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Author: Subject: More cooling fan issues
mcramsay

posted on 12/2/17 at 04:36 PM Reply With Quote
More cooling fan issues

Following on from my earlier post I changed my front grille to something less restrictive and added some water wetter ( when doing so I realised the antifreeze mix is far too strong which I am going to address) there was a marked improvement with the new grille with temps much lower when at 30 mph. However the fan still comes on when pottering around slower. I started to notice temps increasing and the fan was not cutting in, luckily I was just pulling into my drive. I noticed the voltmeter was swinging between 14 down to 12 constantly and I could hear the fan pulsing on and off, I turned the car off and the fan sprung into life. This is the first time I've noticed this happen, and due to my small battery and huge fan it's normal to see the bolt meter drop to about 12.5 when the fan starts at idle. I've never seen it bounce like it was.

I pulled off the fan relay cover and found the switch cool terminals burnt, cleaned them up and still had the same problem, the fan was starting and stopping repeatedly and then eventually it would run.

I pulled off the relay cover and observed what was happening which you can see in the vid below looking at the condition of the relay contacts inside something has not been right for a while... why it has failed now I don't know

https://youtu.be/iADgz-ZHuzY

I moved the fan kenlowe controller earths with no improvement.

I believe I have found the issue on the 12v supply to the controller. I could never get my alternator to start charging when using an LED light on the dash, as a work around I split the switched 12v that feeds the fan controller to also feed the excitation post on the alternator. With this cable to the alternator disconnected the fan relay no longer clicks in and out... but the fan is not running for the correct length of time. I am guessing the alternator is no longer seeing the load on the electrical system and the volt drop is causing the controller to drop out....

The main power feed for the fan comes straight off the alternator b+ post due to it being so close, rather than run a cable from the battery all the way to the controller as it requires a 40a supply.

I am going to seperate the controller and alternator supply wiring.... sound plausible?

Apologies for the massive post!

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Oddified

posted on 12/2/17 at 07:32 PM Reply With Quote
Alternator type/amps??.

Ian

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gremlin1234

posted on 12/2/17 at 07:59 PM Reply With Quote
quote:
Originally posted by mcramsayI could never get my alternator to start charging when using an LED light on the dash,
the alternator needs a load on the dash/indicator, it uses it for sensing/'feedback' for charging. (you could uses a 12V 2.2W resistor, but the original bulb is simpler!)

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mcramsay

posted on 12/2/17 at 08:02 PM Reply With Quote
Alternator is an up rated 60A classic mini type LRA 602. I am starting to wonder if the battery is nackered... I just checked resting voltage is 12.3v which is really low, this drops to 11.8 volts with the ignition turned on. With the engine running I get around 13.8 v going into the battery at idle, however when the fan cuts in the voltage drops to just above 12. I have been starting up the car and only doing short trips maybe max 20 mins driving today, possibly I'm running the battery flat... although even after fully charged I do get the same volt drop with the fan cutting in.... time to get a clip on ammeter.

I'm tempted to get a standard sized battery and stick it in the boot.

As for the charge light I couldn't find a proper bulb that would fit in the same hole in the dash hence giving it a switched 12v rather than going through a light..the alternator seems to give out the correct voltage like this... happy to be told it should be done differently though....

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gremlin1234

posted on 12/2/17 at 08:46 PM Reply With Quote
quote:
Originally posted by mcramsay
As for the charge light I couldn't find a proper bulb that would fit in the same hole in the dash hence giving it a switched 12v rather than going through a light..the alternator seems to give out the correct voltage like this... happy to be told it should be done differently though....
it should not be connected directly to the 12v, note the bulb does not have to be visible! (ie hide it under the bonnet somewhere.)
if I get a chance, I shall look out the alternator diagrams that show how it uses the bulb

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mcramsay

posted on 12/2/17 at 08:58 PM Reply With Quote
So if I put a bulb in the engine bay in the 12v supply line to the alternator it should see the load of the fan and regulate the alternator voltage? Do you have a link to the bulb/lamp I should buy?

Out of interest what is wrong with the way I have it connected currently?

I am going to give the battery a good charge and see if the fan behaves the same or not.. today is the first time I've actually seen this issue and I have not changed anything apart from the car has been on two 20 min trips...

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gremlin1234

posted on 12/2/17 at 09:15 PM Reply With Quote
quote:
Originally posted by mcramsayOut of interest what is wrong with the way I have it connected currently?
the alternator uses the drop across the bulb as a sensor.
get the bulb as per the classic mini dash bulb, (probably 2.2W @12V)
ps for testing, don't charge the battery, else it will take another hour (or so) of use for the charge levels to get to the 'problem' voltages -you already know it works ok with a fully charged battery, but battery charging may be the problem.

edit, just looked the the vid, it looks likely that as soon as the relay switches, the load is so high* that the voltage drops, and the relay drops out, and causing it to chatter. this would result in burned relay contacts.
* the startup current of a fan is very high

[Edited on 12/2/17 by gremlin1234]

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mcramsay

posted on 12/2/17 at 09:28 PM Reply With Quote
I'm going to get a clip on ammeter from work tomorrow and see what the alternator is putting out. Even though it's putting out 13.8 -14v at idle it may not be spinning fast enough to give the required amps to charge the battery and run the fan. Seen as the fan is operating a lot more than I thought it would. I might be slowly running the battery down...the kenlowe fan has a hell of an amp draw
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britishtrident

posted on 12/2/17 at 09:32 PM Reply With Quote
(1) You need to fit an incandescant 2.2 to 4 watt bulb or an LED by-pass resistor on the warning light wiring circut.
(2) Check the drive belt tension and condition, ie it driving on the Vee of the pulleys not bottomed out in the pulley.
(3) Clean the male spade terminnals on the rear of alternator with a nail board and check the female spade connetors are making a good bite.
(4) You should charge the battery fully then allow it to rest for a few hours before any testing.
(5) Battery voltage resting voltage really depends on the state of charge of the battery rather than the condition of the battery.
(6) With Lucas alternators is is not unknown for the alternator to output an apparently healthy voltage but have a diode leakage problem.

