Do Not Deviate From Your Routine! Batt Woes

montenido · #1 (**permalink**) 06-23-2009

Hi all. I just got back from my boat and for the first time ever, I had a battery issue. I normally leave my "A" batteries on as I am plugged into shore power and have a Xantrex 40A charger. Well, today I arrived to find my "A" bank totally flat. Strange, because I checked the shore power cord and everything was as it should be. You know what I did differently last week? I flipped off the AC breaker before disconnecting the shore power. Why? Well it seems that I almost dropped it into the drink. Anyway, the boat sat for a week with no shore power, which should not be much of a problem. All the switches were off (except bilge pumps) and there was no sign off excess water in the bilge.

When I switched to the "B" bank, all was well and they showed full levels of charge. When I flipped on the AC breaker I would have thought that the charger would immediately go to full capacity for a while, but it didn't. It just acted like both banks were fine. Any ideas what I can check? I forgot to check the age of the batteries today, but they came with the boat. Maybe they were getting close to needing replacement and this event set them off?

I went sailing anyway, leaving the switch on "B" for the entire time. Everything went fine and I left it charging as normal at the dock. I will check it in a few days to see if the "A" bank was able to get a charge.

In the meantime, I am open to ideas and suggestions. It seems like anytime I deviate from my normal routines, something gets forgotten

.

Thanks in advance, Bill

sailingdog · #2 (**permalink**) 06-23-2009

Some battery chargers won't charge a totally flat battery bank. What was the voltage on the A bank???

montenido · #3 (**permalink**) 06-23-2009

SD, according to the built-in gauge, "A" bank was zero volts. About as dead as can be. I didn't check it with my meter because I was pressed for time (as usual). So, chargers don't like dead batteries, huh? Go figure.

Thanks, Bill

US27inKS · #4 (**permalink**) 06-23-2009

Even a battery charger that will charge a flat battery takes a while to get going. With a large roll around automotive battery charger capable of 40 amps, it takes a while to bring one off zero.

camaraderie · #5 (**permalink**) 06-23-2009

Did the battery just go flat all by itself in a week...or was bilge pump, lights, fridge etc. on to draw it down?
If it went flat all by itself...don't bother recharging!

sailortjk1 · #6 (**permalink**) 06-23-2009

I'm thinking along the same lines as Cam.
Why would it die completely after only one week?
Might be better served to start fresh.

JohnRPollard · #7 (**permalink**) 06-23-2009

Another thought I had was whether the battery is truly flat. Could you have a bad reading? Or did you actually try to use it?

Over the course of half a dozen years I've had one or two instances where the voltmeter display panel temporarily indicated zero on one or the other of our batteries. Fortunately, it always turned out to be an electrical chimera and the battery was fine upon re-checking.

macduff · #8 (**permalink**) 07-11-2009

I would caution about leaving your shorepower charger on while you are away from the boat. I did that for a week and came back to find the battery gassing and almost red-hot and accepting high amperage from the smart charger because it had become suphated and the smart charger couldn't recognize that fact. I was lucky the boat didn't burn up. I've turned to using a small solar panel to supply a small trickle charge to the battery while I am away.