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Archive for August 7th, 2013

Wouxun KG-UV3D Batteries: Age and Cycle Effects

The first Wouxun (evidently pronounced “ocean”) KG-UV3D HT spent a month or two in my bike, lashed to a kludged version of the APRS+voice interface box and powered by its own lithium-ion pack. After I got the circuit worked out and built a duplicate, I picked up a second HT for Mary’s bike; as a result, that battery pack never got much use.

A pair of discharge tests shows the difference:

Wouxun 7.4 V Packs

Wouxun 7.4 V Packs

The 2011-03 battery has almost exactly the rated 1.7 A·h capacity, at least if you’re willing to run it down to 6 V, and the 2012-06 pack delivers 1.9 A·h. Electronic gadgets measure state-of-charge using the battery voltage, so the older pack “looks” like it has much less capacity: it runs about 100 mV lower than the newer pack out to 1.2 A·h, then falls off the cliff. Looks to me like one of the two cells inside is fading faster than the other; so it goes.

I’m still thinking of using these to power some LED taillights, because they have a nice form factor and built-in latches:

Wouxun KG-UV3D - battery pack latch

Wouxun KG-UV3D – battery pack latch

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