Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 14, 2025 ...

Re: Chassis Battery Voltage

Reply #50 – February 17, 2018, 12:18:20 pm

That should read about 13.4 volts also?

I know about being careful, I have had knuckles thumped before 

Quote Selected

Re: Chassis Battery Voltage

Reply #51 – February 17, 2018, 01:18:56 pm

IF the alternator/voltage regulator is functioning correctly,

and

IF the sense wire is connected correctly (so it sees START battery voltage),

and

IF the isolator is functioning correctly,

THEN, you would like to see at least 14.8 volts at the alternator (+) output terminal, to insure complete battery charge.  A little higher (14.8 - 14.9) wouldn't hurt, but you don't want it much more than that.  See the battery manufacturer's guidance for optimum charging voltage.  Try to set the alternator to put out optimum plus another 0.7 volt to account for losses through the isolator.

Quote Selected

Re: Chassis Battery Voltage

Reply #52 – February 17, 2018, 03:02:07 pm

Thanks I will add this to my list, i am up to about 2 1/2 pages 

Quote Selected

Re: Chassis Battery Voltage

Reply #53 – February 17, 2018, 05:08:14 pm

Once you battery banks are fully charged higher than float voltage measured at the battery is overcharging them.

If in hot weather float voltage can be 13.2 or less. 

If you drive long runs that high of an overcharge voltage can definitely damage the banks.

Wolfe10 mentioned the same voltage I ended up using.  13.6 as a compromise.

Switching to a auto combiner eliminated the isolater losses. 

Both dash digital plug in gauges show 13.5 or 13.6 driving. 

VPMS shows engine at 13.3 nominally.

Future step is a starting battery temp controlled alternator.  Then its voltage could be turned up for winter type weather max charging.

Perfect charging makes everything last longer in my experience.

Left my dash red digital battery voltage gauge plugged in with the coach stored and door switch off and combiner in auto.

Engine start was at 12.5 house was 13.6. 

Without the digital gauge on the solar and auto combiner keep both at 13.5.

Remove the gauge until at the coach it seems.

Quote Selected

Re: Chassis Battery Voltage

Reply #54 – February 17, 2018, 06:49:42 pm

Thanks Bob, I will add that to my spread sheet but that may be a project for next fall unless my current issue calls for doing it now.

Quote Selected