9 volt or 12 volt battery

[Guest]

Hello everyone<BR>I have a 1913 Cadillac. The car has a 6 volt wet cell battery for the starter-generator and electric lighting. There is also a second dist that uses 6 each 1-1/2 volt round batteries connected in series, 9 volts. That ignition system is independent of the other system and uses a ignition relay. The new 1-1/2 volt batteries are now made with a plastic case and the two 8-32 thread screws are crimped internally to two thin pieces of metal. Either regular hex nuts or the plastic coated round nuts work loose due to vibration. I tried nylon insert lock nuts<BR>and some tighten. The brasss screws spin before the nut tightens on some of the others due to the cheap construction. Can I use a small 12 volt ATV wet cell battery? Will the 12 volts hurt the points or ignition relay? Any other ideas?<BR>Thanks in advance.

[56Roadmaster]

Hi,<BR> I would be a little leary of going the twelve volt route the points would be ok, you could add a condser, but unless you added a resistor inline to the relay I would not do it. You can figure the size resistor by ohms law: current=voltage/resistance so you would need to find the amperage to the relay by testing it under load with a meter. then the information could be used to find the resistance is series (resistance directly adds) needed.looks like R1=(V-IR2)/I<BR>R1= resistance needed to add, R2 resistance of your relay(measure with meter) V=12volts I= current(measured with 9 volt) resistance in ohms. resistors can bought at Radio shack or auto parts stores.<BR> Other suggestion, carefully and thoroughly clean the dry cell posts of plating with wire brush, clean up correct size brass nuts and connect, then using good electrical grade solder with electric iron solder the nuts and wire to the posts.Use plenty of flux.<BR> Third suggestion try double nutting the connection. <BR> Hope that helps.

[Guest Hal Davis (MODEL A HAL)]

You could use a little Loctite on the threads. Don't use so much that it runs down onto your teminal and insulates it, though.

[Guest]

I, too would stay with the 9 volt. Is the screw long enough to put 2 nuts on them? (you know, a nut & a lock nut). If not, try using a bras nut and drop a bead of solder to hold it in place.

[Guest stude8]

I know this is tricky but you could try to drill and tap into the cell buss of the 12v ATV battery between the 3rd & 4th cells to have a 9v source. You could still charge it as a 12v across the regular posts. It would be a lot more reliable than the dry cell series hookup I would bet. Be sure the use a variable speed drill at very slow speed, the lead busses will grab a bit rather suddenly if you use too much speed. Start with a very small pilot like 1/8" or less then slowly enlarge the hole step by step to get up to about a #10-24 stove bolt thread tap size.<BR>Stude8