YACT: Battery Charging

[TubStain]

So today is officially the start of spring here in Michigan, so I decided I'm going to wash & wax my car, which I did to the music pumping in my car, then I wondered if I would kill my battery by doing that, since my engine wasn't on. So the questions is:

If I keep my engine running, does that power up the battery, or does the car need to be moving for the battery to be charged up?

 

[ElFenix]

the engine charges the battery if the engine is on. but some music isn't gonna kill it. if you want you can go drive around a bit and get it up to a peak charge again

 

[The Stigenator]

idiling for long is not good.

your battery should be fine... most times it charges only beyond 2000 rpm.

Depends on how strong your battery is.. if not you can always charge it after your done wash and waxing.

 

[justint]

Unless you are going to be washing and waxing the car for something like 18 hours straight don't worry about it.

 

[ElFenix]

Originally posted by: The_good_guy
idiling for long is not good.

your battery should be fine... most times it charges only beyond 2000 rpm.

Depends on how strong your battery is.. if not you can always charge it after your done wash and waxing.

idling is bad, but there is a belt connected to the alternator and that is what powers everything when the car is on, its not just when you're over 2k rpm.

 

[Zenmervolt]

That's dependant on the car, the battery, and the stereo. If it's a stock stereo (or just an aftermarket head unit) then you'll be fine as long as the battery isn't old and weak. If it's a large custom system with an amp or two, then I've seen batteries go dead in an hour.

As for what TGG says about batteries only charging when the engine's above 2000 RPM, that's only true of motorcycles. An automobile in proper condition will charge the battery at idle. The typical charging system should generate 13 to 14 volts at idle, and 12.5 to 13.5 under load at idle (those are "rule of thumb" numbers, actual numbers vary by the type of car).

ZV

 

[kmac1914]

Originally posted by: Zenmervolt
That's dependant on the car, the battery, and the stereo. If it's a stock stereo (or just an aftermarket head unit) then you'll be fine as long as the battery isn't old and weak. If it's a large custom system with an amp or two, then I've seen batteries go dead in an hour.

As for what TGG says about batteries only charging when the engine's above 2000 RPM, that's only true of motorcycles. An automobile in proper condition will charge the battery at idle. The typical charging system should generate 13 to 14 volts at idle, and 12.5 to 13.5 under load at idle (those are "rule of thumb" numbers, actual numbers vary by the type of car).

ZV

This is VERY true. I found this out the hard way went i went on my senior trip in HS. I left my car at home for about 3-4 days, and when i got back, it would not even crank....no power anywhere. Apparently, when my first amp was installed for my stereo system, instead of being set to power on and off when i turned on the engine, somehow it was set to being on all the time, and it drained my battery. Crappy way to find out, though.

 

[Eli]

What's this "idling is bad" nonsense? Who/what started that crap? :frown:

So, if idling is bad.. what do you guys think about redline? 😛

 

[The Stigenator]

Originally posted by: Eli
What's this "idling is bad" nonsense? Who/what started that crap? :frown:

So, if idling is bad.. what do you guys think about redline? 😛

I have always been told that idling for extended times puts an load on the engine (something heat related)...

that's why highway mile cars are actually preferred to city stop & go type where the idle time is higher but then you also do stop and go.

If I buy a used car i prefer a used rental car knowing its been on highway miles a lot more (despite it being possibly abused).

 

[Zenmervolt]

Originally posted by: The_good_guy

Originally posted by: Eli
What's this "idling is bad" nonsense? Who/what started that crap? :frown:

So, if idling is bad.. what do you guys think about redline? 😛

I have always been told that idling for extended times puts an load on the engine (something heat related)...

that's why highway mile cars are actually preferred to city stop & go type where the idle time is higher but then you also do stop and go.

If I buy a used car i prefer a used rental car knowing its been on highway miles a lot more (despite it being possibly abused).

You're sort of right, but not quite. The reason that all the stop and go of the city is worse than highway is for two reasons: Acceleration is much harder on an engine than maintaining a constant speed. Since speed is changing all the time in the city, the engine is always working hard to accelerate the car, unlike on the freeway. Think of it this way, when you're riding a bicycle which is easier, maintaining about 10 mph or going zero to 5 to zero to 5 to zero to 5 to zero to 5? You'll get tired much faster the second way, and you'll cover less distance doing it. The second reason that highway miles are "better" is that one highway mile is equal to less time. On the freeway, one mile is equal to less than one minute of time on the engine. In the city I've had times where one mile was equal to 30 minutes.

Your point about heat is well taken though. A car is more likely to overheat in city driving, but that's mainly due to a cooling system failure being more problematic at low speeds. On the freeway if the cooling fan fails, there is no effect since at freeway speeds, more air is forced through the radiator by the car's speed than could be drawn in by the fan. Under about 35 mph though, if the fan fails, the engine can't get enough air through the radiator and it will overheat. Assuming that the cooling system is operating properly though, the car won't overheat from idling.

ZV

EDIT: Idling with an AIR-COOLED engine for an extended period of time, especially an air-cooled engine without a fan (such as is on a motorcycle) can be disasterous. Now that I think about it, most liquid-cooled bikes lack a fan for the radiator, which is probably why idling is cautioned against on motorcycles. Since a motorcycle is entirely dependant on vehicle motion for cooling air, it makes sense that idling is not good for it.

A car with a properly-functioning cooling system isn't going to have trouble though.

 

[Eli]

Originally posted by: The_good_guy

Originally posted by: Eli
What's this "idling is bad" nonsense? Who/what started that crap? :frown:

So, if idling is bad.. what do you guys think about redline? 😛

I have always been told that idling for extended times puts an load on the engine (something heat related)...

that's why highway mile cars are actually preferred to city stop & go type where the idle time is higher but then you also do stop and go.

If I buy a used car i prefer a used rental car knowing its been on highway miles a lot more (despite it being possibly abused).

As Zenmervolt has said.. nope. Idling is not going to hurt your car at all. The engine is creating the least ammount of heat when it is idling. Unless you have a cooling system problem, your engine will never ovearheat at idle compared to driving.

The reason highway milage cars are preferred over city driven cars is because... when you're cruising down the highway, your RPMs are (usually) just above an idle. Think about it. 😉

RPMs kill.. period.