charging system vs ihkr/defrost

[tim eh?]

i have an electrical issue and i don't know where to start....

i put in a rebuilt alternator about a month ago, also a rebuilt ihkrI 'sword' a little earlier as i had a burnout there... not sure what caused it.

the charging system works well except with the blower fan on max ('4') or the rear defogger activated... using the obc test#9 the system voltage goes as low as 11.5 with these activated (car idling), otherwise never below 13.3 and as high as 14.7 no matter what else... i'm wondering if this would be symptomatic of a bad ground somewhere as i suspect the alternator is good. (belt is tight, btw and the terminal connections are good afaicantell i redid them again just in case)

i am still wondering what caused the fry-out at the ihkr (http://www.bimmernut.com/forum/showthread.php?t=38910) it melted pretty bad... everything works well though, rear defog included... the ground wire leading to it is pretty heavy duty guage so a lot of current must pass through there... maybe my wiring fix is bad there but i don't think so.

i would be very interested how much the rear defog affects the system voltage on other cars, also if the top blower has an effect. thanks!

[bmwrp8]

bump

[Claude]

i have an electrical issue and i don't know where to start....

i put in a rebuilt alternator about a month ago, also a rebuilt ihkrI 'sword' a little earlier as i had a burnout there... not sure what caused it.

the charging system works well except with the blower fan on max ('4') or the rear defogger activated... using the obc test#9 the system voltage goes as low as 11.5 with these activated (car idling), otherwise never below 13.3 and as high as 14.7 no matter what else... i'm wondering if this would be symptomatic of a bad ground somewhere as i suspect the alternator is good. (belt is tight, btw and the terminal connections are good afaicantell i redid them again just in case)

i am still wondering what caused the fry-out at the ihkr (http://www.bimmernut.com/forum/showthread.php?t=38910) it melted pretty bad... everything works well though, rear defog included... the ground wire leading to it is pretty heavy duty guage so a lot of current must pass through there... maybe my wiring fix is bad there but i don't think so.

i would be very interested how much the rear defog affects the system voltage on other cars, also if the top blower has an effect. thanks!


... test results on my car, voltages taken with a digital voltmeter directly on the 12 volts terminal under the hood:

- No key no nothing : 12.80 volts
- engine idle everythings fan at usual position (2) else OFF : 13.98 V
- engine idle rear window defogger ON : 13.95 V
- engine idle rear window defogger OFF fan at max speed (4) : 13.95 V
- engine idle rear window defogger ON & fan at max speed (4) : 13.92 V

My battery is 6 years old but in good shape. So as you may see the voltage is almost stable with or without those a large load like the defogger.

Based of your tests results i would suspect the quality of your battery; how does it react (voltage drop) when starting the car, for exemple if you try to start it with all the heavy loads ON (defogger, headlights, wipers fan...)

The 1HKR control module controls the SWORD which controls the Fan, the fan is fused 30 amp (under the hood fuses box). The 1HKR control module controls a relay which controls the rear window defogger, defogger also fused 30 amp, both the relay and the fuse are located under the rear seat.

Hope this may help.

[tim eh?]

much appreciated claude! that is pretty much what i thought i should expect.

i already switched the relay with the wiper relay and both work ok it seems...

the battery is nearly new and holds a good charge for a long time after it has been actually charged... battery terminals are in good shape.

i am going to check behind the rear c panels, i think there is some kind of box that is there for the rear defrost/antennae that might have been knocked around when i had the rear shock mounts replaced.

also will test for bad leads at the alternator.

but the more i look at this the more i think i should dig for the receipt for this alternator... damn...

ps thanks for the bump!

[tim eh?]

actually, claude i think you're right...

battery is a 'moll' and less than a year old... have to get some more readings but it is now suspect #1. wish i had more gear but i only have a voltmeter and a booster pack.

...gotta get this tested properly... autolectra (where i bought the battery) won't do a load test unless battery is fully charged which means waiting for 4-5 hours with the battery out (doesn't end up higher than 12.5 no matter how many rpms i give it) and they are far.

can i borrow a battery from another car if the amp output is similar? i'm thinking i could compare symptoms or just use it to drop mine off if i can tie it down tight enough.

whacked Q: how 'bout my 700 amp booster pack? can it be used in place of the car battery just to test system voltage (ie engine running no driving) or is that just a recipe for disaster? so far i have restrained myself (think exploding acid everywhere...)

so sorry for the typical noob questions...

