what amperage alt should i run?

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moparmat2000

moparmat2000

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I have dewired the amp gage out of the dash wiring, and the only additional power requirements i will have on my barracuda will be an electric fan. I dont plan on adding A/C or radio. Car was radio delete anyways. I prefer the roar of an unmuffled V8 to a stereo anyways.

What.do y'all think of a 50 amp alt for what i am doing ??.is it sufficient ?

Thanks
Matt
 
The electric fans can have a BIG draw on amps and without knowing the draw of amps from the fans, I'd say 100 amps.
 
I run an alternator from an 88 4 runner. Think it's a 60 but it starts at 700rpm so no dimming lights or charging problems at idle.
 
I have been told by the local guru that 65 amps is plenty unless your getting way up into all the fancy accessories like power windows, seats, sun roof etc etc etc, electric fans are a big draw but will jive ok as long as EVERYthing is wired correctly. The newer ones comming off the assembly lines today are up to 120 amps but hell they have 110V power invertors in em and plenty of outlets to plug laptops into, front and back and onboard computerized everything.
 
Im running a stock alternator, 60amp I believe. I was running twin electric fans, aftermarket radio with 6 speakers, and have it wired for a electric fuel pump but not running that yet. A stock alternator should be plenty for what your doing. Oh and look at adding in the relays for the headlights, its a nice upgrade. I think it was crackedback that sold a kit.
 
Add up all the big power draws that you will need - and rpm.
You can do worst case if you don't have or want to figure out the exact. Worst case being your fuse or circuit breaker.

Headlights, Wipers motor, heater blower and your electric fan could all be running at the same time and at idle rpm.
A CD ignition can pull a fair amount, but more as rpm climbs. So usually less an issue.

The problem is other than a Chrysler original part, the amp ratings of alternators is at an unknown condition. Safe bet it is their max output which means you can't directly compare it to the Chrysler rating.

If your engine's idle speed is fairly low, and you're adding that electric fan, I'd suggest that your odds are better with a 'square back' with not too high of a rating. One way to get higher max output trades off the low speed output. In my experience square backs really do a little better at low rpm than the round backs. Of course theirs no guarentee what's inside on rebuild - that's why I said 'odds are'.
 
Mattax said:
Add up all the big power draws that you will need - and rpm.
You can do worst case if you don't have or want to figure out the exact. Worst case being your fuse or circuit breaker.

Headlights, Wipers motor, heater blower and your electric fan could all be running at the same time and at idle rpm.
A CD ignition can pull a fair amount, but more as rpm climbs. So usually less an issue.

The problem is other than a Chrysler original part, the amp ratings of alternators is at an unknown condition. Safe bet it is their max output which means you can't directly compare it to the Chrysler rating.

If your engine's idle speed is fairly low, and you're adding that electric fan, I'd suggest that your odds are better with a 'square back' with not too high of a rating. One way to get higher max output trades off the low speed output. In my experience square backs really do a little better at low rpm than the round backs. Of course theirs no guarentee what's inside on rebuild - that's why I said 'odds are'.
Click to expand...


I have access to 2 mopar alternators both are Delco remans. A 50, and a 60 amp. Both round back style. I have a brand new year one engine harness i modded to bypass the bulkhead and run straight to the battery. I still need to install a fusible link. As such the main wire out of the alternator in this repop harness is stock diameter.

Matt
 
straightlinespeed said:
Im running a stock alternator, 60amp I believe. I was running twin electric fans, aftermarket radio with 6 speakers, and have it wired for a electric fuel pump but not running that yet. A stock alternator should be plenty for what your doing. Oh and look at adding in the relays for the headlights, its a nice upgrade. I think it was crackedback that sold a kit.
Click to expand...

Please give me more info on the relays for lights and how to wire....

Thank you!
 
The ammeter bypass doesn't matter to the load, it just has you "flying blind". Whatever you do, buy a cheap cigarette lighter voltmeter to monitor as you drive.

A radiator fan is a big load, but only when it is running. That depends on operation, climate, ... On the highway w/ a good radiator, it shouldn't run. The alternator doesn't have to match the peak load, only keep the battery charged.
 
HIPOVALIANT said:
Here is the thread.

http://www.forabodiesonly.com/mopar/showthread.php?t=216514
Click to expand...

Thank you Hipovaliant.

The mad kit is decent. You need two kits to do one car, high and low beam circuits. I believe they use the lower cost relays, not tyco/bosch. I can sell a kit for the same cost including superior relays and materials.

When doing the headlight kit, IMO, the relays, HL plugs and wire sizing are EVERYTHING! It's a waste of effort to put in relays and use 16-18ga wire. The only real benefits in that situation are reducing the load on your bulkhead/ammeter and minimal shortening of wire run lengths. You will experience unnecessary voltage drop using inferior wire sizing. A body cars use 18ga for HL wiring, B and E body use 16ga.

Here's an E body car on low beam with a before and after using one of my kits with 12ga wire.

Cudanight004-1.jpg




More before and after pics are coming.
 
If you plan a lot of relays (fan, headlights, fuel pump, EFI, ...) individual relays soon become a clutter. I installed a relay/fuse box in both my A's which also replaced the factory firewall starter & horn relays. In my avatar, the black box on driver's inner fender. Search for my post "Modernized ...". 67Dart273 did similar.
 
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