I fully agree with Cliff. Small subs that
aren’t designed for great depth and have relatively light hulls usually
need ballast weight anyway. The most important thing that I look for is a
battery type that is less likely to release gas. The old sub uses Deka gel golf
cart batteries and the new sub has SeaBatteries from deep sea power. I’m
no expert on Lithium, but I have heard that they can explode on contact with
water.
Has any one else heard that?
Greg Cottrell
Project Manager
http://www.precisionplastics.com
P please consider the environment before printing
this email
From: owner-
Sent: Sunday, October 03, 2010
12:46 PM
To:
Subject: Re: [PSUBS-MAILIST]
Batteries Bank
Based on the experience with my boat, I think AGM's are the
way to go. If I built a new boat, I would use these. As a point of
comparison, I can give you my experience with AGM batteries for a
psub application.
I purchased 10 Lifeline Gp-2700T batteries about five years
ago. These are 12V batteries rated at 100Ahr. They weigh
63lbs each. I operate my battery bank at 120 VDC. During the build
phase of the boat, these were periodically top off with a
dedicated 120 VDC battery charger that was setup for these particular
batteries. Over the years, I have recharged these
approximately 250 times. The initial cost of the batteries was $160 and
the current cost is about $280 each. Over the five years, I have never,
not one time smelled any off gassing during a charge cycle. I have never
had any leaked battery fluid. I had to replace one of the batteries
because I dropped it while removing it and riped a hole in the side.
Even then, it still did not leak. Now that I am in an
operational mode on the boat, I noticed that the battery life was not as long
as when they were new. To analyze this, I built a poor mans battery
tester which consisted of a 1200 Watt inverter that was connected to a bank of
incandescent light bulbs with a light dimmer switch so that I could adjust
load. I tested each of the 10 batteries against a 10 amp load
and compared how long it took for them to drop below 11
volts. Compared to the data published by the manufacturer, these
batteries tested between 40 and 70% of their initial capacity. The bottom
line is it is time to replace the battery bank.
To me, one of the major arguments for using lithium
batteries is they have a better power density (power to weight ratio).
While this is important for a car, to me it is not as important for a psub as
most of the time, we have to add ballast anyway to submerge. So using a
less expensive battery that provides both power a ballast makes more sense to
me. While they are inexpensive, conventional lead-acid car batteries leak
acid and off gas while charging. As such, to me a good compromise
is AGM.
Cliff
Cliff Redus
Redus Engineering
cliffordredus@sbcglobal.com
From: Jon
Wallace <jonw@psubs.org>
To:
Sent: Sun, October 3, 2010 9:22:22
AM
Subject: Re: [PSUBS-MAILIST]
Batteries Bank
The electrical requirements to fulfill the operating parameters of cars and
subs are different enough I think, that the greater reserve capacity of Lithium
is not enough to justify the added expense. It would be interesting to
hear how many psubbers have found that lead/acid does not adequately serve
their needs and would move to lithium if they could. Some time ago (in a
different lead vs (?) battery discussion) Phil Nuytten advised that from his
experience lead/acid provided the best "bang for the buck" for
home-builders. The US Battery Rep that we had as a guest in July talked
about all battery types and seemed to confirm that for all its supposed
weaknesses, the good ole lead/acid battery was the way to go. That was my
impression at least.
Jon
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