Which rechargeable battery you prefer for the HP-41?

[ijabbott]

(08-22-2018 03:29 PM)smp Wrote:  

(08-22-2018 02:22 PM)Sylvain Cote Wrote:  <...snip...>
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.

Yes, I've experienced this same thing, and I solved the issue the same way. I never leave the battery in the dump charger for more than a minute, and it's always enough to get it going properly in the smart charger again.

smp

If you don't have a dumb charger, another option is to "jump start" the dud battery by connecting it in parallel with one of the other discharged batteries for a few seconds.