Hey everybody. This time im wondering about my alternator. I need to know the amperage output?? I think thats what it called. Basically I need to know how many amps my alternator can handle. I want to install some off road lights and need to know if she can handle it. Its an87 F250 with a 6.9L IDI. All stock motor. Thanks for the help in advance.-JD

 

Probably 75 amps if your truck has AC.
But from my snow plow use I can tell you if you are running the engine slow which a diesel is so easy to do in, the alternator can not keep up.

I upgraded to a 150 amp for a little more money at replacement time.

 

The factory alternators were 65-75 amps, with a heavy duty version that developed 100 amps. Look for stamped numbers in the casing, you should see a 65A or something along those lines somewhere on the back of the alternator. You might have the 100A unit because of the diesel engine.

 

OK im gunna go look right now. Thanks for the quick responses. I picked up a baja light bar that looks pretty good on the truck. It has 4 mounting tabs for lights and i found a couple of deals on lights. I would like the 130w set because well more is better. Theres also 100w sets but. you can never have enough light in the desert. What do yall think?

 

Well I looked and theres no markings. I should have mentioned that the truck does NOT have AC. I see that its a motorcraft but thats all it says.

 

You should first think about........this mod.
https://www.ford-trucks.com/article/...r_Brights.html