Which rechargeable battery you prefer for the HP-41?

[Sylvain Cote]

I have bought through Robert a couple years back, several (20+) 500mAh NiMh 'N' batteries and 8x N-to-AA sleeves from Ogaz.
I am using with great success my smart battery chargers (BC700 & BC1000) from La Crosse Technology configured at 200mAh.
Sometime the smart battery charger does not see a battery because it is too low and report NULL.
When that happens, I put the battery into a dump charger for 30 seconds, then put it back into the smart charger which normally sees it and start the charging process.
Sylvain