[Claude]

actually, claude i think you're right...

battery is a 'moll' and less than a year old... have to get some more readings but it is now suspect #1. wish i had more gear but i only have a voltmeter and a booster pack.

...gotta get this tested properly... autolectra (where i bought the battery) won't do a load test unless battery is fully charged which means waiting for 4-5 hours with the battery out (doesn't end up higher than 12.5 no matter how many rpms i give it) and they are far.

can i borrow a battery from another car if the amp output is similar? i'm thinking i could compare symptoms or just use it to drop mine off if i can tie it down tight enough.

whacked Q: how 'bout my 700 amp booster pack? can it be used in place of the car battery just to test system voltage (ie engine running no driving) or is that just a recipe for disaster? so far i have restrained myself (think exploding acid everywhere...)

so sorry for the typical noob questions...

Good idea to make tests with another battery. Nothing you can do with the battery charger alone.

With another good battery you will be able to compare the results with the actual, you will have to make those tests it over one or two days running the car in different conditions (with and without heavy loads, just doing short runs... not enough time for the battery to completly recharge... and a long run... couple of hours on highway enough time for the battery to normaly recharge).

You still may suspect both your battery and your new alternator, if the alternator does not do is job properly any battery will fall overtime... and a real bad battery (short inside) may scarp the alternator (to much load for him) you see that's the dog and tail. But at a glance, unless your alternator has intermittent trouble it look fine to me according to the voltage you get from it.

Good luck.

[Ferret]

whacked Q: how 'bout my 700 amp booster pack? can it be used in place of the car battery just to test system voltage (ie engine running no driving) or is that just a recipe for disaster? so far i have restrained myself (think exploding acid everywhere...)

so sorry for the typical noob questions...

Be careful here mate, that'll have a sealed lead acid pack in it, if your alternator tries to pump full current into that for more than a few minutes it'll vent with a pop, game over.

Other than that they have slightly different internal resistances so charging will produce minorly different voltages, but it'd give you a good guideline for a quick test.

Just only do it in short bursts :)

[tim eh?]

Be careful here mate, that'll have a sealed lead acid pack in it, if your alternator tries to pump full current into that for more than a few minutes it'll vent with a pop, game over.

Other than that they have slightly different internal resistances so charging will produce minorly different voltages, but it'd give you a good guideline for a quick test.

Just only do it in short bursts :)

thanks- i think i'll just not go anywhere near that idea. i'm comfortable draining batteries... charging them i like doing less.

this morning's readings.... i am now measuring across the battery terminals although obc test #9 seems to be pretty accurate, consistently about .5v below what i get on the voltmeter.

before i started (no key, 'no nothing':)) - 12.0v

idle, nothing on - 14.3v

idle, everything on - 12.4v

idle, everything on except rear defrost - 13.3v

right away after these tests (no nothing) - 12.8v

30 minutes later, no nothing - 12.40v

i don't think my meter has the right setting for a static draw test... i tried with it set at 200mA DCA which is as high as it goes - am i doing it right?

http://www.bimmernut.com/forum/attachment.php?attachmentid=6186&stc=1&d=1225553846http://www.bimmernut.com/forum/attachment.php?attachmentid=6187&stc=1&d=1225553846http://www.bimmernut.com/forum/attachment.php?attachmentid=6188&stc=1&d=1225554537

sorry the photos are lame it's hard to do it all at the same time. that rustroofing crud is soooooo gross!

edit-

You still may suspect both your battery and your new alternator, if the alternator does not do is job properly any battery will fall overtime... and a real bad battery (short inside) may scarp the alternator (to much load for him) you see that's the dog and tail.

...so it would make sense that the old alternator which i'm pretty sure crapped out last may could have killed the battery installed 5 months previously... the help is much appreciated... one month to go before the guarantee expires...

