How long can the T run on battery ignition ?

[joe.wal]

What is new to my T is that it sputters under acceleration (even on level ground).
I opened both outlets at the bowl and carburetor - fuel was running freely and was clean.
After that for a few miles everything was fine, regular acceleration power.
Then again sputtering (I hear 'patch patchadipatchpatch' from the carburetor), letting fuel flow, fine again.
After doing that three times within 10 miles I just let it go under less power where everything is smooth.
Only after some while it came to my mind that the issue could be ignition and not fuel (ignistion is set correct, no overheating and fine starting).
So while driving I changed from magneto to battery and acceleration was regular for the rest of the tour which were uphill mostly.
Until those new issues running on magneto was fine and even better than on battery.
All sparkplugs are still firing fine on magneto.
Did not check the connection of the magneto pole yet, perhaps this got loose and does not have full contact.

Anyway, should I have a magneto issue: how long (how many miles) is a T supposed to run ona a fresh 12V battery ?

[Charlie B in N.J.]

Probably as long as the battery has voltage. Not a problem. Although the coils are AC units they run fine on DC. Some say slightly better. As to your problem: I suppose checking the mag post for dirt or lint is first. From there on the list grows.

[TXGOAT2]

The car should run several hours on a good, full size battery that is fully charged, assuming only the ignition is drawing power from the battery. It sounds like you may have a magneto problem or wiring problem in the magneto circuit. If the magneto, etc, is OK, it's possible you have a coil problem, or a coil box insulation problem, or a high tension spark plug lead problem that only emerges when the system voltage is high, such as when running at road speed on the magneto. Another possibility is the ignition switch itself.

[John kuehn]

When driving your car slightly jiggle the key in both positions. Mag and battery. See if you notice a slight hiccup or sputter on either position.
Remove the mag contact and clean it. Make sure the contact spring is pressing well against the mag ring contact. Good luck.

[Norman Kling]

A few questions:
1. What year is your car? Does it have a generator or Alternator?
2. Why are you using a 12 volt battery? Ford used 6 volts in the cars with a generator.

Now a few things to check:
1. Output of magneto. At the connection at the output of the magneto, you should have at least 6 volts AC at idle. The voltage should increase with the speed of the engine to nearly 30 volts, so if everything is working correctly your power should actually smooth out with speed.
2. Spark plug gap. Should be about .025 inch.
3. Adjustment of the coils. They should be set to fire at the same amperage about 1.5 amps. It runs smoother if they are the same amperage.

If you have a generator or alternator, your car can run for many miles on battery. I drove one for about 10 years on a 6 volt battery. It was a bit slower than it would be on magneto, but it ran smoothly.

Things which can go wrong with a magneto:
1. Open circuit. When this happens the magneto doesn't work at all.
2. Short. Depending on the location, it might lose voltage but still put out some power.
3: Most likely if you still have some output would be either of two things. The magnets are losing their charge. or the magnets are too far from the coils.
The magnets can be re-charged in the car, but the distance from the coils is usually from wear on the 3rd main bearing of the engine. The thrust surface wears out. This happens because of running in neutral or uphill. There is pressure to move the crankshaft to the rear and eventually it moves so far, the magneto gets weak or stops working. This problem is easier to fix with the engine out of the car.
Anyway, if you crank start the engine, the battery will last longer. If you use a starter, it will be fine as long as you have a generator or alternator to replenish the charge.
Norm

[Been Here Before]

Running a total loss battery ignition system are you?

May want to see how those who race motorcycles and want to save weight use such a system example: http://forums.sohc4.net/index.php?topic=28711.0

[Scott_Conger]

The answer to the question posed by the title is: easily several days of touring if the starter and lights are not used much or at all

The above is assuming that the wiring is in good shape and there are no parasitic current draws from pinched, oil-soaked wiring. I once had a T which would barely start after sitting 2 days after a full recharge of the battery. A new wiring harness now allows the car to sit for months on end and start right up on 6V. Good wiring makes a big difference!

either 6V or 12V automotive batteries will have several hundred amp-hours capacity and coils draw very little current. It's a fairly straight-forward math problem

[John Codman]

I am far from an expert on Model T coils, but it would seem to me that running the oscillators on double the voltage that they were designed for would shorten their life. Most model Ts that have been converted to 12V are run on Mag.

