Click here to a camera li-ion battery charger as a UPS for an OpenWRT router

This is a mod to replace the old Ni-Cad batteries in the Icom BP-22 battery pack with a Li-ion battery salvaged from a Nikon camera. This new battery provides approximately 8.2VDC, which this HT is happy on. Of course, the old Ni-Cad charger is no longer suitable to charge the Li-ion battery, but I do have the Nikon charger that does pair with the new battery.

I gutted the Ni-Cads out of the Icom BP-22 battery pack and installed the new Li-ion battery in it. And I needed to use a three pin connector to connect 3 wires to the charger. Turns out, with this battery, the center contact is not used. The charger had two spring contacts that touch the + battery terminal. This "tells" the charger, via the 3rd contact (the other 2 are the + and the -), that the battery is present when connected to it. I used the 3 pin pin connector to maintain the charger being told that the battery is connected. Also, the new 3 pin connector will not allow the old Ni-Cad charger to be connected. I did not use a stereo headphone jack, as the battery and/or the charger might see a momentary short with such when plugging it in or unplugging it. I removed the spring contacts from the charger, and connected the 3 wire with connector pigtail to the corresponding points where the spring contacts connected on the charger circuit board.

Below are closeups of the battery nameplate, and the nameplate of its charger.

You can operate the radio while the charger is connected.

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One of these camera battery chargers with its battery can function as a UPS to power an OpenWRT WRT54G router that has some files stored in its RAM. The charger is the only power source here, and its "FULL" LED indicator is lit, meaning the charger has switched itself from "CHARGE" mode (constant current) to "FULL" (constant voltage) mode. The charger measures the battery voltage, and based on this, it changes modes when the battery reaches the desired voltage. The router's current draw doesn't seem to confuse this function, as it's less than the current the battery draws in "charge" mode. This is known as a parasitic load, and even though this charger wasn't designed for this, it seems to deal with it fine. This should be safe for the battery, as it doesn't see any other power source than the charger.

I connected a DC power cord (to feed the router) to the terminals inside the charger, the ones that connect to the battery's + and - terminals. The battery (a Li-ion) doesn't seem to mind floating on the charger. It's been this way for over a year and the battery still holds a charge.