Karcher 18v Cordless Mower battery problem

[kPATm]

So as the weather is finally changing I decided to give the grass a going over, no dice. The battery should have a digital display showing percentage left but the display is blank and it doesnt register on the charger. I tried the trick where you "jump start" the battery but I only have a 18v 2mah battery where as the Karcher is 5mah.

It does show as having 18v after the jump start but as soon as I disconect it the voltage rapidly drops to 13v. I opened it up and checked all the cells individually and they all read a steady 3.5v. Any help is appreciated

 

[Bigpops]

You'd have to check each cell's internal resistance. If a cell has hi IR, it will show the correct voltage with no load, but that will drop rapidly once a load is applied.

I doubt it's worth the hassle unless replacement packs are unobtainable.

 

[kPATm]

They are unobtainable to me at the moment at £90 a pop. Im wondering if I could remove all the batteries and charge them in my Vape battery charger. They are only 18650s