[TRDxB2]

Batteries for modern cars sell based on the CCA specification because the cars have battery charges and alternators to provide power while driving. Model T "starter cars" used a 6 volt lead acid battery (Type Group 1) with a generator to charge them while driving.
Given no starter and no method of recharging then....
There are three specifications related to your battery's ability to provide power whether it be 6 or 12 volt, lead acid or gel or other type.
CCA, cold crank amps,is a rating that defines a battery’s ability to start an engine in cold temperatures. The rating refers to the number of amps it can deliver at 0°F for 30 seconds while maintaining a specific voltage (for 12 volt at least 7.2 volts per cell). The higher the CCA rating, the greater the starting power in the battery. This isn't applicable to your question.
RC, Reserve Capacity, is a very important battery rating. Example for a 12 volt battery, it is the number of minutes a fully charged battery at 80°F will discharge 25 amps until the battery drops below 10.5 volts. Can be confused with Ah
Ah, Amp hours, is a rating usually found on deep cycle batteries. The standard rating is an amp rating taken for 20 hours. What this means for a 100 Ah rated battery is this: Draw from the battery for 20 hours, and it will provide a total of 100 amp hours. That translates to about 5 amps an hour. (5 x 20 = 100). However, it's very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64 amp hours
https://www.batterystuff.com/kb/article ... asics.html

A lot depends on what items are "on" consuming power while driving and/or starting (lights, oils, starter, other), and if the battery being charged while driving. Even though a Model T amp gauge isn't very accurate it can give you an approximation. So lets say the battery isn't being recharged while driving and no starter car. An ammeter in series to measure the draw on the battery and shows -4 amps while driving on battery (doesn't matter what else besides coils). If you have a 400 Ah battery the 400Ah/4amps = 100 hours (likely 10% less) even if the CCA is 600amps

There are many reasons to chose one type of battery over another Placement, starting power, running uncharged, cost, personal preference, and etc. The point of the following attachment is to show differences in specifications because Today's batteries are primarily advertised for what Modern Cars need.

[Scott_Conger]

John

With respect to Ford "T"s, the coils were designed and adjusted to operate on AC magneto varying from about 4V to around 30V. I know you know this, but for newer hobbiests, batteries didn't come along in Model Ts until later when equipped with electric lights/starters (so the coils we specifically use were not designed for either a 6V or 12V battery)

Early auto electrical systems were designed for 6VDC, thus the car eventually came with a 6V battery. That should not be confused with running the coils on a "wrong battery" if operated on 12VDC. Yes, it's very hard on the starter, but in fact the coils gobble it up and percolate very happily (and more efficiently for our engines) on 12VDC.

As an aside, coils can be made to operate very well on battery, and run poorly on MAG; they can be made to operate very well on MAG and not so well on battery, and in the hands of someone with knowledge and patience (and the appropriate tester(s)) can be made to operate very well on both systems.

Finally, if someone's car starts reliably on MAG by simply hand-cranking, and they're a little overweight and looking for more exercise, just give the coils to a friend that says "hell, I just tune 'em all by ear". They'll soon be doing a lot more walking.

[Art M]

Coils powered with 12 volts dc will experience early point failure. That is why the auto industry selected 6 volts years ago. They had tried 12 volts and found it didn't work so well.
In the 1950s 12 volt was successful after ballist resisters were used to drop the voltage.
We keep hearing about the auto industry going to a 42 volt system with gasoline powered cars. The problem with switch failure has not been economically solved.
Keep in mind that the open voltage on stick welding is only about 30 volts.
Art Mirtes

[TXGOAT2]

A coil designed for a 12 volt system will have roughly twice as many turns in the primary winding as one designed for 6 volts. Both 6 and twelve volt systems deliver about the same wattage (power) to the various electrical loads. A 12 volt system can use smaller gauge wire and is less prone to trouble from loose connections, but not by much. As far as coil voltage, newer systems use a coil that is designed for about 10 volts and have a resistor that is switched into the primary circuit whenever the starter is not operating. This allows the coil to receive full rated primary voltage when the starter is engaged, which will typically drop the system voltage down to about 10 volts. Typical system voltage on later model cars runs around 13-14 volts when running down the road. 6 volt Ford cars had a "7 volt" generator for many years. Most older 6 volt systems will keep an 8 volt battery charged. I'd expect a Model T generator system to show anywhere from 6 to 8 or 9 volts when going over about 20 mph, depending on the battery's state of charge and any accessory draw. As pointed out, the Model T magneto will supply from around 4 volts to around 30 volts depending on engine speed. Coils are inductive devices, and they do not behave the same as a device with a fixed resistance. Model T coils will be supplied with either interrupted DC battery current via the vibrating points, or AC current at a range of frequencies, which is further modified by the vibrator points and the inductive properties of the coil windings.

[joe.wal]

THANKS everyone for contributing !
(although I admit I do not understand everything of the electricity related explanations - sorry ...)

My 1916 T does have the original engine, no generator but electric starter and conversion to 12 V by the vendor of the car.
Driving only 150 -200 miles a year I suppose I do not have to worry too much about the coil vibrator points when driving on battery.
As mentioned my coils ran better on magneto ever since I own the T.
With loss of 4 AMP / hour the battery will last for my driving purposes pretty well.

