House batteries not holding a charge

brandonmayberry

My Rinker 342 has 3 sets of batteries. I assume two batteries for port, two for starboard and the other two i know are for my house batteries. The house are 31 series batteries that were replaced 8 months ago. Both batteries there tested good. When the charger is on and connected to shore power or on the generator they show a proper voltage but then drop to around 11.8 or lower very quickly.

 The issue that made me discover this is that the amps for the stereos will shut off. I can leave the boat on the shower power with charger on all week and then head out in the boat and within usually 15-20 minutes the amps will shut themselves off because of lower batteries. They do this even when im driving the boat. I thought the alternators running should be charging them and i shouldnt have that issue. I also know its not the amps that are bad because the CO Detector started beeping like it does when batteries are low.

We were on the dock overnight till monday then went out and within a few hours the batteries were low enough to cause the Co detector to go off and we werent even running the stereo at that point due to it shutting off so much.

I had both batteries tested multiple ways and they test good. Not sure where to start at.

Thanks

skennelly

Perhaps the isolator is bad causing both batteries to drain?? And then not charge from the alternator.

brandonmayberry

That would make sense about the alternators not doing the job and i will look into that but i wonder if it would be the issue since i can be on shore power and get a full charge and they seem to still drain very quickly.

skennelly

The only thing I can think of is if one of the batteries is bad and not holding charge and the isolator is bad that it would want to drain all the other battery's.  The isolators job is not only to allow the alternator to charge all the batteries, but also "isolate" all the batteries from each other so one bad battery doesn't drain the others.

Stodge

That's a whole lot of batteries.    I only have 4: 1 starting battery for each engine, then 2 G31 in parallel for house.  I've not have any issues with starters going dead.  I anchor out on the hook over night and have had the house get so low the fridge stopped working.  Part of that was the fridge being old and freezing solid.  We had our first night on the hook with the new fridge and it seems to have helped there.  

I'd check the settings on the fridges.  Might be able to turn them down a little to lower the load.  Also look at anything you leave on over night (light in head, TV, etc.).

brandonmayberry

I haven't adjusted anything since the problem started but the settings were all the same when the issue wasn't present as well. Maybe one of the fridges is going bad and causing a huge power draw. 

Stodge

Easy test is to turn them off at the fridge and see how your house holds up.  

I also have 12V TV and antenna amp.  The amp runs all the time.  Granted it should be a small draw, but little stuff adds up.

Good luck.

Black_Diamond

Three (3) sets of batteries?  dang.  2 house (31's) and one for each engine (24's) on my 342.  No way you need 2 batteries per engine.  JMO

The batteries were load tested at like an auto parts store?  If you are dropping voltage that fast there is either a large load on them (stereo / amps can be the biggie) or the battery(s) are faulty.  Are they filled with water too?

brandonmayberry

They are interstate brand maintenance free batteries so no water. They were load tested on both by the marina and at Oreilly's by their auto meter tester. 

And yea yea for some reason each engine has two batteries. Not sure why they did that but I'm not one to change things if they are working. I think I'm going to try turning each fridge off and see how they act. 

Handymans342

What voltage are you seeing when plugged into shore power and charger on? Does your charger have an amp meter on it?

brandonmayberry

it has the digital meter on the panel and it shows around 13 if i remember correctly. I do know that it drops to below 12 within 15 or 20 minutes.

Handymans342

That's not right. My charger will let the batteries drop to 12.6 and then start charging back to over 14 volts before it drops back down. 

brandonmayberry

That could be an issue with the charger, gauge or isolator i guess. Im going to take a meter down to the boat and test them this weekend and see how much im getting from the charger and alternators. They dont charge through the alternators at all it seems.

brandonmayberry

Well i think i discovered the problem. It infact was not the house batteries, rather the issue is that the amplifiers are wired to a separate set of batteries that i thought were for my starboard motor but dont appear to be so. I tested those batteries and they are bad. Im going to replace them and then spend an afternoon figuring out my mess of a battery situation. Im not sure which batteries are controlling what anymore.