Voltage fluctuations

[Dezerts10]

I have seen my voltage o the scan gauge fluctuating over the last week or so. I’ve seen as low as 12.3 to as much as 14.4.

Engine rpm does not seem to affect voltage either

Could my alternator or battery be taking a dump? Or is this normal?


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[Kanoe]

Not Normal. Looks like you have an intermittent charging / not charging situation.

If you still have your original OEM alternator in, there is a chance that the brushes have reached the end of their useful life. This will act intermittently 'til they fail all together. Brushes are cheap and should be replaceable.

Of course there are other possibilities...

 

[thecole1098]

I’ve had this on my rig before. In my case it was loose connections on the terminals of the battery but I could also be a loose ground elsewhere.

 

[Dezerts10]

Loose terminals or terminal issues makes sense.

I really need to relocate my battery and redo my cables. They are a mess and the battery that’s in my 4Runner moves a little and doesn’t fit the stock holder.

I think I’ll plan to do my relocation and battery box in the trunk area and go from there.

Thanks


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[jgue467]

I have seen my voltage o the scan gauge fluctuating over the last week or so. I’ve seen as low as 12.3 to as much as 14.4.

Engine rpm does not seem to affect voltage either

Could my alternator or battery be taking a dump? Or is this normal?

I think it is normal (not taking a dump either) because I've noticed my 01 has done about the same thing for all the 7 yrs i've owned it observed via torque pro. It changes at every odb2 reading (about every 2 seconds) and as stated doesn't matter what rpm is, accessories being used or a/c on/off, drls only or full lights with fogs, idling or not. I thought it was odd but what do i know about all the details of how an alternator works in a toyota? My charging system is all original. Continued luck! :cowboy:

 

[thegipper]

Mine fluctuates to some degree also but generally within the first 5 minutes of starting it. It doesn't ever drop that low though, it usually sits between 13.3-14.3v. When I have the heater going full blast, lights on, rear window defrost and so on at a stop light is when I see it dip down to 13.3v. This only happens when I'm at a stop, the second I take off again, it goes right back up to 14+ volts.

 

[pkachoochoo]

Not sure if it's related to your problem but I think mine is doing the same thing. I don't have a scangauge to confirm but I'm getting road noise through the radio when the motor is running and it increases with throttle. I've also noticed that my blower motor will speed up if I hit the throttle. Does that sound like the same thing thats happening to you? (sorry if I'm off topic but i tried to find the most relevant thread)

 

[thecole1098]

Not sure if it's related to your problem but I think mine is doing the same thing. I don't have a scangauge to confirm but I'm getting road noise through the radio when the motor is running and it increases with throttle. I've also noticed that my blower motor will speed up if I hit the throttle. Does that sound like the same thing thats happening to you? (sorry if I'm off topic but i tried to find the most relevant thread)

Mine does this as well at night with the lights on at idle. My voltage will go as low as 12.5 until I have the RPMs around 850 due to my shitty parts store alternator. I plan on doing the CS144 alt upgrade once I get my winch to remedy this.

 

[pkachoochoo]

Mine does this as well at night with the lights on at idle. My voltage will go as low as 12.5 until I have the RPMs around 850 due to my shitty parts store alternator. I plan on doing the CS144 alt upgrade once I get my winch to remedy this.

I really want to do that upgrade but I can't weld so I'm stuck with the factory one. PO of my rig put a giant 27F battery in too so stock definitely can't keep it fully charged.

 

[alumarine]

I really want to do that upgrade but I can't weld so I'm stuck with the factory one. PO of my rig put a giant 27F battery in too so stock definitely can't keep it fully charged.

A stock alternator working properly can keep that charged no problem.

If you're worried about it get both the battery and alternator tested.

I wouldn't rely on a scan gauge or the torque app alone to determine charging fluctuations.
I'd put a meter on the battery and check it out.

 

[Buckaroo]

I have seen my voltage o the scan gauge fluctuating over the last week or so. I’ve seen as low as 12.3 to as much as 14.4.

Engine rpm does not seem to affect voltage either

Could my alternator or battery be taking a dump? Or is this normal?


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With no other symptoms, I would consider this normal and not do anything. Voltage will vary with RPM and accessories moving on & off-line. The alternator will compensate based on demand but the response is not immediate.

Buckaroo

 

[cbr900boy]

Voltage output definitely fluctuates based on load and temperature. When cold, the output is higher, when hot the output is lower. That is the job of the voltage regulator located on the alternator itself. My old voltage regulator failed and my output was always at 14.2 volts. I though this was normal....wrong! I was wheeling on a hot day and the alternator overcharged my AGM battery which was less than a year old. The sulfur smell was overwhelming. At first I thought it was the battery but later realized it was the alternator. Got a replacement battery (Love O'reilys) and ordered a Denso alternator and now my system works flawlessly. My voltage meter now shows a constant fluctuation in voltage output between 13.0 to 14.2 depending on load and temp.

 

[tarsun]

mine failed and pegg'd at 18+ volts....