Re: (ET) Solar charging, part 2

[Jim Coate <jbc coate org>]

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