DC Voltage

TUS NUA

TUS NUA

Member
Dec 4, 2019
54
Boat Info
2003 320 Sundancer, Garmin GPSmaps 741xs
Engines
350 Mercruisers (twin)
My boat has been winterized and is staying in the water this winter. Friday, and again this evening my voltage reading for DC power is 12 volts. I have seen it higher. Is this something I should worry about?

I was hoping this evening that the reading would be higher but at least it’s holding at the moment.
 
Sounds low if connected to the charger. Is it charging?
 
12.0 or 12 point something, i do not recall? Where is this reading obtained? On a good battery, 12.0V is about 75% discharged. Even without a charger, a good battery with no parasitic drains, should be holding 12.4 after a long layup.

Need to specify whats after the decimal. It actually matters.
 
I would say it’s 12 point something. I’m getting this off the gauge on my switch panel below deck.
 
As mentioned, the "something" really does matter. Take a volt meter with you to the boat the next time you are there. Disconnect the shorepower. Check the voltage directly at each battery. Operate the windlass up and down a couple times - say 5 or 10 feet worth. Wait about 5 minutes, then check the voltage again. Then, turn the power (and charger) back on and immediately check the voltage again. Report back with those numbers. Also, compare what you see on your volt meter and make note of that.

It will be 13 to 14 volts ONLY when the charger is actively charging or the engines are running, by the way.

You'll see the same range of volts in your car.
 
Ok, your last sentence “It will be 13 to 14 volts ONLY when the charger is actively charging or the engines are running, by the way.” is what I am comparing against.

I’ll head over to the boat tomorrow and do what you recommended. I’ll report back. Thanks!
 
FWIW. leaving a boat in the water for months without being connected to a charger is ill-advised. Should the boat start taking on water, you want to be sure the bilge pump does not drain your battery and stop working. At the very least, consider a solar panel to keep the battery maintained.
 
Boat is connected to shore power and battery charger.
 
If you have wet cells then make sure they are full. Post the battery make and model and the voltage at the terminals with the cables removed from the boat if you want us to give you a reliable answer.
 
superwa said:
Sounds low if connected to the charger. Is it charging?
Click to expand...
I thought it was low...lower than what it was only last week. Although connected to the charger, I’m worried that the charger may be failing, or the batteries are failing.

since the boat is new to me, I don’t know what is normal.
 
A fully charged battery should read 12.6 volts after rest from charger for 8 hrs. with nothing running. Most batteries last about 5 years if maintained properly and don't get frozen. Always check the fluid level every 30 days or so, a battery on a charger with no fluid will warp the plates and kill it. If you have a switch turn it to off when your not using the boat, your bilge pumps should be wired so they are always hot. Your charger will maintain your batteries if you don't want to have anything going.
 
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