Re: (ET) Solar charging, part 2 :using a stationary pack

["SteveS" <ssawtelle fcc net>]

I would think one solution would be to use a DC-DC converter to go from 24V
to the max charge voltage you want - I imagine 42V or so? This then would
feed the charge controller. Down side is some energy loss (maybe 10-20%) 
for
the DC-DC and cost of the DC-DC which will be directly related to the max
charge current you want. I guess a cheaper method would be to use a charge
controller that uses the available 24V and charges the batteries 2 or 3 at 
a
time (12V or 18V). Of course this requires more 'hands on' to switch 
between
banks. One good thing perhaps is,  I imagine 12V charge controllers are
pretty available.

I'm enjoying this discussion as I have two panels waiting to be used for
something!

- SteveS




----- Original Message -----
From: "Jeremy" <nagidog starband net>
To: "elec trak yahoo group" <>
Sent: Wednesday, April 23, 2003 12:45 PM
Subject: Re: (ET) Solar charging, part 2 :using a stationary pack


> Hi there,
>
> OK, I'll admit it.  After a long winter with marginal solar power I
decided
> to take my e-12 to a friends house to get a good solid charge.  I haven't
> had my elec trak long, and am still figuring it out.  The charger seems
very
> primitive, charging continuously at a constant amperage.  Solar charge
> controller ease off the charge as the batteries reach their fill, which 
> is
> much better for the batteries.  It seems like we are all paying a price 
> to
> fully charge our batteries using the onboard charger.  Charging via solar
> panels and charge controller would allow for a more complete charge, and
> better control over an equalizing charge.  A good compromise between 
> total
> solar charging from panels and charging from a main battery bank via on
> board charger would be to somehow get 36 volt charging out of my existing
> solar system without major modifications to the setup.  I run 12 panels 
> in
> three series of 48 volts, which gets bumped down to the 24 volt battery
bank
> by the Solar Boost 3048 charge controller.  I think the best approach to
> this would be to take the 24 volts from the bank and bump it up to 36+/-
> volts DC and run it through a charge controller to the elec trak bank.
> Anybody already doing this or might know how to do it without changing 
> the
> configuration of the main battery bank.
>
> Jeremy
>
> ----- Original Message -----
> From: "Christopher Zach" <czach computer org>
> To: <jbc coate org>; "elec-trak" <elec-trak cosmos phy tufts edu>
> Sent: Wednesday, April 23, 2003 6:33 AM
> Subject: Re: (ET) Solar charging, part 2 :using a stationary pack
>
>
> >
> > Yes, that is another possibility. I use a 100 watt grid-tie inverter
> hooked
> > to my main battery pile (300amps at 24 volts) to divert surplus sun
power
> > from my panels into the grid. I do like inertae: it is the best way to
get
> > efficiency out of a solar panel setup.
> >
> > However I will say that the efficiency of my solar charger is pretty
close
> > to 100%. The efficiency of the Elec-Trak's on-board charger is nowhere
> near
> > as good (lot o' heat). Thus by using the grid-tie approach, it is not 
> > as
> > efficient as charging directly from the panels.
> >
> > The typical "solar" way is as follows:
> >
> > Tractor gets top priority for charging
> > Bringing the shed batteries to 25 volts gets second priority
> > Rest is sold to the grid.
> >
> > The batteries in the shed typically get a full charge during the 
> > morning
> > (the panels can put in up to 15 amps, the inverter takes out 4 tops) 
> > and
> > then get discharged down to 70% or so during the afternoon. The size of
> the
> > battery core is large enough that I can run tools, toys, lights in the
> > evening without dropping the pack below 40%.
> >
> > Works pretty well actually.
> > Chris
> >
> > ----- Original Message -----
> > From: "Jim Coate" <jbc coate org>
> > To: "elec-trak" <elec-trak cosmos phy tufts edu>
> > Sent: Wednesday, April 23, 2003 9:13 AM
> > Subject: Re: (ET) Solar charging, part 2 :using a stationary pack
> >
> >
> > >
> > > Another variation is to use a grid-intertied system. For those of us
> > > already on the grid, this can be done with out any stationary battery
> > > pack (although won't have the blackout backup). Any solar power
> > > available goes into "the grid" when the sun shines and the ET is
plugged
> > > in and charges from the grid (regardless of the amount of sun shine 
> > > at
> > > that moment). I have just two smallish panels and an intertie
controller
> > > (Chris Zach may have had one first that I read about??) for a 100 
> > > watt
> > > system. Similar to what Jeremy and Eric and all have been saying, 
> > > this
> > > gets the most power possible from the panels as there is always some
> > > place for it to go.
> > >
> > >
> > > Eric wrote:
> > > >    In my opinion I think charging a stationary pack instead of
> directly
> > > > charging the Elec-trak gives you the freedom to do more (than just
> > charging
> > > > the ET). Coupling together the ability to recharge the ET along 
> > > > with
> > other
> > > > uses makes the investment in solar panels a wise investment. Don't
> > forget to
> > > > explain to the wife how if the electricity goes off again at least
we
> > have a
> > > > back up system to hold us over till the electricity in our area is
> > restored.
> > > --
> > >
> > > _________
> > > Jim Coate
> > > 1992 Chevy S10
> > > 1970's Elec-Trak
> > > http://www.eeevee.com
> > >
> > >
> > >
> >
> >
> >
>
>
>