Lost power while driving

subaru
electrical-wiring
legacy
batteries

#1

Hey folks –



This evening I drove our Subaru Legacy Wagon (1999) about 3 miles or so to the gym. When I pulled into the lot, I noticed my radio (tuned to NPR, no less) had gone off. Curious! A few seconds later, dashboard lights come on (ABS, maybe others). After that, engine goes quiet, car is dead – turning the key does nothing at all, and the car is completely without power. Only the dome light works, and barely.



I get a jump, and eventually the car starts back up — but it took a while, and several tries, before I could get the engine going. On the way home, I kept a careful eye on the RPMs – when I was close, I noticed the ABS light pop back on, and the RPM needle go down to zero. I tried my best to keep the RPMs up by staying in first, and managed to park. Of course, the car was unresponsive when I immediatley tried to restart it.



Some quick internet searches suggest alternator, bad connections to the batter, and some other ideas.



We’ve never had this problem before. The twist is that we’re literally on the brink of selling this car – we’ve got one more than we need. Thus, we’d be pretty bummed if we had to put much, if any, cash into the car just so we can get rid of it days later.



Thoughts?


#2

This is most likely a bad alternator. Was the battery light on at all while you were driving? Before the other dash lights began to go on? With a bad alternator, once the battery voltage drops below 10V, the electronics in the car start to act strange. This includes the engine cutting out.


#3

How old is the battery?


#4

Didn’t notice the battery light come on — on the way home, only the check engine light was on (which has been on for a while).


#5

Good question – it’s my financee’s car. She’ll probably have those records. I’ll try to find out.

When I opened the hood to do the jump, I did notice some corrosion on the battery.


#6

That corrosion MUST GO…ASAP…it caused your battery to drain and may have caused its death.

If you clean and grease the batt terms and clamps…put them back nice and tight…get a jump and drive for a while…that should charge the batt back up IF the batt hasnt died because of chronic under charge state…

It sounds as tho your alternator died tho (because you actually have several things afoot at the moment hard to say which it is at this point the way things are)…

You can do this test…get the car started…pull off the pos terminal clamp and hold it away from ground…you wont be shocked trust me…if the engine dies immediately…your alternator is done… If it stays running its your batt or batt connections and your alternator is good.

You have to clean the terminals first…get a jump, then test.

When you got a jump prior and it took a while…you charged your batt…then drove on bat power…The reason I say it could be your alternator is bec the corrosion may cause it to have the same symptoms of a failed alternator…bec the charge from the alternator will not pass thru the corrosion.

My guess is that you got home on battery power alone…no alternator or the alt couldnt charge the batt bec of corrosion…


#7

Brief internet searches pulled up your test for alternator vs. battery problems as well. I guess that would be a good start.

Should one generally wipe corrosion of a battery when you see it? My RAV4 (our other car) had corrosion on the battery some time ago — discovered after it wouldn’t start one morning. I knocked most of it off, came back the next day, and the thing was fine (and has been fine since… that was nearly a year ago).