Battery Drain Ideads needed

[eshasek]

I am new to the forum (2002 260 DA) and am very interested in thoughts on comments about a battery drain issue I had this weekend.

I purchesed and had professionally installed two new glass mat batteries in Feb. I have run my boat no less than every two weeks over the winter and the volts looked strong all the way out to Caladisi Island Marina this past Saturday. We left the battery switch set to "both" and walked to the beach for about 2 hours with no equipment running, just he main panel was on. No other breakers were on.

When I returned the CO3 moniter was giving a low battery cherp and after investigation I realized that the volt gauge was at zero!

I connected to shore power and turned on the AC converter for 2 hours to get to 10 volts, then turned her over with the shore power still connected. She fired up slowly but made contact. I unhooked and reved the engine in idol till we read 12 volts then headed home. volts were back to 14 after a 4 mile run. and everything was fine when I re-started the engine to flush at home.

Any ideas as to what happened???

 

[Sundancer]

First of all you defeated the purpose of the "both" position. When running to charge them it's OK, but I used to charge one battery at a time. If they were in the both position you could have had water in the bilge from a leak, a toilet issue (vacuflush?), water pump running, fridge door left open, or a combination of things that would kill both. One battery may not be charging off the motor and the other could be draining into the other battery trying to charge it. There are a host of things that could have depleted the battery. I'd do a similar test with one battery at a time and see if one drains quicker than the other.

 

[eshasek]

Okay. That makes total sense. I guess I am in the habit of running on "both" to keep them topped up, and should have switched to 1 when we were sitting. I also read int he owners manual that even with the battery switch off, power is still available to the bilge pump and the stereo memory. So I guess I am more comfertable leaving the boat on one battery knowing that if it is depleated the other will still be able to power the bilge or start the boat in a critical situation.

Having said that, I am still suprised that both drianed in less than 2 hours. In addition to all equipment being off (above), I also confirmed that the vacuflush was off. I think I will be taking it in for an electrical inspection this week to be safe.

 

[Sundancer]

That is suspicious. Maybe a float switch on the bilge was stuck or there is something else going on. It's hard to say. Keep us posted, we'd love to know what was wrong so we can check our own boats too!

 

[Lazy Daze]

Definitely suspicious. If your batteries died in just two hours, something is wrong - much more than just leaving an accessory on. The radio won't even kill one battery in two hours. Heck, you could run the fridge for two hours (and more) and still have plenty of juice to start the engine.

But, if you want to be sure you don't have too much parasitic draw, you could do an amp-draw test. Shootin' from the hip here a bit, but IIRC, you should see somewhere around 50 to 100 milliamps.

I'd suggest you get your batteries load tested, just to be sure. I know you mentioned they're new, but weirder things can happen.

 

[tobnpr]

Okay. That makes total sense. I guess I am in the habit of running on "both" to keep them topped up, and should have switched to 1 when we were sitting. I also read int he owners manual that even with the battery switch off, power is still available to the bilge pump and the stereo memory. So I guess I am more comfertable leaving the boat on one battery knowing that if it is depleated the other will still be able to power the bilge or start the boat in a critical situation.

Having said that, I am still suprised that both drianed in less than 2 hours. In addition to all equipment being off (above), I also confirmed that the vacuflush was off. I think I will be taking it in for an electrical inspection this week to be safe.

You should install a battery combiner which will parallel the batteries when charging (allowing both to charge, whether by alternator or charger), and islolates them when not being charged.

http://www.defender.com/product.jsp?path=-1|328|51495|606044&id=605576

Once you have a combiner installed, there are a number of ways to assure a fully charged starting battery. Rather than having to keep switching the battery switch back and forth, I recommend connecting everything EXCEPT the engine to one batt, and the engine ONLY to the second battery. This way, no matter what you do you'll always have a fully charged starting battery. The only time you'll ever need to use the battery switch (to "both") would be if you need to parallel them in the event your engine-only starting battery fails for some reason. My $.02.

BTW- you picked a great day for Caladesi (make that the only decent day in months!) Figures... have my MIL visiting...

 

[eshasek]

Okay, here is the deal. I talked to Ron Piper today at Piper Marine in Tampa today (shameless plug because he took the time to talk to me without hesitation). He suggested a simple test that I did tonight that isolated the problem.

As you see in my original post, these are new Optima glass mat batteries purchased Feb. 2010. They are rare to fail, but knowing everything was just services not 2 months ago he wanted me to attempt a start tonight on each battery separately after they had sat cold for two days.

Just got back from the yard, and I am happy to say that I got a strong start on Battery #1 and #2 was dead to rights.

Apparently I have a rare defective optima battery that is now int he back of my truck to be replaced under warranty. When I let the boat sit with the switch on "Both" the defective battery drained the good battery very quickly.

Actually, they are both in my truck because I couldn't figure out which one was #1 or #2. I wouldn't mind them both being checked anyway if they are from the same batch.

This is about the best possible outcome, because the fix costs me just an hour or two of my time pulling and replacing the batteries and driving around town a bit.

Thanks for all of the suggestions above. Hope to see some of your Tampa area folks out on the water.

 

[ChuckW]

Good lesson learned for us all. Thanks for sharing...