Quick alternator question

[MkKin420 10+ year member]

I picked up a 200a HO alt form Ohio gen. What I am wondering is if I am going to have any trouble like loss of output at idle from low rpm, and if there are any other outcomes I might need to thing about ahead of time. The bench sheet says it will put out about 2a at 2000 alt rpm 37a at 2400 alt rpm and 137a at 3500 alt rpm and 182 at 5000. Its going on a 3.1 l engine. Anything you guys can think of that I might need to look into. Max output is at 6500 rpm.

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[jdawg 5,000+ posts]

lol

 

[MkKin420 10+ year member]

lol

Alright I deserved that but seriously, anything I need to look into or should I be fine.

 

[bball09124 10+ year member]

That thing does 2 amps at 2k rpms? ****, return that thing ASAP. You idle somewhere between 500-1000 rpms, the alt is gonna do less than 2 amps.

 

[MkKin420 10+ year member]

Before I jump the gun and return it those are alternator RPMs. If I can manage to idle at say 800-900 engine rpms, with a puley ratio of 3:1 I should get about 2400-2700 alternator rpms which will give me about 40 amps or so.

 

[bball09124 10+ year member]

Before I jump the gun and return it those are alternator RPMs.

Oh, sorry I missed that. I forget how they equate to engine RPMs. Disregard my last comment.

 

[jdawg 5,000+ posts]

its still low thought, thats why I lol, so thats like 200rpm? Im not sure but it seems really low. Mechamn alts do 150amp at idle.

 

[jdawg 5,000+ posts]

just lookd around 2000 alt rpm is 800 engine in general, so thats idle, 2 amps? lol

 

[MkKin420 10+ year member]

That's why I am asking you guys. It seems kinda low to me. I am not really worried about playing it at idle as much as while I am actually moving fast enough to generate the power needed by the amps. See it says that it will do abut 40 amps at 2400 alternator rpm, which with a pulley ratio of 3:1 I would need an engine idle speed of about 800 rpm. The thing that I don't know is what my actual idle speed is and if their is a possible way for it to be increased in the event that it is too slow.

 

[jdawg 5,000+ posts]

what about sittin at stop lights and your alt is putting out 2 amps and your amps and cars electrical is draining the shit out of your battery and you are getting only 12v?

 

[jdawg 5,000+ posts]

your idle is probably around 800 rpm

 

[MkKin420 10+ year member]

what about sittin at stop lights and your alt is putting out 2 amps and your amps and cars electrical is draining the shit out of your battery and you are getting only 12v?

Great point. This is what I am trying to figure out ahead of time. Would a deep cycle (yellow top) up front help to make up for it, then making sure I drive on the highway for a good amount of time to recharge the battery? If I can get 800 engine rpm at idle would 40 amps be enough to keep it runnign without draining the battery.

 

[MkKin420 10+ year member]

Here's a copy of the test sheet so I don't confuse anyone.