Picture of the completed replacement. After this, you just snap
the cover back on
The original battery packs are only
600mAh units. The new ones are more than three times the capacity
(I used NiMH), and should last us a few days between recharging with
even daily use. Remember to recycle your used batteries as they
After some use it became clear that the circuitry in the charger needed
to be modified to provide more charge current for the batteries.
Tracing the circuit, I came up with this schematic.
Circuit diagram of the charger. Each radio is charged on a
different half cycle of the AC waveform.
To increase the charging current, I shorted R3 and R6 with a jumper and
replaced R2 and R5 with a 10 Ohm resistor. This quadruples the
charging current from the standard 39mA to 155mA (both measured).
It is still below the C/10 slow
rate, so it should be safe to leave the radios charging for
if you do this replacement.
I would like to hear about it.
On a somewhat related note, I
tend to collect somewhat unusual wrist watches
so I decided to buy this pair of
radios on ebay for $25.
Cool Dick Tracy wrist watch radios that I bought on ebay. They
FRS/GMRS channels with privacy code. The latter feature is
unusual among wrist watch FRS radios.