charging woes part III "The Return"

[tim eh?]

ok we've been through this before.... how complicated can a charging system be?

(depends on the idiot testing it, i guess )

3rd alternator exhibits the same symptoms as the previous 2... basically...
-14.3v at idle nothing on
-12.0v at idle everything on
supplier insists all 3 were good.

Battery loses charge overnight (last night 12.50 to 12.39... maybe not so bad? I will try again tonight...)

Draw test = 20mA very consistently now.

Everything stock except stereo head unit which I am very confident is not suspect.
Anything electrical works 100% except a fog light indicator in the clusterboard, the passenger in-seat heat, and the fuel guage is whacked.

Battery passed a load test at a trusted garage last wednesday. New december 2007. Moll 91, i guess that's small but it's stock size at least.

I'm testing with two cheap multimeters but they compare well so I am confident with my results.

if you are bored with life you can read some long backgrounds (ptI ptII) and a funny noob hijack of an otherwise useful shogun thread that is somewhat related,
but I think that's all the important stuff.

it's gotsta be the battery? no? how 4sure is a load test?

aaaaargh i'm going !




*-AE was right all along i hope? since this post i had it tested and it passed... but... (?)

I'd venture to guess you have a bad cell or two in the battery so you have voltage but not the amperage to back it up, and it is dragging your alternator output down by being a constant load.

[sal_park]

-14.3v at idle nothing on
-12.0v at idle everything on

Sounds like the voltage regulator is broken, normally located on the back of the Alternator. Not sure if this can be changed separately to the alternator on an E34 as I've not touched mine. From memory, it should be around 14v (+/- 0.5v) no matter what the load (within reason )

sal

[tim eh?]

Sounds like the voltage regulator is broken, normally located on the back of the Alternator. Not sure if this can be changed separately to the alternator on an E34 as I've not touched mine. From memory, it should be around 14v (+/- 0.5v) no matter what the load (within reason )

sal

3 bad voltage regulators???? and i'm sure they tested the heck out of the last one they gave me....

[Claude]

ok we've been through this before.... how complicated can a charging system be?

(depends on the idiot testing it, i guess )

3rd alternator exhibits the same symptoms as the previous 2... basically...
-14.3v at idle nothing on
-12.0v at idle everything on
supplier insists all 3 were good.

Battery loses charge overnight (last night 12.50 to 12.39... maybe not so bad? I will try again tonight...)

Draw test = 20mA very consistently now.

Everything stock except stereo head unit which I am very confident is not suspect.
Anything electrical works 100% except a fog light indicator in the clusterboard, the passenger in-seat heat, and the fuel guage is whacked.

Battery passed a load test at a trusted garage last wednesday. New december 2007. Moll 91, i guess that's small but it's stock size at least.

I'm testing with two cheap multimeters but they compare well so I am confident with my results.

if you are bored with life you can read some long backgrounds (ptI ptII) and a funny noob hijack of an otherwise useful shogun thread that is somewhat related,
but I think that's all the important stuff.

it's gotsta be the battery? no? how 4sure is a load test?

aaaaargh i'm going !




*-AE was right all along i hope? since this post i had it tested and it passed... but... (?)

Tim if you forgot all those voltage / current readings / tests results, what's the problem ? Does your battery fall completly dead no able to start the car ? How would you describe it ?

[Rick L]

It shouldn't drop voltage like that while engine running. Just wondering if you considered higher output alternator than what you currently have? I had this problem with drop in voltage while engine running on the Mase. Stock alternator was inadequate so I installed an alternator with higher output and the voltage drop issue is gone. But still, it shouldn't drain battery overnight. Have you tried unplugging fuses to isolate the issue?

ok we've been through this before.... how complicated can a charging system be?

(depends on the idiot testing it, i guess )

3rd alternator exhibits the same symptoms as the previous 2... basically...
-14.3v at idle nothing on
-12.0v at idle everything on
supplier insists all 3 were good.

Battery loses charge overnight (last night 12.50 to 12.39... maybe not so bad? I will try again tonight...)

Draw test = 20mA very consistently now.

Everything stock except stereo head unit which I am very confident is not suspect.
Anything electrical works 100% except a fog light indicator in the clusterboard, the passenger in-seat heat, and the fuel guage is whacked.

Battery passed a load test at a trusted garage last wednesday. New december 2007. Moll 91, i guess that's small but it's stock size at least.

I'm testing with two cheap multimeters but they compare well so I am confident with my results.

if you are bored with life you can read some long backgrounds (ptI ptII) and a funny noob hijack of an otherwise useful shogun thread that is somewhat related,
but I think that's all the important stuff.

it's gotsta be the battery? no? how 4sure is a load test?

aaaaargh i'm going !




*-AE was right all along i hope? since this post i had it tested and it passed... but... (?)

[Ross]

Hmmm

[tim eh?]

It shouldn't drop voltage like that while engine running. Just wondering if you considered higher output alternator than what you currently have? [...] But still, it shouldn't drain battery overnight. Have you tried unplugging fuses to isolate the issue?

