[NTLK] Battery cells and the C thing

From: Frank Gruendel (fg2_at_pda-soft.de)
Date: Sat Jan 24 2004 - 09:47:45 PST


> I read an app note from Panasonic that indicated that NiMH
> cells should be charged at at least 0.5C and less than 1.0C.
> Does anyone know what charging current the Newton 2100 uses?

If you power it from the OMP / MP100 / MP 110-120-130 adapter,
it will charge with approx. 500 mA. If you use the 2x00 / eMate
adapter, charge current will be about 1200 mA.

> Since the original 2100 used 1200mAh cells, if we assume
> they were charging at 1.0C, then a swap of up to 2400mAh
> could be done without causing the cells to crystalize.
> At 0.5C, you could not go above 1200mAh cells and the people
> that are selling the 2000mAh recells are doing their
> customers a disservice.

Well, so far not a single one of my customers has complained.
Don't worry about crystallization of cells, charge current
doesn't have anything to do with that. The "C" thing is more
important to ensure that cells that can't be charged with
high currents won't be charged with high currents. The Newton
monitors both the voltage, the temperature and (this is just
an educated guess) the voltage curve. It knows when to stop.
All that will happen if you use higher capacity cells is that
it will take longer to charge them.

Frank

-- Newton Software and Hardware at http://www.pda-soft.de

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