Short lifetime of leisure battery

[blackbeard]

I think the OP is fairly well aware of what is happening so far as current drain and volts at battery terminals are concerned, so a battery monitor wouldn't help all that much. I'm getting about 14.4 or 14.5 volts during engine running ie the alternator is doing its stuff.

From all the above it seems to me that:
a. I'm not doing enough engine running to completely re-charge the battery
b. I'm taking enough Ah out of the battery to give more depth of discharge than the battery likes, and
c. these batteries seem to be even more sensitive to this sort of thing than I thought they were.

Current (ouch!) intention is to fit another battery somehow, somewhere, in parallel with existing domestic battery (which I will have to replace, of course). This will
a. give me more reserve capacity should I need it (but I haven't had a problem with this)
b. reduce depth of discharge, given that normally I will use about the same amount of Ah as before, and
c. since each battery will not be discharged as deeply as the single battery I had been using, charging will be quicker and thus more complete. (I hope.)

Also I now have a smart charger, and 240 v available on the pontoon (when I am on the boat). All I need now is somewhere to put a solar cell .... (wind generator on a boat this size is NOT practical).

I will need to stick to 70 Ah batteries I expect, I would like to use 110 Ah jobs, but anyone who has tried to fit another battery in a 25 - footer will recognise the problem. So that will give 140 Ah (nominal) from the domestic bank. I expect someone will tell me I need at least 210 Ah, I'll consider this but am not hopeful of finding the space.

Which leaves one final mystery - why others with just a single 70 Ah battery haven't had as much or more trouble than I have. Or are they just keeping quiet about it?

 

[halcyon]

I I'm getting about 14.4 or 14.5 volts during engine running ie the alternator is doing its stuff.

From all the above it seems to me that:
a. I'm not doing enough engine running to completely re-charge the battery
b. I'm taking enough Ah out of the battery to give more depth of discharge than the battery likes, and
c. these batteries seem to be even more sensitive to this sort of thing than I thought they were.

a ) monitor the charge amps to charge volts.

You want to see a slow rise in volts, and a steady charge amperage. If the voltage shoots up, and the current falls you are short charging. May be sulphation, could be the alternator is to big. But you convert the active material on the outside of the plate, this gives a high voltage and the battery starts to gass, the result is high resistance and low charge.

b ) do not run the batteries below 12 volt in use ( dawing 5% of battery Ah ), or 12.3 no load, this will give you around 50% min capacity.

If you are charging batteries on your way into your mooring, monitor voltage when you get on board. Next time you come on board you should have the same voltage, if it is lower you are under charging, run the engine for longer and make note. When you come on board and the batteries are the same or a little higher you are there.

Brian

 

[snooks]

I think the OP is fairly well aware of what is happening so far as current drain and volts at battery terminals are concerned, so a battery monitor wouldn't help all that much.

A (smartgauge) battery monitor accurately tells you the SOC as percentage, no matter how old or young your batteries are, so it would help a hell of a lot . With a press of a button by you could find out the state of charge of the batteries. You'll see what percentage they go down to in use, and how full they are when you charge them, as you charge them. It's a magic bit of kit, and one that warned us our alternator was on the way out.

Whether it's worth it only you can decide. But it would help you