Alternators Replace or Refurb?

[KennyKen1988]

After what appears to be 18 years of solid work for my Denso alternator It is definately time to remove this part for a refresh! Mine appears to work fine running at 14.2v / 14.3v from the get go, but after plenty of driving and in this summer heat I'm noticing an output as low as 13.6v to 13.8v! I live in Kent so I was wondering if anyone can recommened places that perhaps trade in + money old for refurbished Denso units? I know I could just buy a new one but I'm unsure about these other third party branded ones with price variations ranging from £100-£300? My other option was to have a go at rebuilding the alternator myself by renewing the voltage regulator? Any advice welcome.

[oldcodger]

Hi,

Sure you know that to get 14.2v you need to be runing at about 1500-2000 rpm , not tick over.

You will need to replace both bearing and the diodes, but there are other checks you need to do first,

Ytube has a few videos showing how to first esure your cars wiring, alternator to Battery etc can be tested and if needed, how to refurbish the alternator.

https://www.youtube.com/watch?v=hmx2fHdmBIw

Car Mechanics magazine have done an article on places refurbishing alternators, but looking at their site today the back isssue section which used to clearly list all the old copies seems to be been changed / messed up ? 

Though the cost of the parts may seem low compared price of a new one, the time and trouble of doing it yourself may be outwieghed, not withstanding all the time your car will be off the road.

Worth checking in your local area if you have an auto electrical company who do such rebuilds, not always well known to joe public, more a trade shop.

 

 

[ob1cnoby]

Hi I found a guy in Batley (between Leeds and Bradford) called Alternate (google him very good) as my alternator packed up- and needed a new diode pack- the parts on eBay were £35- but this guy- provided the parts- and built it backup for £50- tested and checked it- how can you go wrong at this price- unfortunately- I pulled the wires out of the 3 pin plug at the rear of he alternator- anyone got any ideas- the colours are- yellow-  white red - and black pink (maybe brown) Thanks

[flash22]

The middle pin is ignition voltage the other 2 are sense and the warning light

Sense - perm 12v from the Battery

Ignition - 12v with the key on

Light - if you ground this it will put the Battery light on

 

http://wilbo666.pbworks.com/w/page/39441708/Toyota Alternators#AlternatorRegulatorLTerminal

connector views are as you look at the terminals

 

[KennyKen1988]

I've been monitoring the voltage real time via accessory power. I converted my cigarette lighter into twin USB with LCD Battery status. My Battery failed last month so I've got a nice Varta D15 on there 12.6V. On startup straight away I get 14.2V idle but after say 15 minutes the voltage begins falling, 13.8V or so... Stopping for five minutes or so then starting up and driving back with headlights on, fans, stereo etc. 13.4V.

I'm going to check it with alternate. I've found there website will give Colin an email see what they can do.

[oldcodger]

Hi,

Think you will find the alternators output voltage is not always a constant 14.2 v.  Its more normal to measure the alternators output at around 1500 -2500 rpm.  At tickover 13.8v is more likely after the initial kick up due to starting.

As well as a new Battery, have you done the basics such as cleaning all the wires terminals between the alternator and the Battery as thats where most of any voltage loss is likey to be,  Also clean up the Battery to Chassis terminal thats usually down on the side of the inner wing bodywork.

Ensure you fully disconnect the battery before doing such work.

Sounds more like an old battery was your real problem, now you have a new one, after cleanng up the above terminals, just run the car for a few weeks, if the alternator is faulty you will end up with a flat battery, but you should see that happening with your voltage monitor as below. ( think I would check your voltage monitor against a decent multimeter, as they may not be that accurate.)

Quote -   The resting voltage should ideally be no lower than 12.6V. Bear in mind that when a battery goes down to 12.2V it's actually only 50% charged, and below 12V it's classed as discharged.

[KennyKen1988]

Hi Codger,

I think I'm going to go off the Chrisfix video on Youtube with my meter to see what readings I get. I will definately trace all the wiring to check for any fatigue/damage will investigate everything today hopefully.

[oldcodger]

Hi,

Its best to unbolt the bigger teminals as they can oxidize / corrode on the unseen surfaces.

With the smaller connectors, just uplugging and replugging them tends to act as a self cleaning action, but again always inspect the mating surfaces.

[KennyKen1988]

I'll explain what happened regarding the old battery:

I got in the car and switched to just accessory power, from there I always look at my Battery indicator and It was on 11.5V. I went to start the car and it cranked over really sluggish twice but surprisingly fired up (good compression in the 2ZZ I'm guessing). After twenty seconds or so the whole car shutdown by itself (dashboard flickered erratically) and then the car fired itself back up again! Every minute or so the car was shutting off like something was tripping out. I immediately turned the car off and assumed the Battery had failed internally. I took out the old Battery and got the brand new one. Fitted that and the car is running great no problems whatsoever.

So I have done some tests and I'm not sure what to make from the tests regarding the alternator and the voltage drop tests.

I think I really need to go over all the wiring especially my Ground/Earth points. I think I definitely need to check this chassis to battery terminal and all wiring to and from the alternator.

Alternator ID: Denso 27060 - 22210 / 10 22 11 - 2421

Meter used for tests: Digital auto sensing.

