Random Battery Light Flashes

[jimoreno]

I searched here but couldn't find anything similar to my issue.
I'm getting random battery light flashes that I haven't been able to connect to any event. I've turned lights on and off, AC on and off,brake lights, I mean I've switched major consumers on and off and that doesn't trigger the light. I unlocked my cluster and drove to work one day and the voltage stayed around 13.7-.9 volts and only dipped to 12.7 when the engine RPM's dropped to idle and about a second or two later it went back up to 13.7-.9. Also this might not happen for days and then start all of the sudden. Forgot to mention that it happens at any engine RPM (idle, 3K, 1K).
The car is behaving great (specially after the transmission service this weekend) with no quirks or issues (maybe I shouldn't say that out loud!).
Should I start looking for a new alternator? (Battery has a manufacture date of 09/2016)

[Timm]

The 'battery light is actually a warning from the alternator - on the facelift models this is processor-controlled (from the alternator), if the light comes on the alternator is warning you that it is not charging. As this happens at any engine speed I doubt it is a belt slipping.

However, we do know that the processor does fail, possibly it is intermittently failing and restarting but does not affect the charging - who knows, but it is an alternator problem!

[TheAngryBear]

I would check connections and grounds. Make sure they are clean and tight. Otherwise as Timm says


2001 750iL DD74441
Stock

RIP: 2003 540iA Sport GS56111
H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1

[jimoreno]

I've checked all connections, front and back and everything is nice and tight. So I guess I better start planning on an alternator replacement. I guess working with the heater valve at the same time makes sense since I'll have to drain the coolant.
Thanks folks!

[mdavid9412]

I have the same problem with my 2000 740iL. The battery light was blinking almost all the time and started getting the dreaded "Transmission Failure" message and random voltages (anywhere from 3v to 18v). First I replaced the 3 year old battery, because some others in these forums swore it was the result of a bad battery. That didnt help at all. Took it to my independent mechanic who said it was a result of the 2 year old cheap replacement alternator. He replaced the alternator with a brand new Bosch alternator. Now the voltage is under control, always around 13.7 to 13.9, but still get the flashing battery light, although a lot less frequently. The mechanic attached a volt meter and kept the care for several days and drove it to and from home to work, and whenever the battery light was flashing the voltage output from the alternator was always over 13v. He also checked all the connections because someone else on this forum suggested that could be the source of the problem. Sure wish I knew what is the REAL source of this electrical gremlin.

[Thresher]

I guess working with the heater valve at the same time makes sense since I'll have to drain the coolant.

Yes! Combine the two if you can. I have had my 740iL for 6 months now and have unfortunately seen my coolant replaced several times due to different repairs requiring the coolant to be drained (radiator, hoses, thermostat; alternator; heater valve; more cooling hoses...).

[purplecty]

Hey Jim, was the flashing battery light issue ever resolved?

[Mayorchuck]

Hey Jim, was the flashing battery light issue ever resolved?

Still??

[purplecty]

Still??

Still as in mine having the same issue? If that's what you mean then yes I am still having the same issue but the voltage output remains normal and I have been daily driving with the cluster voltage unlocked to make sure it is still showing 13+ volts. I spoke with Jim and he said he has since sold his e38 but did replace his battery and alternator and the cluster battery flickering persisted after the alternator replacement...

[Mayorchuck]

Still as in mine having the same issue?

Yes. Really curious what that turns out to be.

[purplecty]

Yes. Really curious what that turns out to be.

You and me both! I have seen some reports on Xoutpost of the ignition switch being the culprit and resolution but Jim said he had also replaced this for other reasons and also still had the battery icon flicker issue. I have also read it can potentially be the oil level sensor and or wiring. I would hate to spend the time and money on an unnecessary repair...