Help! Battery gauge drops to Low

[cculter]

I am going with the alternator. When you load everything it sounds like you are losing power. I have replaced my alternator already and I am having the same problem again.

 

[smokey91052]

I'm having a pretty much the same prob., my battery is new and my alternator is fairly new too. My buddy (whom is very knowledgeable with fords) told me to ground out my windshield wiper motor, I haven't tried it yet and don't see why it would make a difference, but i will give it a shot and post what i find out!

 

[patrick112390]

Well after I replaced the tensioner and belt the steering and idle has been fine. Now when I turn my heat on and turn the steering wheel the battery gauge fluctuates a lot. If I am driving or rev it up it's fine. Only at an idle. which makes me believe my alternator is getting weak. don't you think? My plugs and wires are new. I don't know what else it could be?

if youve replaced all you say you have, it could be the voltage regulator on your alternator, this regulates voltage to around 13-15 but if its malfunctioning, the alternator will not kick up the voltage for the extra accessories when they are running......

 

[kako]

its the alternator ..
i had the same problem .. the thing is that when you load the battery the alternator since its bad i wont recharge the battery quick ..
make sure u dont travel long distances or you would regret it ... i had my alternator test and everything came out good till
it decided to die on me on the high way ...

 

[Bairsdad]

OK check this out..... What is your IDLE speed the alt works best at almost 900 rpm lower then you don't charge as well especially under load (lights fan etc)
bump up rpm's and that should solve it Low idle will make steering difficult also but only at low rpm's This is what fixed mind had the same problem, and I have a plow so the problem was even bigger

 

[medievil]

was this ever resolved..I am having a similar issue.. gauge jumps up and down at idol, but if I turn the lights on or the blower, it steadies (About 14 volts measured) when it is jumping to goes from 12.2x ish to 13 ish measured at the battery... brand new alt (Replaced the old one because voltage was dropping when turning things on and slow to recover) it was not long for life cause spinning it after I took it out, it had a slight grind internally...Battery is about 5 months old
I am wondering if the AC compressor "Could" be the issue...failing bearing possible that is causing strain... tensioner is about 5 years old....but it does do a dance when the gauge is jumping (you can hear changes in idol as well as the alt kick on and )

ground should NOT be an issue..voltage between positive and negative on battery and positive on battery and ground on Alt is identical

 

[Cobraguy]

Is the compressor cycling when the voltage jumps? Where did you get the alternator? Most of the parts houses offer a Chinese version I wouldn't put on my worst enemies car. Regulators are very suspect in those as well.

 

[medievil]

I've got it unplugged so no, no cycling (needs recharged)
got the alt from Advance... gonna try a different battery just to make sure, but I am thinking that alt is just bad..behavior is exact opposite of the reason I changed it... before gauge would drop and slow recover with lights etc... now it smooths out with lights....

 

[Cobraguy]

This sounds like an alternator/regulator issue. Try and see if you can get an alternator from Motorcraft...even a reman. I would bet the farm you got a cheapo Chinese version from Advanced. Of course, this is assuming the basics have all been checked. All the connections are clean and tight, battery terminals are clean and tight, belt is properly tensioned...pulley is tight and not slipping, etc.

 

[medievil]

belt should be fine, was with the old alt.. brand new battery terminals..voltages read the same on alt and batter so cabling should be ok...and battery to alt case reads the same as battery to battery so grounding should be correct..
I am leaning toward the alt as well, unless the old one messed the battery up

 

[Cobraguy]

I can't imagine the old one damaging the battery. That's not to say the battery doesn't have an issue, but if it does, it shouldn't be from the old alternator. It would have to be overcharging like crazy to do that.

A fully charged battery with the surface charge burned off should be 12.6 volts. So if you charge it, then burn the surface charge off by cranking the engine for a few seconds (but don't start it...kill the ignition) it should read around 12.6 volts. There are cycle tests, load tests, and others that can be done with some good equipment, but if you pass the voltage test and it isn't going dead, etc, I'm betting it's fine.

 

[medievil]

thats about what it reads if I recall... the alt cycling at idol it reads 12.6-13.6/14ish back and forth... turn the lights on, it goes to 13.6ish-14ish constant

 

[medievil]

just ran the "Duh" why didn't I try that earlier test...
started it, waited until the gauge started rocking, took the neg terminal off and bam, motor died.. put the terminal back on, started it, turned the lights on, waited till it idled down and took the neg terminal off... kept running...has to be a bad voltage regulator turning the charging circuit off

 

[medievil]

new alt solved the issue....
changed out the idler pulley as well... wasn't loose but was noisy...
sounds smoother than a brand new explorer now

 

[Cobraguy]

Man...that is a very bad way to test your system, but it seems to have worked out for you. Damn Chinese parts anyway!!