simonr Posted June 10, 2008 Share Posted June 10, 2008 Kim, the advantage of using a remote sensed alternator is that you don't need to modify it or change the regulator. I tested a 300tdi one (on my lathe) and it seemed to work pretty well! For welding, you just use a 3 phase diode pack to deliver DC with a bit of ripple. Again vary the excitation current to change the welding voltage. Si Quote Link to comment Share on other sites More sharing options...
landroversforever Posted June 10, 2008 Share Posted June 10, 2008 Another option which does not need a third battery at all is to use a voltage divider (two resistors) connected between 24v and earth. The junction of the resistors will sit half way between the two batteries (normally 12v) You need to build a simple comparitor which detects a difference between your potential divider reference and the junction of the two batteries. If both batteries are similarly charged, the reference will be at the same voltage as the 12v junction. In this state the alternator charge lead is connected to the 24v terminal. If the difference is more than a couple of volts, the comparitor switches the chang-over contacts on the relay which switches the charge lead from the alternator from the +ve of the 24v set to the 12v junction of the batteries. You connect your 12v circuits to the junction of the two batteries.This way, the 12v junction is charged only when that battery voltage has fallen below that of the other battery - and it needs boosting. Otherwise, both batteries are charged in series at 24v. I've not decided which I'm going to use yet - but the simplest and lightest weight is to run high current stuff off the 24v circuit and everything else from a dropper (I conveniently have a pair of 30A droppers). I'll certainly be using my 12v alternator at 24v though - and I might even add some trickery to make it spit out 230v mains, and 36v for welding! ================================================== Si You beat me to it! I think thats what i was thinking of, only i know them as a potential divider. Quote Link to comment Share on other sites More sharing options...
simonr Posted June 10, 2008 Share Posted June 10, 2008 You beat me to it!I think thats what i was thinking of, only i know them as a potential divider. Me too - just Voltage divider is more self-explanatory! Si Quote Link to comment Share on other sites More sharing options...
landroversforever Posted June 10, 2008 Share Posted June 10, 2008 Me too - just Voltage divider is more self-explanatory!Si ahh yeh i see...for the less electronically minded Quote Link to comment Share on other sites More sharing options...
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