Mondial Electrical problems solved Alternatorbattery load mismatch

I remember there were two or three other reasons why I chose to go with such a beefy alternator and those were the Heavy Duty windings, diodes, wiring, bearings and of course a bigger heat sink etc. . I'm not looking for a bandaid fix as many of the threads here seem to refer to, multiple repairs etc. I just wanted it done right the first time and I think that yes, I could probably do with a smaller alternator I rather go big now than try to go bigger once again later. I was also concerned about the added vibration so it just made sense outside of just doing it to pump out some more juice from my stereo that by adding slightly larger mass to the unit I would reduce the vibrations and ensure any future upgrades if there would be any such as this upgrades I had in mind, for example this one is from an MR2, I think I can add larger fans...

Hi!

I only try to point to the reasons why the electrical system of old cars makes problems. This is no isolated Ferrari problem, but due to the relative long distance of alternator – battery – fuse box and some interconnections, may be more pronounced on our mid engined cars.

If you use more electrical power than your alternator delivers, the only solution is a larger alternator. No larger battery will fix this.

If the output voltage of the alternator is not found at the battery terminals, a permanent under charge will be the result. No high power alternator or large battery will help.

So before you try to fix things, find the source of your problem.

These cars had no problems when they were new, so why should parts, that did the job 15 years ago, be wrong today?

Please don’t focus on alternator and battery size so much, do your self a favour and consider the installation that connects these parts to be old and restrictive.

Only if connectors, contacts, relays and wires are in perfect condition, the main parts can work as supposed to.

The cost of a new battery wire and a second, thinner one as a sense line, are much lower than a new high power alternator with custom brackets and belts!
This upgrade in wires is a must with HP alternators anyway, why not try this single modification first?

I don’t say alternator upgrades are unnecessary, but maybe they don’t have the desired effect!

Could in some cases be the same like fitting a stronger engine to compensate for top speed lost due to a flat tire!

A 105A alternator puts out 1500 watts. That is a lot more than the car realy needs! A 65A might be a little weak if the car is driven in stop and go traffic, lights and aircon switched on.

Chris

[consejero]

Alright I know everyone posted their opinions here as to how wrong I was and I shouldn't do this or that.
If anyone is still following this thread, I wanted to let you all know that it worked.

My new Delco Alternator is in. It works like a charm. lights work great and voltage is up throughout the system.

I retained all original hardware. I had to modify the bottom bracket by grinding the front arm somewhat, if the pictures from the previous format would still work you'd see that.

I retained the original belt, pulley and everything else. I was concerned that heat from the rear header would cause a premature failure for the alternator, I addresed this by using exhaust wrap. note: "the exhaust wrap" worked great. It reduced the rear engine compartment temperature considerably. I can touch my exhaust after running it without any painfull screams.

I used my trusty multimeter and found a possitive ignition hot wire in the engine compartment where the engine plugs into the side to hook up the 3rd alternator wire.

prior to the new alt. I measured 10.5V on this wire. Using this wire for my reference voltage, after the new install, as I predicted, it's up to 12.4V.

RESULT:
Headlights are much brighter. Windows operate much faster although still slower than my other cars but I am getting good voltage so more than likely it's just old motors.

Future replacement is easily accessible from any parts store and in a reasonable price range ($100 or so)

Unexpected side effect was the extinguishing of the "brake failure" light. I'm not sure why it was blinking on and off at idle before but with the new alternator the fault has gone away.

I've also noticed that my Tach is not jumping around as much. All in all I am very happy with results. Total spent? $120 -

New alternator is from a 1985 Cadillac Seville. 120A, heavy duty. Definately much better than the old 65A one.

I wonder what impact the higher voltage will have on the coils? I noticed that there's a much stronger spark mainly because one of my wires is .... leaking??

so that's the next project. New wires. There used to be this awesome thread on replacements but now I can't find it. I love this new format but I miss all the great pictures that had been posted by users.

Anyhoot. I'm sure someone will probably have something to say regarding how wrong I set up the system or how it's not supposed to work.

It works for me and I'm very happy. I'll try to post some pictures that I took along the way for anyone that's interested.

[snj5]

So, besides the alternator, to effect this change:

1. grind down the front bracket -- on the alternator or the engine?
2. use third wire from ignition feed
3. same belts apply

To corraborate other input:
ensure no sig. loss in main battery wire
ensure battery is good to start with

I am coating my headers and have 'opened up that side of the engine to improved airflow - I am hoping that will be enough.

