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(no email)
Date: Sat Aug 21 2004 - 17:39:56 EDT
[Note. Tim is referring to this article
http://www.yandina.com/hints.htm#BatterySaver]
Hi, Tim,
The charger cycling is normal and to be expected.
I also have no space but when at the dock I just sit a $35 battery on a
companionway in the engine room and connect it with a couple of jumper
cables. It doesn't have to be in a box or fixed down - it gets removed
before we leave the dock.
I believe it is exactly that repetitive cycling of your expensive main
bank(s) you mention, between just about fixed points - full charge 100% and
1 refrigerator run say 96% - that does the damage. The battery never gets
below that 96% point and gets "lazy" through leaving the remainder of the
capacity stagnant. I know that wasn't a very scientific description but it
represents what I've seen happen. I think it applies to sealed batteries
more than lead-acid but the same applies to some extent. It seems like if
your batteries are good for 1000 cycles, you are using up those cycles
unnecessarily under the float conditions even though they may only be 4%
cycles. You are wearing out that spot on the plates.
The wearing out can be imagined as metal being plated back and forth across
the electrolyte. That metal starts out as a nice flat machined surface.
Every time you plate some off, then plate it back it never goes exactly back
in the spot where it came from so your nice flat plate ends up with bumps
and hollows. With age those bumps and hollows get bad enough to cause
shorts or opens. So if this is happening in the same few fractions of a
millimeter on the surface all the time, it will get spongy or crusty and
disfigured. By periodically cycling the batteries to a deeper and not a
consistent level as you do when cruising, you break up the crusty top and
bury it with fresh metal.
Again, I can claim no technical articles or support for this but with 15
years experience this is what I've seen happen and it makes sense to destroy
a cheap automobile battery doing dock duty than risk wearing out your
expensive bank.
Regards,
Andina Marie Foster,
----- Original Message -----
From: "Tim Holock"
To: <>
Sent: Saturday, August 21, 2004 3:53 PM
Subject: Battery Saver question
> Hi guys! An off-the-list question:
>
> I've read your battery saver project several times over the years, and did
> what you recommended on a previous boat. My current boat, an Endeavour 32,
> is pretty much maxed out on battery space - 6 golf cart batteries already,
> so its hard to fit another cheap one.
>
> Here's the question. I charge the banks using a Guest Chargepro smart
> charger, 10 amp. It tends to cycle quite often, like every day or so. If
the
> refrigerator comes on when several lights are on, for instance, it sees
the
> voltage drop and goes into bulk charge. I have thought that this was a
flaw,
> and considered returning it to WM, but now I read your article again and
> wonder: could the cycling between 13 and 14 volts actually be better for
the
> batteries, and retard the damage you talk about? (I divide the batteries
and
> usually only use two, the oldest and weakest, when hooked to the dock.)
>
> Thanks!
>
> Tim Holock
> Annapolis
>
>
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