Gel-cell VS Sealed Lead Acid Battery for Astronomy
Chotechai
I have been searching this subject all over the net, and finally
confuse myself as to whether Gel-cell and Sealed Lead acid are the
same type of battery?
Anyone please shed the light for me. As I can find only Sealed lead
acid battery type in Bangkok, Thailand.
Thank you in advance.
Welcome to http://fly.to/lyra
Michael Edelman
>
> Dear all,
>
> I have been searching this subject all over the net, and finally
> confuse myself as to whether Gel-cell and Sealed Lead acid are the
> same type of battery?
Basically, yes. A gel-cell is a type of lead acid battery in a sealed
case with a gelled electrolyte. This makes gel cells more suitable in
applications where the battery may be in different positions (as they
can't spill electrolyte) and where they are not regularly inspected for
leaks and electrolyte levels.
-- mike
---------------------------------------------------------------
Michael Edelman m...@spamcop.net
http://www.foldingkayaks.org (nomadics)
http://www.findascope.com (choosing a telescope)
John
should be kept top side up. There is still a vent for Hydrogen
gas to escape, but a twisted vent that usually stops any acid leaks.
You are better off if you keep the top UP when in use (discharging
OR charging).
Gell cells are REALLY sealed and can be used in any position.
I've seen sealed lead-acid CELLS (in "C" and"D" sizes) with
no vents, too. Not strictly Gell's but can be used the same.
I've never been in your part of the world, but that is what applies
here. Your Milage May Vary, etc.
On 27 Jul 2001 07:29:25 -0700, chot...@iname.com (Chotechai) wrote:
!Dear all,
!
!I have been searching this subject all over the net, and finally
!confuse myself as to whether Gel-cell and Sealed Lead acid are the
!same type of battery?
!
!Anyone please shed the light for me. As I can find only Sealed lead
!acid battery type in Bangkok, Thailand.
!
!Thank you in advance.
!
!Welcome to http://fly.to/lyra
Fix my email address by removing "no" words and the "com.ercial"
. Don't kill Clinton or spy encrypted h-bombs or trust the NSA
or weed the Columbian plot for bricks of dollars.
greg nowell
Mr Edelman's answer is right, the gell cell is safer. I'm not sure if
it's a big deal. I have a cheap plastic battery box around my lead acid
battery. It's so big and heavy that it's not going to turn over in
transport and so far "safety" hasn't been an issue.
Cost per amp-hour on the gell cell is MUCH higher than for lead acid.
I initiatlly "set up cheap" with a $35 wal mart 75 amp hour battery and
a $20 charger that didn't turn off when done. I suspect A) the battery
wasn't great to begin with and B) the charger may have ruined what parts
of it that were good. So I had to re-do my power supply after only six
months. I got a well-recognized lead acid marine battery (Interstate)
and a charger that turns itself off. This combo was $60 + $50. It
performs MUCH MUCH better.
So:
1. Buy "marine" or "deep discharge" if you buy lead acid. These are
used on sail boats, on lakes for fishing, etc.
2. Calculate your needs in amp hours. My equipment draws 5-7 amps and
my new 85 amp hour battery is good for 15-17 hours. Your highest power
requirements are if you need dew control technology. If you don't, then
you might be fine with a gell cell. If money is no object then get a
very expensive gell cell.
greg nowell
HAVRILIAK
>From: greg nowell
I now use 3 of those nice portable packs used for quick jumps and can't get
through the night. I considering your solution but instead on 1 large, I'm
planning on two for the following reasons. First. when 1 goes dead your stuck,
if you have 2, then you can shut some things down. Second, I keep hearing
stories about equipment interactions when a single power source is used.
Jeff Polston
Don't confuse a "marine" battery with a "deep discharge" battery.
For example, my boat has a marine battery on it but it isn't designed
to be deep discharged. The "marine" part means it's designed to
withstand the beating and bouncing about that it can get from the
boat doing what boats do (i.e. going across the waves and such).
Make sure you get a battery that can withstand being drained of power
and recharged, i.e. a deep discharge battery. You'll find "Marine deep
discharge" batteries. These are designed for use with trolling motors
and such and are perfect for astronomy.
