12 volts to 6 volts

[Alan R]

Does anyone have a parts number for a part (resistor??) that will reduce 12 volts to 6? I'd like to try to protect my low tension coils, and it seems a lot easier to pick up 12 v. batteries Some say it wom't hurt them, but...
Thanks, Alan

[Phillip Hutchinson]

G"DAY Alan. Re 12 to 6 volts resistor:
What you need to do is to go down to your local Auto Electrical store with the ignighter coil,then ask them for a "ballast resistor" to drop the voltage to 6 volts.A ballasst resistor is the resistor used on most pre electronic ignition cars to reduce the IGN coil voltage to 7 volts,there are a few different values so it should be possible to get near enough to what you need.
It does work coz I use one on my Fuller & Johnson no problem.
Happy cranking Phillip

[Elden DuRand]

Originally Posted by Alan R

Does anyone have a parts number for a part (resistor??) that will reduce 12 volts to 6? I'd like to try to protect my low tension coils, and it seems a lot easier to pick up 12 v. batteries Some say it wom't hurt them, but...
Thanks, Alan

Alan:

What I've always used is an automotive tail and brake light bulb (two filaments). Just solder one wire to -both- of the contacts of the bulb and another wire to the metal base of the bulb. Hook this in series with the coil and you're in business.

It also will indicate if your engine has stopped with the points closed.

Works for me!

Take care - Elden
http://home.cybertron.com/~edurand

[BobRR]

If going the ballast resistor route ask for one for a 1960's chrysler product.BobRR

[ListerDiesel]

Originally Posted by Alan R

Does anyone have a parts number for a part (resistor??) that will reduce 12 volts to 6? I'd like to try to protect my low tension coils, and it seems a lot easier to pick up 12 v. batteries Some say it wom't hurt them, but...
Thanks, Alan

Most of the sealed lead-acid battery makers do a 6V in 2.2AH, 4AH and 12AH sizes.

If you got hold of 5 nicad 7AH or 4AH cells they would be better from the point of not being damaged through not being kept charged up, but need a slightly different charging regime to Lead-Acid. Easy to keep charged up though, just hook across the car battery with a selected resistor value ** to give to 400mA charge, that will take a few days to trickle them up to full capacity, but if you forget to take them off charge they won't come to any harm.

** A 22ohm wirewound resistor will limit the maximum charge into the Nicad to 400mA under conditions of a dead flat battery and 14V on the car battery. This will fall to 300mA when the pack voltage rises towards full charge.

We use 6V 12AH batteries in sets of 5 (30V nominal) for substation tripping supplies on 11kV switchgear, and do a Nicad version with 25 cells in series.

The sealed 6V batteries are used a lot in kid's indoor trikes and cycles etc, as you can get more capacity with 2 X 6V 12AH than a single 12V 7AH.

Happy to answer questions on the subject off-list if anyone needs any help.

Peter

[ListerDiesel]

Originally Posted by Alan R

Does anyone have a parts number for a part (resistor??) that will reduce 12 volts to 6? I'd like to try to protect my low tension coils, and it seems a lot easier to pick up 12 v. batteries Some say it wom't hurt them, but...
Thanks, Alan

Alan:

Answering your original question:

A ballast resistor will only limit the current into the battery and will not prevent overcharge if the battery is Lead-Acid.

You can knock up a small regulator with a few parts from Radio Shack that will give you a properly regulated 7.35V supply that will recharge a 6V lead-acid battery correctly.

If you look up the data sheet for the National Semiconductor LM317K or LM317T regulators, there are a couple of constant voltage circuits there that need less than a couple of dollars worth of parts to knock together. If you need more current, then the LM350K or the LM338K give higher outputs, but all will need a heatsink or piece of aluminium to dissipate heat when running.

If there is interest on the forum, I'll post a circuit.

Peter

[styrie]

Allen,
Measure the resistance of the coil and get a resister of the same value.
Be sure it's at least a 10 or 20 Watt rated, flameproof type.

PS, I like Eldon's method that uses the stop/tail lamp.

Steve

[Will]

Alan,
I found small 0.05 amp 6 volt batts on the web at : http://store.yahoo.com/batterysupplyco/ They have worked just fine on my low ten coils. I had to go to JC Whintey to find a charger for them. It seems I paid like $12.00 each for them. Again, they have worked great on my engines for a few years now.

Will

[Ralph Leonard]

Alan, I use a lengh of 22 gage wire (that's what I had on hand) for a voltage dropping resistor.

In the pic there is 20 ft (black) between A&B and 35 ft (red) between A&C, all in series with coil and bat.

A jumper across A to C gives full 12 volts

A jumper across B to C gives 10 volts

A jumper across A to B gives 8 volts

No jumper gives 6 volts

I usually start on a higher voltage and then remove the jumper. As someone said earlier the resistance of your coil will determine the amount of resistance you need. Connect a volt meter across the coil and adjust the wire lengh to get the voltage you want.

[Ed Malcom]

I use computer backup batteries for mine and a cheap charger is anything designed for rechargeable lights etc. Just use one with the correct voltage and cut the plug off and put alligator clips on. Use your meter to find which wire is positive. The batteries always have red around the pos side.

[hit-n-miss166922]

Hello from Wisconsin!!!
I have used the following " NAPA" echlin Part number IRC23.
Seems that it gives 7.9-8 volts from 12v battery. Hope it works for you.

[BWegher]

A buzz coil primary is around 1 ohm. A one ohm resistor would be fine.
A 6 volt automotive light bulb would work fine. It should not be hard to find a small 6 volt battery. I use a 10 amp-hour emergency lighting sealed lead acid.

[Alan R]

THANKS GUYS.. The greatest thing about this site is the number of ways you can come up with to solve a problem. Now to figure out which way is best for me.
Thanks again, Alan

[J Milne]

I have used these folks for both 12v and 6v requirements. I use gel-cells which give excellent results.

They have 6v gel-cells up to 36AH.

http://www.hcbaker.com/Lavaa/_htm/Index.htm

Jim