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318i-Not charging

21K views 15 replies 5 participants last post by  thedogs 
#1 ·
My '85 318i will not charge the battery. The old alternator was bad (tested). The new one will not charge/turn on. I get 12v at the redwire, and .05v at the blue wires when the key in in the forward position, and someone else told me that a burnt out dashboard light could also cause the alternator to not charge.

So what do I do now? I don't even know what all those lights mean!?

I bought this car as a daily driver (my 1st import car) so I could overhaul the engine on my IROC-Z, but the BMW died the same day I bought it.

I wish BMW's were as easy to fix as my IROC :cry
 
#3 ·
:wrench Further data I found on your problem

http://versioni.addr.com/Tech/battery.html

What do you Mean the Battery is dead? I just charged it!...
This shamelessly stolen from
Pre 85 E30s battery charging problems
by Chris Diersen

If you own a pre-1985 318i, you may fall victim to the same electrical system flaw that stranded me three or four times and cost me a new battery and alternator (replaced unnecessarily) before I found the true problem! That is: BMW designed (in their infinite wisdom) the idiot light for the charging system (the little red light with a battery on it) in SERIES with the charging system, as opposed to PARALLEL, the logical choice... This occurred only in the pre 1985 318i's. As a result, if the bulb burned out, or the contacts on the instrument cluster board went bad (as in my car) the charging system would cease to work. Read: alternator no longer charging the battery. In my case it was double bad, as the bulb made intermittent contact, so it only failed sometimes! I replaced the battery and alternator (ouch!) before reading of this problem in the Haynes (thank you Haynes!) manual. I diagnosed the circuit board failure by banging the instrument cluster with the ignition on (but the engine not running). The battery light would flicker on and off. BMW's solution to this problem was to (on later models) wire a resistor in series with the bulb. That way, if the bulb or its contacts went bad, the charging circuit would not be broken, and the charging system would still work. If you experience a failure similar to mine (where the contacts on the circuit board for the instrument cluster shot craps) you can replace it with the resistor-equipped circuit board (dealer part only: $176.00!) or you can do what I did: Buy a brand new bulb that is identical to the bulb for the charging system idiot light ($1.20 at AutoZone). Locate the wires that run to the charging system idiot light by tracing the connections on the instrument cluster circuit board from the charging system idiot light to the multi-pin connector that connects it to the wiring harness. There are two wires that run to this light. You may want to make sure you have the right two wires by checking the continuity with a Multimeter. Once you locate them, splice a wire into each of these, *soldering* the splice to be sure it takes. After completing the splice, connect the two new wires to the new bulb that you bought, affix the bulb under the dash somewhere (I hot-glued it to the center console), and re-assemble the instrument cluster. That's it! When you turn the ignition on, the new bulb should light up until you start the car, at which time it should turn off (sometimes slowly). Essentially, you are adding a "resistor" (the bulb) to the circuit, just like BMW did later, only you can check your "resistor" by looking at it. Not a bad idea if (like me) you're not an electrician and bungle thing quite frequently. You may want to do this to your pre-1985 318i BEFORE it fails, although the dealer mechanic says he *never* heard of this problem actually happening to anyone...(Sure; that's why it's one of the first electrical system notes in the Haynes manual...) You *do* have to remove the instrument cluster to make this repair (unless you're a contortionist)! To do this, simply remove the steering wheel (pop off the roundel and use the BMW-supplied wheel lug wrench (it fits!) to unscrew the wheel...my little trick! Be sure to mark the wheel's position on the stem with a marker before removing it, or be prepared to suffer eternal "mis-aligned steering wheel spoke annoyance!"), unscrew all the trim around the instrument cluster, remove the four bolts that hold the cluster in place, and tipping it *forward* (back may break the top two "tangs") carefully lift the cluster out. I won't tell you what color wires to splice into, because they're probably different on your car. Good luck!
Chris Diersen

This tip from All BMW PARTS
Battery Maintenance

Ever wonder why BMWs don't come equipped with maintenance-free batteries?
BMW's come with lead-acid batteries, but most maintenance-free batteries are lead-calcium batteries. Interstate's new Pinnacle battery line uses 'silver calcium' chemistry. These battery types differ in their characteristics and operation. Maintenance-free batteries require a higher charging rate than lead-acid batteries, but BMW voltage regulators are calibrated at a lower charging rate than the maintenance-free batteries require. Another difference between the two battery types is that lead-acid batteries have a different internal resistance than maintenance-free batteries. This internal electrical resistance difference causes the voltage regulator to set the charge rate even lower than it would if a lead-acid battery was installed. In effect, it "fools" the voltage regular into thinking that the battery is in a higher state of charge than it really is. What occurs is that the maintenance-free's need for a higher voltage is not met, but the battery's different resistance causing the charging voltage rate to be lower resulting in a perpetually undercharged battery condition. Recharging a lead-acid battery requires around 14 volts. Many maintenance-free batteries need closer to 15 volts to fully recharge (a Delco Dura-Power, for example). A typical BMW charging system ranges between 13.8 to 14.5 volts. I have personally seen up to a .5 voltage drop caused by a maintenance-free battery installed in a BMW. Dropping one-half volt of charging rate causes the voltage to fall out of the acceptable range if that particular car is marginal to begin with. One case in particular stands out in my mind. A BMW owner was mystified that his battery would discharge after sitting in the garage for only a few days. The combination of a maintenance-free battery and a typically low charging rate setting for that model never allowed the battery to attain a full charge level. In normal driving the battery would slowly discharge. By the time the car was back in the garage, the battery had been partially discharged. The normal radio memory, accessory draw and computer memory finished the rest off. When he went to start the car, the battery was stone-cold dead. Testing for a parasitic drain would always come up negative and a low charge rate didn't raise any flags. No conclusive fault could be found with the voltage regulator or the alternator. Installing a new lead-acid battery cured the problem entirely - despite the chain stores' recommendation for maintenance-free batteries in BMW applications. Be SURE to specify the correct lead-acid battery for your BMW.
 
