboya

Esteemed Pedelecer
Aug 10, 2016
1,137
90
73
uk
Usually the outer connections are connected as + and -, often the middle two are not. If they are it is just to share the load.

So with multimeter if the probes are thin enough, just touch them on the outer connections, with the battery switch turned on.

Fully charged should say 42V give or take a few tenths.
oh so you mean these two marked in yellow not the centre 2. So basically - = 1 - = 2 + = 3 + = 4 So just use no 1 and no 4.
 

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matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,862
1,346
oh so you mean these two marked in yellow not the centre 2. So basically - = 1 - = 2 + = 3 + = 4 So just use no 1 and no 4.
Yes.