100 Amp Alt.?

[rjewkes]

Do i need a different Volt reg for this or is the reg. only interested in the voltage?


It wires identical to ours except the posts are ontop of the back of the casing and not directly on the back.

Are volt regs amperage specific?

[xxxtina63]

As long as the alt. incorporates an external regulator I would think you would be fine. Why do you need a 100 amp?

[rjewkes]

Becuase i got a pair brand new for 104.00. So I figured i'd run one see if the truck liked them betrter and who knows maybe down the road a mild radio system.

[xxxtina63]

2 alternators?

[rjewkes]

yup one i will leave on the shelf for when the first one burns out.

[xxxtina63]

Good deal considering last time I bought a stock 55 amp? was around $60.

[rjewkes]

i know. Thats why i hopped on it. musta been misslisted on ebay cuase i was the only bidder.

[kid]

The voltage regulator also looks at current. You can see the alt light kick on if the resistance changes in the requlator resistors so the current drops but voltage stays high <11.5Vdc

[rjewkes]

Kid does that mean i need a higher current/voltage/resistance rated Voltreg? these alts are suppossedly designed for the same engines but in 69-75 Marquis? or vans too.

I don't want or need to burn anything up.

[kid]

You should get the regulator for the car the alternator came out of. I fried a GTO when I replaces the 80 with a 120 and left the requlator alone. The regulation resistor got so hot it melted and shorted to the body. No fun at 120mph in the middle of the night on Texas Farm to Market roads.

[rjewkes]

Thanks kid. I'll look at the auction page and reread what car they came from.

looks like for the years mentioned 100 amp alt is still a vr749 wells volt reg.

Think an f100 61 amp is a vr 730 or also a vr 741 still only 18 bucks.

So to upgrade to a 79-91 econoline 100 amp alternator you need a vr 749.
I'll have to see if it wires upto our models correctly.


any thoughts as to what i'd gain from this upgrade?

[kid]

The standard headlights draw about 35 watts 35/12=3 amps * 2 for 6 amps, not much so now we had Halogens at 65watts /12=5.5 amps * 2 for 11 amps add up the other lights and you draw on my 350 a whopping 28 amps in lights with markers.

Add a stereo at 240W and you get 20 amps. For a total of 48 amps. Not bad unless I add more lights for driving or a winch 25 amps.

Plus I have to feed about 5 amps back to the battery after every start for several minutes. Better to run in the middle of your alternator than at the top end where it's life will be shortened. Especially if you get a resistance short instead direct short where the requirements for a the short until a wire melts or a fuse blows will take away the other remaining 17 amps of my original alternator and cause it to fail.

Oh and crank the starter and watch 100 amps of battery power surge on the first turn then drop to 60 amps. If your lights are on as the motor comes to life enough to energize the alternator it will max out for a couple of revs feeding the starter, battery and lights. Bigger is better up to a point.

[rjewkes]

you don't think i'm going to big do you? I'd probably only realy go with a few cab monted clearance lights 5. And a 200w stereo.

so if i had the 48-55 amps being drawn out of a 61 amp alternator i'd be close for a moment to running at the top on a 61 amp but a 100 amp i'd only be in the middle? It won't overcharge anything will it?

[kid]

No you aren't going too big and only a battery can be overcharged by drawing current through it.

Voltage pushes current draws. A 35W light at 12 volts draws 2.9166 Amps due to its design. Because a battery pushes voltage and draws current plus stores it makes it prone to overcharging failures. A regulator stops that from happening by measuring the draw of the vehicle and reducing it when the draw is low while maintaining the proper voltage.

[rjewkes]

Ok Cool. Once i get the alternator in i'll be sure to grab the matching volt reg. Before i install it.