does AC affect battery life?

[SteveSRT8]

My 68 Impala also disengages all electrical load while starting. The AC will cut out for full throttle too!

The Chrysler monitors high side ac pressure and will apply 'bursts' of full speed fan to get it down during crazy hot weather. Those fans on high are another HUGE draw.

Modern cars need a drastic voltage increase to accommodate these ridiculous current loads!

 

[jim302]

I have never heard anything about A/C reducing battery life. However, high temperatures tend to shorten battery life. A/C is, of course, used more often in places with high temperatures.

Modern cars have very good electrical systems that should have no problem keeping the battery fully charged unless there are a lot of after-market accessories.

 

[Vikas]

Could it be that heat causes the batteries not to last? Hot climate battery life is always shorter than the the cold climate.

- Vikas

 

[mechtech2]

If we agree that ANY extra load is bad for the battery, then yes, AC use is detrimental.
But real life is not like that. The AC clutch is not much of a draw. Fans surely can be, but in the overall scheme of things, are not a problem. Besides, with no AC on, aren't we going to use the fan a lot more with vents?

So technically, yes, but in reality, not a problem.

 

[eljefino]

Originally Posted By: 440Magnum
Originally Posted By: eljefino
It might relate to "harder cranking" if you leave the AC on when you start the car... if you have something non computerized from 1975.


My 1960s Mopars kill all the electrical accessories whenever the engine is cranking. Its a dirt-simple extra terminal in the ignition switch- accessory power is separate from ignition power and the accessory terminal is de-energized when you turn the key all the way to "crank," it comes back on when the key snaps back to the "run" position. My old Fords were that way, too. In fact, I've never owned a car that you *could* crank with the AC clutch engaged without hot-wiring it.


Ok, new hypothesis, direct drive starter motor that gets warm after a long highway run next to a big V8, turns over real slow from the hot magnets after a stop for gas leaving the AC on.

Scares the driver because it barely catches, then he says, hey dummy, I left the AC on.

Urban legends don't have to have much basis in fact! Cars used to make us superstitious... should I give it gas and flood it? Is the moon waxing or waning?

 

[meep]

I have personally measured A/C compressors in the 3-5 amp range and have "hotwired" them with 18ga wire.

Raised underhood temps are real.

also is the correlation that there will be more A/C use in hot climates that are worse for batts anyway.... so the "data" could be "skewed."

most modern vehicles have larger alts, and some will bump idle up if the vehicle voltage is too low, in addition to idle compensation when the compressor kicks in. Butt warmers, etc. require big alts....

AFA electric fan programming, varies per vehicle-- so underhood temps with A/C use may not be consistent across all makes. My jeep "idles" the elec fan almost full time and varies rpm with heat load. ymmv.

 

[mechtech2]

It's the windings in the starter motor that get increased resistance with heat and cause slow cranking, NOT the magnets.

Except for carbon , the resistance of most materials goes up with heat.

 

[pidster]

Originally Posted By: mechanicx
Well heat kills car batteries. Maybe higher temperatures and using A/C got associated with batteries dying when the heat would've got them anyway. I know when I lived in TX car batteries would conk out a lot and adding water would get them working. I think for a hot climate a non sealed battery you can add water to is useful.


Exactly. High temps DESTROY lead-acid batteries. I forget the formula, but I read a "X degree rise in battery temp shortens life X amount" estimation before. Seems to be true, people always seem to have better battery life in mild climates, folks in Florida or Texas or Mexico are junking them every 3-4 years. These are the places that AC is on non-stop and I think that's just getting confused with heat as a cause of failure.

Cold temps make it harder to get that power out of a battery while cold but don't actually damage it long term. A lot of folks here blame the cold winters but it's actually our very hot summer season that does the damage. The results of the damage then make themselves known in January when the battery no longer has the strength to crank in the -20 C morning.

 

[pidster]

And also right about the non-sealed batts, while all cars seem to come with sealed maint free batteries new I always replace them with old school "top-up" types, they always work better as far as replacements go.

It's also little known but many "sealed" batteries are just regular ones with a "magic eye" and the conventional caps glued down or covered with a label and actually can be topped up with water, they are just a little harder to open.

 

[otis24]

Per the GM reps recommendation, I decided to put the charger on my battery to bring it to full charge "once per year" (see my post above). My battery charger displays volts and % of charge. To my surprise, my vehicle showed an 85% charge. This vehicle is driven 75 miles one way on the hiway five days per week. Occasionaly, I have the radio on and maybe the AC once in awhile. The battery is an Interstate battery that is two years old.

 

[Falcon_LS]

The longest my battery has ever lasted here is 18 months, and that's pushing it. 120+ degree weather is not uncommon, and the AC is definitely on whenever the engine is 9-10 months of the year. I've got Deka batteries on both my vehicles, both of which were replaced last August. Will be interesting to see how long they last.