90 minutes later, no nothng - 12.33v

editII - 150 minutes later, no nothing - 12.25v

[Claude]

thanks- i think i'll just not go anywhere near that idea. i'm comfortable draining batteries... charging them i like doing less.

this morning's readings.... i am now measuring across the battery terminals although obc test #9 seems to be pretty accurate, consistently about .5v below what i get on the voltmeter.

before i started (no key, 'no nothing':)) - 12.0v

idle, nothing on - 14.3v

idle, everything on - 12.4v

idle, everything on except rear defrost - 13.3v

right away after these tests (no nothing) - 12.8v

30 minutes later, no nothing - 12.40v

i don't think my meter has the right setting for a static draw test... i tried with it set at 200mA DCA which is as high as it goes - am i doing it right?

http://www.bimmernut.com/forum/attachment.php?attachmentid=6186&stc=1&d=1225553846http://www.bimmernut.com/forum/attachment.php?attachmentid=6187&stc=1&d=1225553846http://www.bimmernut.com/forum/attachment.php?attachmentid=6188&stc=1&d=1225554537

sorry the photos are lame it's hard to do it all at the same time. that rustroofing crud is soooooo gross!

edit-

...so it would make sense that the old alternator which i'm pretty sure crapped out last may could have killed the battery installed 5 months previously... the help is much appreciated... one month to go before the guarantee expires...

90 minutes later, no nothng - 12.33v

editII - 150 minutes later, no nothing - 12.25v


You are doing it right.

12 V without any charge is a bit low, it suggests that the battery is partialy charge; it may be normal if the car has been drive for weeks / months only within the city most of the time doing short trip with loads like head lights, wipers, rear defogger... even with a good alternator it's difficult oin those conditions to keep the battery fully charge.

If it's the case you may now try to give a good slow and long charge to your battery (low current from the charger at least 8 hours) to fill it up.

[tim eh?]

so that means i have 0.0mA draw when everything's off?

that does describe usual driving conditions... usually it is 10 minutes pretty clear sailing (ie no long idles at stop lights or in traffic) and it does get some highway time.

i unfortunately don't have a charger - that box is a booster pack.

tried a friend's battery and got the same results almost exactly - his was 12.5 volts before (and after) i tried anything.
unfortunately it didn't fit well enough (too tall) to drive around with so i was stuck trying it parked only.

tried both batteries at 2000 rpm (in park) with everything on both were running around 12.5v.

richard's battery... (http://www.bimmernut.com/forum/attachment.php?attachmentid=6206&stc=1&d=1225577434) ugly but new last january. (i know, i was there, it was cold) 580cca compared to the moll's 650. his car is mostly highway driven.

changed a couple of iffy terminals but it made no difference... positive battery terminal (http://www.bimmernut.com/forum/attachment.php?attachmentid=6205&stc=1&d=1225577434) and alt check light terminal (before (http://www.bimmernut.com/forum/attachment.php?attachmentid=6202&stc=1&d=1225577434)... after (http://www.bimmernut.com/forum/attachment.php?attachmentid=6203&stc=1&d=1225577434)).

...wondering what this plug (http://www.bimmernut.com/forum/attachment.php?attachmentid=6207&stc=1&d=1225577434)is that comes out of the wiring harness that runs down the side of the washer fluid tank. any relation to this? (http://www.bimmernut.com/forum/attachment.php?attachmentid=5786&stc=1&d=1217076942)
my abs is good, spared all 9 of a cat's lives the other day.

all my dash lights work pre- liftoff and i never get a charge light when i'm driving, nor do i get the flickering abs light i used to get before i changed the alternator.

one weird symptom... once the engine is warmed up i will get worse readings... the system does a lot better when the car is cold. that 2000 rpm test i mentioned would read lower if i had been driving around for a bit.

suspect... my front bumper wiring fix (http://www.bimmernut.com/forum/showthread.php?p=303635#post303635)? i get no error messages ever and all electrical accessories including the aftermarket stereo (no high load amps or anything just the head) work...
edit- actually the burned out bulb warnings do work tho... love that feature so long as i'm not particularly jumpy when they 'gong'.

another suspect? ...maybe the fusible link (http://www.bimmernut.com/forum/attachment.php?attachmentid=6204&stc=1&d=1225577434) i should have changed before it got rustproofed?.... ewwwww.

i dunno, some of this stuff it's good to change anyway to be sure but i'm starting to think i should take this car back to it's second home (the shop) on laurier :D (only kind of funny...)

