Magneto and battery charging system

[Dennis_Brown]

When using a diode and 1156 bulb to charge a battery off of the magneto, can you splice into the mag wire before the diode and run the coils off mag? You should be able to as nothing should feed back thru the diode from the battery and the mag should be able to produce enough voltage to do both

[Kerry]

Why splice, leave the mag wiring alone, just run your charge wire from the mag post to the diode, globe then battery.

[speedytinc]

Early coil boxes with separate battery & mag inputs : Hook to mag post on the coil box.
Later coil boxes with one power input : hook to terminal (red) wire.
[This could be an unusual application where a non generator motor is in a late car or in a non generator equipped 19 & later motor]

[Oldav8tor]

The magneto battery charger does not interfere with operating the coils from the magneto. For non-generator cars John Regan makes a neat little circuit board that spans the mag and battery posts. Otherwise everything functions normally.

[speedytinc]

The magneto battery charger does not interfere with operating the coils from the magneto. For non-generator cars John Regan makes a neat little circuit board that spans the mag and battery posts. Otherwise everything functions normally.

charger.jpeg

Power drain from the addition of a rectifier is negligible.
The 2 motors I have rectifiers on, for example, read mag putout @ 35 volts AC without & 32V with.
I first used 1 filament of the bulb. It was real bright @ idle & burned out @ hi speed. I changed to both filaments.
The bulbs have not burned out yet.
12V battery shows a 2-3 amp charge.

I didnt think the Regan unit was still available.

The unit installed on a 24 T

[Oldav8tor]

I forget what bulb John Regan uses but at idle it is so dim you have to look hard to see if the filament is glowing. It never seems to reach full brightness when I play with the throttle. I have checked my magneto output with a "St. Louis Electrical Works" Mag checker and it's output is normal. In the unlikely event the diode should fail closed, the light bulb will quickly burn out, protecting the magneto.

Note: You want to be very careful to route the spark plug wires such that there is no chance of a spark jumping to the charger circuit. John is very careful to warn people about that. The photo shows how I routed my wires. It also shows how dim the filament is at idle.

[J1MGOLDEN]

Tim, my bulbs only have CEC 199 on the base.

[TXGOAT2]

The battery's state of charge can affect how brightly the lamp glows, as will the engine's speed.

[MWalker]

I'm looking for some advice here. I had to pull my engine/trans. to replace the clutch. I didn't know it at the time, but the clutch I put in the car when I built it a few years ago was a bad one. Anyway, I got that done and finally got the car started today. It won't run on the mag. I have a Regan mag/battery charger as is pictured above. Its bulb burns out immediately. Tim Juhl mentioned above that if the diode is bad it could cause that. How do I check it?

[TRDxB2]

Why splice? Depending on where you choose to mount the Bulb/diode trick you can run a wire to it from the magneto post or from the coil box.
Its always hard to answer a question without knowing what the objective of the modification is.
https://www.mtfca.com/discus/messages/29/23876.html

Fuse it
By John F. Regan on Tuesday, January 23, 2007 - 01:05 pm:
As I have repeatedly stated - Diodes FAIL SHORTED. They never fail open unless they were not built right in the first place. They CAN be BLOWN apart and thus open if they are used without any fuse or current limiting device to prevent catastrophic over current when they short. This is why you need to be very carefull when charging a battery from the magneto. If you don't address the issue carefully then a shorted diode will result in the battery applying its voltage directly to the mag ring which can discharge the magnets and in a worst case scenario, open up the mag ring. Nasty. The bulb is in the circuit to do 2 things. 1) In unlikely event of diode failure - prevent the battery from discharging into the magneto ring by more than a small amount which is safe. 2) prevent the battery from hogging all the magneto current and thus not allowing the coils to have enough to still run properly. The choice of diode is really not critical so long as it has a rating of at least twice the peak output voltage of the magneto and also a current rating that gives ample safety margin of current being more than than the magneto and bulb combo can supply. I do NOT use the 1N5402 in my kit but that is simply because better diodes came along with higher ratings that were the same price. One thing that is important and frankly is what costs us the most in our kit is a GOOD PLATED BULB socket. So many of the sockets are not even plated and start to rust quickly. The socket we chose is easiest of all to mount to something and is a good plated socket. I don't like rube goldberg mounting creations and really don't like them when they carry battery current.

Proper Bulb fro 6volts 1156 for 12v 1156 or 1129 se below
By John F. Regan on Sunday, January 21, 2007 - 11:32 am:
You can use the same bulb but you will get less charging using a 12V battery because there is less potential difference between the nominal 28VAC of the magneto and the 12V battery versus 28VAC and a 6V battery. If the battery is used only for hot shot starting and possibly powering a brake light then the bulb we supply in the kit probably will work fine. If you need MORE charge then you can use an 1129 bulb (which is a 6V bulb actually) in the circuit with your 12V battery. You cannot use an 1129 bulb to get more charging with 6V battery since it will burn out rather quickly. The bulb we supply in the kit is an industrial bulb that is about the lowest resistance bulb we could find that was 12V. Everage charge rate will also be reduced if you are running a 3:1 rear end due to lower average RPM of engine.

[Steve Jelf]

I like my charger inside where I can see it.