Date: Sat, 29 Sep 2007 09:51:32 -0700
Reply-To: Roger Whittaker <rogerwhitt1@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Roger Whittaker <rogerwhitt1@GMAIL.COM>
Subject: Re: New fridge replacement option for the Dometic
In-Reply-To: <46FE6BC5.40600@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
for those who like doing jiggery pokery stuff...
i recently picked up a 120v to 12v power supply at a second hand store
it was designed to run an intercom system ...
anyway the output is 1Amp and will make an excellent trickle charger ...
the old panasonic 12 v power supply for broadcast video camera works the
same way
this added to the inverter and one could charge very well ...
just information for ther jiggery pokery sorts
yours
On 9/29/07, Michael Elliott <camping.elliott@gmail.com> wrote:
>
> I have eyeballed that wheelchair battery scheme and agree that charging
> has to be handled carefully. strapping them to the output of the
> alternator is just asking for trouble. They need smart, not dumb,
> charging.
>
> For on the road charging, there are a couple possibilities, both of which
> add an additional layer or two of jiggery-pokery. The first is the obvious
> one: run an inverter off the alternator and use it to power a 120VAC smart
> charger, i.e.,
>
> alternator --> inverter --> 120VAC/12VAC charger --> house battery.
>
> If the normal and recommended battery disconnect relay or separator is
> shown it would be:
>
> alternator --> relay --> inverter --> 120VAC/12VAC charger --> house
> battery.
>
> That's two layers of complexity, and not super efficient but it gets its
> power from the alternator that's no worry. Advantages include: you can
> connect your charger to shore power if such is available, and 120VAC from
> the inverter for household current appliances, although it's powered from
> the alternator/engine battery so it should only be used while the engine
> is running (or only very lightly).
>
> A second approach to smart-charging the batteries is to use a 12VDC car
> charger for wheelchair batteries, such as
> http://www.powerstream.com/WC.htm -- it's a four-stage charger which takes
> the output of the alternator ((10-15 volt) and uses that to charge the
> batteries, i.e.,
>
> alternator --> relay --> 12VDC/12VDC charger --> house battery.
>
> Only one layer of complexity and about the same price, or lower, than an
> inverter+smart 120VAC charger. Disadvantages include: no way direct way to
> use shore power to charge the batteries, and no 120VAC available anywhere.
>
> --
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>
>
>
> On 9/29/2007 7:09 AM David Etter wrote:
>
> > Hi Warren:
> > Just be careful that these Wheelchair Batteries when parallel
> > linked require special charging technology. They cannot be charged by
> > the usual direct alternator input. They require a much lower and
> > slower charge rate and will overheat and die an early death if
> > charged at normal battery rates.
> > I was planning the same 4 - 6 battery system until I read the
> > charging requirements. I'm not saying it can't be done, it's just
> > that you would have to arrange another layer of "jiggery pokery"
> > (technical term for fiddling around) in the Westy system.
> > If you ask someone who regularly uses these batteries you
> > will find that they traditionally plug them in for overnight charging
> > on a 2- 3 amp 'brick' style adapter.
> > Good Luck and if you do come up with a good satisfactory SIMPLE
> > system , please let me know as I still believe that the small 12 volt
> > Wheelchair batteries are a good idea.
> >
> > Regards!
> > David
> >
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> >
> >> Karl,
> >>
> >> This looks identical to the "Isotherm CR65" unit I bought a few months
> >> ago. I first saw one of these in Eric Abercrombie's Syncro at Syncro
> de
> >> Mayo a few years ago.
> >>
> >> It's a little shorter than the Dometic but volume is much better due to
> >> extra depth. 2.3 cu ft. I believe.
> >>
> >> I think you may be a little optimistic about how long it will run on a
> >> given battery charge though....unless you've had it in long enough to
> test
> >> it in actual use. "4 days" seems very optimistic.
> >>
> >> The Danfoss compress draws a max of 2.7 amps. I "bench tested" mine
> with
> >> some food inside and based on how often it cycled I estimated it would
> use
> >> somewhere between 18-22 amp hrs daily. It ran a used but charged,
> starting
> >> battery we had around to "dead" in about a day and a half. I estimate
> >> that the popular 55ah Optima...if drawn down to 50% of its capacity (to
> >> preserve life), or 27.5 amp hrs useable, would only last about a day
> and a
> >> half.
> >>
> >> Seems we will need more deep cyle battery capacity...or supplemental
> solar
> >> charging for a weekend camp out.
> >>
> >> A few months ago Mark Drillock and I were discussing use of several
> 22ah
> >> wheelchair batteries linked in series. Only 2.9" wide and 6.8" tall,
> four
> >> would fit under the driver's seat for 88hrs, enough for 2+ camping
> days.
> >> Mark plans a bank of six in a tray under the van near the sliding door.
> >> I'm considering 4 more in the engine bay....I want to avoid the expense
> >> and hassles of solar charging.
> >>
> >> Some of these wheel chair batteries can be drawn down to 80% of
> capacity
> >> instead of 50% and recharging life will be reduced, but the
> >> reduction ...to something like 225 re charges...instead of 500...seems
> >> like something I can live with..(at the number of trips I take
> >> annually)....for the benefit of the extra useable amp hours.
> >>
> >> What's your real world experience been like?
> >>
> >> Warren C.
> >
>
--
roger w
There are two kinds of jobs in the world:
Picking up garbage and telling people things.
Successful people do both, with the same good attitude. (riw)
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