Re: (ET) Solar charging, part 2

["Christopher Zach" <czach computer org>]

Hm. 3 panels should do fine; remember that a "12 volt" panel can put out
over 21 volts under full sun and open circuit. Three of them plus a
controller is all you really need.

That being said, I would recommend www.thelastplaceyoulooked.com for a 36
volt solar charger.

Chris

----- Original Message -----
From: "Travis Creswell" <ozsolar ipa net>
To: "ELECTRAK" <elec-trak cosmos phy tufts edu>
Sent: Tuesday, April 22, 2003 10:23 AM
Subject: Re: (ET) Solar charging, part 2


> I charge my E-15 with solar.  Yes, you will need a charge controller.  On
my
> old pack, which was a very abused set of batteries before I got them the
> solar wouldn't overcharge them, even in a week.  Now, I have a new pack 
> of
> T-105's and I had to get charge controller.  I found my battery pack
> regularly at 16 volts per battery if I didn't pay attention and shut the
> array off.  I mow approximately less then .75 acres and the new pack
charges
> up in just a few days with 340 watts of solar.  I'm using a maximum power
> point tracker to charge it.  I use four 85 watt solar panels wired in
series
> (48 volts nominal) and the charge controller converts it to the 36 volts
the
> tractor needs.  I've set the charge limit to 45.6 (temp compensated).  If
> you are interested in this charge controller I use you can check them out
at
> www.outbackpower.com.
>
> Travis
>
> Joplin, MO
> E-15
>
>
> ----------
> >From: Jim Coate <jbc coate org>
> >To: ELECTRAK <elec-trak cosmos phy tufts edu>
> >Subject: Re: (ET) Solar charging, part 2
> >Date: Tue, Apr 22, 2003, 8:32 AM
> >
>
> >Christopher Zach wrote:
> >> In the meantime, some thoughts: I am beginning to think that you could
> >> simply take 3 60 watt panels, connect them in series, plug them into a
> >> breaker box/disconnect with a 10 amp fuse (DC RATED!) and run a cable
into
> >> the Elec-Trak. Put a single diode in there to prevent back-feeding the
> >> panels from the tractor and let it rip.
> >
> >This would basically work, but...
> >
> >> I doubt that the three panels could produce enough current (5 amp 
> >> hours
> >> *tops*) to overcharge the batteries.
> >
> >Note that current is measured in *amps*. So these panels would be
> >producing 5 amps. IF left connected for 1 hour, would then have 5x1 = 5
> >amp-hours (or if left for 20 hours would have 5x20 = 100 amp-hours).
> >
> >> But that would be enough to put 100
> >> amps into the batteries over the course of a week; enough to top them
off.
> >
> >This would be 100 *amp-hours*. So, as above, 20 hours of full sun, or
> >just under 3 hours per day. During the summer months you'd probably get
> >much more than that. During the winter, possibly less.
> >
> >> Any thoughts? Can a T105 last with a float charge of < 5 amps?
> >
> >A "float charge" normally refers to a fixed voltage source. Once
> >charged, 5 amps is enough to get a T105 gassing nicely. If you use the
> >tractor once a week, it would take a few days to fill up so wouldn't be
> >until near the end of the week that during mid-day sun it would get to
> >the gassing point, so could end up with just a nice amount of
> >equalization. However... if you don't use the ET for a while (no rain in
> >August so no new growth to mow) then might get a bit over charged. The
> >flip side is that if really run the batteries pretty far down (and then
> >it rains for a couple of days), then could take many days to charge back
> >up, which could promote sulfation.
> >
> >So, not the ideal charger but... probably just as good as the OEM
> >charger which tortures the batteries in different ways yet people get 5+
> >years out of a pack. And it's solar.
> >
> >
> >_________
> >Jim Coate
> >1992 Chevy S10
> >1970's Elec-Trak
> >http://www.eeevee.com
> >
> >
>
>