Fin,
I have found the two batteries will fight on another and deteriorate.

Any un equal difference will constantly pull on one and push the other to hold more which eventually made them both go bad prematurely..

Doug

  ----- Original Message ----- 
  From: Fin Beven 
  To: vanagon@GERRY.VANAGON.COM 
  Sent: Monday, June 07, 2004 5:14 PM
  Subject: Re: Dual-Battery Question

  For years I have linked my two (identical) batteries with a solid run of 4 ga. wire, with crimped-on terminals at both ends.  This effectively turns the two batteries into one LARGE battery.  What's critically important is to use VERY high quality wire and terminals.  If you have access to marine grade (West Marine on the Internet) I think that it's worth the price, as they assume that their equipment will be used in a very harsh electronic environment (salt air).

  This is not a recommendation, but no problems have resulted.  However, I do have a good quality volt-meter that can be left on when the batteries are being used but the engine charging system is not (as when camped overnight).  I'm just cautious not to let the voltage drop below 11.8 in moderate weather.  

  Fin Beven
  '90 Carat, Custom Camper Conversion
  Pasadena, CA
    ----- Original Message ----- 
    From: Joe Federici 
    To: vanagon@GERRY.VANAGON.COM 
    Sent: Monday, June 07, 2004 11:10 AM
    Subject: Re: Dual-Battery Question

    I wouldn't consider it safe but to each his own. That said if your
    going to do it I would use as large around 6 gauge or better and fuse
    it for sure it won't take much to over charge the battery and really
    BAD stuff can happen one you reach that point.

      The isolator or relay setup isn't that had to do maybe you could take
    it with you and hook it up on vacation?

    JFF

    On Jun 7, 2004, at 1:38 PM, Russell, William wrote:

    Well, after a weekend of work, I've managed to get my Optima Yellow top
    installed and the stereo switched over to it.  However, I have not yet
    installed a relay or isolator yet.  What I would like to do, for this
    trip
    (I leave tomorrow), is employ a manual system.  It would seem to me that
    hooking a wire from the + of the starter batter to the + of the Optima
    while
    the car is running would work.  I would like to use something a little
    more
    graceful than a jumper cable as I will be living in the van for the next
    week.  If I were to route a wire between the two batter compartments
    and use
    alligator clips to connect it, would this be safe?  What gauge of wire
    should I use?  Should it be fused?

    Any help is much appreciated.

    \/\/i!!y

    1980 Westfalia "Jazzy"