I installed this unit, and it charges both batteries as well as keeping them maintained, when plugged into shore power.  I've been VERY happy with this, and the price is great!

https://www.amazon.com/gp/product/B00F5EBR1C/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Very easy to hook up to the batteries too.

Jack

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Richard Koerner
Sent: Saturday, October 24, 2020 6:05 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Trickle charger on hard to access House Battery

Mine is an 85 tintop.  I added the GoWesty auxillary battery setup 12 years ago with a group 41 Walmart battery.  I'll have to check my records to see if I've ever replaced that battery.  Here is the kit:  Auxiliary Battery Kit [1980-83 Air-Cooled Camper and 1980-91 Non-Campers] | GoWesty

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Auxiliary Battery Kit [1980-83 Air-Cool...
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I added a bunch of cabinetry to my van behind driver seat, making access to the Aux Battery a little hard to get to.  I also used a Greenlee sheet metal punch to provide a hole just behind parking brake lever to add a 12 VDC cigarette lighter socket; the idea was to have a convenient port operating directly off Aux Battery (I added an inline fuse).  The setup has been working just fine these last 12 years; at least I think so, it always works and I'm assuming the alternator via the relay in the kit is doing it's job; my camping electrical needs are very minimal, but I do run a laptop and some interior lighting; and also for charging phone and camera batteries.
But with Covid, my travels lately have really declined.  So....I got this bright idea that maybe I should trickle charge my Aux Battery with a cigarette plug into the nearby outlet and connected to my trickle charge?  I assume there will be minimal Hydrogen gas being emitted during the charging process but should quickly rise and ventilate out of garage.  I assume all of this would work and be safe...but wanted to pass it by the Vanagon brain trust before I do it.
Rich
San Diego