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Old 08-30-2010, 02:31 PM
Godfrey Godfrey is offline
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Join Date: Aug 2010
Posts: 78
Here is an update on my own investigations for what it's worth. I have just apparently burned out a relay. It's not completely dead, but it doesn't work for more than a second or so. It's cheap to replace and I'm glad I incorporated a harness in my setup so I just have to unplug the relay and swap it out.

Using the normally open contact on the relay to drive a second coil has so far proved problematic. I have observed that too much of the back EMF activity is happening in the circuit, because of the voltage collapse in the relay coil, when the normally open contact actually closes. As a consequence, the current and voltage fed to the additional coil is poor. The back emf is also not being channeled very well to the charging battery and therefore causes sparking and excessive heat to happen on the relay.

An expanded circuit that actually works may involve more that one relay. We'll see. I still would like to here from more people who have added more coils to this circuit successfully.

The basic relay circuit has worked very well for me. I will continue to charge batteries with it. What remains its real charm is that the parts are easy to scrounge from local junk. The relays are also available at the auto parts stores as well as Radio Shack in my area.

- Godfrey
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