Dead alternator? Dead battery? Or just incompetence?

[moroza]

Couple of days ago, I get a set of E32 rear maplights, and proceed to test them out. I draw a circuit diagram, determine that at worst, it might blow a fuse. Hook one up, it's fine. Disconnect it, everything still works.

Last night, I adjust my steering gearbox, and notice that the hoodlight is really dim. I also notice that even when I turn the key back to 0 and pull it out, I still see, faintly, "FASTEN SEATBELTS" and the brake fluid light. Plus my radar detector is showing, faintly, all of its numbers, even though I didn't turn it on . Interior lights are all dim if I turn them on. It's possible I left some light on previously, so I figure the battery's weak, so I'll get a jump from my housemate and go for a drive to test the box.

Just now, I hooked up jumper cables to an 06 Accord - red to red, black to black (on hers), red to the hood clamp, black to the bolt...thing...near my heater core, on mine. First thing I notice is smoke from the gator clips and a burning smell. I panic and disconnect them, and tell her to start her car (worried that I fried both cars). Hers runs just fine, so I assume mine is fine, too, and connect the cables back up. They continue smoking, but I figure there's just some crap on them (they're old and rusty, though not broken per se). I try to turn the key...

Nothing. No clicking, no lights, no anything. Her car was off in the meantime, but I figured that was my cue to quit while I was ahead.

What on earth happened? What was that smoke about? Did I hook things up backwards and kill something? All my fuses are fine, but nothing electrical works at all. My battery was never very strong and was once shut down by leaving my trunk open for a night, but I wasn't getting *anything* even with another battery hooked up, albeit probably a smaller one. Is there some "master fuse" to replace or a breaker to reset? Am I looking at a new battery or alternator (or a new car )?

Electric stuff is my weakness, I'm afraid...



UPDATE: Apparently, some stuff is working now. Interior lights are ~80% there. Front exterior lights are completely gone. Rear exterior lights are ~30% there, radar detector is very faintly flashing all its symbols at me, glowing red dice (powered by the front cig lighter) look to be 100% there. Instrument lighting is 30% there until I turn the key to 2, when they're completely gone. Warning lights are 100% on, but there's no MID message. Pending further information, I'm not going to try starting the car or running any motors. WTF is going on?

[techjunkie]

Its hard to tell from your post what caused the original problem or what happened when you connected the jumper cables but at this point I would connect a battery charger. The battery charger, not a wimpy trickle charger or battery tender should supply 10 amps or more. It will limit the current available (in case there is a short somewhere) and recharge the battery. This will allow you to figure out what is working, what isnt and try to start the car. If you want a quicker fix with more risk, plop in a new battery and see what happens!

[twn75]

maybe take the battery to like a pepboys or something and have it load tested if you don't have a load tester. A shitty battery can do all kinds of weird stuff to an e34, like what you're describing.

[attack eagle]

you just hooked the battery cables backwards. red was positive, black was negative.

i'd guess you had a weak battery. did the maplights turn off as they should?

[moroza]

I disconnected the maplights after testing, and I'dn't messed with the stock wiring at all.

So everyone says weak battery...I thought batteries gradually got worse, not crap out suddenly? And is there a technical explanation for why it'd cause random electrical weirdness, not just a partial or complete shutdown as one might expect?

[Binjammin]

Low voltage conditions can do seriously wonky things with cars. I've seen headlights and wipers turn on and stay on with under 9 volts and the car running.

"red to the hood clamp, black to the bolt...thing"

Ok, you've got your points backwards on your car, but pray tell, what's the hood clamp? Depending on what you're talking about, I don't know that you've chosen a good spot for the ground.

[attack eagle]

nope, batteries can either age and slowly get worse, or they can just fail out of the blue. if ti wasn't toast before, it probably is now due to the massive discharge rates in short circuiting it with jumper cables and trying to charge it reverse polarity..

[Qsilver7]

You totally lost me with this description...where is this hood clamp located? My hood is covered with insulation when you open it and swing it up and back:

"red to the hood clamp, black to the bolt...thing...near my heater core, on mine."

About the only thing that gives any clue as to what you meant is the last part about connecting the negative battery cable to a bolt near your heater core.

BUT...that sounds like you connected the cable to the wrong thing. The remote POS battery post is the hex bolt that is near the fuse box and heater valves near the fire wall on the drivers side of the car.

The NEG jumper cable should be connected to the hex bolt or one of the bolts on the shock tower.

(M30 engine)

[zubbie]

Smoke is never a good sign. It means that a lot of current is being drawn through the wires, which heat up and burn off the insulation.

Perhaps it's time to do a current draw test. You may have inadvertently created a short in your car. This is covered in the bentley but the short version (no pun intended) is to disconnect the negative battery post and put a Volt meter (set on current) between the battery post and the negative cable. You should read no more than about 20 milliamps with all accessories off, doors closed etc. If it is 100 milliamps or more you have some kind of parasitic draw or worse a short.

