BMW Parasitic drain found! Bad Diodes in Alternator, how to test and fix.
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- čas přidán 2. 11. 2020
- #BMW #DeadBattery
My BMW X5 keeps giving me "High Battery Drain" error messages. Tested the alternator and found I had bad Diodes. Watch the video to see how testing was done to figure out the battery drain.
Increased Battery Drain was also one of the early error messages I received from the car. - Auta a dopravní prostředky
Great video thank you for sharing and explaining everything .
Great video
Thank you
Excellent video 👍. What if I'm getting 0.003v in both testing? And if I do continuity it bips in both testing as well.
I'm having a large parasitic drain on my battery, that started 2 days ago.
I wonder if the 2015 Subaru Outback has this type of alternator.
I'll have to try it, and see what I get.
When it started doing it, it's draining the battery in less than 2 hours...
Turned out i had this problem on my old land rover, put brand new battery in, and still drained over night ( then learnt it was a alternator problem) my question is after initially replacement of brand new battery i done a parasitic draw test (still with bad alternator in place) and the draw was only 15 milli amps, assuming it simply my dash clock, with such low drawit shouldn't have drained the battery but diodes were definitely gone in alternator, draw test was done at battery terminal, it appears you have answered my question ( draw test means battery is still hooked up so it didn't show anything besides that dash clock draw) does this sound correct or do you think something else was at play, i watched about twenty five vids and your the only one who mentioned the battery must be disconnected to check diodes correctly, wish yours was the first i saw, would have saved me a lot of time.
Will autozone alternator test be able to detect bad diodes?
I was told I could have a bad alternator since my battery drains
Took it to autozone to get it tested and they said it was working good
Is the diode test with a multimeter the only way to actually tell?
Hi friend if we remove alternator fuse can it sold the battery drain as a temporary fix, as if the drain come from bad diode in the alternator, thanks
I got 0L and other way 1300mv ( should be 500-800) but when i measure diodes seperately it shows 600mv , what may cause this .
Thank you brother ❤️🔥❤️🔥❤️🔥
doesn't the Bat+ terminal on the back of the alternator connect directly to the POSITIVE Terminal of the battery? and if the frame of the Alternator is Grounded.. then aren't you essentially measure the terminals of the battery too?.. What if I disconnect the GROUND cable to the Battery and then Test it? Thanks for the video.. :)
You can test both ways, but if the diodes are good there should be no difference. We are measuring for battery drain.
Do you have to take the main power wire off the alternator and unplug the wiring harness before you do this test or can you just test it in place?
I did the test with the wire in place. You want to see if the diodes are pulling power with it connected to the system.
@@Jay-May I appreciate you writing me back. I'm going to try both ways I think. I had another guy (different video) who told me I should remove the wires. I'm still learning.
I have the same issue with a mk4 Golf and I measured the diodes with the cable connected and disconnected from the output of the alternator (negative pole of the battery was previously disconnected). When the cable was connected at the output of the alternator, I measure 0.453V on one polarity and 1.366V with the other polarity (the value increases to 1.366V), which means the same issue shown on the video. However, when I disconnected the cable and measuring again gives 0.5V on one polarity and nothing with other polarity, which is correct if the diodes are well. So I think we should measure with the cable disconnected. I haven't found the source of my parasitic drain on the alternator circuit ( drain of 1.33A). Any clue?
@@PauloM463 Makes sense, thank you. Sorry, I'm not sure about the 1.33 amp drain. What about radio and other memories, could it be drawing that much? Is your battery dying? There are videos of how to track down what is draining, but not sure which video is best or really works. Sorry I can't really help. My friend, the reason I posted a question here, ended up just having a bad battery.
Hi my e90 is reading 32 both ways. What could this be? A short somewhere within the alternator itself or the voltage regulator?
What year is the e90
Tests showed nothing wron BUT Amp Clamp showed battery drain 0.34 amps back through alternator. Changed rectifier and no more drain.
I have this same problem! Except I have an outright failed diode, it beeps at me when testing. A new brush/regulator should do the trick (way less $$ than a whole new alternator). BTW you should test with the negative on the positive terminal of the alternator, with the battery negative disconnected.
You ever figure it out
@@hunnitkaydj Yup - replaced the voltage regulator $40 - reduced the standby drain a bit (had other issues keeping the car awake) until g30 relay turns off.
@@GP-SEA you know what the other issues were?
@@GP-SEA thank you🙌🏽
@@hunnitkaydj I'm pretty sure I have a module not going to sleep when it should - I think it's the transmission 'park' selection switch in the transmission that is keeping that module 'awake' until the G30 relay times out. The LED on the shifter isn't solid / fully illuminated...
I did this test and with the positive on the positive terminal of the alternator and negative on alternator casing I get no reading at all. When I reverse them and put the positive on the casing and the negative on the positive terminal of the alternator I get a reading of over 250. Does this mean my alternator is toast and causing my parasitic draw and not even charging my battery properly?
The way he explained it is wrong, when you put positive on the positive terminal and the negative on the casing you shouldn’t get any reading but if you have the negative on the positive terminal and positive on the casing then you should get a reading of 500 to 800
@@ortegaaugie THIS is how everyone was taught back in electrial theory anyway. So thanx for pointing that out. The meter & the electron flow. lol
dammit i mean electrical. way back. 80's at the end of vacuum tube theory. flow from negative to positive. dam i hope it still has believers
hi there,
i just checked mine and: when i put black lead of multimeter on plus from alternator it shows 402. after i switch them for 2 seconds its shows 1200 then go to 1 and stay there. after i take the leads out and touch again red on + and black on - nothing apears, just staing at 1.
black to + and red to alternator body = 402
red to + and black to alternator body = it goes for 2 sec to 1200 (oscilating fast)
next move i put again red to + and black to alternator body = and nothing happen.
if i switch black to + and red to alternator body and then red to + and black to alternator body its go again with that 2 sec to 1200.
is this ok or my alternator´s diode are gone and is draining my battery?
Do you have symptoms of battery drain currently?
@@Jay-May HI and thk for reply. if i leave the car untouched for 2-3 days battery dies. i change the alternator these days and i didnt have the cance to check after 2-3 days to see what is happening. what do you have in mind?
@@djovidius3545 Have you found the cause of the battery drain?
Is 442 alternator diodes bad?
I'm getting 455 on mine im thinking this is the reason i have a draining battery
Did new alternator sort this?
Yes, the new alternator fixed this issue. Even though it was charging the battery, the alternator was causing drain on the system when the car was off.
Another thing you might want to consider if you have comfort access on your BMW is to keep the keys away from the car as it will put the car in a constant check state/readiness which will drain the battery as well.
@@Jay-May no comfort access tx
I get OL on both 😂😅