Date:         Mon, 26 Jun 2006 11:22:39 -0700
Reply-To:     Michael Elliott <j.michael.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael Elliott <j.michael.elliott@GMAIL.COM>
Subject:      Re: Installing a 1000W converter
Comments: To: dhaynes@OPTONLINE.NET
In-Reply-To:  <e28a9832bc2b.449fe287@optonline.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Dennis Haynes wrote:
> Why do you need a 1,000 watt inverter? How long do you think an Optima will operateit? 1,000 watts will need 85 amps assuming 100% effeciency. That will give ~40 minutes run time in a perfect world. In actuality, an 85 A/H load for 45 minutes will give you a damaged battery. You should plan on 2 or 3 Optimas to run that thing.
>

Dennis, you are right. But there are still times where a larger inverter
can be useful. I use a 1000W inverter because my coffee bean grinder
pulls a hefty bit of current when it is first started. Smaller inverters
go into Protect if I try to use them. I only run the grinder about 20
seconds, and it consumes 130W, or about 10A on the 12-volt side, during
operation. That's 0.06 A-H.

It really is very sobering to realize how much power we use on a daily
basis around the house. The electrical system is surprisingly efficient,
so we seldom think about how many amps our appliances use (except when
it's time to pay the electrical bill!). But when we go "off grid," and
try to run what we consider the basics from a battery . . . reality, in
the form of the limitations of our present-day battery technology, kicks
us in the butt. My first awakening was back in my Coleman popup camper
days. It came with a nice hitch-mounted aux battery. Midway through the
first night, camping in Colorado in winter, the heater ground to a halt.
It was a LPG forced-air furnace, and trying to keep that cloth bag warm
quickly ran the battery down. Got a bit colder until the sun came out.
In the morning it took me a few minutes to sort out what happened, but I
quickly grasped the relationship between amps drawn and the amp-hour
rating of a battery.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR