Technical Alternator failed

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Technical Alternator failed

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It is generally good practive to overate electrical devices. A 120A alternator running at 110A continuous load is (in theory) MORE likely to fail than a 150A rated device.

Also (within reason) the heat generated by the alternator due to losses will be about the same on a 120A unit and a 150A unit.

This possibly leaves just the physical size and air circulation space. Or the 120A casings are better ventilated than the 150A casings.

The factor that limits the current produced by the alternator is the alternator itself. If the battery voltage dips due to a surge of demand (e.g. starting the engine), then the 150A one will run at 150A until the voltage recovers. The 120A one will only supply 120A but for longer. The peak temperature of the 150A one will be higher, but for a shorter time. Generally low temp, long duration is less damaging then high temp, short duration.

The 150A one will generate more heat than the 120A one when each is running at 100%.

I can't think of a reason why a Croma should need a higher capacity than the Vectra. Perhaps Fiat added a safety margin to the capacity, without realising that Opel put in one with just enough capacity for good reason.

Perhaps the 140A version may be a safer compromise - I'd need to look at what differentiates the two versions of the Vectra.
 
isnt it strange than if people claim benifits of the state everbody thinks its bad, but when people dont pay into the pot everybody thinks its great

Dave ,

I'm all for giving back , but as I pay my taxes , NI and do my charity every year , the way I see it , we pay VAT everyday for everything we buy , every service . So , If someone gives me an option and seeing how tight my budget is now thanks to my £ 270 a month insurance , I will opt to save it because I desperately need it . I just mentioned for those who can't afford to pay £ 40-50 VAT everytime something goes wrong with their car , pay cash don't pay by card , much cheaper this way . Last month alone I paid £127 VAT for changing tyres + checking oil + and topping up coolant . I'm not santa , just a normal person working on minimum wage living in a bad economy :D

The probled with ASR solved now , nothing to panic about , silly me :D
 
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Dave ,

I'm all for giving back , but as I pay my taxes , NI and do my charity every year , the way I see it , we pay VAT everyday for everything we buy , every service . So , If someone gives me an option and seeing how tight my budget is now thanks to my £ 270 a month insurance , I will opt to save it because I desperately need it . I just mentioned for those who can't afford to pay £ 40-50 VAT everytime something goes wrong with their car , pay cash don't pay by card , much cheaper this way . Last month alone I paid £127 VAT for changing tyres + checking oil + and topping up coolant . I'm not santa , just a normal person working on minimum wage living in a bad economy :D

The probled with ASR solved now , nothing to panic about , silly me :D

A bit silly mentioning the company name and the fact that you and they are tax-dodgers on a public forum though. I don't think they'll thank you for that. If you ask a mod very nicely they might remove the company name.
 
what are people doing with their old Alternators?

Why not recon them and swap them over again when new fails?
Or sell them?
If rotor and field windings are good and insulated, everything else can be replaced if you know the type of the altenator.
Bearings and rectifier probably need replacing. Vreg, brushes and sliprings maybe if theyre bad.
Recently rebuilt one for my 20v marea. Old was 11 year old original unit, and failed due to just being old and collecting corrosion on rectifier negative base, diode blew. Simple job to repair, just remeber to clean off crud between casings and under the rectifier.
The thing wont overheat on marea as it is exposed to rainwater and all other nice stuff from the cutouts on the bumper.

Seems like the 1.9 croma alternator even uses same internal as the one on my marea? eBay item no. 150792604892 (same electrical parts on my marelli A127IR. Listing does not include pulley end bearing, but if its same, its 6303 2RS C3 for those who might be interested, on electrical end its 6003, didnt use any "special small bearings". Also item 120849114167 for those who might seek for cheap rectifier).
 
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i've kept mine
garage has told me that those alternators are not economically repairable

on closer inspection, mine looks alright, moving freely - so bearings are ok
something burned out tho..., i could smell it when it went
i'm good with multimeter and electrics, so if someone could give a hint what to look for, i could try to diagnose what went on it, unit is Denso
 
i've kept mine
garage has told me that those alternators are not economically repairable

on closer inspection, mine looks alright, moving freely - so bearings are ok
something burned out tho..., i could smell it when it went
i'm good with multimeter and electrics, so if someone could give a hint what to look for, i could try to diagnose what went on it, unit is Denso

:yeahthat:

This is what I've been told too. Not economic to repair.

However, I wonder how much they are worth in scrap given all the copper and aluminium in them?

I didn't ask for my old one back.
 
I put mine in the electricals pile at the local tip!

