I would like to try LED bulbs for my headlamps but I am not sure which style would work best. I have decided to go this way instead of using my mag to power the lights (too dim at low speeds).
I have seen other posts on the subject and wonder if someone is currently using LED's on their mag driven T and if so how was it wired up for the 2 pin set up? I have a 12v battery wired up just in case I need to start the T on Battery instead of magneto.
Do you charge your battery off the magneto? That's what I do with my six volt battery, which is perfectly adequate to buzz the coils for battery starting. But the current used briefly for starting is one thing, and the steady drain on the battery for lighting is quite another. I wonder if the mag charger can keep the battery up for headlights. I do use LED tail lights that run off the six volt battery, and so far they're fine. But I've used them only on short runs. I don't know if the mag charger can keep up with them on a long drive, or how it would be for headlights.
I have a 12V charging system that uses a 1:1 isolation transformer on the mag output.
This allows the use of a full wave bridge rectifier to convert the mag AC to DC.
I use this DC to charge the 12V car battery.
I run two 50 CP headlamps and the system keeps up OK.
I have run 90+ miles in the dark with no problem.
I have LED bulbs in headlights of my stem-winder cars that are non-acetylene powered. Wired to the battery, I can drive for hours and hours before needing to charge the battery because the draw is so very minimal.
Mark. Amazon has a lot of LED bulbs. some operate directly off A/C 10 to 18 volts. "Built in bridge rectifier" which might work directly off Mag with a small dropping resistor may be some brightness change from hi to low rpm ? The LEDs draw just a fraction of what the Magneto headlight bulbs draw So it would seem You could run 6/12 volt LED headlights off a 6/12 volt battery with a mag battery charger ? Just haft to be careful of the base pins. Battery cars have parallel guide pins. some of the super bright LEDs which seem to be ideal for headlights use a 1157 type base which has off set guide pins which wont fit. some use one of the two base contacts for + and the other for minus.But I think Mag cars only had one center contact like a 1156 tail light bulb. No Hi/Lo switching which should make the conversion much easier ?
I have used the off set pin bulbs in sockets for even pins by filing off one of the pins. Mag bulbs use two contacts even pins, one in one out they are not grounded to the base like 1157 for example.
Thanks Mark. Bob and keith I was typing while You were posting You pretty well covered it good to know. Did the mag cars have a focus adjustment ? I tried filing off one pin but My bulb seemed loose in the socket.
Yes they have a focus, same as later cars. You could squeeze the side of the socket in some or add a piece of brass shim stock.
I've done it. For magneto, I think some magneto lights had 2 pins, an in and an out side, no earth, so you'd have to re-wire them in parallel like a regular battery T, not series.
As for the bulb? an 1157 works just fine in white, I squeezed the socket a little tighter but would prefer to just dab a little solder on where the pin should be.
Here are the LED's I have in the headlights of my '15. Properly focused, they are adequate even on unlit roads. I have two sealed lead-acid batteries under the seat, one 6V for the coils, and one 12V for the lights. The 12V battery and the two LED headlights added up to less than $40, so there's no need to cobble a circuit together to run off the main battery, and there's certainly no reason to convert the whole car to 12V just to run a couple of light bulbs.
First thing is, don't worry about an in-car charging circuit. I drive at night a lot. I charge the batteries maybe twice a season. LED's draw that little. For example, we just returned from a four-day tour in eastern Oregon. We were on the road during the days, so I ended up taking some of the locals for Model T rides out on Highway 26 at night. When I got back to Portland, I went to top off the batteries, and the charger showed green - full charge.
So here's what to search for... If you have single pin sockets, look for LED equivalents to the 1156 bulb. If you have dual-pin sockets, look for 1142 bulbs (1157's won't work.) 300 lumens or more will do the job. If your headlights are wired in series, you'll need to change that to parallel. Finally, choose only "warm white" bulbs, which keeps your Model T from looking like it has Xenon headlights.
Why do you recommend the 1142 over 1157 bulbs? Is it because of the staggered pins 1157 have?
Correction: PLEASE disregard the above circuit diagram. The original had a charging circuit for the 12V battery. I pulled the components for the charger to illustrate the circuit without one, but... I forgot to remove the wire from the mag.
Kep: The staggered pins of the 1157 are there to make sure the bulb only goes in one way. 1157's are dual-circuit bulbs, generally for stop/tail light applications. Each contact goes to one filament (or LED emitter), then grounds to the socket shell. 1142 bulbs are single circuit, with both contacts going to the single filament (or LED) and the socket shell connected to nothing.
Bottom line is, it's not just the pins. The internal wiring is different between the 1142 and the 1157, and they're not compatible.
Bruce, thank you very much. This is what I was looking for. I have a small 12v battery in the car for cold starts if needed as my car has no starter or generator, I could use this in the circuit as well I suppose.
Has anyone found led bulbs that I can use directly on the 6 volt battery of the coupe?
Tony try "Fordbarn.com; 6 volt LED bulbs"
Is there any reason not to charge the batteries off the mag?
Why have a separate 6V battery for the coils? They work fine on 12V.