Cheap battery charger wanted

I just bought a Yaesu VX-7R and am looking for some cheap way to charge a spare 7.2 volt battery using a 12 volt source while it is not on the radio.

I only have a need for a few days a year and there is not time to charge the spare and the working batery on the radio during the off time. (and if there is I'm not likely to wake up to make the change.)

I don't have the radio yet. There is a "12 volt external source" cable available but all th manual says is that while on the wall wart it can't be used to transmit.

I found a camcorder lithium battery charger that charges 3.6 and 7.2 volt li-ion batteries using a 12v input. If it was a 3.6v lithium battery there are a lots of cheap chargers out there on cpf for those, perhaps one of the vendors of such chargers knows where to get a 7.2v version of the charger also.

Thanks. I solved the problem. While it does not seem to be mentioned, one of their brochures shows that a 12 volt input will both charge and allow full power.
I bought a 12 volt unit that can be used as an external source and to start cars,etc.