#4 ·
I just got around to checking my bulbs and they all tested good !? I did notice some green stuff on the contacts for my cluster and cleaned it off, but still the battery light will not turn on.

I am getting ~13v from the alternator and ~5v from the blue wire coming from the alternator (charging circuit?) But the car still dies after running for a while and/or if I remove a battery terminal to see if it's running off the alternator (method works on old american cars, not sure about BMW's)

I did notice that the two small batteries in my SI board look like they are about to explode (leaking white paste). Could these batteries be the root all my problems?

With all these hurricanes coming to Florida, by the end of the season I might not even have a BMW left to fix :cry

BTW, removing the steering wheel is uneccesary, my cluster came out without a hitch.
 
#5 ·
replaced the SI batteries. No more funky lights! :)

But when I turn the key forwards I still don't get the battery light for the charging circuit to come on in the dash. :banghead

I am going to check the circuit for resitance continuity and voltage (duh). Should it be continuous and/or have a certain resistance and voltage?

The starter on the 'ROC died so now i'm driving a crappy-ass granny Lincoln cause I have no cars left. :driving
 
#7 ·
Is the alternator supposed to be isolated from the engine ground?

I removed the bottom bolt (on the lower bracket) and the light comes on in the dash and the system charges (until the belt slips off!)

I returned the alternator and am trying a new one today, maybe the first one had grounded out on the inside? :confused
 
#8 ·
how many amps do these altenators put out? I wanna put my system from my camaro into this, 1000w amp 2 12"s. i might put 2 15"s cause i can get a good deal, think the amp can support the 12s?
 
#9 ·
Originally posted by theratdude64@Oct 11 2004, 09:41 PM
how many amps do these altenators put out? I wanna put my system from my camaro into this, 1000w amp 2 12"s. i might put 2 15"s cause i can get a good deal, think the amp can support the 12s?
[snapback]209678[/snapback]​
~80amps

Since your Camaro is an '86, it a V-belt system, so it might be possible.

GM alternators are weird though, the one on my IROC puts out 11.5v when all of my accesories are on, and my brother's RS puts out 14.5v! Careful you don't toast your electrical system. $$$
 
#10 ·
Originally posted by Hypnogaja+Oct 12 2004, 12:09 AM--><div class='quotetop'>QUOTE(Hypnogaja @ Oct 12 2004, 12:09 AM)</div><div class='quotemain'><!--QuoteBegin-theratdude64@Oct 11 2004, 09:41 PM
how many amps do these altenators put out? I wanna put my system from my camaro into this, 1000w amp 2 12"s. i might put 2 15"s cause i can get a good deal, think the amp can support the 12s?
[snapback]209678[/snapback]​
~80amps

Since your Camaro is an '86, it a V-belt system, so it might be possible.

GM alternators are weird though, the one on my IROC puts out 11.5v when all of my accesories are on, and my brother's RS puts out 14.5v! Careful you don't toast your electrical system. $$$
[snapback]209773[/snapback]​
[/b][/quote]

na na na the system is currently in the camaro, and it works perfectly fine, has for like a year. im wondering if the BMW altenator would handle it. are you saying the BMW is 80? I thikn my camaro is 97A
 
#12 ·
:D I've made progress!!!! I guess it's not supposed to be isolated after all.

If I take the upper ground wire (from the top bracket) and let it touch the body of the alternator, it runs fine! (Dash lights, system charges, etc)

IS this safe to do? (body of alternator directly wired to block/chassis), or will something else blow up?

After all these repairs I think i'm going to sell it and get a C4 Vette, LS1 Camaro, or newer BMW. 3mos for an electrical problem fix and $300 later is too much for me. :drunk
 
#13 ·
Ok so Hows the "fix"going.
so you just grounded the alternator an all is well?
I've the exact same problem....exact same. I bought the beemer so I could work on my 3rdgen 'bird an do the heads,cam etc an my new shiny beemer died 45 mins into it's ride home. exact same symptons as yours.
The guy at the parts store found the wire behind where you connect the cables at the back was broken inside the alternator. $20 fix
He said I might want to check the fuses an relays 'coz it probabley blew them.
Haven't a chiltons so not sure which fuse is which or where.
I agree I wish these where as simple an roomy as SBC's.

what I want to know is...is it still workin???
has anything happened...?
if all is well then first chance I get I'm going to ground the alternator. But I think that may be bypassing the fuse or relay I'm supposed to be checking.

'87 325e
89 firebird V8
 
#14 ·
There is an unused terminal on the back of the alternator (mine is a refurb) under the + wires. I ran a ground wire from there to the ground point on the engine where the original wire is. So far it's been working great, but I can't drive it anymore. Refer to "leaky clutch" thread to see what I mean.

[attachmentid=14390][attachmentid=14391]


-1985 318i
-no mods

-1989 IROC-Z 5.7L
-700R4 trans w/Corvette servo & springs
-Crane cam
-TPI manifold & runners (SLP)
- 9 bolt Disc limited slip rear w/2.77 gears
-Flowtech shorty headers & Flowmasters
-BBK adj. fuel regulator
-no CATS <meow :) >
-removed smog pump
coming soon -MSD ignition system
 

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