House Battery Dying Fast

[nvuocolo]

Have a 2023 AR250, first boat I’ve ever owned. This is the first time I’ve prepped for the season after winterizing. I reconnected the batteries myself. I noticed immediately the house was running at 11.4, and the cranking battery was at 12.4 like usual. I ran the boat for probably 3-4 hours to burn up the fuel, I did some fishing in float mode and suddenly the alarm for the house battery went off. I fired up the boat and headed in and during that time the house was dying fast and I mean, fast.

I called the dealer and they told me I need to make sure the tiny black wire was reconnected. When I looked I noticed it wasn’t connected when I hooked up the batteries. When I turn on the batteries while out of the water the blower alone will drain that battery incredibly fast.

I did test the battery with a meter and it shows 11.3-11.4 volts. My questions are, do you think the house will recharge once I put it back in the water and run it? And can anyone explain or provide any more information on what this tiny wire does?

Please forgive my ignorance I know I’m a newb and the only way I’ll learn is by reaching out. Any help would be GREATLY appreciated.

 

[BlueBulls]

Check your voltages with a voltmeter to be sure, my Connext never seems to be super accurate (it sucks at everything, really). If 11.3v is accurate you are in the range of potential long-term damage depending on how long it was allowed to be that low. If the batteries are identical and were not kept on a charger over the winter the voltage difference between the two is definitely a concern. If your dealer actually gave you a deep cycle battery for the house you will be in a better place in regards to potential cell damage.

The stators on these motors are not alternators and seem to struggle at recharging depleted batteries, and especially at idle or low RPMs. Recharge them both with a charger and invest in a long-term solution like an onboard charger for use in between trips or over the winter. Your engines and electronics will thank you as well - these boats are very sensitive to voltage issues.

A fully charged lead-acid battery will not freeze until almost -100 degrees - I keep a charger on mine all winter and they never come off the boat. We get down to about -10 here in East Tennessee. Come to think of it, where were yours stored over the winter? If they were outside at all in New York and not fully charged all winter that may be the issue.

BEP diagram just to help make sure all the wires got back where they belong.

 

[Bottom Bracket]

This is the wire that has to be hooked up to the negative post of the house battery.


An onboard battery charger will help with this challenge, ask your dealer.
Until then you might want to pick up a portable charger to keep
Your house battery topped off.
I like the battery tenders for a maintainer that I move from vehicle to vehicle.
I use a noco 2x2 for an on board charger/maintainer.

 

[bobholthaus]

Okay, I see that that black wire is connected to my Start battery negative. Is that why my BEP has the red light on randomly? Does “Common Battery” mean the house battery?

Second question: my onboard ProMariner ProSport 12 dual battery charger became disconnected this winter (plug at the dock needed to be wiggled; didn’t check this all winter, which I now realize is a total screw up (and likely costly)). When I opened the boat this weekend, Start battery was at like 8.5v, house battery was at 12.5v. Since I bought this boat new in 2020 (242SE). I have thought that the BEP was wired incorrectly, and/or there is some parasitic drain on my battery (which I see now is clearly the Start battery, since it appears dead). The charger has been on it for 48 hours; when I just got here and I turned the key on (after disconnecting charger), the House stayed at 12.8 but the house got down to like 11.8 (and may have been dropping still - I’ll update this in an hour). When I went to start it, there wasn’t enough voltage to turn it over (it wouldn’t even crank); I switched the Emergency Parallel and the Connext showed 12.8 on both batteries and it fired right up.

1. Did I kill my AGM battery this winter by having it discharge to the 8s?

2. Is my BEP wired incorrectly since the little black wire is wired to the Start battery?

3. If so, could this be my parasitic draw?

4. When I got here this morning, the red “combined” light was on on the BEP. This light is randomly on at times that it doesn’t seem like it should be on; this is why I’ve thought this system was not correct since I bought it. Could it all be because the little black wire was on the wrong battery? I’m googling that now; the pic above is not clear to me where that little wire should go.

5. I’ll leave the ProMariner 12 hooked up all week to see if the Start battery will hold more of a charge next weekend. I leave for vacation for 10 days of boating on Lake Michigan next week and won’t have the ability to charge the batteries each night. I’m considering just swapping my House and Start until I get back from vacation.

What else should I be thinking about? Thanks guys.

Update: I put marker tape around every wire when I installed my upgraded AGM batteries in 2020, to “ensure” I got them all back onto the correct battery. And I now see that I had a marker on the little black wire, telling me that it was initially connected to the House battery. I just moved it.

And my Start battery is down to 11.5 after 30 min. I’m guessing I killed it. I’ll leave the charger on it all week and will see where it sits next weekend. Expensive mistake not checking to ensure the charger was running all winter. Next winter I will remove all of the cables so there is no chance of parasitic draw all winter, in case this happens again. I know I should take them out and put them in my basement all winter, but they’re so damn heavy and is a big pain in the butt. More of a pain than this?! Good question.

 

[Bottom Bracket]

Well you could rip out all that mess and replace it with 1 big lifepoop battery and a perko switch or 2.