Ken wrote in message . ..
On 22 Apr 2004 21:37:37 -0700, (Mark Keith) wrote:
I only spent about $50 bucks for a 12/2 amp automatic charger. I ran a
battery and a 3 amp trickle charger for years using a ic-730. It will
keep up in most instances as you don't talk all the time. Neither the
730, or the 706 I use now have any problems with the slightly lower
voltage. Both are 100w radios. MK

My experience with automotive 12/2 automatic chargers is they drop to
trickle charge, not float charge. If you leave them hooked up
permanently, they kill the battery in a month or so. Also, they can't
be used with SLA, but marine chargers can -- and they drop to "float,"
not trickle. This is necessary because boat owners hook up to shore
power for long periods of time and don't want to bother switching the
battery charger on and off. Because of that -- and their built-in
isolators to handle more than one (non-parallel) battery -- they cost
$150 instead of $50.

The radios you have that run well off batteries, What do the specs
recite as the required supply voltage? I know that my FT990 wants
13.8 volts and really drops off quickly on 105AH battery power. OTOH,
my FT817 is happy with anything down to 9.6V (if memory serves).

Apparently, there is a [possibly small] market for the battery
boosters:
http://www.eham.net/reviews/detail/3404

Ken KC2JDY


Ken
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Hi Ken,
as other people have mentioned, it is not a problem running radios on
12v - or indeed, 12.6 volts for a charged battery. Why make this so
complicated - cheap SLA battery chargers/float chargers are available
off the shelf in the local supermarket, if you want automatic
changeover then wire up a BIG relay, coil operated by your mains power
supply, which then switches to the batteries on power fail.

As amateurs, we should be able to think a bit laterally and come up
with simple, cheap, off the shelf solutions - remember, if it aint hi
tech its less likely to go wrong when you ned it.

73 de VK3BFA Andrew