Marine Battery? Jump-Start Battery? Power Inverter?

drdrb wrote:

Please note that while the term "marine battery" is oftened used as a
synonym for "deep cycle battery", manufacturers also make marine
starting batteries which are not deep cycle. Starting batteries (such
as jump start batteries) have high cold cranking amp ratings, but do
not tolerate deep discharge without damage. A marine starting battery
is just a starting battery built to be resistant to the pounding
sometimes experienced in boats, and is no better than any other
starting battery for deep cycle use.

What you want is a deep cycle battery, marine or otherwise. Wheelchair
batteries (available at Sears, etc.) are deep cycle batteries and come
in various sizes which would probably meet your portability
requirements.

A minor note: no need to look specifically for wheelchair batteries at
Sears. The conventional Diehard brand marine deep cycle batteries will
do the job nicely if you don't mind handling lead-acid models. For all
of my power-hungry hardware, a couple of them (Diehard part number
27494) cover my requirements and they usually go for about $60 per pop
in the automotive department...
---
Mike
http://www.concentric.net/~richmann/

On Fri, 31 Oct 2003 19:04:46 GMT, "Al"
wrote:


"Al Hall" wrote in message
.. .

Any reason not to use a deep cycle marine battery in the car in place
of a regular auto battery?


Seems like a very good question to me. I asked this very question when I
was buying some batteries for astronomy use and I'll paraphrase what I was
told...

A boat and a car place different requirements on a battery and it's a good
idea to buy a battery that's made for those requirements. As an example,
it's very important for a car to have a big reserve of cold cranking power,
while this is not too important in a boat that is used during the warm
weather months. On the other hand, it's common to draw small amounts of
power from a boat battery while the engine is shut down and the system is
not charging. Of course, when you're ready to go home, it's important that
the battery has enough power to get you home.

In spite of the superior marine batteries available today, you should see
some of the batteries going into boats these days. I have a huge 75 pound
battery for each of the engines, plus a bank of 3 deep cycle batteries to
operate accessories. Not too many gas stations out there. These days,
boatmen pray that they never need a tow, as a tow could cost you a thousand
dollars or more.

Al


Hi Al,

Makes sense. OTOH, if you were planning on using the car battery to
power a scope through the cigarette lighter outlet maybe a deep cycle
battery would be better as long as it would start the car too. A few
years ago I had a small camper van that I set up with a second deep
cycle battery to run accessories when the engine was turned off. It
was isolated from the starter battery with a diode based battery
isolator that I got from a camper outlet. When the primary [starting]
battery went bad one time, I switched it with the deep cycle and ran
the van for weeks with no problem until I got around to buying a new
primary battery when they went on sale. Since then I've always
wondered if the deep cycle battery wouldn't be a better choice for
those amateurs who use their car battery to power their scopes.

[the other] Al