Wild battery voltage fluctuations/inconsistencies

[mhorvath1218]

My ‘22 2.7 has been showing some strange voltages lately and I was hoping you guys may be able to help pinpoint my issue.

I noticed my voltage gauge showing upwards of 15v pretty often. Usually somewhere between 14.9-15.3v mainly after start up and idling and then when coasting without my foot on the gas. Sometimes when I hit the gas pedal, it will drop somewhere around 13.3-13.6v and then jump up again when I let off.

i tried searching around but didn’t find any threads with my same issue. I tightened all battery, ground and fusebox connections and fuses and still have the same problem.

I put a multimeter on the battery and am showing about 14.7-14.8v at idle (even though dash gauge doesnt match up - sometimes higher sometimes lower).

i’m not sure if this is a battery or alternator issue or if it would be a warranty covered thing. This is my daily and I don’t have time to drop it at the dealer at the moment, so I’m trying to narrow down or fix the issue on my own first.

I have also been noticing a very obvious headlight flicker when restarting with ASS but honestly can’t remember if it was doing that before and now I’m just extra sensitive to this stuff.

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[RagnarKon]

It's not an issue... normal behavior.

The Bronco includes an AGM battery versus the traditional lead acid battery. There is a battery monitoring system on the Bronco that will dynamically change the charging voltage to optimize performance and the battery voltage during the vehicle's use.

 

[mhorvath1218]

It's not an issue... normal behavior.

The Bronco includes an AGM battery versus the traditional lead acid battery. There is a battery monitoring system on the Bronco that will dynamically change the charging voltage to optimize performance and the battery voltage during the vehicle's use.

I understand that, but I’ve had it for 6 months and 12,000 miles and it just started doing this within the last week or two. I’ve never seen voltage changes so quick and dramatic while driving this or any car before so it seems stange.

 

[Paul Gagnon]

It's a smart regulator. It will reduce the output of the alternator when full output is not necessary. It's a bit concerning when you first see it but it is normal operation. When there is a heavy load it increases the output. This reduces parasitic drag for fuel economy reasons.

 

[Ground_zero298]

Mine does it. I consider it normal. All my gm’s do it too. 15 is the highest I’ve seen on mine so far. It calls for what it needs. Colder weather, higher draw.

 

[RagnarKon]

I understand that, but I’ve had it for 6 months and 12,000 miles and it just started doing this within the last week or two. I’ve never seen voltage changes so quick and dramatic while driving this or any car before so it seems stange.

You'd have to test the battery monitoring sensor and the battery itself to see if there is actually an issue or not.

BUT I can say that the voltages will jump around a bit more as the battery ages--particularly in colder weather. If you park your vehicle outside during the winter or if your garage is not insulated that could be a big reason.

I personally park outside here in southern New England. Hasn't gotten super cold yet, but it has reached the point where the start/stop system won't function anymore. That's just the battery monitoring system doing it's normal thing and worrying about battery health.

 

[Ksjrb03]

My '21 has always done it. The only thing that concerns me sometimes, is I hear the HVAC fan fluctuate based on the voltage. I can watch the voltage meter, and listen to the fan, and they are in tune. Couldnt figure out why the fan always sounded like it was surging until saw how wildly the voltage swings.

 

[mhorvath1218]

You'd have to test the battery monitoring sensor and the battery itself to see if there is actually an issue or not.

BUT I can say that the voltages will jump around a bit more as the battery ages--particularly in colder weather. If you park your vehicle outside during the winter or if your garage is not insulated that could be a big reason.

I personally park outside here in southern New England. Hasn't gotten super cold yet, but it has reached the point where the start/stop system won't function anymore. That's just the battery monitoring system doing it's normal thing and worrying about battery health.

My '21 has always done it. The only thing that concerns me sometimes, is I hear the HVAC fan fluctuate based on the voltage. I can watch the voltage meter, and listen to the fan, and they are in tune. Couldnt figure out why the fan always sounded like it was surging until saw how wildly the voltage swings.

ok you guys are making me feel better about this, thank you. Im in NJ and do park outside overnight and its my first winter with the bronco so its all lining up. I have also noticed the hvac fan surging and was mildly concerned about that as well. I just never noticed any of this with the two grand cherokees I had prior to the bronco.

 

[ejaffe]

Mine does it and it seems that when the voltage drops into the 12s, the radio volume goes up and down on it's own but when it's running in the 14s the radio volume stays where it is set.

 

[ejaffe]

More testing and analysis done and it seems that it doesn't matter what the voltage meter reads, the volume changes. At this point I am going to remove the amp and see what happens in the stock configuration. I am wondering at this point does it have something to do with the gain settings and not the head unit.

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