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Re: [PSUBS-MAILIST] uneven charging
Hi Ron,
Thanks for the info. I will definately consider forklift batteries. I was
not aware that they could be disassembled.
Thanks Again,
Jim K
----- Original Message -----
From: "Ron Leonard" <ronleonard@shaw.ca>
To: <personal_submersibles@psubs.org>
Sent: Saturday, May 10, 2008 12:50 PM
Subject: RE: [PSUBS-MAILIST] uneven charging
Jim, forklift batteries are almost always custom assembled from individual
cells. All cells are the standard 2.2v. The most common is an '85' cell
which is 85 amps and is 22" tall and 6.2" wide. You can specify the number
of plates per cell. A 7 plate cell is 2.75" deep and 49 pounds, 9 plate is
3.5" and 61 pounds, 11 plate is 4.25" and 73 pounds, 13 plate is 5" and 85
pounds. Any of those will fit through the hatch, and then you assemble and
wire the cells in the battery box (tray) into a battery of whatever size and
voltage you require.
The disadvantage to car-sized batteries is: thin plates, and no clearance
for slag in the bottom of the battery case. With the current that a sub can
pull with all thrusters running, warping of plates is a concern and can ruin
a battery. As a battery is used, the lead plates drop slag into the bottom
of the case which can short out a battery, again, ruining it. Forklift cells
have thick plates, and lots of room at the bottom of the cell for slag. If
you've got the space, it's hard to beat forklift batteries.
Ron
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Jim Kocourek
Sent: Saturday, May 10, 2008 7:03 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] uneven charging
Hi Irox,
Forklift batteries are exceptional for continous drain situations and last a
long time due to the extremely deep charge that they will accept. Unless you
are the exception to the rule, they are unusable in a Psub because the will
not fit thru a 24 inch hatch and cannot be replaced that way. If you have a
way to solve this problem it is probably the best battery on a cost/output
basis that can be found!!
Best Regards,
Jim K
----- Original Message -----
From: "irox" <irox@ix.netcom.com>
To: <personal_submersibles@psubs.org>
Sent: Friday, May 09, 2008 6:28 PM
Subject: RE: [PSUBS-MAILIST] uneven charging
Has anybody compared forklift batteries to 12V deep cycle batteries
as far as cost and capacity?
I've been looking around for a battery solution for my sub. I've got
plenty of volume, so space isn't really an issue. I would like as
much capacity as I can afford - I like the figure "3tons".
I figure I'll probably kill my first set of batteries through improper
use (although I do plan to try my best to not damage them). So I
thinking going with a number of smaller isolated battery banks, these
should provide at least several hours of operation time, before they
get drain to the point that I have to switch to the next bank. This
way I can start with one or two banks, and once I'm happy I've got a
solution that works reliably, build out the rest of battery banks.
Cheers,
Ian.
-----Original Message-----
From: "Jay K. Jeffries" <bottomgun@mindspring.com>
Sent: May 9, 2008 6:44 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] uneven charging
Forklifts and large submarines have a luxury that unfortunately we cannot
afford in PSUBS and that is the use of large volume batteries. An
application closer to us is the scooters used in tech diving that are used
to explore miles of underwater caves in a given dive. They test their
batteries by measuring the various discharge rates of batteries and group
similar discharge rated batteries together as they have the same charging
rate and do not display the issues described in previous posts. They are
tested regularly over their lifetime to insure matched service. When you
purchase batteries, you can request that the battery firm provide you with
a
matched set for a small premium and thus save buying a bunch of batteries
and matching them yourself. If you replace one, you have to replace all
to
keep matched service.
R/Jay
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
Vive vt vivas
- Live that you may live
_____________________________________________
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Hugh Fulton
Sent: Friday, May 09, 2008 18:07
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] uneven charging
The best solution, I have been told, is to use 2 volt cells in series.
This is how forklifts etc do it as it is very hard to get the internal
resistance of batteries to be the same. Forklift batteries generally have
2
volt cells that are up to 2000 Amp-hours per cell. This is why you should
always recharge batteries, that are in parallel, in isolation. Also
batteries left in parallel can discharge themselves through this
unevenness.
All this was explained to me by a battery importer. Makes sense to me but
I
am still going for parallel as the 2volt cells with high amp hours are a
crazy size physically. This probably explains some of the problems I have
in my boat which has 3 batteries in parallel. It is very common advice in
the marine industry that id you are using batteries in parallel you should
use the same manufacturer, size and model of battery.
Hugh
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