25/09/2009 Progress

EV Batteries

• Purchased the RSP-1000-48. Very cheap. In Australia (Hooray !).
• Purchased a new LM338K, and some resistors (to balance the pack safely).
• More research, and I'm more certain that previous LM338K was killed either by temperature (soldering) or a short (lack of suggested diodes when large external capacitors in use). Will test this afternoon.
• Also discovered a new source for IC's (Farnell - much better !).
• Tried the new LM338K ... and killed it. That's two dead ! I think the reason is, that the "Economiser" circuit that is built into the Contactor, does not play well with the voltage regulator. It seems likely that there is some kind of feedback, or something, which is stuffing up the regulator.
• More thinking.
• I came up with a great (temporary ?) solution. The Economiser circuit changes resistance. It wants a high inrush current, and then low current after that. I can use the Economiser itself as the resistor in a zener regulator circuit. The Zener will always provide the balance resistance required so that the Economizer sees the other voltage (so ... for 12V Zener, full battery = 30volts ... empty battery = 18volts. Perfect !).
• Tried it, and it works.
• Modified the circuit board to work, and now all I need is a BD682 (PNP) instead of the BD681 (NPN).