Voltage Fluctuation
 

Hello peeps. This question is for those of you who monitor your voltage via the cluster or some device capable of displaying live data.

I have been in the process of tracking down an issue over the past week, and have been monitoring voltage to assist. I have it pegged, but in the process noticed the flux and was courious.

How much does your voltage fluctuate while driving?

Me, .8 v.

Mine does depending on how much junk I'm running. But it doesn't really fluctuate while I'm driving unless I'm turning things on and off.

0.8 Volt variation in charging Voltage is nothing when you are dealing with 150-200 Amp output on an alternator and the heavy electrical demand on modern vehicles.

As long as the Voltage does not drop below 13.5 Volts or go above say 15.0 Volts on a regular basis, I would not be too worried. But like anything you will need to get a feel for your specific vehicle. If you are using the Hidden OBC Menu, note that often I had a 0.2-0.3 Volt correction factor to the display due to internal Voltage drop in the vehicle, often the Voltage a the battery is slightly higher than what is displayed on the OBC.

Most modern vehicles tend to operate in the 13.5-14.5 Volt range. I give a slight bit of variation on the upper end of the Voltage range, just because I do sometimes see some occasional upper range spikes when electrical demand is removed and the regulator is slightly slow to respond.

Sweet. So how much does your e53 fluctuate during normal driving?

I do not have an E53 at the momement, I have an E39, E46 and E70. I also have a GMC Truck that has a special charging system with a current loop and the alternator is actually shuts off at times and will draw directly from the battery at times (this is for fuel savings). So my GMC truck varies by as much as 2 Volts or more.

I believe my BMW's may vary on the extreme by maybe 1.5 Volts, but typically under 1.0 Volt is pretty much the norm.

I think 13.8 Volts tends to be the sweet spot for most of my BMW's as I recall.

It does vary quite a bit. With a brand new Valeo 140A alternator I would see 13.2-13.8.

OBC Voltage??

If so, the low end should be fine.

I monitor mine, usually sits at 13.5, but occasionally 13.3-13.5... That's with my cruise set @ about 85... :thumbup:

Yup, from the OBC.

From a quick 10 mile round trip tonight, mine fluctuated between 13.2-13.9 but stayed mostly right around 13.8

(via OBC)