See this link for more info that may help:
http://www.uuhome.de/william.darden/dcfaq4.htm

My interpretation is that a 10 AMP draw would last at least 5 hrs if
your RC is 120 (at 25 AMP).

BTW your RC number is impressive.  I use an Odyssey
http://www.odysseyfactory.com/specs.htm PC1200 deep cycle in my Westy
and it has a RC of 78.  It will last for 5-6 days of camping with
reckless use of lights etc, so I think your Optima would be much
better.

Laurence Smith
Hamilton, ON
90 Westy (fanumbos)

> -----Original Message-----
> From: Vanagon Mailing List
> [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
> Of Larry Chase
> Sent: Friday, October 11, 2002 11:04 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Battery Reserve Capacity Calculations - 2nd Posting
>
>
> Volks,
>
> Originally posted this question a week ago.
>
> Got no reply!
>
> - - - -
>
> I'm getting ready to do some Battery requirement calculations.
>
> Assuming a OPTIMA D750 Yellow Top Deep Cycle Battery
>
> Rated at 120 minutes of Reserve Capacity at a 25 Amp draw.
>
> Specifications.
>
> Reserve Capacity - Minutes: 124
> Capacity (C/2 rate) - Amp Hours: 52
> Capacity (C20 rate) - Amp Hours: 65
>
> Am I correct in assuming that a 10 Amp Per Hour Power requirement
> would mean this battery would last 5 hours before needing a
> recharge?
>
> Hitting the Trail Soon,
>
> Larry Chase
> Email: lchase@attglobal.net
> Web: www.roadhaus.com - Under Construction
> What: The Great North American Tour
> When:  01.02.03
> How: RoadHaus - 1990 VW Westfalia Syncro
> Today: Denver, CO (Engine Transplant)
> From: Mesa,  AZ
>