[attack eagle]

e34s had a 1000 ca battery in them. your voltage is dropping rather fast, probably a combination of age and an undersized battery.

at .7 volts drop every hour you'd be under 11.5 overnight.

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.

[tim eh?]

e34s had a 1000 ca battery in them. your voltage is dropping rather fast, probably a combination of age and an undersized battery.

at .7 volts drop every hour you'd be under 11.5 overnight.

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.

thanks that's helpful - that's what i'm hoping it is... i just have to get enough volts into it so autolectra can do a load test.

i'm surprised i can't even find a tiny draw with the static test tho.

the battery is usually around 12.0 v after overnight.

1000cca??? wow. i thought i had the right battery... #91 here (http://www.mollbatterien.com/MollKamina/tabid/705/Default.aspx) maybe i should get the 93 this time...

[attack eagle]

correct. the right battery is either a type 93 or a type49

here in the US that usually means autozone 49DL or the interstate Mtp93

mine had a 48 in it, and it failed after only 18 months. luckily i got the local Az to cover it because I had the shop receipt where It was purchased by the PO. they even upgraded me to the 49... more than 2 years later and nary an issue.


100 aH compared to your 65ah... it does make a big difference.

[tim eh?]

correct. the right battery is either a type 93 or a type49

here in the US that usually means autozone 49DL or the interstate Mtp93

mine had a 48 in it, and it failed after only 18 months. luckily i got the local Az to cover it because I had the shop receipt where It was purchased by the PO. they even upgraded me to the 49... more than 2 years later and nary an issue.


100 aH compared to your 65ah... it does make a big difference.

thanks again-

if i manage to return this under warranty i will have to get another moll as that is what they sell.
i'll have to find some specs for battery size- those other ones have bigger dimensions and i have the engine bay battery not the one under the seat.

[tim eh?]

... user manual says 65Ah, but bigger is better right? esp. with the winters we get here i guess. looks like there's holes for one 40mm bigger, not much room heightwise. if i go by that, the 93 or 49 won't fit.

12.09v this morning.

it really bugs me i can't get a reading for current draw when it's sitting.
tried it on 200mA, 20 mA, 2mA - nothing but zeroes. shouldn't i be picking something up?

[Claude]

... user manual says 65Ah, but bigger is better right? esp. with the winters we get here i guess. looks like there's holes for one 40mm bigger, not much room heightwise. if i go by that, the 93 or 49 won't fit.

12.09v this morning.

it really bugs me i can't get a reading for current draw when it's sitting.
tried it on 200mA, 20 mA, 2mA - nothing but zeroes. shouldn't i be picking something up?

Strange, you should have a small (normal) drain current at least in the 30-50 ma range, do you trust your meter on that testing mode ? you may want to check it with a small 1.5 volt battery and a resistor in serie (ex: you should read 20 ma with 100 ohms).

Otherwise i stick with my first idea: give your battery a good long charge, and redo your loading tests.

[tim eh?]

Strange, you should have a small (normal) drain current at least in the 30-50 ma range, do you trust your meter on that testing mode ? you may want to check it with a small 1.5 volt battery and a resistor in serie (ex: you should read 20 ma with 100 ohms).

Otherwise i stick with my first idea: give your battery a good long charge, and redo your loading tests.

nice one claude, yes it looks like the meter is garbage... couldn't find a 100 ohm resistor (i did actually look!) but i get zilch from this computer fan.
http://www.bimmernut.com/forum/attachment.php?attachmentid=6223&stc=1&d=1225746067http://www.bimmernut.com/forum/attachment.php?attachmentid=6225&stc=1&d=1225746067

edit- look closely at the wiring in pic 2... (pic 1 is correct) :D whoops! anyway i redid it properly and got 0 anyway no pic sorry. haha sometimes i really crack myself up!

so... battery remains suspect#1 i'll do something... tests or buy a charger or borrow a battery thanks for the great advice guys - anyone have a 49 or 93 battery in the engine compartment i'd be interested to know.

edit2- whacked question... how small a battery can i run off temporarily? eventually i want a small second battery (for the fridge i'll put in of course) maybe i could just buy a little 'un and run off it for a day or two... (?)