Hi, folks - I would like to try running my Icom R-75 at home from a 12
- 13.8 volt cell or battery. The requirements would be that the cell
would be able to recharge from 115v AC during the radio's off time, and
that while the radio is turned on, the battery would be electrically
disconnected from the wall AC. It does not matter to me whether this
connect / disconnect is manual or automatic.

This device might also run an MFJ Noise Canceller unit, which uses
lower voltage (I would need to provide a step-down for this device, or
a separate battery).

I would like the battery to be nice and big, something that would
provide an easy constant 36 watts (12v at about 3 amp max) for several
hours straight without strain. It would be nice if this device did not
develop a memory (no NiCads, please). It would be nice if it were not
an ugly thang with potential leaky chemicals like a car battery.

Can anyone recommend such a set-up, and/or some specific manufacturers
and model nos. that might fill the bill?

Thanks so much ~
Bruce Jensen

I have a big very heavy Sears Marine deep cycle 12 volt battery (like
the kind used in motorhomes and such like) I bought at the local Sears
store about six years ago.Those kinds of batteries (deep cycle
batteries) shouldn't be drawn down to more than about half capacity,or
so I once read in an article.With proper care and maintnance,deep cycle
marine grade batteries should last ten to twelve years or more.
cuhulin

There are plastic cases available for wet cell "car type" batteries that
help prevent spilling the battery acid in case the battery tips over.You
could set the battery in your garage (don't set the battery on a
concrete floor) and run two long wires from the battery to inside your
house.A good automatic battery charger and amp meter will help to keep
the battery in good condition.Occasionally,use a piece of an old rag and
a cup of warm water with baking soda in the water and wipe the battery.
cuhulin

Interstate brand name batteries are over rated and over priced.Sears Die
Hard batteries are just as good and lower price.
cuhulin

BpnJ,

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hth ~ RHF

I suggest getting a gell cell to avoid battery acid spills or fumes. I
only use mine when in the field, so I don't have a set up as you
suggest. I charge my battery from a bench supply using 13.8v as a
float voltage.

Depending where you live, you may find used gell cells that are part of
a data center backup system. These batteries live indoors and spend
most of their life on float (OK for SLA batteries) and maybe once in a
while provide backup. Alarms use similar style battiers, but not very
high capacity. The Yuasa NP7-12 is a real common back-up battery. It is
only 7 amp hours, but what you might do is get two of them, keeping one
on the charger while you use the other. Typically in alarms or data
backup, the batteries are replaced on a schedule rather than waiting
for a failure, so there are plenty of free or low cost batteries
available.

If you don't want to use a bench supply, West Marine sells all sorts of
chargers, though a bit pricey.

bpnjensen wrote:
Hi, folks - I would like to try running my Icom R-75 at home from a 12
- 13.8 volt cell or battery. The requirements would be that the cell
would be able to recharge from 115v AC during the radio's off time, and
that while the radio is turned on, the battery would be electrically
disconnected from the wall AC. It does not matter to me whether this
connect / disconnect is manual or automatic.

This device might also run an MFJ Noise Canceller unit, which uses
lower voltage (I would need to provide a step-down for this device, or
a separate battery).

I would like the battery to be nice and big, something that would
provide an easy constant 36 watts (12v at about 3 amp max) for several
hours straight without strain. It would be nice if this device did not
develop a memory (no NiCads, please). It would be nice if it were not
an ugly thang with potential leaky chemicals like a car battery.

Can anyone recommend such a set-up, and/or some specific manufacturers
and model nos. that might fill the bill?

Thanks so much ~
Bruce Jensen

Cuhulin,

We should all Die Hard with a Smile on our face )

omg - the devil made me do it ~ RHF

I don't wait till my car is stuck in the dead of winter with a dead
battery to replace it. I have 4 daughters that drive, so you can
understand my concerns. I usually have a couple of car batteries
kicking around here. I'm actually getting ready to go off the grid
with my R75 and 2m rigs as well. My 2m rig actually displays the
battery voltage for a few seconds when power up.

I don't think I need to be worried about creating hydrogen from
charging a battery in the basement. Do I? It will only be a trickle
charge.

So there ya go. Go look at your loved one's car battery and if it
looks like it might be a little iffy why just yank it out and drag it
into the shack. Tell the old lady your concerned that she might get
stuck this winter and have her fork over the cash for a new battery.
Everybody is happy.

73
Bob

Most regular car batteries are good for about four years (especially in
cold weather climates) before they should be replaced with new
batteries,so if the battery in your vehicle is about four years old and
still in good condition and if you live in a cold weather climate,why
not use the old battery for your radio(s) and buy a new battery for your
vehicle? I don't know for sure,but some computer back up battery
units/systems (I use an APC model 1000 computer backup unit for my
computer www.apc.com) just might have a connection on them for 12
volts D.C.current,it's worth cheking out.You could rig a couple of wires
directly (with a proper fuse,of course) to the battery in your battery
computer backup system.I think.
cuhulin

M...sushi.com wrote:

I suggest getting a gell cell to avoid battery acid spills or fumes. I
only use mine when in the field, so I don't have a set up as you
suggest. I charge my battery from a bench supply using 13.8v as a
float voltage.

Thanks, also to RHF and Cuhulin. I just took a look at these gel cells
on a couple of websites, incluidng the one recommended by RHF and some
others. This, of course, raises more questions :-)

How big a charger must one have? Must the current available on the
charger be some minimum fraction of the amp-hours of the battery, or
can one use a smaller charger and just leave it on longer?

Also, is the charge time a simple proportion between the charger
current and the battery amp-hour value? i.e., to recharge an 18
amp-hour battery with a 10-amp charger, the charge time is 1.8 hours -
?

Is it OK to drain a gel cell until it loses almost all of its charge?
Or is there some minimum level at which one must stop (25%, 50% or
etc)?

Finally, once the gel cell battery is fully charged, how does one know,
and will it hurt if the charger is kept on without checking? Does a
charger have a device to shut off when full charge is reached?

Thanks,
Bruce