# Alternator stopped working then came back **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [July 29, 2019, 7:22pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523 "2019-07-29T19:22:34Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 29, 2019, 7:22pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/1 "2019-07-29T19:22:34Z")
2005 Mustang Gt with month old alternator. Yesterday, Stopped at train and started to lose electric power. Battery gauge all the way to zero. Car died and wouldn’t start. With a jump, the car started and runs fine now. Battery has 12.24V, and Alternator is putting out 13.8V. Any guesses at what happened? ---
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 29, 2019, 7:32pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/2 "2019-07-29T19:32:41Z")
Wiring is good. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [July 29, 2019, 7:40pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/3 "2019-07-29T19:40:10Z")
The ECU regulates the voltage out of the alternator dependent on the power demand of the vehicle. Brain fart? Tester ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [July 29, 2019, 7:43pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/4 "2019-07-29T19:43:02Z")
> [@blackbelt99\_154374](#): > > Wiring is good. I guess that means the battery posts and connectors a clean and tight including the other ends . ---
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 29, 2019, 7:54pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/5 "2019-07-29T19:54:10Z")
Battery posts clean and tight and alternator has internal voltage regulator. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [July 29, 2019, 7:55pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/6 "2019-07-29T19:55:18Z")
> [@blackbelt99\_154374](#): > > alternator has internal voltage regulator. Which the ECU controls. Tester ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [July 29, 2019, 8:46pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/7 "2019-07-29T20:46:23Z")
I guess I’d put a charger on the battery to see if it takes a better charge before you ruin the new alternator. If the alternator is putting out 13.8, I’d bet you need a battery. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [July 29, 2019, 8:58pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/8 "2019-07-29T20:58:00Z")
> [@bing](#): > > If the alternator is putting out 13.8, I’d bet you need a battery. Or that’s all the voltage that’s required for the vehicle as measured by the ECU. > **[Computer-Controlled, 'Smart' Charging System: Volts Are Smart, Amps Are Smarter](https://www.underhoodservice.com/computer-controlled-smart-charging-system-strategies-why-volts-are-smart-but-amps-are-smarter/)** > > When diagnosing a charging system on any modern import, think "smart." I learned this lesson several decades ago when repairing a cranking, no-start condition on a 1989 Honda Civic, which was equipped with one of the first "smart" charging systems.... Tester ---
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 29, 2019, 10:42pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/9 "2019-07-29T22:42:32Z")
I’ll charge overnight and see what it takes in the morning. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [July 30, 2019, 1:14pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/10 "2019-07-30T13:14:49Z")
> [@blackbelt99\_154374](#): > > month old alternator Where’d that alternator come from? Many aftermarket remans are junk. My first suspicion is poorly seated brushes. An old serpentine belt that slipped when it got a little wet is my second. The battery at 12.24V needs a long (6+ hours) slow (5- amps) charge at ~14.5V. Then test it. ---
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 30, 2019, 1:42pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/11 "2019-07-30T13:42:24Z")
AdvanceAuto, yes their alternators may be junk. The one before this was dead out of the box. I charged overnight with a 2 amp battery tender. I’ll see what happens. The battery is about 3- 4 years old. Going to check manufacturing date to see actual age. ---
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 30, 2019, 2:21pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/12 "2019-07-30T14:21:40Z")
![image](https://global.discourse-cdn.com/cartalk/original/3X/3/d/3dbb56c9f6077b34457978efa68ed210492a27cf.jpeg) Belt is new also. It was a very hot day when car died sitting at idle for train. 5-7 minutes. But water temperature was only upper 190’s. The car is extremely well kept in heated garage looks like new. Also has Edelbrock supercharger, headers, and cam installed. I keep track of all engine parameters with Interceptor gauge mounted in dash. Checked all wiring last month when received bad alternator. Battery was fully charged this morning at 12.6V, after starting, measured 14.1V. Battery is Durolast Gold, made 10/16. Will take for drive now and see what happens. ---
**Author:** ![blackbelt99\_154374](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@blackbelt99\_154374](https://community.cartalk.com/u/blackbelt99_154374)\ **Post date:** [July 30, 2019, 3:16pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/13 "2019-07-30T15:16:19Z")
After 10 miles, the alternator was at13.8V the whole time and at idle after drive. Battery was at 12.8V after shut down ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [July 30, 2019, 3:25pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/14 "2019-07-30T15:25:27Z")
Re the belt: somehow after reading the original post and the replies “train” mutated into “rain” in my ageing head, and I thought of the belt getting wet. 13.8V from alternator is OK in hot weather. ---
**Author:** ![anon86613489](https://avatars.discourse-cdn.com/v4/letter/a/ad7895/32.png) [@anon86613489](https://community.cartalk.com/u/anon86613489)\ **Post date:** [July 30, 2019, 3:38pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/15 "2019-07-30T15:38:24Z")
> [@circuitsmith](#): > > and the replies “train” mutated into “rain” in my ageing head, It might not be Your ageing head. A while back, I bought 8 rolls of toiletpaper, but when I got home with them, they had mutated into 4 kitchen rolls. I don’t know what’s going on nowadays. ---
**Author:** ![RandomTroll](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/randomtroll/32/12184_2.png) [@RandomTroll](https://community.cartalk.com/u/RandomTroll)\ **Post date:** [July 30, 2019, 8:28pm UTC](https://community.cartalk.com/t/alternator-stopped-working-then-came-back/145523/16 "2019-07-30T20:28:39Z")
Once my battery’s contacts rattled off; once the alternator belt started slipping. The 31-year-old alternator keeps on working.