Hi Dave,
I haven't spoken of it in years and have forgotten many of the details, but
I went all the way
down that road, design wise, about 15 years ago, it's a very interesting
concept! Although there
have been minor improvements in AC efficiency, they have a very optimistic
way of rating minisplits.
That's not the point however, there are several major considerations for
such a system, namely load,
load, load, battery capacity and battery charging. There is a reason 2 roof
units will barely cool a GMC
in the sun in the South East. Not to be a naysayer, but the system you have
mentioned would probably
offer reasonable battery capacity, cooling a typical GMC on a 79 degreed day
in full shade. If you are well
versed in psychrometrics you can do the calculations yourself. The system I
designed took several MAJOR
DESIGN ELEMENTS to make it workable. It took major upgrades in thermal
insulation for which there is not room
in a conventional GMC (and still have headroom), the design required moving
the floor below the aluminum framing
to gain space and flooring with aluminum to gain space for floor insulation.
That much of the project I completed before
running out of time and money. The design also added foam roof insulation on
the outside, again for headroom, and also
very special window treatment! The other MAJOR element was battery charging,
for that I came up with an AC Delco 24 volt
bus alternator capable of 9 KW output! Even that was complex in that it
required a variable speed drive to both prevent over speeding
the alternator at high engine speed and being able to charge at idle. I
actually found a company that built such a drive. The system would
have provided full Air Conditioning in any environment and other electrical
needs, with a maximum of two 30 minute coach engine idling
times a day!
It wouldn't be terribly difficult to try out your idea and it would be
interesting to see the results. I don't have any more time right now, but if
you are interested in discussing it, private email me and I will give you my
cell #, my email address can be found under properties of this message.
Marsh (rarely post anymore) Wilkes
Perry Florida
-----Original Message-----
From: dave silva
Sent: Saturday, February 19, 2022 8:36 AM
To: gmclist
Subject: [GMCnet] Ductless minisplit and batteries instead of genset.
I'm thinking about it. The math keeps getting better.
There are a bunch of 120V ductless minisplit heat pumps that will fit in the
generator compartment (mine is currently empty)
The vandweller kids are doing the math in youtube videos - the 12,000 btu
ductless pulls 700 watts for initial cool down and 200-300 watts to
maintain.
THat comes to around 700amps worth or battery (discharged to 50%) and half
that if i go with lithium. (I currently have 500 amps worth of flooded
batteries to use up)
Who else has gone down this road?
--
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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