Replacing lawn mower battery pack - how to wire?

chris_m

1 mW
Joined
Jul 26, 2019
Messages
15
Not sure if this question is out of place here, but I'll try:

My mom has an old Gardena lawn mower which takes a 36V 3.0Ah Li-Ion battery.
This battery connects to the mower with a plug that has six wires: Red-Brown-ThinRed-ThinBlack-Blue-Black
The Red and Brown are marked with + + and the Blue and Black with - -

On the mower there are five receptors, that connect to the Red-Brown-_-ThinBlack-Blue-Black wires from the battery. So the thin red one seems not to connect to the mower (it's probably for the charger only).

Now, this battery is pretty old and doesn't hold the charge for very long.

I have some battery packs for other power tools which are 36V Li-Ion (also intended for lawn mowers, chain saws etc) . These are 2.6Ah or 4.0Ah.
These batteries only have four connectors, which are marked B+/P+ _ NTC _ CH- _ P-

Now my question: Can I wire my batteries to mom's lawn mower to replace the original battery?

And if so - how should I wire it? I am guessing I should use the B+/P+ and P- on the "new" batteries, but should I wire them to the receptors for the old battery's red and black ones on the mower? And why would there be two positive (red and brown) and two negative (black and blue) coming from the old battery? (I should maybe mention there is an indication on the old battery stating "2x54Wh" and it consists of 20 cells that are wired 10s2p)

Also, I guess that the NTC marking on my batteries is a temperature sensor. Not sure if this is used for charging or for discharging or both. Would the battery not work if that connection is not used for the lawn mower? Or would it not cut out if overheated?
 
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