http://cattlecorner.com/conversions/wiregauge.htm

2.5mm is slightly smaller than 12 gauge. 16 amp fusing is fine.
If permanently installing a battery charger it should be designed for that
and UL listed for use in an RV application. Also consider if it is designed
to support charging with a connected load and be careful of its termination
or  "LID" voltage. Most RV chargers stop at 14.5 volts. Chargers designed to
fully charger a battery will go to 16 volts or even higher. Light bulbs, the
stereo, ECU etc. may not like that also. Also some of thee chargers will
have very poor filtering and allow a lot of "ripple" which can also damage
sensitive electronics. Progressive Dynamics makes some excellent chargers at
reasonable prices, ( for what they are).

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Jonce Fancher
Sent: Sunday, March 04, 2012 10:32 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 2.5 in AWG

Hi all
Trying to get a idea of the Wire Gauge on a connector in the Vanagon.
It is for the fuse behind the drivers seat Below the seat belt retractor for
the Fridge.
I removed the fridge years ago and put in shelves.
I was thinking of using the wiring to Back feed the Battery when plugging to
110V power. I know I will have to remove the Relay under the seat and Hard
wire it but it will be fused at 16 Amp as well as fused in the charge unit.
I looked up in the Bentley and it states it is 2.5, Is that like 14 Gauge
(AWG) Or ???
It does use a 16 Amp Fuse. So if it is large enough I will just back feed
from there.
If not I will have to run wire to the main battery.

I also plan on putting in a 2nd battery just did not follow the thread but
have the full instructions and relay so it should be not all that bad.

Thanks Jonce