# Battery discharge when driving **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** cherokee, jeep\ **Created:** [March 10, 2017, 12:53am UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004 "2017-03-10T00:53:53Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![chris12942000](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@chris12942000](https://community.cartalk.com/u/chris12942000)\ **Post date:** [March 10, 2017, 12:53am UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/1 "2017-03-10T00:53:53Z")
Day one: check gauge light comes on, 20 miles later, radio dies, air bag lights come on, battery gauge plumets, car dies, I get a tow. Day two: husband puts in a new battery Day three: drive 25 miles to work, battery gauge light comes on, plumets down, get a tow, start the car and battery gauge is back up but I don’t want to drive the darn thing. Day four: any ideas? Thanks! ---
**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\ **Post date:** [March 10, 2017, 1:17am UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/2 "2017-03-10T01:17:57Z")
Sounds like a bad alternator first guess. A reliable analysis for a reliable repair. ---
**Author:** ![chris12942000](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@chris12942000](https://community.cartalk.com/u/chris12942000)\ **Post date:** [March 10, 2017, 1:29am UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/3 "2017-03-10T01:29:01Z")
Okay thanks will get it checked! ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [March 10, 2017, 1:34am UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/4 "2017-03-10T01:34:47Z")
> [@Barkydog](#): > > Sounds like a bad alternator first guess. A reliable analysis for a reliable repair. Yup, I agree emphatically. Have the alternator load tested. Post back with the results. ---
**Author:** ![chris12942000](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@chris12942000](https://community.cartalk.com/u/chris12942000)\ **Post date:** [March 11, 2017, 7:05pm UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/5 "2017-03-11T19:05:30Z")
Not the alternator…Ground wire? ---
**Author:** ![BillRussell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/billrussell/32/3179_2.png) [@BillRussell](https://community.cartalk.com/u/BillRussell)\ **Post date:** [March 11, 2017, 8:49pm UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/6 "2017-03-11T20:49:49Z")
Could be any of the heavy cables that attach to the battery, corroded. Or you could have a partial short somewhere in the electrical system, draining more current than the alternator can supply. But this seems unlikely, as that is a huge amount of power and heat. Or whoever tested the alternator did it incorrectly. Edit: get a $10 voltmeter that plugs into the cig. socket. Use that to monitor the battery voltage under various conditions. Eg, car on but not started (should be about 12.6 volts) attempting to start (10.5 volts or higher) or with engine running (12-15 volts0. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [March 11, 2017, 9:11pm UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/7 "2017-03-11T21:11:04Z")
> [@chris12942000](#): > > Not the alternator…Ground wire? I don’t believe the charging system will test good if a ground wire is missing. If the low voltage warning light is on and the battery discharges as you drive you have a charging system problem. The charging system should be inspected and tested. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [March 12, 2017, 12:57am UTC](https://community.cartalk.com/t/battery-discharge-when-driving/101004/8 "2017-03-12T00:57:03Z")
I had this same problem on my Corolla, alternator tests ok, but not charging battery. Turned out the wire between the alternator and the battery got buggered up with battery acid from a leaking battery. Soldering that back together solved the problem. Ask your shop to measure the main alternator voltage output with the engine running. It should match closely to the voltage at the battery posts. Usually in the 13.5 - 16.0 volt range. If there’s a difference of more than 0.5 volt between what you measure at the alternator vs the battery, you likely have a problem in that connection. I think there may be a fuse in that path also on some vehicles. So that’s another possibility, a blown fuse. It’s often called a “fusible link” rather than just a “fuse” b/c of the large currents involved.