Date: Thu, 6 Feb 2003 22:45:33 -0500
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Inverter Question
In-Reply-To: <3E431197.1DAA2D45@rogers.com>
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At 08:53 PM 2/6/2003, Greg Marshall wrote:
>I'm into 24 hour mountain bike races, and would like to have the ability
>to recharge NiCad and NiMH batteries using an inverter. It would also
>be nice to plug in a small 30 watt work light to shine on my workstand,
>but my primary need is for charging batteries. Here's the specs from my
>cycle light battery charger...
>
>Input 120VAC 60 HZ 5W
>
>Output 7.5VDC 300mA
>
>Say I had two of these plugged into the inverter. How large an inverter
>would I need. How many Watts?
Well, you'd need ten watts for the pair, if the nameplate is
right. Smallest you can get is prolly around 40 or so. for small laptop
computers...150 is a nice convenient small size.
>Also, is it absolutely neccesary to use a yellow top or similiar
>battery? Could I get away with using a regular battery? Once the van
>is parked at the race site, the engine won't usually run for just over
>24 hours. I suppose I could start it once in a while, just not at night
>when the rest of the team is sleeping.
For ten watts out of the inverter you're drawing likely a bit more than an
amp -- doing that for 24 hours would be 24 amp-hours. You could probably
get away with that once in a while with your starting battery, not even use
a second one. If you only run the pair 12 hours that leaves you half of
that budget for your stereo -- if you play it quietly it won't take much
more than it does with sound completely down. Measure the draw and see
what it needs.
Thirty watts on the light will draw about three amps. An hour would be
about three amp-hours, ten would be 30 etc.
If you do it a lot for a long time it will be cheaper in the end to use a
proper deep-cycle battery, but you can certainly get away with a lot less
up-front cost by using cheap deep-cycle or even decent starter battery if
you do it a few times a year. But starter batteries really really hate
being run flat, that's not their goal in life at all, so even a minimum
deep-cycle would be an improvement if you do it very often. But you might
try with the cheapest battery you can find and see how long it takes to
wreck it...your needs are pretty modest really. You'd be nuts to run the
fridge on battery if propane is available, don't even think about it. :)
david
--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"
