b3av3r

iTrader: (3)

Is there away to measure how many amps an alternator is putting out at a specific RPM?

I know how to check the voltage and make sure the alternator is charging, but I just added a high output alternator and would like to check to see it is putting out what it is suppose to.

I have a basic Craftsmen multimeter to use for testing

Thanks

04BlackGmc

iTrader: (19)

no much you can do with that. go to your local parts store and have em test it, i work weekend at Autozone. They can do a ALt test and it will do a 2,000 RPM load test and will load the system a good amount. Your test result should fall within 70-80% of your Alt's total output.. My 130 amp actually is under rated and put out around 160 amps.

b3av3r

iTrader: (3)

thanks, I'll do that before I throw it on tomorrow

is there a multimeter I can buy that will test it for me? and if so what setting should I be looking for it to have?

thanks

Doc

iTrader: (9)

Not unless you are going to attempt to test it in the car under a load (read while driving). The Auto parts store benches don't really load down alternators that much. They are designed to check a stocker with a "stock" load value that you are probably way beyond anyways. You could go beyond all of this but is it really worth it? I mean do you trust the re / builder of the alternator in the first place?

04BlackGmc

iTrader: (19)

yea my fluke has a attachment for mine, but the problem is getting a good load really.. even if you turn on all the lights and acces. the bears tester still give more of a load.

brad8266

iTrader: (23)

Have very long meter wires first, long enough to go from the alternator to the cabin.

Take your multimeter and place it inline with the main power line on the alternator, then plave the meter in the car on the Amps setting and drive aroubnd and monitor.

Frost

iTrader: (45)

Yah I don't think you wanna do that. The output exceeds any handheld DMM that I have ever seen. 95+% of them are 10A max. Remeber, you aren't "reading" it like a voltage; all of that current actually has to be routed to pass through the meter.

brad8266

iTrader: (23)

oh yeah, duh, an alternator put out way too much amperage for a meter. There is an attachment though for the meter that allows you to run high amps.

01WS6/tamu

iTrader: (37)

Its an inductive adapter that you use with the fluke. I use them for refrigeration work. It is very accurate but it will only tell you the amount of amperage being drawn with a load placed on the system. It will not tell you the full power output capability of your alternator.

edcmat-l1

iTrader: (10)

DING DING DING!!!! inductive amp probe. but again, it will only show you what your alt is putting out with X amount of load on the other end. To take it a little further, alternators arent made to put out max amps for any length of time. It'll kill most of them. the best way to test with the inductive amp probe is to turn the headlights on, without the car running, leave them on for a couple minutes. That should drain the battery enough so that after starting it'll make the alt really pump out the amps.

brad8266

iTrader: (23)

Or just start the car and then disconnect the battery while the car is running, that will place the entire load on the alternator.

04BlackGmc

iTrader: (19)

please say you didnt just say that... never do that.

brad8266

iTrader: (23)

why??

04BlackGmc

iTrader: (19)

A battery as like a voltage stabilizer if you disconnect it you can do major damage to many elec components.

brad8266

iTrader: (23)

oh ok, I always thought thats what the voltage regulator was for.

04BlackGmc

iTrader: (19)

and where are all voltage regulators now? in the Alt..

brad8266

iTrader: (23)

yeah i know, that was my point.

Frost

iTrader: (45)

NAh..... What do you think happens when a battery dies via something like a bad cell?

04BlackGmc

iTrader: (19)

ok you guys believe what you want.

brad8266

iTrader: (23)

lol, I was asking for an explanation of what you meant because I havent heard it before. Thanks for the attitude though. Since you seem to not have a good explanation for what you said then i will assume you dont know what you are talking about.

Fall right in with the other 90% of internet techs that cant ever explain a damn thing that they say.