37PC - how long will your boat run on house batteries until they die ?


NH-PC

NH-PC

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I bought a 2011 37 PC with axxius. It sat for three years and it acquired a lot of the electrical issues. Before I figured those out I might have killed 2 new deep cycle house batteries do to discharges over a six week period. Now that the system charges properly and most electrical systems are working I still get a very low runtime on two batteries that are but months old. I have to get them more properly tested but want to see if I?m barking up the wrong tree? I might get 40 minutes to a few hours

If you were sitting and had your refrigerator running plus some cabin lights plus having a radio amplifier running, and the occasional toilet flush, how long would you expect your house batteries to run?
 
It depends on what size and type of batteries you have. If you have 2 house batteries then I would guess that they should last longer than an hour.
 
I'm interested in this because we plan to do the great loop some day, and solar + batteries is only getting better and better.

https://www.youtube.com/watch?v=OO23RTRIVGU

With fuel costs, noise, smoke, smells, possible death, etc, I'd love to not need/run a generator. This stuff is so cool.

could you offset your battery drain with some panels?
 
You could use some solar but on a Formula there aren’t as many good places to mount panels as on a trawler. On mine I don’t really have anywhere I would want to mount them, they would look terrible since there isn’t any large flat area to mount them on.
 
that is true. I would be able to put some on my 292, assuming I could walk on them *if* needed.

I only have a radio that we run all day just fine on hybrid 12v (starting/deep cycle). Otherwise I'd love to put 1-2 panels on it. even 50 watt would be sweet. It would charge in the sun all day (I don't/can't use the boat every day).

https://www.custommarineproducts.com/marine-solar-panels.html

the tech gets better every day. I wonder if we will someday see 'white' solar panels that would blend in more with a boat, and flexible enough to wrap onto the deck and walk on would be very cool.

I assume from your ask you do not have a generator or don't want to run it?

Is the fridge A/C or D/C?

if it's A/C you can use a kill-a-watt to find how much it's pulling, if it's DC you have to interrupt the circuit to find the draw.
https://www.amazon.com/P3-P4400-Ele...qid=1657215677&sprefix=killa+a+,aps,87&sr=8-2

from that, or maybe you can get the specs from the manufacture? Once you have the watts, we can figure out how long X would last based upon run cycle and battery kWh.

I would personally expect to run the boat on batteries at least 4-6 hours.
 
This is great info, thanks

The fridge is DC but I did read somewhere that it might be a C as well but I don’t think so.
The second fridge in the cockpit is AC only which is kind of a bummer since unless I am on AC when we’re out anything we put in there can get warm. we just try to not open it much.

I have to get the battery part numbers but they are the appropriate batteries for houses, just trying to figure out whether this is normal, we hurt these batteries, or I have some parasitic draw

I do have a generator but I’m trying not to use it all the time. I spent a lot of money on the boat then fixing it then transporting it to me and fixing it more but I just don’t want to buy a generator this year


I think my next step is to wire the multimeter in line and have everything off then test one thing at a time and I’ll put three prime numbers here as an FYI for others

if the combine amp hours don’t come out close to where the batteries are when they could be damaged
 
On our 41PC to get to the secondary fuel filter the cockpit refer had to be removed and then open a hatch in the deck. Add to that the refer was 120 only, so we removed that refer and I had a door made and now it is storage for PFDs. Much better use.
 
I’m curious. A fridge and radio and a few lights… Shouldn’t you be good for at least a few hours?
 
For me, we stay on our boat for days on a mooring and run the fridge non-stop. I run the generator a couple times a day to top the batteries up (my house batteries are 2 group 29's). I would say if your batteries are good, you should get at least 8-10 hours.
 
gustaf said:
For me, we stay on our boat for days on a mooring and run the fridge non-stop. I run the generator a couple times a day to top the batteries up (my house batteries are 2 group 29's). I would say if your batteries are good, you should get at least 8-10 hours.
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I know this is an old thread, but if you're still engaged, how long do you typically have to run your generator to top off the batteries. And what is the Ah rating of your group 29's?
 
The group 29 deep cycles are likely in the area of 115 AHs. As to how long they will last it depends on the load you are putting on them. Also with LA batteries you don’t want to use more than 50%. You need to either calculate or measure the normal load and then you can use 50% of your batteries. Contact the battery manufacturer to see exactly how many AHs your battery has.
 
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