I'm wondering about running a 12V battery on my coils for starting instead of the 6V as I've used in the past. This is a non-starter, non-generator car. The battery is used only while hand cranking, then switched over to magneto. The only other use for the battery is the stop lite, which can be easily changed to a 12V bulb.
My reason for considering the change is the easy availability of motorcycle type batteries as opposed to the full size 6V car battery that I've used in the past. That full sized battery is mighty heavy for a guy with a bad back to get in and out of the car.
So, do I need to readjust the coils or change anything else ? Will the higher voltage overheat the coils or burn the points ? I know that the magneto puts out a lot more than 12V, but that's only when the engine is running and the full voltage is only applied to the coils for very short pulses. When hand cranking, the coils can run continuously for many seconds.
I've been running a 12-volt system on my '15 Touring for three or four years and haven't had any issues with the coils. I start the car on battery (either by crank or electric starter) and then switch over to the mag.
The coils should be just fine with the 12 volts, especially if you use the mag for your normal driving.
Or you could drive the car to the store and have one of the strong young "associates" put in the new battery.
Lots of people with non working magnetos run all the time on 12 volt batteries with no problem.
My 15 runs off a 12v battery for starting. Lawn tractor batteries can be even cheaper than motorcycle batteries and will run headlights, brakelights, and ignition for quite a while.
In the pic below you can see the battery installed under the back seat. The quick connect pigtail is for a cheap chinese float charger that I hook up for a day or so once a month or after a night ride with a lot of headlight use. The quick connect was later moved to an under hood location.
No problem with the coils and engine starts on 1st crank after priming.
FWIW....ever think of trying a regular 6 volt cheap lantern battery from the hardware store? Yes, it actually does work with good coils and lasts a pretty fair amount of time at that if you click over to mag and drive I knew a guy that went 20 years that way changing the battery once a season
Bud, I was going to suggest a lawn tractor battery too. In fact it would be my first choice if I were considering what Dick is. Keep in mind, as with all batteries, cheap = lower amps = less useable time. I believe, during the E-Timer debates, a chart was posted with coil/voltage/AC-DC. A wide range of how the coils operated with various voltages. The 12 vt. DC was slightly better than the 6vt. DC result so there you go.
Coils and a brake light don't use much battery power. Think about it, when you have a dead battery and get your friends to give you a little push, there is still enough juice to get a spark and get you going.
My truck does not have a working generator, I use the starter for every start, I drive it a lot, and I go several months between charges if I don't use the headlights too much.
If weight and easy removal / charging is your primary concern, consider one of the portable jump starters. They contain a sealed battery that can be used in any position, have lots of power, and are relatively inexpensive. Many have a 12V lighter type power socket which could be used to power your coils and brake light and still be quickly disconnected. Larger units have larger batteries and some even have built in air compressors, an added bonus for touring. They can be easily removed and used for a jump start or to fill a tire, and can be taken into the house or motel room for recharging too.
Perhaps you need to find a better way to lift the battery. If you switch to 12 volts, you will have to live with the shame of explaining at car shows and such why your car is not correct to everyone who asks (and they will), why 6 volts isn't enough even though it worked for Henry for decades. I find the 6 volt system to be perfectly adequate, day or night.
Quote, Dave Wells: "Perhaps you need to find a better way to lift the battery. If you switch to 12 volts, you will have to live with the shame of explaining at car shows and such why your car is not correct to everyone who asks (and they will), why 6 volts isn't enough even though it worked for Henry for decades. I find the 6 volt system to be perfectly adequate, day or night."
Another good reason not to attend car shows. Does anyone know for sure whether Ford ever provided a battery of any kind in 1912 ?
By the way, I did buy a lawn tractor battery at Walmart this afternoon. Sure is easy to pick up and move around without bumping into doors, upholstery, etc. If there were such a thing as a 6V lawn tractor battery I would have gotten that.
George, I ran my '14 quite a bit that way one summer when its mag was dead, except I used two little 6V lantern batteries wired together for 12V.
I was at my local drugstore when the regular battery died (I had forgotten to charge it). I walked down to the hardware and when I came back, my school's Driver Ed class had gathered around the car to check it out. They were pretty surprised when they found out that it belonged to their English teacher, and even more surprised when I showed them how I was going to get the car going. They just couldn't get over those two little batteries running the car when I cranked up and spun off in a cloud of dust.
Just to set the record with factual info:
The software that the E-Timer uses has different programs to perform just as well on 6 volts or 12 volts...... both have the power that the internal magneto produces...... and doing it with the automatic timing feature.
Also ran a test running the E-Timer ignition on a 9 volt transistor radio battery..... lasted for an hour without charging,
The chart I referred to actually has nothing to do with the e-timer. It concerned itself strictly with how coils perform with differing voltages/AC-DC. The chart posted was part of an e-timer post.
All of this work and it still runs on mag? How much battery does one need for a few seconds of running?
I built a wooden box to hold two 6 volt lantern batteries. It has terminals for 6 and 12 volt. I use the 12 volt terminal for the brake lights (LED strip across the top of my license plate. Available only in 12v) and the 6 volt terminal for the coils. Yeah, I know coils will run on 12 volts, but they just sound like they are overworking themselves. And they will overheat if left buzzing for any extended amount of time. Not usually a problem, but sometimes, when it gets finicky, it can choose to not start right away....
When the 6 volt gets weak, the car is hard to start and runs rough. That is the signal to swap the coils over to the 12 volt terminal and buy some more batteries next time you think about it.
I use both the mag and a small 6 volt sealed battery to fire the coils when starting my Model K. As soon as it's running I switch to mag only. Last year I used the battery all summer and into the fall (and it was still working well) before recharging it with a small battery maintainer.
For what it's worth, batteries.com (and I have no connection to the business) sells several varieties of modestly priced compact 6 volt sealed batteries.
Just a thought . . .
I would be tempted to make a unobtrusive holder for a 12 volt lithium-ion
cordless tool battery such as Makita or Ridgid use. Carry the flashlight with
it’s own battery and you have a backup battery and a trouble light as well.
It should easily outlast a lantern battery and is rechargeable as well.
Recharge time on my 18 volt Makita 3.0 AH batteries (when cool) is 12 – 15 min.
I think that Ridgid even have a lifetime warranty on their batteries.
Put a full sized 12 battery under the back seat. Select one that is the same size as your modern car, then you have a two way spare.
I installed a 12v car battery somewhere up under the car on my 12 Torpedo and ran a wire to a hidden cigarette lighter that's behind the rear license plate. I learned that trick from the famous RDR so when the car is in the garage I can plug in my float charger or solar battery charger.
The mag keeps the battery charged.
Also carry another tiny 12V battery under the seat for the GPS not connected to the mag.
PS Not one person has ever asked me why I use a 12V syst.