Battery one and two are both connected to the starter via the switch "common " terminal. This means the regulator serves both batteries.
So, the problems you having most likely are from the batteries, unless they are known to be good, test these first before making any changes to the switch etc.  
The fact that you need a jump says either you have a filed charging system (alternator) or batteries or both.  

----- Original Message -----
Wrom: SFDULHPQQWOY
Sent: Thursday, July 11, 2002 1:19 PM
To: vanagon@GERRY.VANAGON.COM
Subject: FW: Battery Switch

Oh yeah...glad you reminded me. I forgot to mention this. If I jump-start the van and leave the switch to "both", after about 20 minutes of driving, the aux. is at full charge (green LED) and the primary is at half charge (yellow LED).  This leads me to believe that the alternator is charging everything okay, but in a day or two everything's dead again.  Should I be able to start the van with the switch set to "battery 2"???  I know it won't start with it's set to "none"...probably for the reason stated in other replies (i.e. voltage regulator).  Do you suppose the voltage regulator is connected only to battery 1????

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Wrom: IYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEG
Sent:   Thursday, July 11, 2002 2:44 PM
To:     vanagon@GERRY.VANAGON.COM
Subject:        Re: Battery Switch

You have a marine -type boat switch and unless it has corroded contacts or you have other bad connections, the switch isn't the problem. The 4 position switch connects both batteries for more cranking power or dual charging. Switching to auxiliary allows you to run the vehicle or accessories on number 2 battery, and have the main for starting.  You should check your charging output at the alternator, and at the battery, to see if the switch is the problem.  Robert
1982 WestfaliaGet more from the Web.  FREE MSN Explorer download : http://explorer.msn.com