You could find a nicad charger at batteryspace for your voltage. Either a 12v one or a 24v one if you series connected the packs.
Also, RC lipo chargers do everything, Lead, nicad, nimh, and lipo. For nicad, idealy you'd have a temp sensor hooked up to the charger.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.