No, they don't have that much capacity. That is what they are rated
for, but if you discharge that deeply, they will die very quickly. For
extended use (ie sitting at anchor and recharging once or twice a day
with the engine, etc.) you can only figure on discharging down to 50%,
and recharging back to about 80%. In other words, you only get to use
about 30% of the batteries Amp-hour rating on one cycle. A pair of
Trojan 105's are rated at a bit over 200 Amp-hours, so you can figure on
about 60 Amp-hours in practice.

BTW, I've been using 4 T105's with a large fridge and freezer as the
major load for 5 years, including some extended cruising, so I have some
experience with these. My previous boat had a similar, though smaller
setup.

As for Harlan's question, it can't really be answered without knowing
the draw of the equipment. I'd guess the load is around a few amps, so
overnight should be less than 40 amps-hours. Also, we need to know the
size of the boat and the charging methods used. There are lots of
possibilities - the t105's are the most cost effective, but I'd also
consider an AGM battery. They have a bit less capacity but can be
discharged deeper without damage. Also, they have less self-discharge,
handy if the boar were to be left unattended without a charger.

Bottom line, there is no one "ideal battery" for all situations, you
have to tell us more about the application.


MikeH wrote:
Harlan,
I wanted a lot of capacity for my electricals while at hook, so I
researched a lot of batteries. I finally put two Trojan 105's (6V deep
cycles) in series for my boat. They have 447 minutes (7.45 hours) of
capacity at 25 amps and were about $85 each. The only drawback is they
weigh 60 Lbs apiece! Hope this helps.
Fair winds,
MikeH
s/v Making Memories
Perrysburg, OH

Harlan Lachman wrote:

I have sleep apnea. That means I have to hook up my nose to a machine
blowing air into me all night long. Heated humidification makes it
better but in the summer, if humidity levels are high enough is not as
important.

This takes electricity. At a dock and plugged in, no problem. But
since I have been plugged in, I have not had the joy of dropping a
hook in a beautiful gunkhole. This is gonna change.

Anyone have a recommendation for a deep cycle battery with lots of
(the most?) amp hours which I can drain at night and rely on fully
recharging during the day?

harlan