If this is the case then you are in to the isolate the fault phase. Watch the meter while you pull fuses. If there is no change replace the fuse. When you current drops to normal (~20 milliamps) then you have found the culprit cuircuit and can further isolated it to crossed wires, or shorted accessory.

Good luck

[moroza]

Sorry about the confusion about what a hood clamp is. I meant the hood hinge/strut assembly.

So I hooked up the cables backwards, huh? Bollocks...the other car was completely fine, though, and I didn't end up drenched in battery acid or anything, as I was taught to believe would happen.

Is the POS terminal in the engine bay directly connected to the battery, or is there some kind of fuse (or worse, other electronics) between them?

I blew my multimeter's 0.5A fuse by passing an estimated 5A through it, when doing the maplights, so I'll have to wait for a new fuse to try the short test. But thanks much to all for the help! I'll be checking back...

(Any chance it's the alternator? A part of me's long been looking for an excuse to replace mine)

[jel]

Take the battery to an auto store for a free test; most places will charge it first if you'll nice to them. Step 1 to solving your problem is having a fully charged battery; as others posted lots of strange symptoms appear just because of a low battery. Disconnect the negative terminal first and connect it last when installing.

[moroza]

So I took it to Kragen's, and they did something with it and told me it was dead and gone. They don't carry a replacement.

Maybe I was spoiled by shops on the east coast, but this autoparts store is quite crappy in various ways, and I'm willing to bet they don't actually know what they're doing. I'm still looking for a fuse for my multimeter (guess who doesn't carry it? ), but pending that... The battery is made by Interstate and is well within its 85-month warranty. I'm going to try to get it replaced under warranty (I have the receipt from a mech who replaced it for the previous owner), but failing that, I'll need to shell out for a new one.

It was never that strong to begin with, so an upgrade would be welcome. I'm willing to pay extra for a good one, and to fiddle with the mounting brackets and maybe the wiring to fit a bigger one. Any suggestions/recommendations?

[jel]

Search, there are threads about Duralast? & other batteriess carried by various stores. I think you can get help from an Interstate dealer w/replacement since you have the receipt. Make sure to get a vented battery, has a nipple & small hose on top. Oem size is OK.

[moroza]

Smoke is never a good sign. It means that a lot of current is being drawn through the wires, which heat up and burn off the insulation.

Perhaps it's time to do a current draw test. You may have inadvertently created a short in your car. This is covered in the bentley but the short version (no pun intended) is to disconnect the negative battery post and put a Volt meter (set on current) between the battery post and the negative cable. You should read no more than about 20 milliamps with all accessories off, doors closed etc. If it is 100 milliamps or more you have some kind of parasitic draw or worse a short.

If this is the case then you are in to the isolate the fault phase. Watch the meter while you pull fuses. If there is no change replace the fuse. When you current drops to normal (~20 milliamps) then you have found the culprit cuircuit and can further isolated it to crossed wires, or shorted accessory.

Good luck

Thanks, I got a new battery and finally did this. Sorta found the culprit, "sorta" meaning that I know what fuse it is, but I can't find any associated numbers - it's one of the three fuses under the backseat. Specifically, the one closest to the big plastic box of relays and stuff. It controls central locking and power windows, but there are several that do that, and the Bentley book is a bit sparse on information (and sometimes contradicts the stickers in the car itself). Whatever it is, it's drawing ~195mA, compared to ~5mA for everything else - if I understand the numbers correctly, that'd drain the battery in about 3 weeks.

So I guess this is my first real short-hunt. Any suggestions of where to start looking?

[Whackamac]

well i replaced my battery with a similar issue too. It turned out to be my voltage regulator. replaced that and it runs and powers like a new car... Mine was worn down really bad and was not making contact properly with the alternator shaft

[xatlas0]

If you switched the terminals, you could have a lot more problems than you think.

1. Voltage Regulator- more than likely. Check your running voltage. If it isn't at least 13.5, that could stand to be replaced. Not very expensive, either, so a good starting point.

2. Coil- the coil doesn't like reverse voltage. Check the coil resistance against the Bently value. I know mine was fried after my battery fiasco. Caused a parasitic loss.

3. Alternator diodes- This one is a bit more tricky to diagnose. To really see it, and not just the effects, you have to have an O-scope on hand, not something most people (or even shops) have anymore. (truly a shame, they are so darn handy!) The voltage will be fine, but the car will not be charging. The dash light may be off or ever-so-slightly on. The thing is, the car will not charge the battery, so you'll be driving and suddenly the voltage will tank, leaving you to mutter a few choice obscenities and limp the car to the nearest parts shop for a battery. This will happen either a few days or a few miles after the new battery is in. Since BMW doesn't supply rebuild kits or internal components for alternators anymore, the only fix is to buy a rebuilt alternator, and even then, the diodes are not commonly checked. Either way, it is a crap shoot. I had to go through two rebuilt alternators before I got one that worked, because the diodes were bad. Also caused a parasitic loss.

Thankfully, the DME is shielded I think, so that should be ok.