Bits and pieces [RE-wrenches]

[R. Sparks Scott]

	Just back from two days in Portland (Oregon), catching up on some running
topics:

>I am not sure why you don't run your system like mine?. I wonder why you
did >not get one of the more efficient batteryless grid intertied inverters

	Todd;

	The ST model was not even available when I got the SW. Additionally, the
2512 is used for six weeks as a stand-alone generator-based power system to
run the Main Camp Kitchen, Quarter Master and Fair Central operation at the
Oregon Country Fair each year. See <http://www.mrsharkey.com/solar.htm> for
more details. The page is a bit outdated, double the PV's and multiply the
wind machine by x4. The entire battery and inverter
control/metering/distribution/etc. is mounted in a dual axle trailer for
portability, see <http://www.mrsharkey.com/trailer.htm> for that.
	I kind of thought that your overnight loads would be too much for
batteries. I've been waiting patiently ten years for the grid to fail, if
only for an hour, so I could make use of all this technology to stay
connected. 
	

>can i use a large 36 volt battery bank to charge eleven 36 volt carts or
can i do it >from a 48 volt battery bank?? 

	Kurt;

	No you really can't transfer power from a 36 volt bank to a 36 volt bank.
It would be possible to charge 36 volt from a 48 volt bank, but you would
need very high powered, carefully designed and adjusted power processing
equipment, and even at that, the efficiencies would be terrible, for the
most part.
	Since there is very little use for golf carts at night, they need to be on
PV chargers during the day. This is a problem, as they are out being used
when the sun shines. Putting small PV's on the carts themselves is mostly
window dressing. Like all other EV's, by the time you put enough solar
modules in the vehicle to make a real difference, it will be to big and
heavy to go anywhere.
	Trying to store up enough ampere-hours to refill eleven 36 volt, 220 Ah
batteries is a totally ambitious project. Stay with the inverter to feed
the grid, and concentrate your efforts on finding a more efficient charger
for the carts, something without big iron transformers and *for sure*
something that doesn't use typical 'ferro-resonant' charger technology.

>I take it you mean that the lowered float voltage setting will over-ride
the sell
>voltage setting and that the sell back will begin at the float level
rather than the
>sell level ??

	Carl;

	Eh?? well, what I was saying is that the Trace isn't like a regulated
supply voltage in the grid inirtie mode, it doesn't just come up to a
voltage and stop there like a one-way charger would, it actually will
'consume' current (feeding it back to the grid) to *pull* the voltage down
until it reaches the float voltage. And no, if you tell it to sell down to
a voltage lower than the float, it will sell down to that voltage.

	I'm going back to the posts and try to get caught up.

	-S

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