On 10/15/05 12:59 PM, "David Marshall" <mailinglist@FASTFORWARD.CA> wrote:

> I am at the understanding that yellow is deep cycle designed to be
> discharged on a repeated basis, but I am wondering about the blue top
> batteries.  These almost appear to be a mix of a starting battery and deep
> cycle - is this true?
>
> What I am looking for is a battery that will act as a reserve battery, but
> will also have a 8000lb winch attached to it that will draw considerable
> current from it.  To me, this appears to the blue marine battery... am I
> correct?

The D34 Yellow Top commonly used as a Vanagon aux battery is exactly the
same as the Blue Top (marine) counterpart, the D34M, in terms of
performance.  Tech specs are identical* and both are supposed to be "dual
purpose" starter/deep-cycle batteries.  CCA's are slightly lower than the
Red Top starter batteries, but still higher than most "standard" starter
batteries.

*The only differences are:

A) D34M Blue Top has an 18 month warranty, vs. the D34 Yellow Top 12 month
warranty.
B) D34M Blue Top has additional 5/16" accessory posts on top.  (The D34
Yellow Top has only the standard top posts and D34/78 Yellow Top adds side
terminals)

I confirmed this with Optima customer service.  Their response:

"Only the post configuration and the warranty make these
two batteries [D34 & D34M] different. They will perform exactly the same."

I've found the D34 and D34M to be the same in price, and therefore it was a
no-brainer to go with the D34M Blue Top when I set up the second battery in
my Carat.  With the 5/16" studs and wing-nuts, adding accessories is very
easy using 5/16" ring terminals on all the incoming wires.

http://home.earthlink.net/~tornadored/vanagon/optima/IMG_1283.jpg
http://home.earthlink.net/~tornadored/vanagon/optima/IMG_1338.jpg

Note: In a Westy, if you install the Optima under the driver seat, the D34M
can make installation a little trickier since the extra posts create added
clearance issues in the already cramped quarter.  I still used the Blue Top
in my Westy, mounting it on its side.  It just required a bit more cutting
of the seat base to fit (This is because I cut notches out of the seat base
"tab" to allow the posts to clear when inserting the battery.  If the entire
tab is cut off, it wouldn't matter)

But If you are installing under the rear bench, I can't see any downside to
going w/ the D34M Blue Top.  However, I don't know anything about winches,
so I don't know if there are specific battery requirements for that.

James V