Alternator not charging house battery and strange electricity power outages (M-ACR)

[jonatande]

Dear commnity, New boat owner and already ran into problems so seeking out for advice and would really appreciate your feedback!

I have a problem with ACR not charging my boat.* Thought first it was bad battery but then I realize it seem to be more complicated. See attached pic for how everything is wired.

Symptoms:
1. Engine stopped and couldnt start again when I activated the trim planes - The trim planes are bypassing the ACR and goes directly to house battery. If house battery was bad how come it also affected the start battery making the boat unable to start again?
2. Next day it started and trim planes were functioning properly
2.* 14 days later couldnt start my engine when (No clicks) which is connected to the start battery. However, it started when I changed the position of the batteries and the "bad 12.34v" battery was set to start battery and the better battery 12.64 was set to House battery. Really strange yet again...

Testing:
1. Batteries are 12.34 and 12.64 correctly
2. Only the start battery charges when engine is idling (Voltage above 14) - House battery voltage is only affected by the trim planes activation.
3. M-ACR does not light up indicating "charging" when engine idling
4. Trim planes connected to positive house battery but negative start battery - problem if ACR not working propertly?

Spec:
Engine Mercruiser 3.0 TKI
ACR: Blue system M-ACR

 

[Simi 60]

Welcome and have fun (-;

 

[TowLou]

Check ground to your ACR. Is there a ground to the switch to. Need that for the led to function. Has the acr ever worked for you?

 

[Mischief Managed]

I think there's a loose or corroded "ground" connection where all the battery - terminals are connected together. Might be on the back of your engine on one of the bell housing bolts, Mercruiser uses those bolts as a ground bus.

 

[kchace]

I'll add, if the LED on the ACR is not lighting up, then the ACR is not closing. Note that it takes up to a minute AFTER charge voltage is present for the ACR to close.


I second to recheck the wiring. There may be a poor connection someplace and/or it may not be connected as you think it is.


While it will work either way, IMO if your wiring diagram is correct, the ACR is connected to the wrong side of the battery switch. The "B" side of the ACR should be connected directly to the house battery.



Ken

 

[SteveK]

Maybe this will help. ALT should go to house battery side first.