MobilePro not fully charging

I just bought a used MobilePro from a very well known MobilePro Ebayer. I purchased a universal charger at WalMart and set the charger volt to both 7.5 and then 9v since the NEC adapter for the 780 online says it is a 9Volt adapter. Both tries and the battery will only charge to 20% and then says I am running on external power. HELP! Am I doing something wrong?

Well, chances are your battery is old and cannot charge beyond that. You can either get new batteries or refurb your batteries with new 18650 cells.

What is the current (milliamp) rating of your universal wall wart? When I rebuilt two MP780s for my nieces, I found that anything with a current capacity less than 800ma will not provide enough amps to fully charge the battery. I knew the batteries were good because I used my NEC charger on them and they took a full charge ok.

Lithium ions are strange that way. Unlike SLA, NiCd or NiMH which can at least get to 90% on trickle charging, a LIon needs a specified minimum charging current. Your charger could provide enough to keep the MP running and charge the batteries a *little* but it doesn't have enough amps to fully drive the electrochemical process in the cells in reverse.

Edited by Zapper 2005-07-12 9:15 PM

Come on Jenny, tell them the rest...tell them about how your a/c adapter is only rated at 300mAh....

oh ya, its true that most of the ac adapter for li-ion devices are 1A or 2A or more. Also, the original ones from manufacturer usually have constant-current regulators inside. This part is critical, or so it seems. The crappy OEM ones tend to have problem with constant current when the load changes or when the adapter heats up. But some OEM ones are just as good anyway.

Hiya. Update. I bought the Powerline universal with a 1000 rating and all juiced up to 100% today. Thanks again! Sorry I forgot to mention that I had the 300Ma one first. Now I can't sync. Posted another thread here: http://www.hpcfactor.com/forums/forums/thread-view.asp?tid=1775&posts=1#M15054