Voltage difference at idle

[jmauld]

Is it normal for one voltage to be at 12.9-13.1 at idle and the other engine to be at 13.8?
Above 1000rpm they bot jump up to 14.x

Both batteries are fresh, installed about two weeks ago.

 

[jgoedd99]

Is it normal for one voltage to be at 12.9-13.1 at idle and the other engine to be at 13.8?
Above 1000rpm they bot jump up to 14.x

Both batteries are fresh, installed about two weeks ago.

Wiw, on my 370 da, with engines on, the starboard side voltage is always a little lower , especially at lower speed. I attributed that to the refrigerator and other house loads being on the starboard side but I've never investigated it any further than that.

 

[Wylie_Tunes]

If one engine's battery serves as, or charges the house bank, then a heavy load on that alternator can explain the lower idle voltage.

 

[jmauld]

The house bank is two independent batteries. Charge off of the generator, or shore power.

 

[Quint4]

Sometimes a battery isolater is used on one side and has this effect.

 

[bajturner]

The house bank is two independent batteries. Charge off of the generator, or shore power.

It's two batteries that aren't connected in parallel?

 

[jmauld]

Sorry, I Meant they are independent of the two starter batteries, so they shouldn’t have an effect on this, right?

Also, is it normal for the bow thruster to be connected to an engine battery? Seems like it should be connected to the house batteries?

 

[Seapig]

Is it normal for one voltage to be at 12.9-13.1 at idle and the other engine to be at 13.8?
Above 1000rpm they bot jump up to 14.x

Both batteries are fresh, installed about two weeks ago.

My 2012 310 consistently shows starboard voltage lower than actual voltage when compared to what I measure with a voltmeter. The error is worse with engine bay heat.

I believe it’s due to faulty internal circuitry in this model of ECUs. When I look at ECU data with a scan tool, “system voltage” is displayed correctly while “battery voltage” shows lower than actual.

 

[Craig]

Its normal

 

[Seapig]

Taken at key on/engine off. IMO the two voltages should be the same. They are the same on my port ECU but not on Starboard. Measured voltage agrees with “system voltage”

My gauge and vessel view voltage agree with “battery voltage” which is inaccurate.