Battery Voltage Monitor
Built this little battery monitor a while back. I picked up the readout at a flea market for $4 and mounted it in a small box. The switch on the side turns the display on/off. Sure makes for a quick ...
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Just as an adder: That great little digital voltmeter link I gave the link to above earlier - besides being ultra-reliable for the last 5-6 years and inexpensive - did not get neatly built into a panel in the coach on purpose.
I just Velcro'd it to the dash and routed it's long lead back to a 12V receptable in the coach area that was the closest to the cab dash.
I did this so that I was just monitoring voltage on the coach battery terminals ... but for convenient and good-enough simultaneous monitoring of the voltage of both 1), the coach batteries while driving or camped and 2), the RV's 12V system while driving or camped (bearing in mind that this monitored voltage could at times read a bit low versus actual coach battery terminal voltage whenever 12V items in the motorhome were being powered and hence dropping the voltage along the line leading to the coach 12V receptacle where the voltmeter was plugged in).
The most important parts of the 2) reason were: To keep an eye on the main engine alternator's voltage indirectly by watching what was winding up on the RV's 12V system with the engine running, to keep on eye on the condition of the contacts in the inter-connect solenoid between the alternator and the coach batteries, and to keep an eye on whether or not I had turned the coach battery switch back "ON' after refueling the motorhome so that the refrigerator would continue to work while traveling.
So far this dash mounted voltmeter has saved our bacon once ... by indicating why the coach batteries were not getting charged between campsites due to a bad solenoid with corroded/oxidated contacts, and saved our bacon many times ... by indicating that the refrigerator was not working while traveling because the coach batteries had not been reconnected to the coach system after refueling.
I just Velcro'd it to the dash and routed it's long lead back to a 12V receptable in the coach area that was the closest to the cab dash.
I did this so that I was just monitoring voltage on the coach battery terminals ... but for convenient and good-enough simultaneous monitoring of the voltage of both 1), the coach batteries while driving or camped and 2), the RV's 12V system while driving or camped (bearing in mind that this monitored voltage could at times read a bit low versus actual coach battery terminal voltage whenever 12V items in the motorhome were being powered and hence dropping the voltage along the line leading to the coach 12V receptacle where the voltmeter was plugged in).
The most important parts of the 2) reason were: To keep an eye on the main engine alternator's voltage indirectly by watching what was winding up on the RV's 12V system with the engine running, to keep on eye on the condition of the contacts in the inter-connect solenoid between the alternator and the coach batteries, and to keep an eye on whether or not I had turned the coach battery switch back "ON' after refueling the motorhome so that the refrigerator would continue to work while traveling.
So far this dash mounted voltmeter has saved our bacon once ... by indicating why the coach batteries were not getting charged between campsites due to a bad solenoid with corroded/oxidated contacts, and saved our bacon many times ... by indicating that the refrigerator was not working while traveling because the coach batteries had not been reconnected to the coach system after refueling.
