Bob:
Yes, the small 7 amp-hour battery was probably a gel cell and may have
just had too much internal resistance to run the Corsair. 90 amp-hours
is more than enough. I think you could get by with much less. Most size
34 deep cycle batteries that I've see, like the Optima, are about 55 amp
hours.
The Corsair draws about 600 ma on receive and about 18 amps key down at
full power. If you work SSB with about a 50-50 transmit-receive ratio,
and assuming the SSB wave form has about a 25% duty cycle, you will
draw on average per hour: 0.5 hr receive X 0.6 amps = .3 amp/hr
+ 0.5 hr transmit X 18 amps X 0.25 duty cycle = 2.25 amp/hr
Total is 2.55 amp/hr average drain. If you use a 55 amp-hour battery,
and derate it, say 20%, you get 55/2.55 X 0.8 = 17.25 hours.
If you run CW, figure a 50% duty cycle on transmit, so you can run about
9.16 hours.
This assumes that you are using a lead calcium deep cycle battery that
is in good condition.
Some hams (myself included) have had poor results running on battery
because they used car batteries, which are not good in a deep cycle
role, and used car batteries, to boot. A three or four year old battery
retired from automotive starting service will have questionable capacity
and they don't hold a charge as long as a deep cycle battery.
73,
Bob WB2VUF
Bob Stephens wrote:
> Please let me clarify this.
>
> The 7 hr gel cell was only a test. I wanted to make one or two contacts to
> see if it would be worthwhile to buy a larger battery. The fully charged,
> almost brand new battery failed the test in the first minute.
>
> The question has changed. I plan to purchase a deep cycle marine battery
> tonight. The 90 amp hour version will be somewhat hard on my weak back,
> although I could carry it around if I'm careful. The question now is :
> would a 65 amp hour deep cycle marine battery power a Corsair for at least
> 5 hours in SSB assuming I'll be listening for at least 50 % or more of the
> time?
>
> 73 -Bob KB1CIW
>
> At 05:09 PM 4/25/2005 -0500, you wrote:
>
>
>>For something like the Corsair, you really need much more than a 7 Amp Hr.
>>battery! Get a full size car or Marine battery, fully charged. The rig
>>wants 12 volts and a bit more for most stable operation, and I think the
>>Corsairs pulled 20 amps on transmit unless you had the power reduced some
>>way.
>>-Stuart
>>K5KVH
>
>
>
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