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Re: [PSUBS-MAILIST] batteries and amps
On Tuesday, Feb 18, 2003, at 14:12 US/Central, Brent Shaw wrote:
> I'm just about to buy the batteries for my project.
>
> I'm thinking of the Trojan 6 volts (reserve mins @ 25
> amp of 475) x 4 for main power and Trojan 12 volts
> (reserve mins @ 25 amp of 150) x 2 for secondary power
> to make two 24 volt systems.
>
> Can someone tell me what my aprox. run time would be
> running two 74lb thrust motors @ 45amps each full
> speed for each main power and secondary power.
I don't know reserve minutes. Is that just how many minutes you can run
that many amps? Like, 475 minutes at 25 amps? No, wait -- that can't be
right -- you'd have like an 11,000 amp-hour battery. I could use one of
those. Whatever are "reserve minutes" then? If I assume those numbers
(475 and 150) are amp-hours, wouldn't you just have something like 10
hours run-time on one set, and something like 3 hours on the smaller
one? Or am I missing something?
I thought there was some factor you're supposed to include to make up
for inefficiencies, and anyway you don't want to run your batteries all
the way down, so you might want to figure 50% or 75% of those figures.
Or maybe I read your message totally wrong.
Is "secondary power" for after you run your main batteries dead, or in
case there's a problem with them? Am I assuming that correctly? The
main benefit of that, of course, is the capacity to say things like,
"Divert all secondary power to the engines!" Woo-hoo!
(I like your pictures. Pretty. This is the one I remember from before:
http://photos.yahoo.com/bc/drydivenz/vwp?.dir=/
drydivenz&.src=ph&.dnm=8.+hull+taking+shape.jpg&.view=t&.done=http%3a//
photos.yahoo.com/bc/drydivenz/lst%3f%26.dir=/
drydivenz%26.src=ph%26.view=t from before -- inspiring!)
- - -
David
buchner@wcta.net
Osage, MN, USA
http://customer.wcta.net/buchner
If we die, we want people to accept it. We are in a risky business,
and we hope that if anything happens to us it will not delay the
program. The conquest of space is worth the risk of life.
- Astronaut Virgil I. Grissom