Free: Contests & Raffles.
Got a picture of what the old on looks like, and the specs on it? Voltage, or number of smaller batteries in the pack? Amps?
I would think AA are 1.5 volts so 5 would be more than 6 volt but 7.5 might still be in range. Solder some wire in series + to - ets then to the connector. Use rechargable batteries which may be a little less voltage. Do you have the charger. ??
Ni-cad rechargable batteries are only 1.2 volts each, unlike alkaline batteries that are 1.5 volts each. So five ni-cads would be 6 volts. Don't know if ni-mh or lithium-ions are the same as ni-cads or not.