Battery discharge

rasbury · September 6

I always seem to have dead battery issues...I made sure I had the vhf off- nothing on and start battery is dead, house seems fo be fine. I've read this could possibly be something to do with the alternator? It sat for about 3 weeks...

Ian · September 6

Mercathode?

captkevin · September 6

How old is battery?

rasbury · September 6

I put two new batteries in probably 2 years ago..Just old leaders...I've only run it a couple of times. All the wiring I'm sure is orgional...including the alternator.

Aqua_Aura · September 6

You could take the batteries to be tested or just disconnect them if you're going to be gone for awhile and see how they work when reconnected. If they are dead then it's the batteries. If they work fine then there must be a draw from something.

Have you methodically gone thru everything to be sure what you think is off is actually off. Is the boat connected to shore power and being charged? If you're not on shore power I would shut the battery switch off. Your bilge pumps should still be powered on this situation.

rasbury · September 6

Yes @Aqua_Aura best I can. It's a 270 so not lots of add on things other than factory. I turn off the battery switch always. Bilge and vhf are the only things I see staying on...

Aqua_Aura · September 6

I would disconnect the negative on the batteries then and see what happens or take them to be tested. Just my 2 cents or maybe it's 5 cents now with inflation 🤷🏾‍♂️

I see you said it's just the start battery. I missed that the first time. The alternator could have abad diode. I actually had this happen on my Chevy Tahoe and you can use a test light to check it. With the batteries on you can check across the alternator and if it lights up the diode is bad. Look it up on YouTube and you'll see what I'm talking about, I'm probably missing some finer details. Basically you get a draw off the alternator because the diode is allowing power the wrong way.

This actually happened when my wife was out of town by herself camping and she diagnosed it based off may same advice of the diode and she replaced it by herself parked out in the woods 😊. I forgot about that story and solution until now.

Lake_Bum · September 7

So......you have a Perko switch that you shutoff every time, and the batteries are still dead? Weird. Unless you're talking several months inbetween starts.

rasbury · September 8

Thanks for the input..@Aqua_Aura that's kind of what i had read- but figured way over my head to figure out- I'm rethinking that and will look. @Lake_Bum today it was just the starter battery- not sure how much juice was in the house. It was probably about a month since it was out. Most of the time the spans between use were pretty large. They seemed to have charged and will run the river a bit am...

PickleRick · September 8

Do you not have auto bilge pumps (turn on every few minutes) and CO2 detectors that are always on even if the switch is off?

That alone could draw down batteries over a few weeks. Excess heat or cold makes batteries discharge at an even faster rate.

Years ago I could leave my group 31s all winter from October til May without issues so long as I charged them before storage. Now my batteries these days don't last more than two seasons if I do that. Back when the admiral and I had a 21 ft sailboat and porta potty our first summer together all I could afford were free lawn mower batteries pulled out of scrappers to make our little battery bank...wasn't ideal but those 6 batteries lasted us for 3-4 seasons and I never had more than a 50 watt solar panel to charge them. Battery quality sucks these days. You guys have dingys with more horse power than the kicker motor I kept on the back of that little boat.

I think my current banks is one 31 and two 27s...I can't remember as they are at least 3 years old. I never turn off by perko switch but I make sure the shore power is always hooked up.

Do you have the ability to add a solar charger.

rasbury · September 8

I'm on a trailer and my 02 are battery. Just replaced them- non replaceable battery and 10 year guarantee. I have no clue just bouncing things around!

PickleRick · September 8

If you don't have the ability to hook the boat up to shore power to make sure the batteries stay topped off a solar panel might come in handy for your application so long as no one decides to take off with it.

Formulaben · September 8

FWIW, I got rid of the battery isolator because it was leaking current to the other battery. Also, I swapped out the standard bilge circuit breakers for circuit breaker switches, so when it's in storage and the battery switch is OFF, I can also flip the bilge switches to OFF, and then there is ZERO power going anywhere. (And yes, this also includes the interior fridge, which I put in a hidden power switch under the sink.)

Here is the C/B I used:
https://www.digikey.com/en/products/detail/sensata-airpax/T11-1-15-0A-01-11C-V/8509109

rasbury · September 8

Thanks all...I'm leaning towards alternator. Bat one was dead this am - but the charger was off. It started on bat 2. I have a little plug in gadget, not sure how accurate it it but it was warning charging volts was less than 13.2 and the dash gauge looked about the same- forgot my meter. When I first started, it was not showing charging it all. I did launch but never turned it off. Ran for a couple of hours. Back at the doc, bat one did not charge. I did restart on bat 2. It has been showing almost 14 volts on the gauge.
Should I be checking connections? Can an auto parts bench test it? If it were my car I'd just replace it, I'm guessing this one is pricy...but I'd like to make sure before I do that...

PickleRick · September 8

You can get a cheap one from db electric but an auto parts store should be able to test it, tell them it's from the same year Chevy v8 pick-up as your boat. Hopefully they won't know painted black means marine

captkevin · September 8

If the alternator is bad wouldn't it not charge either battery? Makes be think battery is bad

YYZRC · September 9

Buy a DB Electric. Great product.

rasbury · September 9

Those prices are not bad at all- car like price.

PickleRick · September 10

They are located (or at least were) in Tennessee so east coast ship times are pretty good

rasbury · September 15

I'll get it pulled ans checked- it's probably about due so I don't think it will repair it.

rasbury · September 25

I pulled the start battery and brought it home for charge and testing. Did not make it to testing. The charger went to 15 amps....thin after a few seconds went to 0, back to 15 and then a braker in the charger kicks out. So that is toast...the other battery raised and lowered the hatch with the new switch installed. I will replace, charge the other battery and do more testing on the alternator via chat gbt. Also had ideas to see if there is a parasitic draw.

** forgot to mention...I thought odd..with what i presume battery one is removed, when I went to lower the hatch it would only work if the battery selector was on both- would not work on one or two?

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