I am also replacing the fuse box connector where it burned out

Thanks for all!!

Will proceed once I get my car back!

[tomdial]

Congratulations, you did it!

OK, lets see what happened: You connected the sense wire to a positive ignition feed.

This wire is switched by the ignition key. So it is a wire with a relative high voltage drop, running all the way through the car

This will trigger the alternator with a low voltage, so it will increase it to its reverence value. So you have compensated for the loss that the cars wires have.

Maybe not the most perfect installation from a scientific point of view, but very practical. If it has the desired effect, fine, where is the problem?

Good work! Maybe list the exact order number of the alternator?

Chris

[steve]

Conj nice job. I have done a few conversions of GM alts to Jaguars and they worked out well. Also GM runs at 14V +/- so are you getting this reading up front in the fuse box areas. And do you get this voltage at idle and when you first start the car? I don't recall the dia. of the stock alt pulley but I assume it was a direct fit to the GM alt and you use the OEM belt. It would be good to go to a standard belt and pulley arrangement. So on the 3 wire hook up the "sense" wire goes to the dash light and you get a switched wire from the ?????(starter or coil). I used to use the 2wire method and just hook up a jumber from the bat. terminal to the field term. I realize this kept the line hot all of the time but it was not a bat. drain issue with the cars I used this hook up on. Hey so once again nice job and thanks.

[charrua]

New Mondial owner here. I have owned the car for about 4 months. After not driving the car for a while, I tried to start it but nothing. I looked at the battery and realized it was 6 years old. Thanks to this forum, I figure out how to get the battery out and installed a new one. Now, the engine will crank but it will not start. None of the dashboard lights are on, nor I hear the sound that I used to hear when I turn on the ignition. Any pointers on what should I look for? A newbie here. Thank you.

[ManolinMondialt]

Originally Posted by Chris Fricke (Tomdial)

Hi!
If you go for the Delco alternator and tune it up with HD rectifiers and a 3 wire (sense) regulator, you can let it monitor battery voltage and you will have a fully charged battery in the future.
Went trough this with my T.

The parts are something like 20US$

I live in California, wish you could help with my mondial t. I doubt the dealership will do this. Let me know if you can help or recommend someone
thanks

[ManolinMondialt]

Originally Posted by charrua

New Mondial owner here. I have owned the car for about 4 months. After not driving the car for a while, I tried to start it but nothing. I looked at the battery and realized it was 6 years old. Thanks to this forum, I figure out how to get the battery out and installed a new one. Now, the engine will crank but it will not start. None of the dashboard lights are on, nor I hear the sound that I used to hear when I turn on the ignition. Any pointers on what should I look for? A newbie here. Thank you.

Can you tell me how to take out the battery. I need the step by step instructions before I due some damage.

[consejero]

i'm so sorry it's taken so long to reply, just got back from a stem cell transplant and it took longer than I though.
Yes on everything below, except the ignition wire. I got lazy and found an ignition wire under the engine..... this was probably not the optimal place. try finding an ignition wire closer to the source ( the key of course) I think this would help.
Also if splicing into an exhisting wire make sure it is a soldered connection as vibration will cause low light output.

I just started it up after a couple of months since the conversion and my lights were dim again... after cuzing up a storm I found out that it was nothing more than my connection to the ignition hot had come a little loose.
once soldered back in business.

Yes I kept the original belt although when I get better that's going to be my next project... how to change the belt system to a better system. I need to find a machine shop willing to manufacture me some new pulleys. My current setup works great but I keep thinking in the back of my mind that even a slight miscalculation in alignment between the alternator pulley and the crank pulley will innevitably cause premature failure of the belt. I inpected after about 50 miles and there's no problem but I do hear it winding a little. I guess it could be the alternator itself but something tells me the belt is misaligned. This is an easy fix, just add or substract washers the problem is that I haven't figured out how to check for alignment.

On a side note; I replaced my cats with test pipes from stebro... I am not impressed and the car sounds lousy.

Found a leaking spark plug wire so that's my next project. There's some great threads on here on how to make your own set of wires.

Does anybody know off the top of their head which US cars wires will fit ? I'm sticking with the 7mm set,
Thanks, to all that emailed me when I was doing the transplant!

JR