Batteries on the hard

I'm getting some work done and have all the battery switches all turned off. How long will the batteries hold a charge like that? I don't want to fall below the 50% charge level. The batteries were at about a 97% charge when I flipped the switches off IIRC.

They are all Lifeline AGM batteries, and they were quite expensive!

Over a year for AGM unless there is some unknown drain. I always disconnect the positive terminals just to be absolutely sure. A few minutes work for peace of mind. A frequent culprit: the yellow memory wire for a stereo wired directly to the battery+.

Damn. I didn't disconnect the terminals. Didn't think about that.

I installed a toggle switch on the memory feed to the stereo. When laid up I flip the switch to stop the drain.

Call the yard and have them pull the positive wires. There is always some vampire load you don't think of that could drag you down. Ask me how I know.

Ok. Thanks all. I called the yard and they are going to plug in the shore power so the battery charger can run.

BTW, the boat is at Cracker Boy in Ft Pierce, and these folks seem to be on top of things. I've had some bad experiences at yards before but maybe I got lucky this time. Cindy in the office always calls me back, and the techs they recommended are actually doing what they said they would do, and they also answer their phones!

I might change my tune when I get the bill however. [emoji30]

The memory of a stereo takes many months to partially drain a bat in good condition. Its only a few milli-amps but it is a 24/7 load.
Lets do the math:
Lets say 5ma drain for 6 months. It would take a thousand hours to drain 5 amp-hours. 6 months = 4320 hrs, so that's about 20 Ah in 6 months.
Great if you know that's all there is.

Another vote for disconnecting the batts. Charging is good but unexpected turn offs can happen.

Tom.B said:

Call the yard and have them pull the positive wires. There is always some vampire load you don't think of that could drag you down. Ask me how I know.

Click to expand...

I know how you know . . .

bayview said:

Another vote for disconnecting the batts. Charging is good but unexpected turn offs can happen.

Click to expand...

Disconnects yes but my trusty Guest brand charger suddenly started having a 16.5v float voltage last winter after years of faithful service. If I hadn't spotted it, it would have boiled away all my batteries. No sitting with a charger on for me... I think we just had this discussion here.

I have put toggle switches on all outlets /or direct wiring for appliances with memory loads, including the printer, microwave, TV etc. These were put in for anchoring where every amp needs to be replaced. Don't know if it is that significant savings but it sure makes me feel better. When we store I disconnect many feeds but not the batteries as I want the bilge pumps to work even on the hard.

Whatever the parasitic loads are on the hard they are more than made up for by the solar panel(s).

WLA batts loose 1/2% (new) to 3% (old) , per month.

The chemistry in your batt set might be a bit better but charging them overnight once a month cant hurt as much as a bill for a new set.