Dual battery question

[fj40scottb]

First time boat owner and I'm still learning the ins and outs. I have a 2012 SAN230TE with dual batteries. I've just been using battery 1 and all is good. Over the weekend I selected battery 2 and the system booted and when I go to fire the engine, the system just reboots. If I select battery 1 or battery 1+2, engine fires fine. Is this normal? Are you not supposed to be able to run on just battery #2? I tested voltage at both batteries and they are slightly over 12v. I was thinking of swapping the batteries 1 for 2 and see if the issue follows. Perhaps battery 2 is good but under load of turning the starter it is not strong enough. Any thoughts for a rookie?

Thanks!
-scott

[charlesml3]

Battery 2 is either dead, bad, or there's a bad connection to it. Check ALL of that. As it is, you have a boat with ONE battery.

One sure sign of a bad battery is it'll provide voltage for the lights, radio, etc, but as soon as you hit the starter it drops out. This would explain your reboot.

At any rate, get this sorted. The last thing you want is to be out in the middle of the lake and have 2 dead batteries.

I have the same setup in my boat. Here's what I do:

- When I get in the boat, I look at the calendar on my phone. Even number days I switch to: Battery 2. Odds, switch to Battery 1. This more-or-less uses each battery evenly and keeps both fully charged. That way I always have a fully charged backup.

-Charles

[fj40scottb]

Thanks that is what I was hoping to hear. I'll chase it down. Thanks.

[charlesml3]

Thanks that is what I was hoping to hear. I'll chase it down. Thanks.

Please come back and let us know what it was. We all like a good troubleshooting resolution.

-Charles

[core-rider]

If you have always kept the switch on #1 and never had #2 on a charger of any kind then your battery is dead or bad. With it being isolated from the alternator it will not be charged. Depending on how long it's gone without a charge it may not hold a good charge anymore. I suggest charging the battery and giving it a try.

I typically always run on all batteries unless sitting for a while playing stereo etc, then I will isolate systems to make sure I have a good battery to start on if the stereo kills the other battery.

[scottb7]

I agree with above. I simply start the boat and run the boat on 1+2 all the time. Except when I park and listen to stereo then I randomly pick one of the 2 batteries to isolate.

[MLA]

If this a new to-to-you boat, I would probably just consider replacing them as you may not know their age or use history,

With that said, still need to find out why the boat wont operate on #2 alone. Could be bad cable, connection, switch or battery.

Also, those numbers after the decimal are important. Huge difference between say 12.2V and 12.8V. Like about 50% capacity.

[shag]

Agree with MLA. If I get a new (used) boat, unless I am for sure the age of the batteries - I just start off with two new freshies. I just alternate batteries each time I go out.

[fj40scottb]

Yea, all good points. All winter I kept both batteries on battery tenders so I was kind of assuming hoping) they were good. I'm going to so so testing and see if I can isolate it to a weak battery. That would be great if it's that easy. I agree and think I will just replace both batteries and ensure a good baseline.

I originally asked my question as I have and have had some old rock crawlers and off road trucks with dual battery setups and sometimes the second battery is wired up as just an accessory battery. I found the battery controller box in the boat and assume that the alternator charge is routed to both batteries as necessary. So yea, I'll always run it on 1+2 once I've got the baseline.

Thanks for all the responses. I'll post up once I've solved it.

[fj40scottb]

Yup, turned out to be a bad battery. However the negative terminal on battery #2 was cracked and broken it just fell apart when I put a wrench on it. So I suspect that caused the battery issues and ended its life earlier than it should have. Crimped on a new terminal end, and swapped in 2 new batteries and we're good to go. Headed to the lake on Saturday.

[HS]

I agree with above. I simply start the boat and run the boat on 1+2 all the time. Except when I park and listen to stereo then I randomly pick one of the 2 batteries to isolate.

+1

[srock]

Battery 2 is either dead, bad, or there's a bad connection to it. Check ALL of that. As it is, you have a boat with ONE battery.



I have the same setup in my boat. Here's what I do:

- When I get in the boat, I look at the calendar on my phone. Even number days I switch to: Battery 2. Odds, switch to Battery 1. This more-or-less uses each battery evenly and keeps both fully charged. That way I always have a fully charged backup.

-Charles

Brilliant! The heck with a fancy combiner/joiner/whatever. The odd/even day is such a practical idea I am going to employ it to my routine.
I like that you pushed the envelop even further when you noted that you reference your phone calendar first . I will be sure to footnote you if anyone ever asks which way do I flip the switch.

[KingsX5]

Another question, when boat is in storage and plugged into the boat charger, do you leave the battery switch in the "off" position?

[fj40scottb]

Another question, when boat is in storage and plugged into the boat charger, do you leave the battery switch in the "off" position?

I do.

[charlesml3]

I do.

Me too. When the boat is back on the lift the switch goes to OFF.

-Charles