Battery/Electrical help requested

[SailorChlud]

Good Day:

Requesting help determining if my battery is bad, or my Blue Seas ACR module is bad, or what?

This weekend I took out my Seafari after it sat for 3 weeks unused, and noticed that my 2nd battery was dead. It is 3 years old, and had been functioning properly up until now. Upon testing, the voltage read 8.8 volts DC. My starting battery was fully charged (I keep that one on a solar trickle charge).

The boat is a single outboard with two batteries - starting and auxiliary, and is wired according to the attached diagram, with a Blue Seas Automatic Charge Relay installed between them

Before I buy a new battery, it occurred to me that I should test that my outboard is outputting the correct charge, and the Blue Seas ACR is sending the proper current to both batteries. Does anyone know how to test that? I have ammeters and voltmeters.

[erebus]

The ACR wont auto-connect the second battery to the main battery if the second battery is below a certain voltage. Hence no charge to second battery. I think its less than 11 or 10? Cant remember.
8.8 will definitely not work.

Sometimes you can fake out the ACR by putting jumper cables or a jump pack onto the low secondary battery while the primary battery is being charged by the power source (battery charger, outboard, alternator etc).
Once the ACR sees that the secondary battery is in a good enough state to charge it will auto-connect, and if you let it charge for awhile should come right back up (as long as the battery is ok).

You can hear the ACR make an audible click when it connects the two batteries.
Also the LED on the front of the ACR will clue you in to what its doing.
I think triple flash means auto disconnect due to low voltage.

While the outboard is running you can check the output of the stator at the battery or the starter. See if you've got 13 volts plus.
Then check at the back of the ACR. Should have charge voltage on one side, and then when the ACR connects charge voltage on the second side.
The ACR is essentially just a solenoid switch so no real chance of it killing the battery or anything.
Also check the ground wire to the ACR.

[SailorChlud]

Thanks - I did not think to look at the ACR while on the water to see if the LED's were lighting up. I do see that the ACR will not charge when the one battery gets below 9.9 volts, so clearly it would not have charged it last trip while the battery was below that. I am just not sure why the battery dropped that low. I charged it overnight and it came up to only 12.06 volts after 12 hours, so I think it is the battery. Thanks for the help!

[erebus]

If you suspect its the battery, best thing to do would be to give it a load test.
I've seen batteries happily charging away at 13 volts and holding 12+ when disconnected, then give them a load test and they immediately drop to 8 or less.
Only taking a superficial surface charge. Bad cell, or the cells are sulfated...
Just a thing that happens to batteries sometimes.



https://www.amazon.com/OTC-3180-Batt...6918388&sr=8-4

[fishstu]

My 12v battery (in good condition) charge to 13.2v straight off the charger and drop a little over time.
Good post - I leant about Battery voltage Load testers

[SailorChlud]

Thanks for the help.

The bad battery will be replaced this weekend. Good cruising weather coming up in NJ.