Engine instruments and Voltage

I notice that when my batteries are not fully charged and the alternator is charging my batteries, the engine instruments read higher than when the bank is full.

Anyone else experience this? I assume it is because of the higher voltage. while it is just a minor inconvenience, I am considering putting in a voltage regulator for the instrument supply to prevent this from happening. Has anyone done this?

hobbystuff said:

I notice that when my batteries are not fully charged and the alternator is charging my batteries, the engine instruments read higher than when the bank is full.

Anyone else experience this? I assume it is because of the higher voltage. while it is just a minor inconvenience, I am considering putting in a voltage regulator for the instrument supply to prevent this from happening. Has anyone done this?

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That is just the nature of temperature and oil pressure systems. I would just realize its there and not worry about it.

Adding a voltage regulator to the circuit IMHO just adds a single point of failure to your engine instrument system.

Have you calibrated them vs mechanical gauges to see which, if any is the right reading? Is that possible on your boat/engines, to have mechanicals in addition to electricals? I really got to appreciate having mechanicals in the ERs to validate what was really happening, exactly.

Electric gauge readings will vary with things like voltage and current going through ground loops. You can run a dedicated ground from gauges to engine block and that sometimes minimizes this. Or just live with it and recognize it as normal behavior, and note when things go abnormal.

Biggest thing is make sure your high coolant temp, high mixer temp and low oil pressure alarms work. Many engines ruined by alarm systems that did not work. Most folks do not watch gauges enough to catch a transient. They can happen fast.

I think I'm just going to live with it.