Charging Issues - Suspected Bad Wiring

[philbey]

Okey dokey, I swapped my starter the other week and I managed to guff up in a most astounding fashion and screwed up my alternator.

 

I've got an externally regulated Denso unit and when I was connecting to the B terminal I didn't realise the plastic bush had dropped out, directly contacted to the alternator casing (ie earth), reconnected the battery and FSSSSSHHHHHT + smoke occurred. I managed to cook the wire back to the starter pretty well, I now realise that I basically connected the starter lead to earth, via the little white wire between the starter and the alternator.... Ouch.

 

See red circled section on the photo below.

 

The wires got some melty bits, I didn't have time to rewire it so I repaired what damaged sections I could.

 

Over the next couple of weeks I had charge issues, but intermittent ones. Charge light would come on, then off, sometimes I'd hit a bump and it would go brighter or duller. Coming home at night and I was running off battery alone (could tell because the stereo would shut of when I flicked the headlights or the thermo fan) then all of a sudden it came good again, charging fine, thermo's fine, radio fine.

 

That alternator was only making about 12.5V so I swapped it out for another identical denso unit.

 

NOW this new alternator is showing a constant but faint charge light, but doesn't flicker on and off intermittently. Alternator is producing 13.8V across terminals but I am losing charge, I've left it on the charger every night except last night, and I've run out of juice today.

 

Here's my theory: My alternator and regulator appear to be fine, but my charge issues may be due to the melted wires? Anyone confirm that theory?

Edited October 14, 2010 by philbey

[altezzaclub]

hmmm.... brushless electric motors, such as power the floor cleaners I work on occasionally, lose their power when they get overheated.

 

So if you run the machine on thick carpet without water in the the tank the motor overheats and re-anneals the copper windings, and although they look perfectly OK the resistance has changed and they don't develop the torque they used to.

 

So you MIGHT have high resistance in some of the wiring, which I assume you could measure with a meter. Somewhere it slows power going from the alty to the battery.

 

How about something melted together that slowly drains the battery, independent of the alty, like a switch or a wire somewhere? Did you replace the regulator?

 

The second alty seems to be putting out good voltage, but if the light is on then you are losing more than it is putting out. Got an ammeter you can try?

 

Is the starter solenoid shorting out slightly?

Edited October 14, 2010 by altezzaclub

[altezzaclub]

You also connected tab B on the regulator to earth via the alty, so if you haven't replaced the regulator I'd say that is a pretty suspicious unit.

 

Does the motor die if you disconnect the battery when its running?

[Benno]

start the car up and let it idle.

grab a multimeter and set it to dc voltage in a 1-10volt scale, put the red lead on to the B+ terminal of the alternator and the black lead onto the positive terminal of the battery. this will tell you voltage drop in the B+ charge wire. a good charge loom should loose no power(ie. less than .1 of a volt). This way is much more accurate way then measuring static resistance in a line because it takes into account the current load on the circuit ie. a length of 18gage wire measured will have negligible resistance, but if you try putting 15 amps through it, you will get a voltage drop that could give problems you won't pick up by checking resistance.

[philbey]

How about something melted together that slowly drains the battery, independent of the alty, like a switch or a wire somewhere? Did you replace the regulator?

 

No regulator replacement. I suspect that there was a poor connection with the first Alternator, hence the drop in/out scenario. Then when I replaced alternator I might have got something to connect or disconnect better hence it's not dropping out now.

 

 

You also connected tab B on the regulator to earth via the alty, so if you haven't replaced the regulator I'd say that is a pretty suspicious unit.

 

Does the motor die if you disconnect the battery when its running?

 

I connected the regulator to earth, but I never ran the car like this; I basically shorted the starter motor high tension lead to earth via the alternator casing. Path of least resistance, the regulator shouldn't have seen any current. To be safe I just got back from Repco and they have no listing for a regulator.... Time to call Mick.

 

BUT they have a brand new "champion" alternator on clearance for 45 bucks so I've ordered that in anyway. If I get really lucky it might be internally regulated!

 

Benno thanks for the tip, I can't really touch the damn car for a few days, I'll give that a shot next week.

[Felix]

The Bosch style internal reg alternators use different mounts that bolt to the block.

 

The front wiring harness for charge, indicators and main power lead is pretty easy to pull out.

[Medicine_Man]

Could have popped a diode and now it is back-feeding the regulator?

[philbey]

Yeh not sure med man, that can be tested can't it? I had an auto elec do it once before.

 

Felix not sure exactly what alternator they'll give me, I can't find any info on Champion alternators. I'll grab it regardless and rewire the cooked leads.

[altezzaclub]

Any multimeter can test a diode, current flows in one direction only, but you need to unsolder it first.

[philbey]

Got an internally regulated alternator today. 45 bucks from Toyoland, with bracket. Not sure of condition but i'll take a punt and wire it in tomorrow.

[philbey]

Fitted that internally regulated alt, pulled out the old loom, made up a brand new loom for alternator and starter and it works a treat now.

 

Pic of the half fabbed loom. I used the 8 gauge speaker wire from Jaycar for the starter, thinner but it's finer wire so it should have higher current capacity.

 

Edited October 25, 2010 by philbey