MTFCA Forum

I would like to recharge magnets in car without removing transmission and I found This diagram on MTFCA Forum. In the lower right corner, it says to leave the current on for 30 seconds to "clear shorts". Isn't this a little long and could it possibly create shorts where none existed before? I have always heard that short bursts of current will do the trick and that leaving the current on for too long might damage or even burn up the coil.

Also did someone already experienced this method with successs ? Please feel free to share any tips or experience.

I have done it with both batteries and the KR Wilson re-charger. Before you attempt it, point the car east/west and check to see if the compass will indicated north/south when you crank it over with it in position shown. Pointing it E/W will show that you are reading the magnets not the earths N/S. Forget about the burning out of shorts and just stick with a few short burst at each of the 4 points.
You are looking for about 36+ volts DC, so 6 6 volt or 3 12 volt batteries will work. I just re-charge mine on using the KR Wilson unit. I had tried using a DC welder but had issues doing so and had no reading with the compass or very little after. I took it to the shop and pointed her E/W, pulled the plugs & put in neutral, got it as close to where is should be re N/S and gave it a couple of good jolts. The magnets got pulled into place by the winding's when current was applied on the first try and was able to proceed after that to re-charge in the other 3 sections. In any case, do take the plugs out and put in neutral, this will allow the engine to turn and center the magnets over the windings.
While it may not be the best way, it works. I have re-charged them and was able to hand crank start on magneto starting with a set that had very little charge left in them.
Oh other thing, do not put the batteries right next to where you are working, have them some distance away. When I do it, I cover them with a piece of plywood in case they blow up.

Recharging the magnets in the car does work well, but if your magneto has not been rebuilt you would do well to replace the field coils, the aluminum spacers and brass screws. Otherwise there is no guarantee that your mag is going to be fully reliable

Stephen

I read somewhere that the 1 3/4" dimension should be to the center of the compass, not to the side of it. That eliminates differences between large and small compasses. Is that correct or would the way shown be good enough that the first jolt aligns magnets as Mark described.

I did this on my ‘26 T Coupe in 2010, and documented it in the attached thread. The results could not have been better. See: www.mtfca.com/discus/messages/118802/159978.html. Over nine years later, my magnets are still as strong as new. Jim Patrick

Hi Jim, I've read this post with great interest, I face the same challenge. I'm not sure about the procedure to use... Can you resume step by step what I have to do please? Maybe I'm a bit slow today but I don,T want to screw anything. I'm in learning process with this. I will make a video in the goal to help other folks like me.

Cheers,

Hi Mario. I re-read my post and the steps are all pretty much spelled out in the post. I would suggest that you read the entire thread several times until you totally understand the procedures, for there is not much I can add to it. I know that if you follow this procedure, you will have a successful outcome. Jim Patrick

Mario you will do just fine!!!!

Hank

I'm surprised no one has told you to read Tom Carnegie's post about charging your mag in the car!

Here's a link: http://www.mtfca.com/discus/messages/506218/528397.html

Tom has a many years of knowledge and experience and is many times winner of the Montana 500. Check out his procedure or search many of the previous MTFCA threads for easy and reliable mag recharging procedures.

I will try tomorrow and let you know how it will work.

I have had best results with hogs head off and charging each magnet individually. I tried to charge a weak magneto using the in car version on a '21 and made it worse. I suspect that the insulation was bad and one of the coils grounded out so actually less output rather than more. Anyway the car runs on battery but has a knock and will probably end up rebuilding the engine at which time will replace the magneto ring.
Norm

I used Murray Fahnstock’s directions, and they worked like a charm. Of course, your magneto coils need to be in good shape. It sure beats pulling the engine and pulling everything off it to get to the magnets.

Has anybody tried this with 2 12volt batteries? I know that Fahnstock used six 6 volt batteries but could you use 2 12 volt batteries to achieve close or the same affect? Just wondering.

I use to have an electric golf cart with six 6 volt batteries in it.
They were already connected in series and it worked great for this. I just disconnected the the leads and connected my cables.

John.
It's not really about the volts but Amps. Ford recommended at least 80 Amps, 6x6v to get the amps up there, that's why some arc welders would do the job and by today's battery AH's 2 heavy truck 12v could have the same resault.
The only problem I've come across in rebuilds is that I've found a few coil rings cracked at the bolting at the block, if from in-car charging I'm only speculating.

Kerry wrote: ↑

Sat Dec 21, 2019 11:05 pm

.... The only problem I've come across in rebuilds is that I've found a few coil rings cracked at the bolting at the block, if from in-car charging I'm only speculating.

This speculation has come up before. And Tom Carnegie addressed it in more detail than I would have expected in his thread about “in-car charging” that Gene referenced earlier. But just in case anyone missed it, here’s the link again:

http://www.mtfca.com/discus/messages/506218/528397.html

Given Tom’s research, I am fairly confident that in-car charging does not significantly contribute to cracked coil rings. But everyone is entitled to their own interpretation and opinion.

Keep crankin’
Eric

Which ever source you use make sure to take Tom's advice about insulating your connection at the mag post!! Some protection from the batteries is also good advice.

Seems like there are plenty of Welders readily available as compared to a bunch of 6 or big 12 V batteries and a bunch of cables.

I doubt any coil rings or magnets are ever damaged from a charge flexing them. Tom did an extensive trial of several. His procedure and testing is sure worth rereading again!

Mario,

I just found your post on the MTFCA forum. Send you a pM as you asked.

I just like to add this:
- Do not leave the connection for 30 seconds but just flash it a few times (5 or 6).
30 seconds risk to give you a result on the coils as shown in the photos. After the coil ring needed a total rebuild.
- Do not use the magneto post to do the charge. Use a screwdriver to make the connection with the coil ring connection spot. Take out the magneto post and use a screwdriver to make the connection. Insulate the screwdriver just behind the point as far that you can't touch the transmission cover and connect the + battery on the top of the screwdriver just under the handle.
- Flash with the negative connection.
- Open the transmission control cover and watch the end of the brass screws. Two should be parallel with the upper side of the cover, then the magnets should be in line with the coils.

Good luck.

On Youtube there are a few videos that show you the job.

Andre
Belgium

In 2012 I did it with one 12V and one 6V battery connected, it was all I had available at that time and it worked fine. The car is still running with this charge.