Date:         Tue, 30 Oct 2018 11:36:33 -0400
Reply-To:     alex@MEVAY.ORG
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alex MeVay <alex@MEVAY.ORG>
Subject:      Re: Lead Acid Battery Bank and Solar Charging
In-Reply-To:  <5BD7BC32.25033.39E367D2@taring.taring.org>
Content-Type: text/plain; charset="UTF-8"

If any of you would prefer a made in USA option, I should mention that my
company makes MPPT solar charge controllers that are a perfect fit for our
vans and other small to medium off grid-systems.  These are made right here
in the USA under two brands:

http://www.genasun.com
http://www.blueskyenergyinc.com

The Blue Sky Energy controllers have a lot of features, like the ability to
take a remote display or to keep a starting battery topped off while
charging a house bank.  The Genasun controllers are more compact and simple
and great for smaller installations (140W or less).

I use my Westy as a mobile test lab for new products, but I'm currently
running a Blue Sky Energy SB1524 with 2x 100W glass panels (installed by
the PO), and a 180Ah LFP battery bank.  This setup provides plenty of power
for a Truckfridge TF65, lights, laptop, stereo, etc.

As others have mentioned, you can get away with a PWM controller if your
panel and battery voltages are matched (15-18Vmp for a 12V battery), but
MPPT will deliver typical gains of ~10-30%.  When using panels that have a
higher voltage relative to the battery, MPPT is mandatory.  With the
explosion of grid-tie solar, it's harder to find 12V panels (which use 36
cells), but larger, higher-voltage panels have become absurdly cheap.  A
60- or 72-cell panel putting out ~220-350W at ~30-40V can be had for under
$0.70/W, will fit on a pop-top, and coupled with an MPPT controller, will
give you more juice than you'll know what to do with.  Lightweight
semi-flexible panels seem to have come of age, and are also a good option.
Questions, just ask.

Happy charging,

Alex