howdy ya'll

[cstgmt]

new to the board.  get my batteries from a UPS (battery backup) company that takes care of remote cell phone/radio station towers for ....free. have three pv's that i've purchased used (less than 3 years old each) and am getting new (still in the crates) 100 watt panels for $3 a watt.  all because i have no absolutely no money to spend on the lifestyle i've chosen.  am currently making battery cables from 4 awg and 3/8" copper tubing soldered on as lugs.  was looking into the scc3 charge controller as i'm currently just using a diode and would like a little better control on input voltage.  the scc3 was schematic'd out a little weak for me though on the full charge state dump load circuit.  any input would be appreciated (keeping in mind the absolutely zero dollar amount i can spend on the way). thanks!

[richhagen]

I'm no expert on this, but couldn't you use Forest's circuit to activate a relay, or supply the gate voltage to a string of parallel FET's and use them to handle the dump current?  keep having fun, Rich Hagen

[Opera House]

I suspect you have a lot more battery than solar panel.  Charge controllers are a waste unless you use a switching regulator to operate the panel at the maximum power point.  Unless you abandon the site for weeks, there is little chance of overcharging.  Currently, I only use an undervoltage monitor to shut off loads.  I am building a maximum point switching regulator for increased output from the panels and so I can operate panels at 24V and convert down to 12V.  The switching losses are more than made up by the savings in resistance losses since the panels are some didtance.

[hvirtane]

Hi,

I think that you should approximately

calculate the Ah of the batteries and the

power of your solar panels and

then also estimate how much you are using

the power. It depends on such things,

if you will need any charge controllers at all.

You might also check (with a volt meter)

sometimes the real condition of the

batteries, before making the decisions,

which kind of controllers to purchase.

- Hannu