Volt meter vs. amp meter & 1 wire alternators

[PANAVIA]

Better Bigger, Alternators mean you are not beating on the battery as much , if you take the car for longer cruises a 65A might work OK.

there are plenty of options in the 90-130A category these days.

If you use a high AMP alt remember to use a suitable BAT+ connection from the power output section of the ALT to the battery lug/post so you dont weld anything accidentally.

like 10GA or better.

Steve

[mjhcobra]

If bigger is always better is the main reason, then I get it, but there is such a thing as overkill. You start to suck HP away after 95 amps or so.

I don't see a difference in my Cobra and a 65 T-bird with the same motor but has accessories out the ass and a 55 amp alternator. Worked then, why not now?????

[DAVID GAGNARD]

Originally Posted by mjhcobra

If bigger is always better is the main reason, then I get it, but there is such a thing as overkill. You start to suck HP away after 95 amps or so.

I don't see a difference in my Cobra and a 65 T-bird with the same motor but has accessories out the ass and a 55 amp alternator. Worked then, why not now?????

As far as sucking HP, that's a not exactly right......an alternator will only supply amps to the battery as needed. If you are cruising down the highway with nothing on,so to speak, your battery drain would be your ignition system and fuel pump (assuming an electrical fuel pump), amp draw would be small, therefore the alternator would not be "working hard" to replenish your battery, the more electrical current used, the more amp draw on the alternator,hence the more required to turn the alternator.......

A battery in good condition, fully charged will not tax the alternator much, HP draw is estimated at 1 to 2 hp!!!!!!!!!!! A weak battery would require more from the alternator, estimates are 3 to 4 hp.....either way, you'll never notice this!!!!!!!!!!!!!

Years ago, I had a camp in the woods with no electricity, we used a gaint battery (from some sort of industrial machinery, took 2 people to carry it) for the 12volt lighting system we had. The battery would last a weekend if you were careful, got tired of hauling back and forth home to charge it, so I took a 70amp GM alternator and mounted it on a homemade frame with a 3hp Briggs lawnmower engine to turn it. It would easily charge up a dead auto battery with no problems, but the big battery would kill the 3 hp motor when it had been used for a weekend, swapped out to a 5hp Briggs and it would easily re-charge the big battery.... The industrial battery was about 3 times the size of a standard auto battery!!!!!!!!!!!!!!

I used that homemade battery charger for years and when I sold the camp, I gave it to the new owner.....

If you have a 55/60 amp alternator, it'll do the job, it'll just have to work harder for a longer time to do the job, and subsequently build up more heat in it doing its job.....start any car and put on the A/C and other accesories for a few minutes and then go put your hand on the alternator case, I've done it, it'll be soo hot, you will not be able to hold you hand on it for more than 2 or 3 seconds, the alternator is working hard....higher amp units have higher output/capacity and don't have to work as hard as long......

Either alternator will do, larger just does it with less effort.......

David

[mjhcobra]

What do you think about using the Lucas ammeter (50 amp rated) with a 55 amp alternator? Can you use a larger alternator with the Lucas ammeter?
Sounds like using an 80 amp alternator with a max demand load of 60 amps with a good battery should work with the Lucas amp gauge-just pushing it to the limits for those peak demands when the battery is dead and everything is on.

Tough decision for originality.

[DAVID GAGNARD]

Originally Posted by mjhcobra

What do you think about using the Lucas ammeter (50 amp rated) with a 55 amp alternator? Can you use a larger alternator with the Lucas ammeter?
Sounds like using an 80 amp alternator with a max demand load of 60 amps with a good battery should work with the Lucas amp gauge-just pushing it to the limits for those peak demands when the battery is dead and everything is on.

Tough decision for originality.

I don't use amp meters on my cars, so I can say anything about using amp meters......I just prefer a volt gauge......My "amp meter" is to turn on the headlights and see how bright they are then, rev it to 2,000rpms and see if they get brighter....

An 60 to 80 amp alternator should work fine and as long as your battery is good condition, you shouldn't have any problems....My battery is a 7 year old, yes 7 year old Optima and it'll spin my motor over all I need and then some.........

One thing I've always done and may have contributed to the Optima's long life is when I know I will not be using my car for 2 weeks or more (which is sometimes often) I disconnect the positive battery terminal........

You may want to go to a local alternator shop and run your thoughts by them, they're experts in the field...

David

[PANAVIA]

My rule of thumb ;

I use voltage gauges on anything that has a alternator, and AMP gauges with generator cars.

My .04 cents.

Steve

[trularin]

I agree with Dave.

I have the 3 wire Ford system @ 60 Amps.

There are a few times when the fan, headlights and everything else is on, the voltmeter shows 12V.

Just my $0.02 worth.

[mjhcobra]

Thanks for all the comments and suggestions. I will be installing the alternator (60-80 amp) and the external regulator with a Smiths volt meter. Tough call, but safety first, easy install second, originality (for this issue) last.