What should my battery voltage be at idle and cruising down the highway? (1 Viewer)

[kcjaz]

So I’ve never really monitored my battery voltage too closely. I run a single lead acid TrueStart battery and do not run any significant house loads like a fridge or anything. I added a battery voltage meter to an OBDFusion dashboard and have noticed that it reads 13.2v at idle and 13.2v 2200 rpm running down the highway. That does make sense to me and I wonder if the OBD reading is not updating or something. 13.2 also seems low to me for idle. While driving the dash voltage gauge reads one tic under 14v, so about 13.4v. I need to check with a multi meter and see how it compares at different rpm’s. When I do this, do I just put the multimeter leads across the battery terminals or do I need to connect the leads to the alternator terminals (given the location of the alternator, that seems difficult)?

 

[TeCKis300]

So I’ve never really monitored my battery voltage too closely. I run a single lead acid TrueStart battery and do not run any significant house loads like a fridge or anything. I added a battery voltage meter to an OBDFusion dashboard and have noticed that it reads 13.2v at idle and 13.2v 2200 rpm running down the highway. That does make sense to me and I wonder if the OBD reading is not updating or something. 13.2 also seems low to me for idle. While driving the dash voltage gauge reads one tic under 14v, so about 13.4v. I need to check with a multi meter and see how it compares at different rpm’s. When I do this, do I just put the multimeter leads across the battery terminals or do I need to connect the leads to the alternator terminals (given the location of the alternator, that seems difficult)?

It's a temperature compensating alternator. I've seen it level out in the range of just under 13V in really hot 95°F+ weather when idling, and when the engine bay gets really hot. When coming to stop at a light, I can see it drop .1V or so from cruising voltages, as the thermistor heats up at the alternator.

13.2V is pretty normal.