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Absolutely positively wrong about battery?

I owe my boyfriend a steak dinner and I don’t mind paying, but I want to understand where I went wrong. We were going out and the car wouldn’t start. It had been sitting in the driveway for 30 minutes with the engine running to keep the AC on while we waited for BF. My friend and I were inside but her teen-aged daughter was in the car with the engine running and the AC/radio on. The kid says she turned the engine off and left the ac and radio running no more than 10 minutes before BF arrived. (I believe her because it was hot and she would have noticed if the AC stopped blowing cold air.)

But when we turned the key, dead silence. After much poking and prodding and banging on what I thought might be the starter, with everyone else saying we should just jump-start it already, I proclaimed I was 100% sure it wasn’t the battery and would spring for the steak dinner if it was, because the engine hadn’t even coughed, yet the lights, AC, radio, etc. all came on. (We turned them off when trying to start it, of course.)

I figured that if the battery had enough juice to run the accessories, then it should have at least given the engine a small turn – and I didn’t think it was possible for the accessories to drain it in 10 minutes in hot weather. But BF insisted on jumpstarting it and it fired right up. Grrrr. It’s a ’98 Subaru Outback. Battery not terribly new, but it has started reliably all week since this happened. What am I missing?

The battery was draining slightly the whole time it was idling with the a/c on, then more when the engine was stopped (by the way, the a/c needs the car running to work, so just leave the engine on). If the battery was very weak it could have done as you describe. This could be combined with a weak starter.

I hear Denny’s has a nice steak!

Battery’s can have a sudden and complete death without warning. It’s happened to me.

Heat is more of an enemy of car starting batteries than cold is. If the battery was old, more than likely with engine idling on a hot day with the A/C on for that period of time caused the underhood temperature to reach a point where it damaged the battery.

By the way, I wouldn’t trust that battery. If it died once it’ll die again. Replace it.


My guess? Good battery but corroded terminals. You could get enough juice from the battery to work a few accessories but not enough to turn the starter.

When someone applied the jumper cables he also wiggled the battery cables enough to overcome the corrosion. Now it will start every time – until more corrosion builds up.

Clean those terminals. And ask for halfsies on the steaks.

Automatic transmission? Seeing as how you mention dead silence I would suspect anyway this problem could be due to a faulty neutral safety switch. That’s the device that prevents an engine from starting in anything other than NEUTRAL or PARK and it’s also a common failure with many different types of cars, not just Subaru.

I’m not sold on the battery theory just yet.

As to why the engine started after jumping that could be conincidental. An iffy neutral switch can be affected by someone slamming a car door, opening the hood, bumping the shift lever, etc, etc, etc. Yes, it can be erratic in nature.

The battery was most likely already low on reserve capacity and leaving the accessories on without the engine running to supply at least some charge to the battery caused the trouble. I suggest you have the battery load tested to see if it is time to think about replacing it before it leaves you stranded somewhere. The AC system won’t work while the engine is off but the compressor clutch may stay on and blower will also. Those two alone draw a significant amount of current from the battery.

The battery can go dead in a hurry. Older batteries are just waiting for a chance to do that. Give one an opportunity and it can surprise you in many ways. Sometimes the car even starts.

Your name is texases and you “hear Denny’s has a nice steak!”???

Denny’s discriminates against black Secret Service agents and the steaks are, well, Dennys.

Running accessories is NOTHING compared to the current the starter needs to draw to start a car. Although Usually when a battery has enough juice to run the lights without dimming then it usually has enough juice to at least try to start it…but it still could be the battery.

Heat is the biggest killer of batteries. So 10 minutes in hot weather…yea…it’s possible.

BTW…if the engine was shut off…there’s no way the AC was on. Maybe the blower fan…but the AC was off.

piter - please increase you ‘joke detector’ setting…

I’d check the battery connections to be sure they are tight and corrosion free, tighten and clean them as needed. Many times you’ll get enough power through loose or dirty connections to run accessories, but you won’t get enough to activate the starter. Your battery may have been good, but when you hooked up the jumper cables you were getting power that may have been in your battery plus power from the other battery which may have produced enough power to start the car even with dirty or loose connections. I’d also have the battery load tested if it tests bad go ahead and replace it to prevent it from going completely out at an inconvenient time or in an unsafe area. Enjoy the steak!

The radio would not draw much from the battery, but if the fan was on high, then that would draw down a battery in a hurry. Also, if the fan was on high when the engine was running, the alternator would not have been supplying enough current to keep the battery charged at idle. It would be worse yet if the daughter turned the ignition switch to off, but back to on/run instead of accessory to listen to the radio.

I dunno, I like their breakfasts but I don’t think I’d buy a steak there. Hard telling where they got it from. I don’t think you’ll find the Denny’s in the northern states like Minnesota discriminating. If they did, they’d be run out of town in a hurry.

I’d agree the battery was probably not holding a huge charge and idling for a while and running the fan and radio did it in. It might still take a charge from jumping but its days are over as a dependable battery.

Story: When I was in high school I took my Dad’s 1960 Falcon out on Friday night. He warned me to not use the radio or the battery would run down. I didn’t believe him and ran the car around town for a couple hours with the radio on. Sure enough it was enough to discharge the battery enough to need a jump start. I don’t think I ever told him and never knew if it was a weak battery or generator.

The radio in a 60 Falcon was a tube type. With the ignition switch in the acc position, they could kill a good battery of that era in about 30 min.

This argument can be settled for sure by having a simple load test performed on the battery. Most parts stores will do this free of charge…

texases July 11 Report
piter - please increase you ‘joke detector’ setting…

Please check your ‘joke emitter’ setting.

The ‘joke detector’ was removed from this model mentat by its Tiailaxu creators.

I assume the “joke emitter” is an integrated component to the joke detector module? :wink:

The '60 Falcon had a generator?
They produce much less current than alternators at idle and low speeds.
Probably the main reason car makers switched to alternators.