This is what I have. I put it in a plastic battery case (about $6 at
Wal-Mart) and have it wired up with a cigarette lighter socket for
getting power and recharging. I also use it on my pop-up camper. It
works great. I power my laptop, dew heaters, and scope with it.
I also got an automatic charger for about $20. Schumacher makes
them.
Jeff
http://www.mindspring.com/~jeffpo
scott
I agree with all of the advice posted so far. My experience with
gel-cells
or batteries using "recombination technology" (used in gel-cells)
would direct
me to favour the flooded lead-acid (sealed or not) battery.
Batteries using "recombination technology or absorbed electrolyte
suffer from
multiple failure modes, ie. premature dryout, thermal runaway,
sensitivity to
AC ripple to name a few. Their life is shorter than a flooded
lead-acid battery. Gel-cells are great in that they can't spill acid
and they work in any orientation but they have compromized life-spans
due to their inherent design deficiencies.
If you are not worried about spilling acid or orientation than I would
just use
a (Walmart) marine deep cycle battery. They are cheap and available
anywhere.
Scott
chot...@iname.com (Chotechai) wrote in message news:<91a66f2f.01072...@posting.google.com>...
greg nowell
said that the gel cell's power output was less reliable over long periods.
A good thing to have is a $4 hydrometer for testing the acid. Basically you want to make sure that you get
"into the green" (good part of reading) after a recharge and that it stays that way over periods of non-use.
The ability of a battery to form acid upon recharging is a fundamental indicator of health. If you're feeling
fancy you can monitor v output over hours of time, but he hydometer is the quick way.
I always figured that my "reserve battery" in case of failure of the my scope battery was the one in my car.
But mainly I don't lug this thing around because I plan on having problems with it. I do however NOW believe
that it's worthwhile to go "high end" on your marine battery for the same reason that I don't screw around
with low-end car batteries. The 0.1% additional chance of failure just isn't worth it if it means losing an
obseving night to save $20.. There are also serious financial economies to be had in buying one big battery
as opposed to many smaller ones.
-gn.
Del Johnson
mention the back breaking weight of an automobile type of battery. I tried
it and gave up on that idea.
I now use a pair of 12V 12amp-hr (24 amp-hr total) Power-Sonic gel cells.
They are clean, very compact and weigh about 10 pounds each. I built a
power box that contains the batteries, a voltmeter, ammeter, multiple
outlets, power cords, AC inverter and the battery charger. Very handy and
easier to lift than the old lead-acid battery.
Gel cell longevity has a lot to do with the charging rate. One must charge
these batteries very slowly with a 500mA trickle charger. It is also very
important to use a charger with an automatic stop to prevent overcharging.
I have used these batteries for many "all-nighters" over several years with
no problems at all.
Someone mentioned separating the two batteries to prevent interference.
That is a great idea. I am going to rewire my battery box to do this.
Del Johnson
"greg nowell" <myreala...@gnowell-at-wsg.net> wrote in message
news:3B675284...@gnowell-at-wsg.net...
Chris L Peterson
>I agree with all of the advice posted so far. My experience with
>gel-cells
>or batteries using "recombination technology" (used in gel-cells)
>would direct
>me to favour the flooded lead-acid (sealed or not) battery.
>
>Batteries using "recombination technology or absorbed electrolyte
>suffer from
>multiple failure modes, ie. premature dryout, thermal runaway,
>sensitivity to
>AC ripple to name a few. Their life is shorter than a flooded
>lead-acid battery. Gel-cells are great in that they can't spill acid
>and they work in any orientation but they have compromized life-spans
>due to their inherent design deficiencies.
I like the absorbed glass mat (AGM) technology being used in new, high
end batteries. Up where I live, lots of people run their homes off
solar panels and batteries, and these are great deep cycle cells. They
are unspillable, valve vented, and can be used in any orientation.
They are extremely robust, hard to damage, and good for around 1500
cycles (80% discharge). Many are guaranteed for 10 years. Under heavy
duty, they outperform flooded cells and are much nicer to work with.
For field work, I'm using a Johnson Controls 125 AH AGM battery that I
picked up for $30 from a UPS contractor. A lot of big computer centers
and ISPs routinely replace their UPS batteries every three years.
These excellent cells are typically as good as new, and can be had
very cheap.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com