140 amp vs 80 amp alternators

[skhochay]

... suppose I got 140 amp alternator replaced my original 80 amp - I do not get it, when idling voltage drops to 11 volt lights dimmed, when I press accelerator voltage goes to 14volts lights got brighter , heater fan spins faster etc. What is the problem? when idling again dimming dash lights, heater fan slows down ??????

 

[maat]

an alternator with a standard sized pulley generally doesnt create the maximum amperage/voltage it's made for at idle. if you want it to be making amps at idle you need a smaller pulley.

 

[jonheld]

This sounds like a discharged or poorly conditioned battery to me.

 

[LFD2037]

Agreed^. My 80 amp NEVER hits 11V. Never drops below 12V & very rarely will drop below 12.5V.

 

[skhochay]

an alternator with a standard sized pulley generally doesnt create the maximum amperage/voltage it's made for at idle. if you want it to be making amps at idle you need a smaller pulley.

where do I get smaller pulley?

 

[LS1FJ40]

I'd listen to @jonheld. Get your battery tested. Hell of a lot easier to replace a battery than to mess with a pulley when you don't know for sure that the pulley is the problem.

There have been numerous threads on MUD recently where people were complaining about various electrical issues. Throwing money and parts at perceived problems only to find out they had a s*** battery.

 

[skhochay]

I'd listen to @jonheld. Get your battery tested. Hell of a lot easier to replace a battery than to mess with a pulley when you don't know for sure that the pulley is the problem.

There have been numerous threads on MUD recently where people were complaining about various electrical issues. Throwing money and parts at perceived problems only to find out they had a s*** battery.

battery is new , works well with 80 amp alternator, I can swap it back , was thinking to give more power as I have lot of LED's

 

[maat]

the voltage on his truck would easily drop to 11v if he was at idle and was running a heap of accessories

 

[maat]

where do I get smaller pulley?

get one machined up? look for a different model that fits? there was a post i read here in the 80 section where a guy was making brackets and smaller pulleys for a higher amperage alternator. give it a search

 

[LS1FJ40]

get one machined up? look for a different model that fits? there was a post i read here in the 80 section where a guy was making brackets and smaller pulleys for a higher amperage alternator. give it a search

That is @Photoman...

 

[maat]

thats him! sorry i dont have time to search at the moment, im meant to be working

 

[skhochay]

thats him! sorry i dont have time to search at the moment, im meant to be working

tx for the info I fount "Bill" who gets me a pulley

 

[LS1FJ40]

I'm hoping that @Photoman will be convinced he needs to figure out a pulley and higher amp alternator for the 3FE!

 

[SmokingRocks]

how much for the pulley. I might want one too.

 

[2KCruiser]

The internal voltage regulator inside the alternator controls how much voltage is going to be output as well as what RPMS it would start raising the voltage at. For example you can have one type put out only 11v at 800rpm while another puts out 13.5v at the same rotating speed. It all comes down to the voltage regulator that decides. Amps generated is completely different, the different styles and sizes of the armature, stator, and rotor inside will depend how much the alternator can charge in respects to amperage.

 

[alia176]

battery is new , works well with 80 amp alternator, I can swap it back , was thinking to give more power as I have lot of LED's

A lot of LEDs shouldn't draw a whole bunch of amps. Can you quantity how many amps total are your LEDs drawing?

 

[2KCruiser]

By changing the pulley into a smaller size you are raising the RPMS of the rotor inside, thus allowing the alternator to kick in earlier and start charging in the lower rpm range.

 

[skhochay]

how much for the pulley. I might want one too.

I got one for $66 with shipping

 

[rblain82]

I'm hoping that @Photoman will be convinced he needs to figure out a pulley and higher amp alternator for the 3FE!

when I bought mine, supposedly had a 140 amp alt on it.. it looks like a chevy alt to me. I'm not real sure. I can take a pic if I need to.

 

[LS1FJ40]

when I bought mine, supposedly had a 140 amp alt on it.. it looks like a chevy alt to me. I'm not real sure. I can take a pic if I need to.

Please do! And of the mount! Thanks!