voltage at 12.1 volts normal?

[tommyk90 5,000+ posts]

i'm sure it could be producing more than 12.5 at idle but could be being drained at that same time from having the engine running. i don't know?i'd like to get a h.o alt soon but also sketchy that reading about those alts not really producing much untill after 2krpm which it could become useless.

where i live in the city the highest speed limit is 35mph. if i drive up the keys it's 55mph, but being in the city i rarely ever drive over 1.5-2krpms unless if it's taking off from a stop or driving aggressively.

what i really need is a bigger/different car with good gas mileage. :/

Actually, most H.O. alts will turn on around 700-800 RPM. I know mine does.

Of course, it doesn't put out it's maximum amperage until ~2k RPM.

 

[fbi90909 5,000+ posts]

Actually, most H.O. alts will turn on around 700-800 RPM. I know mine does.
Of course, it doesn't put out it's maximum amperage until ~2k RPM.

is that with a smaller pully?

also if one were to put on a smaller pully at higher rpm's would it not cause the alt to over ehhh over spin? i know they have a cap of what they can produce at this max rpm but with a smaller pully could it drive an alt over that cap(knowing it's not going to produce any more than capable) and damage the alt?

dunno.

 

[tommyk90 5,000+ posts]

is that with a smaller pully?also if one were to put on a smaller pully at higher rpm's would it not cause the alt to over ehhh over spin? i know they have a cap of what they can produce at this max rpm but with a smaller pully could it drive an alt over that cap(knowing it's not going to produce any more than capable) and damage the alt?

dunno.

Mine came with a slightly smaller than stock pulley. I was going to put a smaller one on it so it would kick on with my engine hot and the RPM's slowed down, but I couldn't find a smaller one.

Depending on the make and size of the alt, most manufacturers use a proper sized pulley that is small enough to charge at lower RPM's but won't overspin the alt at higher RPM's.

 

[fbi90909 5,000+ posts]

Mine came with a slightly smaller than stock pulley. I was going to put a smaller one on it so it would kick on with my engine hot and the RPM's slowed down, but I couldn't find a smaller one.
Depending on the make and size of the alt, most manufacturers use a proper sized pulley that is small enough to charge at lower RPM's but won't overspin the alt at higher RPM's.

good to know, good to know.