# Did I just blow out my truck's alternator jumping the battery? **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** f250, ford\ **Created:** [September 18, 2016, 4:45pm UTC](https://community.cartalk.com/t/did-i-just-blow-out-my-trucks-alternator-jumping-the-battery/95719 "2016-09-18T16:45:16Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![LouAntoine](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/louantoine/32/5018_2.png) [@LouAntoine](https://community.cartalk.com/u/LouAntoine)\ **Post date:** [September 18, 2016, 4:45pm UTC](https://community.cartalk.com/t/did-i-just-blow-out-my-trucks-alternator-jumping-the-battery/95719/1 "2016-09-18T16:45:16Z")
Hey there-- I just did something dumb. I had a dead battery on my '97 power stroke Ford F250. I realize now that when I was jumping it (successfully) I clipped the (black) ground cable to the alternator itself! Doy. The alternator is definitely dead now as I lose power after a few minutes of running the engine. My question is: did I blow a simple fuse or do I need to replace the whole alternator? How likely is it that I did further damage? I ask because I’m contemplating replacing the alternator myself. But maybe it would be wiser to get a tow to the mechanic. I thank anyone who can help me demystify my own rank stupidity. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [September 18, 2016, 6:01pm UTC](https://community.cartalk.com/t/did-i-just-blow-out-my-trucks-alternator-jumping-the-battery/95719/2 "2016-09-18T18:01:27Z")
Just how old is your battery . . . ?! If you have a bad battery, your alternator does not stand a chance of doing its job properly ---
**Author:** ![LouAntoine](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/louantoine/32/5018_2.png) [@LouAntoine](https://community.cartalk.com/u/LouAntoine)\ **Post date:** [September 18, 2016, 6:10pm UTC](https://community.cartalk.com/t/did-i-just-blow-out-my-trucks-alternator-jumping-the-battery/95719/3 "2016-09-18T18:10:50Z")
The battery is pretty new… I killed it by leaving a light on overnight. ---
**Author:** ![Yosemite](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/yosemite/32/643_2.png) [@Yosemite](https://community.cartalk.com/u/Yosemite)\ **Post date:** [September 18, 2016, 6:29pm UTC](https://community.cartalk.com/t/did-i-just-blow-out-my-trucks-alternator-jumping-the-battery/95719/4 "2016-09-18T18:29:54Z")
Clipping the ground side of the jumper cables directly to the alternator body should not have hurt anything. But if that ground clamp touched the B+ post on the back of the alternator you may have damaged something. Either the alternator, the battery, or the charge cable may have been damaged. The charge cable is a fusible link, so keep that in mind as you diagnose this. I would charge the battery on a charger for 6 hours. Then start the engine and measure the voltage at that B+ post on the alternator. It should be around 14 volts with the engine running. If it reads 14 volts…the alternator is fine. Next I would check the voltage between the battery posts (not the cable clamps but the center of the posts themselves). If you do not get 14 volts but did on the B+ terminal of the alternator, then the charge cable is burned out. You can buy the fusible links at any auto parts store. Yosemite ---
**Author:** ![LouAntoine](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/louantoine/32/5018_2.png) [@LouAntoine](https://community.cartalk.com/u/LouAntoine)\ **Post date:** [September 19, 2016, 12:59am UTC](https://community.cartalk.com/t/did-i-just-blow-out-my-trucks-alternator-jumping-the-battery/95719/5 "2016-09-19T00:59:49Z")
Thank you so much Yosemite. I will report back in a few days about how it went.