Just checked the magneto pole - it is fixed (but did not take the whole assembly off).
Also opened the switch - contacts are fine and tight, no effect also by wiggling on the key while running.
To check the voltage output of the magneto I can use a standard measuring instrument ?
Where to attach minus and plus while measuring if there is a constant Voltage at a certain engine speed ?

[Scott_Conger]

Joerg

test your magneto per this procedure: http://www.mtfca.com/discus/messages/70 ... 760271.pdf

RPM (estimated) vs Voltage (good magneto) can be found here: viewtopic.php?t=11870

[Nv Bob]

Crank starting a t battery last afew days easily
I use a safety light battery

[joe.wal]

Thank you @Scott.
Kind of challenge to me but will try it, hope I have that 12V / 27W bulb in some replacement bulb kits from the 80s.

[TXGOAT2]

How long a battery will provide a useful level of power (assuming no replenishment) can vary widely. Just about everything affects it, but some of the major factors are: Size, quality, and condition of the battery, including initial state of charge and the effectiveness and quality of regulation of the charging system, if any. How easily the car starts, starter current draw, driver habits, ignition/accessory draw, the ambient temperature, and number of start events are other major players. The condition of the battery is a major consideration. All batteries deterioirate, some faster than others. Batteries do not always deliver their rated power, even when in top condition. In fact, in my long experience, they usually do not. How many times a car will need to be started during any particular outing, and under what circumstances, cannot always be predicted. For very good reasons, most vehicles are provided with some means of replenishing the battery's level of charge while underway. Ford cars have a long history of having alternate means of starting the car in the event the battery fails to do the job. Ford passenger cars through the 1948 model year were equipped with a means to hand crank the engine if the need arose. Ford pickups and trucks through 1952 or 1953 were similarly equipped. To this very day, auto battery vendors do a brisk replacement business, and equipment for "jump starting" vehicles is widely available.

[MKossor]

It also depends upon what type of ignition you are running. The E-Timer electronic timer operates much more efficiently than a stock timer, only firing the first spark with the full energy to ensure complete combustion. All subsequent sparks fired while the timer is "on contact" are strictly cosmetic so they are fired at reduced energy to conserve battery life. Just for fun, we ran a test to see how long a tiny 9V (0.33Ah) transistor battery would properly operate the Model T engine. Result: 30 minutes.

By linear interpolation, a 50Ah car battery should run Model T engine equipped with an E-Timer ignition for about 75 Hours or about 10 days of touring 8 hours each day before needing to be re-charged. Of course, this excludes electric starting and Head/Tail light operation during this time.

[BarrettR]

I've ran mine all day on battery with no generator.

[fbergski]

Both my t's run on 12v motorcycle batteries, normal duration of driving is forty five minutes around town. I use a battery tender between trips to keep them fully charged. I have done longer trips of two hours with no issues. My mags work but they are weak, they are a backup to the batteries at this point. I don't feel like pulling two engines to repair the mags at this point in time, first project when I retire in a few years.

[Tim Rogers]

149 hours and 23 seconds.

[ewdysar]

149 hours and 23 seconds.

Good answer! I read the question to be like “how many marbles can you fit in a jar?”

Eric

BTW, I’ve driven hundreds of miles on a dry cell lantern battery, stock timer and coils, no mag, no charging.

[joe.wal]

Hello again,

yes, I should have specified the data of my battery for not starting a guessing game - but I am satisfied with the answers as I am now sure that my battery will provide enough power for my standard route in case of 'emergency'.

In the last 10 days I drove abt. 90 miles with my T, 85 miles out of that range on magneto.
What I found out is that there is no stuttering when I move the throttle veeery slowly and steadily down to accelerate - then I can reach max. speed also without stuttering and patching noise. This method also brang me uphill without problems or less power on magneto.
The five miles on battery were uphill in traffic where I did not want to annoy the cars behind me by not getting away and because i am not sure if my recently found 'solution' is dependable.

[TXGOAT2]

"What I found out is that there is no stuttering when I move the throttle veeery slowly and steadily down to accelerate" ///// This suggests a weak ignition system. It may or may not be a battery voltage problem. If you can run on mag most of the time, a good battery will last a long time, assuming you use the starter very little. Besides a problem with other parts in the ignition system such as the timer, any of the coils or related parts, it could be that you have a wiring problem, perhaps between the coils and the timer. It could be that engine vibration under load causes wiring shorts and miss-firing. If your battery has enough power to crank the car, it should operate the ignition for at least several hours. I'd take a very close look at the the timer and the wiring between the timer and the coils. A worn or dirty or oil-flooded timer may work OK on mag or at light loads, but miss fire on battery or under load.