Why my engines draw much amps?

[CassidyNZ]

Originally Posted by Suddy

You do realize that when your engine is running, the alternator is charging the batteries and you will see a negative current because of this. Current out is displayed as positive and current in is displayed as negative.
Greg

Must be something dramatically wrong with my system. When my alternators are charging I get a positive amp reading. What do you mean by “current out” and “current in”? Out from and into what?

On my battery monitor, there is only one connection to the negative pole on the battery bank and that comes from the monitor shunt. Every 12v device has its negative connection to a bus bar (in my case via the main switch panel) which feeds back to the other side of the shunt. Thus every single bit of 12v power used on the boat flows through the shunt and registers on the monitor. If there is any 12v device on the boat that has a negative connection directly to the battery, that current draw will not be shown on the monitor.

To the OP, you may have all your 12v draw running via the shunt and the alternators running directly to the battery bank. In this case you ammeter/battery monitor will always show only amps flowing out because it can’t see the incoming amps from the alternator.

How you fix it is specific to your boat and you’ll need to examine the circuits to see what needs to be changed.

[Wotname]

Originally Posted by CassidyNZ

Must be something dramatically wrong with my system. When my alternators are charging I get a positive amp reading. What do you mean by “current out” and “current in”? Out from and into what?

.........

It is a pertinent question for those who are less than electrically literate!

CassidyNZ, I realise you are electrically literate so the following is for other readers...

Convention has it that current delivered the charging source and entering the storage device is a positive flow and the current being delivered by any source to the load is negative. A battery can considered as a source or a load but is better considered as a storage device.

In a compound system where there are multiples sources (alternator, PV panels, wind turbine etc), storage devices (house batteries etc) and loads (lights, electronics, refrigeration etc), then the convention is if the load currents is greater than the source current, the current to/from the storage device(s) is negative (battery is discharging). Likewise if the source currents exceed the load currents, (i.e. battery is charging), the current is considered to be positive.

JMHO!!!