How to get power only when ignition is on?
I want to install two battery gauges in my dashboard, one for the engine battery and one for the house batteries. The charge/discharge gauge in the instrument cluster no longer works. I could just...
Forum Discussion
I'm assuming your "battery gauges" that you wish to install are voltmeters, not ammeters. The broken gauge on your dashboard may be an ammeter (i.e. it shows whether the battery is currently being charged or discharged, not the voltage present in the electrical system). If they're ammeters, you may not need separate power supplies to the meters, but you do need a shut or some other current sensing device to measure the current.
If they're voltmeters, and you have a somewhat typical sort of battery isolator that connects the two electrical systems together when the engine is running to charge the house battery, you won't really get much useful information from the separate meters. They'll show the same voltage as each other, minus whatever line losses occur between the batteries. You would be able to see if the isolator relay was not connecting properly, but that's about it.
A simple pushbutton for each meter to turn it on momentarily might be more useful in general, truth be told. You could then check on them at any time, parked or not, and ignore them otherwise (and not have possibly bright readouts blazing on your dashboard when you're driving at night).
If they're voltmeters, and you have a somewhat typical sort of battery isolator that connects the two electrical systems together when the engine is running to charge the house battery, you won't really get much useful information from the separate meters. They'll show the same voltage as each other, minus whatever line losses occur between the batteries. You would be able to see if the isolator relay was not connecting properly, but that's about it.
A simple pushbutton for each meter to turn it on momentarily might be more useful in general, truth be told. You could then check on them at any time, parked or not, and ignore them otherwise (and not have possibly bright readouts blazing on your dashboard when you're driving at night).
