Alternator???? 2000xj cold weather

[swabib]

How much does freezing weather effect the alternator? No check engine light but the check guages light comes on and off as it is a loose fitting. I tightened the fittings the best I could while it was 14 degrees out. Do alternators just die, or do they slowly go out. Voltmeter register 11.5 volts while running and slowly went down from there. So no charge to the battery while running. If it is the alternator, is this something I want to try to replace in the cold and dark (easy factor?)

thanks

 

[cwstnsko]

Definitely sounds like it's not charging. It's possible that moisture could have gotten inside and frozen the brushes in place so they aren't making good contact, but I'd expect underhood temps should get warm enough to thaw it out after a bit of idling. If it is shot, it's an annoying job, but not terribly difficult.

 

[joe_peters]

Don't a**ume that the battery is capable of taking or holding a charge.

Fully charge the battery and have it load tested.

The onset of cold weather will kill a marginal battery.

Once fully charged and load tested (or replaced), start the engine and check voltage between the battery terminals, should be 13.0 to 15.3 volts, if not in that range the alternator or battery temperature sensor are likely at fault.

 

[swabib]

It is a new battery that I accidently drained last night coming home (thought my headlights seemed a bit dim). I have a charger at home with an alternator tester, so I charged my battery then ran the test and was not recieving any percentage of charge. Is this an all or nothing test? The "check gauges" light sometimes goes off and my readings on the dash show it charging....sometimes.

Looking at the Haynes guide, it shows the alternator beeing taken apart not fully replaced. Is there a way to buy just the brushes so I dont need to loosen the serpentine belt? Or does the belt need to come off all together?

 

[joe_peters]

Even new batteries fail/can be killed. You might have a parasitic draw draining the battery. Did you disconnect the negative cable before charging the battery? Until you can get a full charge on the battery you will just spin your wheels--figuratively, not literally.

IF you need to change the alternator brushes they have to be soldered in, so you are going to have to pull the alternator to do that or replace it.

Note that MOST of the chain parts stores will test the Nippon Denso alternator and report it as "good" when it in fact bad. Taking it to a alternator shop is your best bet to have it tested.

Remember to test the battery temperature sensor, if it takes a dump the PCM may not tell the alternator to charge.

 

[swabib]

Thank you Mr.Peters for your help. I will search on where the battery temperature sensor is now.

On a side note, is it bad to drive a vehicle with a bad alternator?

 

[casm]

On a side note, is it bad to drive a vehicle with a bad alternator?

Maybe, but that depends on how the alternator has failed / is failing.

If it's seized or barely spinning, expect the fan/serpentine belt to go in short order. Drag from the alternator will also make it harder for other belt-driven items (power steering, water pump, A/C, etc.) to function properly.

A blown voltage regulator can result in anything from no charging to blown fuses or fusible links to an electrical fire. Undercharging puts more stress on batteries, which in turns shortens their lifespans (and can have a knock-on effect with things like the starter). Same for overcharging.

If it was a case of 'I need to drive it across town to get home' and the alternator pulley is spinning, I probably wouldn't be too concerned - just keep the number of electrical devices in use at any time to a minimum to keep as much charge in the battery as possible. If it's seized, though, I'd start making plans other than driving it for the moment.

 

[joe_peters]

Thank you Mr.Peters for your help. I will search on where the battery temperature sensor is now.

Under the battery.

On a side note, is it bad to drive a vehicle with a bad alternator?