Battery Charger upgrade

[RasAzul at aol.com]

Hello List, I have a problem I hope you can help me with, I have a Duo 2300 
running OS 8.6 with a 6gig harddrive and 28mb of ram built in. My problem is 
that I have a typeIII battery I would like to get charged but my power supply 
battery charger (model m1812) won't charge the battery. It seems it needs an 
upgrade in order to do so. Here is the question: does anyone on the list know 
where to find this needed upgrade. I have searched Apple older software downloads 
and can't find it there. Perhaps I overlooked something.
Any and all help will be greatly appreciated.
Brad