I did a selective fuse pull, anything related to the ihkr, lights and the seats (i swapped seats this summer) but by no means an exhaustive test. Still, I'm only getting a 20mA draw when it's sitting, so I don't see how pulling fuses is going to change anything. (I should say 0.02A as I am measuring on the 10A setting.... for a while I was doublechecking with the 200mA setting but it's such a PITA to do I am taking 0.02 as a good reading. It is very consistent, I even get exactly the same readings for the initial current-surge. ....1.8->2.4A....1.13A... 0.31A.... 0.15A .... 0.03A...0.02A...0.02A...0.02A)

I did originally consider a higher output alternator- talked to a few people about it before I replaced the first one who all said not to bother, especially seeing as everything is stock on the car. Still... a brand new 115 amp alternator ought to be adequate to power everything no? If my vehicle (ie not engine) electrical system was pulling more than 50 amps wouldn't I blow one of the fusible links? I think?

Tim if you forgot all those voltage / current readings / tests results, what's the problem ? Does your battery fall completly dead no able to start the car ? How would you describe it ?

I first noticed it one morning about a month ago, the battery just seemed low as the starter didn't turn as fast as usual. So I started to keep my eye on things, using obc test#9 - and pretty much got the readings described above. There is a noticeable dimming of the interior lights when the system reads 12.0 and below, sometimes I get a little engine shake/hiccup that I never ever get otherwise.

Basically that's it... the biggest drains are the blower fan on max, the rear defrost and the fog lights. For a while I compared readings to the voltmeter and it seems to check about right... readings at the terminal compare at .2-.4V above those on test#9.

When the engine is cold, I actually get much better readings... it doesn't go below 13.0V until the motor has been running for a few minutes but after around 3 minutes it will drop immediately to the lower readings.

My morning commute only lasts around ten minutes but it's very early and on a fast highway with onramps - I really need the defrost and max blower and the lights all functioning A+ because it get's damn cold, dark,miserable and dangerous mid-winter (ntm I'm only ever half-awake at best). I'm less (but still slightly) concerned about freezing myself but montreal winters are brutal on cars with inadequate power. Also, the warrantee on the battery expires next month .

Took me a while to figure out how to do a draw test, but I am confident I am doing it right now. Every time I complete the circuit (ie by doing a draw test or by replacing the negative terminal) there is a surge of around 2 amps and I here a few clicks... something resetting... last night I noticed the parking lights flash ever-so-briefly also, no wonder the 315mA fuses on the DMM kept blowing!

I have replaced the positive battery terminal. Checked and quadruple-checked the alternator belt (which is new), my mechanic said it's very tight perhaps too tight... i loosened it a bit i get the exact same readings.

Readings from main alternator lead to ground = same as battery
readings from small alternator lead to ground = 0.0V (that info seemed useful to ferret...)
The battery drain, I hope I'm testing it well... I wonder if I should wait a while or try to charge it more on the road before getting the first reading. It's definitely dropping overnight but the readings I get aren't super-consistent. When it stops raining I'm going to switch this gooey 80A link (any 80Afuse'll do, right?), just for fun but in general, most of the wiring on the car is in top shape as far as I can tell.

That's the best I can explain it, I'm really stumped and I really badly want to fix this before winter weather hits. The people are very helpful where I bought the alternator and most people say really good things about them. I think they would let me upgrade to a 140amp alternator, but I think that would only fix the symptom and not the underlying problem.

Q1-A brand new 115 amp alternator ought to be more than adequate to power everything no?
Q2-Battery test... should I have another one done?
Q3-Should I take this 3rd alternator somewhere to test?

Q4-What about something totally different, like, say, the ignition coil? when it heats up a bit it gets hungry and eats amps? Something like that...?
Cap and rotor are new last year, plugs very recent... never changed the wires or the coil but the engine runs like new all the time and the last plugs were a bit blacker than i'd like after 6 months but i think they went through a lot in that time.

Q5-Could somebody in the Chicago area please go and kick Ross' tires for me as a favour?

[bubba966]

I thought E34's used 140A alternators?

Just looked at 'em at Pelican and see that some models had a 115A option. Interesting...

Anyways, it sounds like the 115A unit isn't putting enough juice out in your 10 minute trips to work to properly charge the battery. And a battery that isn't fully charged is going to drop voltage more overnight than a fully charged battery will.

A 20mA draw when the car is off sounds about right. Don't see any problem there.

And the voltage shouldn't be much if any below 14v while the car is running. Seeing how it does drop also leads me to believe that your 115A alternator isn't cutting it.

I'd be installing a 140A model if I was you...

[attack eagle]

car parts stores like to test batteries at 400cca... especially if it is their battery brand.
I wonder why
I make em test it at the real cca and i watch the cell voltage for low cells.

chassis to engine ground ok?

[tim eh?]

car parts stores like to test batteries at 400cca... especially if it is their battery brand.
I wonder why
I make em test it at the real cca and i watch the cell voltage for low cells.

chassis to engine ground ok?

I think I will take the battery in next week.

I think maybe my mechanic did a low cca test, I will get them to do a high-amp test at the parts store.

I'm not sure what/where to check on chassis to ground... continuity? from where to where?