E53 X5 flickering battery light

[Mikealwa]

I have a brand new battery and the battery light is constantly flickering. Multimeter shows 13.8 volts at idle, with lights and radio on it shows 13.3 at idle. I have the display unlocked and while driving around test 9 shows 13-14v depending on rpm etc. Is it definitely the alternator? I took it out and put it back in while doing the timing chain on the m62 but the connections look good.

[purplecty]

https://youtu.be/Rdo-IeK9HzY

[andrewwynn]

Battery flickering never is the battery. It means the voltage is not stable. That usually means the alternator as you suspect.

On e53 the voltage should not wander more than about ± 0.3v at any rpm but you won't usually get a bat light unless it gets below 12. Check the post where the B+ comes through the firewall. It's a common fault that can give you the symptoms

[Mikealwa]

That post looks all good, might not be the smartest move, but as running voltage looks ok I might just try an ignition switch and hope for the best...I can't see any other common issues that I haven't checked...aside from a failing alternator.

[andrewwynn]

I have a buddy that went for over a year with a blinky bat light it was a bad solder joint in his dash.

[Mikealwa]

Any idea where the main ground straps are?

[andrewwynn]

I don't but the test is to measure voltage from the negative jump terminal to the block it should be very close to zero always


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[Mikealwa]

Using a scan tool the voltage is all over while driving ranging from 12v - 14v. 🥲. I'm goona recheck the battery cables, change the ignition, but I think I know my fate.

[andrewwynn]

Almost always it's the voltage regulator. It usually fails when the brushes wear down and don't have enough spring pressure.

I've replaced the brushes on a few alternators usually for about 10-20$

Also: if you only replace the brushes you'll notice that one slip ring wears about 4-5x as fast as the other. Swapping the polarity of the brushes will extend the life without changing the slip rings.

Search for my alternator awr-fix thread.

[Henn28]

Any idea where the main ground straps are?

quite a few grounds on the car, but check the large one on the right side by the ac compressor…runs to the frame rail under the SAP pump area on the 4.4

[Mikealwa]

Well, after driving checking grounds and driving more I saw the volts jumping all over while driving. I went for a hail Mary and just bought a new alternator. I'm doing new vcg and waiting for those in the mail before I fire it up. Hopefully this fixes it! I already put a new ignition switch in in case.

[Mikealwa]

Also tha ks! I didn't see that ground in the Bentley. Mine is good but is oil covered. I'll clean it up in case.

[andrewwynn]

Test ground while running with as much load as you can turn on: seat heat, rear defrost etc and measure from b- jump to engine block. It should be low millivolts. Maybe 40-50.


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[Mikealwa]

New alternator fixed the problem. Now I got a code for a bad cam sensor, was afraid the timing wheels came loose as I saw happens online, but confirmed the sensor is bad by swapping bank one and two. This car...