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Re: Help with battery/charger combo

From: Vaughan Pratt <>
Date: Thu, 31 Dec 1998 10:17:49 -0800

>The NPF 950 lithium battery is available, though, and has a rather high
>(30+) watt hour rating. Has anyone out there tried this battery? Are they
>huge?

Sony's naming scheme for their lithium batteries seems to be NP-Fnc0
(e.g. for the NP-F950, n=9 and c=5), where n-3 is the number of 3.6v
cells.  So the NP-F530 has 5-3 = 2 cells, the NP-F730 has 4,
the NP-F950 has 6.

The cells are 2.5" long x .7" dia., i.e. about 4/3Af size, and are
nominally 3.6v.  Each pair of cells is connected in series to give 7.2v
and then the pairs are connected in parallel.  A PC board at one end
and the plastic case add about .25" to the length and .1" to the height
and width, making e.g. the NP-750 2.75" x 1.5" x 1.5".  Haven't measured
the NP-950 but on this theory it should be 2.75" x 1.5" x 2.2".  No sign
of an NP-F1150 yet but it would have the dimensions and amperage of two
NP-F750's stuck together and connected in parallel.

The c in NP-Fnc0 is either 3 (discontinued) or 5 denoting respectively
1.35 and 1.5 ampere-hours per battery.  Multiply by (n-3)/2 to get
the capacity of the whole unit, e.g. 1.5 * (7-3)/2 = 3 ampere-hours
(= 3000 mAh, milliampere-hours) for the NP-F750.

The AC-F750 by Ac-Delco is the same as Sony's NP-F750 in the above
respects except it has 10% more capacity and is $5 cheaper, at least
at www.batterybarn.com.  No sign of an AC-F950, too bad.

One way of reducing the profile of the NP-F950 for a wearable is to cut
it open and distribute the 6 cells around your belt.  If you preserve
all the connections it will function electrically identically to when
it's in its case.  The PC board is a mite delicate so you'll want to
give it some physical protection.

Vaughan

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