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Major electrical problems...

Started by _BoltZ_ , Apr 05 2006 02:37 PM

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9 replies to this topic

#1 _BoltZ_

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Posted 05 April 2006 - 02:37 PM

Been having major issues with the Torana of late and i was wondering if anyone can give me any insight into what exactly could be the matter with the car...

She barely turns over after she's been running for a while... sometimes if you try long enough she turns over normally and starts but until then it sounds like the battery is flat..
Negative lead becomes hot after during prolonged attempts to start... negative terminal very hot to touch
Battery becomes flat after a reasonable amount of driving...
Battery drains very quickly when lights and thermo fans are engaged

I'm not sure if the alternator's dodgy (it's barely been used, it's a 120A unit but doesn't seem to charge the battery at idle... once into normal cruising it seems to charge well), or if the (stock) starter motor overheats while driving (common occurance i've been told?), but that still wouldnt' explain the weird starting and the hot negative battery terminal. The car was re-wired and battery was placed in the boot just over a year ago... all 3 batteries i've used, including a new Odessey dry cell, are new, and the same thing happens on each. The motor is also earthed to the car body...

I'm not sure what to make of it... i'd just like to have an idea before i take it to an auto electrician and they charge by the hour trying to locate the problem.....

If anyone can give me any insight into what's going on i'd greatly appreciate it

Cheers,
BoltZ

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#2 Dangerous

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Posted 05 April 2006 - 03:28 PM

Let's start in the middle

The battery neg and +ve lead will get hot if you are cranking the engine for a long time. If one is getting much hotter than the other, check for a poor connection on the hot one. Extended cranking can also kill a starter motor very quickly, as they overheat.

What is your static timing set to? - timing way out of whack can make an engine not want to start. What is your compression ratio? What type of ignition system, cam and carb have you got?

What's the 120 amp alternator out of? Most of them are not designed for car use, but for stationary motor or agricultural use, where the engine revs are more or less constant. It might be charging less than a stock alternator at idle and low revs.

Firstly, try a known good battery with good jumper leads straight to the engine block and starter cable contact. If it starts fine, then you've got a voltage loss and/or charging problem. What diameter of conductor and strand count cable is used on the boot mounted battery +ve and earth leads? If it ain't bloody thick with lots of bloody thin copper strands, then it's probably part of your problem.

Overall, I'd suggest sticking with the Odyssey battery, moving it back to the engine bay, and putting in a VN onwards series 85 amp alternator.
We might be able to assist further when you've tried the check above.

Cheers,

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#3 _devilsadvocate_

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Posted 05 April 2006 - 04:55 PM

all is good advice ^, your alternator may have more info stamped on it, look for two numbers 120/30 or similar, which give you 3000rpm and idle output respectively, or find the model no and check it against a bosch catelogue(go to bosch.com.au)

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#4 _BoltZ_

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Posted 05 April 2006 - 05:19 PM

Firstly, try a known good battery with good jumper leads straight to the engine block and starter cable contact. If it starts fine, then you've got a voltage loss and/or charging problem.

Do you do this while another battery is connected to the terminals in the boot? I'll give this a go in the next few days... my jumper leads are a bit shot at the moment as the ends have melted while attempting to start the car a number of times, they got hot too.... sigh!
The wiring seems fairly decent, it's about 10mm thick with a fairly substantial number of small wires in the core...

devilsadvocate, do you mean "2/120A"? If it's only producing 2A at idle, that'd certainly explain why the battery's running flat and failing to charge.....!!! would this interfere with starting though, in terms of having an engine crank over slowly, then seeming to "come free" and crank at normal speed?

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#5 _[BOTTLEDUP]_

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Posted 05 April 2006 - 05:43 PM

That's the one. Same piece of shit I got conned into buying for the XD. Needless to say I had the same dramas.

VN-VT 5 Litre Commo alt (or VN V6 with a pulley change) would be the way to go. Urs isn't helped either by that Gilmer kit, it turns the alt/water pump slower than std.

Oh and rather than buying another set of jumper leads get one of the booster packs made by Arlec (I think). 800CCA and come with a car and wall charger. Certainly saved my bacon a couple of times. When jump starting don't go onto the battery but get as close to the starter positive as you can. The XD runs a main power junction point in the engine bay and I put the positive to that, and the negative onto the engine block.

Sounds like we've got more than a cam change to tackle hey?

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#6 _Yella SLuR_

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Posted 05 April 2006 - 05:47 PM

How old is the battery? How much charge are you getting out of the alternator? I always try a new regulator/brush set (the black box on the back of the alternator) first, 9 out of 10 times it fixes charging problems. Then take it from there.

Battery could be kaput and not holding charge anymore. Normally only last 3-4 years, although I seem to manage to get 7-10 out of mine.

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#7 _Hotrodder_

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Posted 05 April 2006 - 11:12 PM

First thing I would do is get rid of the neg lead, and run a decent one from the battery straight to the engine block, or even replace the one you have and run another directly to the engine.
reason? Simply there is a crook connection in that neg lead somewhere, and a bad connection will cause a voltage drop, which heats up causing further drop and the problem amplifies itself. Same applies to charging the battery, even if you are getting 0.5 volts drop in that one lead think of all the other paths the electricity has to travel, through the body, every bolted connection at every cable, every spot weld etc etc, and every one of those has a very small voltage drop adding up to quite alot.
You wont be getting full voltage to the starter causing problems there, you wont be getting full voltage to the battery from the alternator and it all points to the same thing I see all the time. This is a very common problem with modified cars with the battery in the boot, we do quite alot of these upgrades/repairs and 9 times out of 10 its the shitty battery leads and connections.

if you want to verify all this get a multimeter and connect it to the battery and crank the engine, and write down the voltage reading. When the engine fires up take another reading and write it down too.
Now go to the alternator and take a reading there with the engine still running, write it down.
Turn off the engine and connect multimeter to the starter lead if possible (or another connection in the car where power is applied regardless of ign switch position), crank the engine and write down the reading.
The battery volts and starter volts under cranking should be almost the same.
The alternator volts and battery volts while engine running should also be almost the same.
If not, fix the lead as above.

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#8 _Hotrodder_

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Posted 05 April 2006 - 11:21 PM

,Apr 5 2006, 06:43 PM] Urs isn't helped either by that Gilmer kit, it turns the alt/water pump slower than std.

That certainly doesnt help, youre right about that.
take a look at the size of a standard crank pulley, and a standard alt pulley sizes, compare to the gilmer drive pulley sizes. Alt has to spin 2-3 times as fast to get the same power out of it.
Usually good for race cars which spend alot of their time at high revs but no damn good for street cars.

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#9 Tiny

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Posted 06 April 2006 - 10:07 AM

Not to mention the loads they impose on all the bearings turning those big arse belts...

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#10 _devilsadvocate_

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Posted 06 April 2006 - 01:00 PM

[

devilsadvocate, do you mean "2/120A"? If it's only producing 2A at idle, that'd certainly explain why the battery's running flat and failing to charge.....!!! would this interfere with starting though, in terms of having an engine crank over slowly, then seeming to "come free" and crank at normal speed?

Is it a Bosch alternator, 2A at idle wouldnt be good for anything, suggest the 2 means something else in this case.