Minimum Voltage?

[Mumbles]

Several of my motors have dead magnets so I’m thinking of hooking up a battery of some kind to see if they will spark. Any idea of the minimum voltage needed to fire a coil?

I’ve seen a YouTube vid of a motor running on a nine volt battery and I do have a holder for three AA batteries which will make 4.5 volts total. I’m not sure if that’s enough or not.

[jeff-register]

Jim,
That is easy! I have used a vibrator out of the MOT & set up a coil driver. Bet with sufficient current it would work on 3 volts D.C. Need to have a good ampere supply to saturate the primary windings more than higher voltage. I don’t think even "D" sized battery will last very long. Example: Set up flashing L.E.D.s for a fake candle inside a repo looking wall clock. Even the LED load depleted the "C" sized battery after 36 or so hours. Bet you need a small 6 volt motorcycle (Scooter) to supply the needed amperes just like the early outboards. The coils draw around 2.5 to 3 amperes readings on my Merc o Tronic meter. Do something trick like use a photovolatic cell to charge the battery while stopped to fish using the lead acid cells in that battery.
Or a few to get a fast charge.

[dave-bernard]

I have seen spark with 3 volts in a buzz box I have. I think flywheels create 6 volts.

[frankr]

Mumbles, I can’t say for certain, but I seriously doubt your three AA batteries will supply the current (amperage) needed. I’d suggest a lawn tractor battery. Small, light, and rechargeable.

[mercuryman]

My Merc O Tronic take about 2 amps @ 7 volts to fire a coil.

[Mumbles]

OK, thanks guys!

Maybe I’ll try a six volt lantern battery when the time comes. I’m a little bit leary of hooking up a 12 volt battery to a magneto coil. I just want to bench test some mags, not take them out on the water, just yet.

[frankr]

A simple resistor takes care of the voltage issue. But a lantern battery makes sense too.

[bh]

Chrysler cars, prior to CDI always used a stand alone ballast resistor that Ford guys said was because MOPAR were too cheap +/- stupid? to switch their coils to 12v from 6V,
so attached the resistor when they went to 12v batterys mid ’50s . .
In fact it was to allow 12v at the coil while starting, and 6v when running.
Quincy loopers using battery ignition used them also, and some early 6 cyl Mercurys ?
They should still be availabe at a NAPA store, cheap?
Use one in-line with a 12v wet cell battery. A dry cell lamp battery
will not supply the current for long.
We used big 6v ‘Hot Shot’ or ‘fencer’ dry cell batterys with the PR’s etc in racing .
Doubt they are still available .

[Anonymous]

OMC battery & coil ignition on 1960’s V-4’s had the ballast built in to a special "1 ohm" lead from the battery to the coil!

[Tubs]

.

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

• This reply was modified 6 years, 9 months ago by Tubs.
• This reply was modified 4 years, 5 months ago by Tubs.

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