Extra 12 volt battery
Anyone carry a cheaper 12v car battery in case regular battery won't start vehicle. I have a conversion van made into a camper. Also have an extra interior battery, charged by solar, to run various( ...
Forum Discussion
I had a rather more lengthy reply, but it basically said what smkettner said while using a lot more words, so I've trimmed it down.
The usual practice is to have only the engine and vehicle related loads on the starting battery and everything else--everything that might be used while parked/camping--on the house battery. That way camping won't run down the starting battery, and the two batteries can be types best suited to their duties (deep discharge for the house battery, and a starting battery capable of supplying high current for the chassis). There's usually an isolator device to permit the vehicle alternator to charge the house battery; this is either a high current diode or a substantial continuous duty solenoid (relay) controlled by the ignition switch. If it's the relay type, it's easy to also add an emergency start button to temporarily connect them and have a sort of built-in jumper cables if your starting battery is dead for some reason while the house battery is charged.
The usual practice is to have only the engine and vehicle related loads on the starting battery and everything else--everything that might be used while parked/camping--on the house battery. That way camping won't run down the starting battery, and the two batteries can be types best suited to their duties (deep discharge for the house battery, and a starting battery capable of supplying high current for the chassis). There's usually an isolator device to permit the vehicle alternator to charge the house battery; this is either a high current diode or a substantial continuous duty solenoid (relay) controlled by the ignition switch. If it's the relay type, it's easy to also add an emergency start button to temporarily connect them and have a sort of built-in jumper cables if your starting battery is dead for some reason while the house battery is charged.
