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HI Frank, I tend to agree with you on getting cheaper batteries first up
but only if they are the same weight as the ones you want to get serious with and
you are able to get the power out of them for the time you want to test. I
found that the Comsub was too heavy and the old batteries were stuffed. I
have found new batteries 3 kg lighter so over 28 batteries that is 84kgs
lighter. The new ones are only good for 300 cycles instead of 750 cycles
so at near half price do I care. I’d love to be able to utilize 750
cycles but that is dreaming. Also the new ones are rated higher in amp
hours. I seem to remember Phil changing his out every year and not going
too techy. When is dunkin donuts day? Cant be too far off.
Chs, Hugh From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Sean T.
Stevenson The caveat to that plan of course is that your charging
system will only be "dialed in" for the battery characteristics of
the particular type of batteries you have employed during testing, and that if
you plan to change battery type later, you must account for any changes in
performance characteristics in your design. There
has been a lot of past discussion on which battery to use and how cost effective
each choice is. The
LOW end is to simply go down to your local auto parts store and by a
"marine battery" starting at $60. The
next step up seems to be the Trojan "traction" type lead acid battery
designed for golf carts at $145 each. They come in either 6 or 12 volt.
Increased life span and more power available. Next
up is the AGM batteries at about $245 each. Longer life, no spillage, good
power output. This
seems to be the most popular choice. Gel
batteries are about the same as AGM but cost a bit more. A
couple of new types based on Lithium-ion are available, but so far there
seems to still be overheating issues with heavy amp draw. The cost for these
types is considerably higher, ranging from $475 to $1200 each for an
equivalent size. The cycle life is reported as much improved over all the lead
acid types, and the weight is about 2/3 of comparable lead acid. Each
type has merit, depending on "how you use them " I've
often considered going the cheapest route for my first set just to get all the
bugs worked out. It's likely the boat will spend considerable time in the shop
fixing/modifying stuff after it's first series of wet tests. An
inexpensive set would give me the opportunity to learn how the boat works, how
it handles, and what it's limits are. Worst case, and the boat gets flooded
during testing.......not that much money lost. I
plan on conducting some pretty rugged tests, some manned and some on remote.
There's a good chance something's going to break. Once
all the systems are tested and working properly, and I've got some hours and
experience behind the wheel, the first set will be just about wearing out. The
charging system will be dialed in, and good test data collected during
operations can be analyzed, making the final choice for batteries more
informed. A
first set of 14 batteries at 12 volt comes to $840 plus tax. If they
lasted long enough to accomplish testing and learning, it seems like a
possible way to go. Frank
D.
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