Battery discharge
rasbury
Member Posts: 8,712 ✭✭✭✭✭
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...
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Regards,
Ian
The Third “B”
Secretary, Ravena Coeymans Yacht Club
https://www.rcyachtclub.com/
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.
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.
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.
Here is the C/B I used:
https://www.digikey.com/en/products/detail/sensata-airpax/T11-1-15-0A-01-11C-V/8509109
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...
** 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?
No warranty on battery 1.
My tester showed battery 2 is ok.
I put the new battery and the good one back in today. GBT gave me a procedure to remove the negative cable and check for amp between the terminal and the cable. . Battery 2 which I don't seem to have as much problem with was a dead 0. The other battery is .10 which would kill the battery within a week or so which sounds about right. I pulled the power wire off the alternator and checked again with the same result. That should rule out the alternator with a bad diode .
So, I've left the negative off that battery until I come up with a plan to figure out the draw. I still do not understand that with battery 2 in and all hooked up the hatch will not work. The trim works, the engine turns on. I had to close it by using the jump box on the terminals at the battery switch. With the completely dead battery still hooked up, the hatch would raise on battery 2. Remove battery one and does not work. Not that I'm going to worry about it now- just seems odd. I have other things on my list to get done. I'll just have to hook that battery up at the ramp. I assume normal charging while running or on shore will keep it up and the draw during a day out won't kill it.
Update: as far as the hatch, it would have helped if I had turned on the accesory switch by tge battery selector. It does beg the question, things that are hot all the time like the radio and the bilge- would they run off battery one ? If it is dead, will the bilge still run off two somehow? I imagine this system is a little complicated than a novice like me will grasp. Searchlight? I tried it yesterday, I put a new control head on it, but nothing would come on yesterday with the negitive off bat 1. I did not try the radio but I will play with tgat a bit. We are only up to 55 today- might be in the water on Friday.
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I am having an issue with the sump pump in the shower. It's locked up. The box is also full of water , i wonder if that pump is wired hot like a bilge? Since the float is trying to turn the pump on, could that be my draw? Im going to cut the pump and will test the wires for power with everything off. I probably won't have time to deep dive in this now but will have to get back to it.
If your sump is full of water and the pump is on, that tells me you either have a clogged hose or the impeller of the pump is clogged with debris; in this case you won't hear it running at all, but it will have a draw on the battery.
FWIW, I bought a brand new sump with pump because mine had a small crack in it...have a new one brought me some peace of mind.
https://www.amazon.com/dp/B01N1FHKQI
I checked the amp draw at the ramp. I had cut out the shower sump motor. Before I replace, sounds like I should try to break the motor loose before I replace...but the amp draw was still the same. Something with everything off is pulling 3 to 4 amps with everything off.
So, to recap ...
I did recheck at the ramp bat 1, interesting to me was with the engine off and checking the amps, it did not matter if bat switch was on or off- same draw of 3 to 4 amps.
Non working sump motor removed.
I did confirm with tester both batteries are getting high 13 and low 14 charging from the alternator. When I first cranked it up the alternator was not anything and glancing at the gauges a few minutes later it was showing 14.
What would be the amps running down the river? I assume running the alternator can overcome this draw?
If so that's normal from my experience, while my engine is a diesel it uses a common GM alternator. It won't put out charge until I bump the throttle.
Was the ignition switch on when checking the amp draw at the ramp?
How about the battery switch?
Just your radio and amp turned on, not playing will draw amps.
I would be looking for the source if your test was done with the battery switch off.