Derby cycle battery charger for 25.2v 18ah battery

[westcoastsurfer]

Hi, looking for advice on my Derby cycle battery adaptor for a 25.2v/18ah battery.. My battery lights up when the red button is pressed but no lights appear when placed on the charger and my battery only as enough power to light up the assist mode on the handlebars! I have a spare 10ah battery that works the bike that I have come across but as no charger with it, I have tried it on my charger but it won't fit! The charger as 2 notches as does the 18ah battery But the 10ah battery only as 1 notch - any advice please on how to get some more charge in the 10ah before it goes flat. I have noticed the charger doesn't get warm at all after long charges- is this normal or could it be faulty? My bike is a old 2012 kalkhoff agattu impulse c8 - any advice will be appreciated if there's a way to fit the 10ah on the charger
Tia

 

[Fat Rat]

Hi welcome

 

[westcoastsurfer]

Hi welcome

Thank you

 

[Gliggsy]

Looking at that, I think that if it were me then I would get a good, sharp wood chisel and carefully remove the offending leg of the charger, either that or a dremel type tool but I can't stress enough that you need to check the polarity of the new battery before attempting any of this