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Archive for December 11th, 2013

Sony NP-FS11 Battery Status & Rebuild

The trio of batteries I built for the Sony DSC-F505V two years ago faded away; that camera seems particularly hard on the batteries, perhaps because they’re two cells in parallel that don’t share well. Two of the three seem pretty well gone:

Sony NP-FS11 2011 Packs - 2013-11 tests

Sony NP-FS11 2011 Packs – 2013-11 tests

Back then, I bought 12 cells, built six into those batteries, and left six charged cells sitting in a bag. After rebuilding the two worst batteries with those new-old-stock cells, it seems they maintained a substantial fraction of their charge while resting in the cool and the dark:

Sony NP-FS11 2011 Cells - 2013 packs - 2013-11-24

Sony NP-FS11 2011 Cells – 2013 packs – 2013-11-24

However, the camera would regard them as discharged, because it infers charge state from voltage. Squinting at the curves, their condition after a few minutes is roughly equal to a new & freshly charged battery produces over on the right when it’s nearly discharged.

The other curves show the result after their first charge in two years: basically, full capacity. The fact that both pairs of curves come pretty close to overlaying means they’re still well matched.

Sony NP-FS11 batteries - rebuilt

Sony NP-FS11 batteries – rebuilt

The third cell isn’t up to their spec, but it’s close enough to not bother rebuilding right now: 1.2 vs 1.4 A·h.

The Kapton tape pull tabs work wonderfully well, as the rebuilt batteries fit the compartment rather more snugly than the un-hacked cases.

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