Battery charging questions

[bononos]

A couple question on battery maintenance..

How long does a car need to be driven to make up for the battery drain after a cold start? 10-30mins? Would the charging be slower if the car was idling in the garage or in slow traffic vs highway speeds?

Should the voltage of the battery be tested with the +ve terminal clamp disconnected (parasitic drain)?

 

[JulesMaximus]

It depends on a great many variables you have left out. Such as, is the car stock or does it have added aftermarket electrical accessories that might cause additional drain on the charging system. These could be as simple as underdrive pulleys, aftermarket stereo/amps/entertainment system. A car with underdrive pulleys may have lower charging at idle or in traffic.

I wouldn't worry at all about this on a vehicle with no modifications that shows no sign of trouble with the charging system or battery (ie, one that cranks and starts easily).

 

[bononos]

I just needed a rough guide on how much powr is drained out after a cold start and whether idling for 1/2 hour would at least keep the battery charged. But it looks like it doesn't.
http://www.theglobeandmail.com/glob...-car-to-prevent-battery-death/article4490484/

 

[natto fire]

Yeah, idling is usually not ideal engine speed to turn the alternator for charging duties.

I would test the voltage while the battery is in the circuit and then isolate it if I found a strange reading, which is less than 12.6 volts.

Just don't do what I have seen too many people do after discharging a battery through the headlights, radio, or powerpoint/lighter. They "check the battery" by starting the engine and the killing it seconds later. Although some do get the spiel afterwards about how cranking the engine those brief seconds did a lot more harm than charging their iPhone for an hour. The engine will either start or it wont, best to wait until you actually need it instead of wasting power to fire it and then just kill it moments afterwards!

 

[lakedude]

Can you keep it hooked up to a trickle charge? My Vette could kill even a good battery like an Optima in about a month while the Ridgeline could sit for a good long while and still be fine on the factory battery. Rather than take a chance I put them on a maintenance charger.

 

[QueBert]

I've always been told by others 15-20 minutes of freeway driving. This is just my experience, but there are plenty of times I got a jump from a a battery drained to the point it barely would click. After a few minutes of driving it would start fine after being shut off. I'm not sure just because this works that it's good to do. It's probably not, but I've never had a problem where I went from a jump then barely driving around the block 2 times to needing a jump the next day or something.

 

[natto fire]

I've always been told by others 15-20 minutes of freeway driving. This is just my experience, but there are plenty of times I got a jump from a a battery drained to the point it barely would click. After a few minutes of driving it would start fine after being shut off. I'm not sure just because this works that it's good to do. It's probably not, but I've never had a problem where I went from a jump then barely driving around the block 2 times to needing a jump the next day or something.

Your scenario involves a good battery. Most car batteries consist of six 2.1 volt lead acid cells. Usually when a battery gets towards EOL, one of the cells will crap out. If the symptom is only caused from plain discharge (lights or other parasitic draw left on) then your scenario plays out and the battery recharges fine. If the battery is failing, then you might get lucky and the errant cell will rejuvenate on the quick drive, but more than likely you will still be dealing with a weak battery the next time you need it.