---------------------------------------------------------------------------------------------------------------------------

Initial Testing at battery terminals (DC)

Battery All Off: 12.61V

Battery Car Engine Running: 14.28V

Battery Car Engine Running (Lights/Stereo/Fans on): 14.18V

Full Shutdown: 13.4V and falling...

---------------------------------------------------------------------------------------------------------------------------

Voltage drop testing negative side (DC) Negative terminal to negative on battery for all the following tests. Reading should be around 0.05V?

Positive scratch connection to alternator housing, RPM raised to 1500-2000RPM: 17.8MV

Positive scratch connection to alternator bracket: 17.0MV

Positive scratch connection to side of engine block: 16.5MV

Positive to contacting chassis ground on passenger (easiest one I could find): 21.9MV

---------------------------------------------------------------------------------------------------------------------------

Voltage drop testing positive side (DC) Positive terminal to positive on battery for all the following tests. Reading should be less than 0.3V?

Negative to the B+ Post of the alternator

At nut thread: 60.0MV

At the nut itself: 58.0MV

On the cable terminal: 56.0MV

[oldcodger]

Hi,

 

Long time since i did such checks  but your  readings  all look fine, do not see any problems with the above figures.

0.05v = 50mv so those readings are well below

0.3v = 300mv so again well below

[KennyKen1988]

Thanks for checking with me Codger!

I'm going to take the Battery out again and start looking at the wiring again.

" clean up the Battery to Chassis terminal that's usually down on the side of the inner wing bodywork. "

Is this somewhere down underneath the Battery tray? Thank you.

[oldcodger]

Hi,

On mine there are two thick black wires going from the Negative Terminal,  one goes down the nearside end of the Battery and under the Battery tray, thats the bodywork  Earth.

The other thicker cable goes down to the top of the clutch bellhousing, which again is worth cleaning up and then sealing with vaseline etc.

Think your duff Battery has made you look for problems that are not really there, though testing and checking those terminals is good maintenance.

These days whenever I notice the engine cranking sound that bit weaker, usually in the winter, I replace the battery soon after as experience has taught me leaving it any longer and you run into lots of weird problems.

[Mooly]

The voltage output of an alternator (on older cars like the T-Sport) is not a constant but is temperature compensated by design to avoid over or under charging the Battery. Measure the initial voltage across the Battery after a sub zero start and you may well see almost 16 volts for a few seconds. That enables the alternator to really force a charge back into the Battery under cold conditions when the battery is less willing to accept a charge.  Measure on a really really hot day when the engine compartment is sizzling and it could be as low as 13.2v. If it were much higher under hot conditions then the batteries normal fully charged 'float' current would increase substantially and that would generate heat within the battery... more heat more leakage... and so on. Result is a dead battery in a short space of time.  

So all this is by design and to protect the battery. 

  

 

 

[flash22]

The regulator is done for, what's the voltage drop between the body and the engine

[KennyKen1988]

Thanks codger I'll look into the negative side and see how it's all looking. I was also wondering I've always seen some cars especially Japanese cars whereby owners have added additional earth wiring kits off their Battery to help strengthen the grounding. Is this something I should get for my car or is it just best to clean up my existing wiring. To be honest I don't really want to add more than what's needed to the engine bay.

Thanks Mooly. So perhaps my worry has just been down to the hot weather? I'm not driving the car much right now but I will continue to monitor things goes into the winter. The week I went to start the car was basically a couple of weeks back in that damn hot week!

The regulator within the alternator? This is the part I had suspected from the start. The Denso alternator is still original from 2002 and I'm thinking I should get it worked over just for the sake of it not letting me down in the future? I'll get back with that drop test tomorrow thanks flash!

[Mooly]

The regulator is normally within the alternator but your readings and tests show zero problems to me... it's all normal. Adding a significant load such as headlights, fan/aircon instrumentation, etc will pull around 15 amps or more from the alternator. Add wipers and heated screen and that's another 20 plus added to the total and so it would be normal to see the voltage fall a little under those conditions due to both the alternator output falling slightly under load and also resistive losses in the wiring. At idle speed the alternator would struggle to maintain its full output but the Battery should not enter a state of being discharged (meaning current is drawn from Battery rather than the alternator).

Remember that any voltage higher than the resting voltage of the Battery means that the battery is not being discharged and so even something as low as 13 volts at idle and high loading is still not discharging the battery.

When you stop a hot engine the alternator will physically get even hotter as it absorbs heat from the engine block and bracket it is bolted onto as there is no air now being drawn into the fan within the alternator. When you restart the hot alternator the voltage will be lower than it was before.

 

 

[oldcodger]

15 hours ago, KennyKen1988 said:

Thanks codger I'll look into the negative side and see how it's all looking. I was also wondering I've always seen some cars especially Japanese cars whereby owners have added additional earth wiring kits off their battery to help strengthen the grounding. Is this something I should get for my car or is it just best to clean up my existing wiring. To be honest I d

Expect most of such extra Earthing is due to them adding massive sound systems and the like which exceeds the original wirings abilities.

Would just check and clean the two earth points mentioned above and that should be fine