[C320-list] Batteries

[Troy Dunn]

For me this is an incredibly easy answer.  If the PO already converted to
6V Trojans I would be really hard pressed to go back to 4Ds (either AGM or
FLA). Here's why.

#1 Those Trojans are true deep cycle batteries and dollar per amp hour
times number of cycles you are likely to get out of them, a better buy.
#2 The 4Ds are incredibly heavy and therefore have high potential for back
injuries.
#3 To get to a similar quality and amp hour rating in a 4D
configuration...you are stuck with AGMs (cha ching).  Others will argue
that there are FLA 4Ds out there that come close, but really cost
competitive 4Ds are hard to pin down on quality, cycles, and specs for 20
hour rating...that’s a red flag.    That doesn’t mean those are bad choices
for those of us stuck with 4Ds and not wanting to reconfigure for GC
batteries at the moment, especially for the casual cruiser or club racer
that leaves the boat mostly on the shore charger.    It’s a crappier chair
to be sitting in than the one you are however...ask me how I know.

I’m not convinced I agree with the theory that changing your battery
configuration may be a bad idea because you are set up for 6V FLAs and you
might mess up the new batteries going back to 4Ds.  It implies you don't
need to worry those things if you don’t reconfigure and I think that’s a
bad idea.   Regardless of what you decide to do, you should understand your
DC power system well enough to know if it is configured properly for
whatever batteries you have in there, even if you go with identical
batteries.  I think it would be a mistake to buy new batteries and assume
your alternator, regulator, charger, and any other devices are properly
configured.   Assuming the PO has this right to begin with is a really bad
idea and could potentially negatively impact the life of an expensive bank
of batteries you are about to spend some coin on.

So to sum up.  Here is my recco.

Replace the Trojans with identical batteries and learn about your charging
systems well enough to ensure the correct bulk, absorption, and float
voltage profiles are being delivered to your new batteries.  Never go below
50% SOC, and try to ensure you get back to full charge with each cycle.

For much much more info, read all the articles in the aforementioned
marinehowto.com website on electrical systems and upgrades.

Good Luck

Troy Dunn
Hull #514