Simple charge controller?

[(unknown)]

Hi everybody, I just finished up building a 12' mill. It's up and flying, but so far it's just powering my dummy load. I'm not going to have much time in the next few months, so I would like to build a real simple charge controller to get going. The only load (at first) will be an electric fencer.

Would it be sufficient to have a comparator that says "if battery terminal voltage > X, then disconnect batteries and connect dummy load"?

I'll go for something more elaborate/efficient later probably, but would that keep my batts full of juice (and not hydrogen)? What should I use for 'X'? Would 14 volts x4 work? (It's a 48v system.)

Thanks in advance,

Adam

[DamonHD]

My limited understanding is that that would be enough.

14Vx4 would be about right, but you need to have that measured pretty accurately, since have a volt either way may make the difference between not-fully-charged and horribly-overcharged.

Rgds

Damon

[kurt]

the usual way to control over voltege in a battery charging windmill system is to never disconnect the mill from the batteries because that could lead to over speed of the mill and catastrophic failure. instead the usual method is to bleed the extra voltage off the battery bank using a diversion controller and a dump load. this way the batteries are not overcharged and you do not risk destroying the mill by disconecting it from the battery bank.  

[rippersoftware]

You might want to look at ghurd's controller.  Can't get much simpler.

http://www.fieldlines.com/story/2007/8/24/172521/889

There are some threads about modifying a homepower shunt requlator to handle higher voltages.

Also look at RedRok.com for shunt regulators and diversion regulators.

Here is a simple windcharger controller that I plan to use to get up and running.  All the parts and board are probably less than $20 depending on where you get your parts and how you build the board.

http://www.fieldlines.com/story/2004/9/20/0406/27488

Much luck!  RipperSoftware

[ZooT]

I've got this devide here that I got on ebay.

Inside are two relays a capacitor and a zener diode.

The way it's supposed to work is

if battery voltage = 14.2vdc

then turn on dump load

if bettery voltage < 13.7vdc

then turn off dump load

I suspect the zener does the work of flipping the small relay, which then flips the big relay and the capacitor provides some sort of hysterisis(?)

If you'd like I can open the case again and do a hand drawing of the circuit