Thinking about it, I should have gone to the scrap metal merchant. They must be worth £20 at least just for the copper and/or aluminium, probably more.
 
i've kept mine
garage has told me that those alternators are not economically repairable

on closer inspection, mine looks alright, moving freely - so bearings are ok
something burned out tho..., i could smell it when it went
i'm good with multimeter and electrics, so if someone could give a hint what to look for, i could try to diagnose what went on it, unit is Denso

Propably diode burned and shorted out, the heated enough to create the smell and went opencircuit?
If you see the eBay link I gave, its for denso, but doesnt matter as matching electrical parts are what you want.

For testing, you need to remove the old rectifier, solder the wires loose. Check field winding with ohms, should be less than say.....1ohm, should be prettymuch shortcircuit, which is good as these supply current (less resistance -> less heat). Also check field windings against casing, should not have any contact, otherwise the insulation is gone.
Check the rotor coil, should be still under 5ohms, mine was 2-3 ohms (so comes to around 5amps max for the coil), also check rotor coil against the rotor shaft, shouldnt have any contact.
Checking vreg might not be option unless you got adjustable source like I do, but I give info incase someone want to try frying their vreg (this is for the two terminal one, idiotlight and Battery+).
Supply power to B+ and field (stator) input. Put around 13V to the thing. I put a 88ohm 1W resistor (was lying on desk, but you just want something high value that acts as rotor winding) between the brushes and shortly apply voltage to the idiotlight terminal. Measure across the resistor (highside is connected directly to windings/B+, you should have voltage across it as its trying to supply current to rotor to incerease the voltage output). Increase voltage until you see 0V across the resistor (dont go over 15V).
The voltage you got over the vreg is the set voltage.
Testing the rectifier is simply diodetest from negative plane to winding connectors and windingconnectors to positive plane.

As for "economically repairable". If you dont count money for your own work, theyre not that expensive. See the set I gave, is 60e for the lot. But if you source the cheap ones, say 20pound for rectifier, 10pounds for quality bearings, 5pounds for new brushes or 20 for new vreg and 5pounds for new slipring.
So say it is 30pounds for the parts on new rectifier and brushes. Not that bad. Mine needed bearings, rectifier and brushes as it was 11year old unit, but replaced sliprings too as they were over halfway trough :p
 
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The factor that limits the current produced by the alternator is the alternator itself. If the battery voltage dips due to a surge of demand (e.g. starting the engine), then the 150A one will run at 150A until the voltage recovers. The 120A one will only supply 120A but for longer. The peak temperature of the 150A one will be higher, but for a shorter time. Generally low temp, long duration is less damaging then high temp, short duration.

The 140A one will generate more heat than the 120A one when each is running at 100%.

Agree with the heat generation when both running at 100%. But with both running a 100A they will be about the same. That is what meant.

An alternator will only provide enough current to restore battery output voltage to the regulated voltage. The amount of delivered current will vary in proportion to the voltage difference. If the dip/difference is large then yes the alternator will hit 100% capacity and then tail off as the battery voltage recovers.

What should be happening during normal running is that (excluding battery leakage charge/loss) is the alternator takes over from the battery. So if your lights/ECUs etc. take 50A then the alternator will deliver a constant 50A and NOT 100A pulses (100% rated amps/delay at 0A/100% rated amps).

Now for the tricky part/questions. (The very very high consumers)

What is the power steering pump required current?
What is the starter motor current?
What is the heater coil current?

Starter motor and hearter coil are a single cylce event. Loads of current, battery charge/voltage loss that will be topped up at 100% of alternator capacity initially and then tailing off. A singe quick start crank cycle on a good battery should not drive the alternator into 100% mode. On an old battery then 100% mode will probably be required.

The power steering pump does worry me. I've not seen/measured a typical stationary wheel steering wheel turn requirement or normal running requirement but I suspect both are high and possibly more than the alternator capacity.

If this is the case AND we have an old battery that can just not provide the reserve, has high leaked etc. then then alternator will be at 100% for very long periods of time. If this is the case then yes to 150A alternator will be developing greater heat.

Vehicle alternators are around 60%.

For my 140A rated alternator maximum power output 2003W at 154A at 13V. (test data supplied with my alternator) Losses are thus about 800W.

For a 120A rated unit I would expect the maximim output to be around 1720W, at 130A at 13V. Losses are about 690W

Either way a continuous 690 to 800 Watts of heat to get rid of is not mean task, bearing in mind surrounding engine air temperature.

Personally I'm not sure 120A or 140A units is the real problem. I'm more inclined to think that battery vitality could be playing a part. The older the battery the higher the alternator duty cycle and thus the heat generation.

What is more concerning is that these alternators are failing. Crap design? Cheap matterials (like low grade, higher loss copper windings)? or just poor air circulation/location?
 
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