With the battery fully charged and disconnected measure the battery voltage then re-check after a few hours resting. A fully charged battery should show about 12.6 to 12.75 volts in UK weather conditions
Re-connected the battery and leave the lights on for a few minutes while monitoring the battery voltage when the lights are switched back off and check the voltage if the voltage has dropped below 12.5v suspect a bad battery.
The other multimeter test you can do easily is a AC voltage ripple test on the alternator.

For a proper battery test you need either a battery load tester (cost about 15 to 30 for one suitable for use on a small car battery) or a battery AC Impedance digital tester (cost 35 upwards on eBay).

In general a battery which is near the end of it is life but not faulty will have less Amp Hours capacity than when new particularly if has been susbject frequent deep discharges, so a 45ah battery may have only 15ah capacity after 2 years but the fully charged voltage accross the termminals will still be a normal 12.4 to 12.75 volts.

In contrast a battery which has a faulty cell will show very close to normal resting voltage but the voltage will drop like stone to 6 to 6.5 volts when put under heavy current load.

A battery which is not fully charged will show a low resting voltage and drop relatively slowly to around 8v when put under heavy load.

I think you have two related problems (1) The battery has suffered because it has been subject to deep discharges (2) Your alternator hasn't been charging properly.


If you have The Lucas-Magneti Marelli A127 Mini alternator then it is very very easy and cheap to replace the alternator regultor and brushes as they are contained in a single unit held on to the outside of alternator by 3 screws.

[Edited on 12/2/17 by britishtrident]

[Edited on 12/2/17 by britishtrident]





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gremlin1234

posted on 12/2/17 at 09:33 PM Reply With Quote
quote:
Originally posted by mcramsay
I'm going to get a clip on ammeter from work tomorrow and see what the alternator is putting out. Even though it's putting out 13.8 -14v at idle it may not be spinning fast enough to give the required amps to charge the battery and run the fan. Seen as the fan is operating a lot more than I thought it would. I might be slowly running the battery down...the kenlowe fan has a hell of an amp draw
make sure the ammeter is suitable for dc amps
try it with and without a bulb in the sense circuit.

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britishtrident

posted on 12/2/17 at 09:42 PM Reply With Quote
Clip ammeters are moving iron they care not if the current is DC or AC, a DC clamp meter like the Unit-T UT203 is even better.

[Edited on 12/2/17 by britishtrident]





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gremlin1234

posted on 12/2/17 at 09:52 PM Reply With Quote
quote:
Originally posted by britishtrident
Clip ammeters are moving iron they care not if the current is DC or AC, a DC clamp meter like the Unit-T UT203 is even better.

[Edited on 12/2/17 by britishtrident]
most cheep clamp meters use transformer coils in the clamps, and only work on ac. the dc ones often use hall effect.
for instance: ac amps only
https://cpc.farnell.com/tenma/ten01026/clamp-meter-ac/dp/IN04878?CMP=CPC-PLA

[Edited on 12/2/17 by gremlin1234]

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mcramsay

posted on 12/2/17 at 10:07 PM Reply With Quote
I can get a dc clip on amp meter from work tomorrow no problem. Having a think about things now the fan speed shot right up when I turned the engine off, it definatley seems like the alternator cannot cope with the load when at idle. The m3 electrics use a fair amount of power.. any tips for testing with the clamp on meter? How do I tell what the alternator is putting out against what the actual load on the alternator is?
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gremlin1234

posted on 12/2/17 at 10:41 PM Reply With Quote
quote:
Originally posted by mcramsay
I can get a dc clip on amp meter from work tomorrow no problem. Having a think about things now the fan speed shot right up when I turned the engine off, it definatley seems like the alternator cannot cope with the load when at idle. The m3 electrics use a fair amount of power.. any tips for testing with the clamp on meter? How do I tell what the alternator is putting out against what the actual load on the alternator is?
I suspect the alternator can cope, it just doesn't know the load.
test the amps to the battery, and to the fan. then put the sensing circuit [ie 2.2W bulb] in and try again. - it might (should) magically work

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MikeRJ

posted on 12/2/17 at 10:47 PM Reply With Quote
quote:
Originally posted by gremlin1234
quote:
Originally posted by britishtrident
Clip ammeters are moving iron they care not if the current is DC or AC, a DC clamp meter like the Unit-T UT203 is even better.

[Edited on 12/2/17 by britishtrident]
most cheep clamp meters use transformer coils in the clamps, and only work on ac. the dc ones often use hall effect.
for instance: ac amps only
https://cpc.farnell.com/tenma/ten01026/clamp-meter-ac/dp/IN04878?CMP=CPC-PLA

[Edited on 12/2/17 by gremlin1234]


BT is talking about the passive clip ammeters that you simply hold against the cable. Analog gauge, no batteries required.

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mcramsay

posted on 13/2/17 at 08:14 PM Reply With Quote
So I did a bit of testing tonight, with ignition on and engine off ( but both hp and lp fuel pumps running) the amp draw was 17 amps, this peaks at 39 with the fan starting but settles at 32 amps but obviously the fan doesn't run all the time. full load with the lights on main was 28 amps. Add the fan to this full load on the electrical system is 43 amps with everything turned on.


Started the car, with all lights off and fan off battery showed 6A flowing in, alternator output was around 23A. I then manually turned the fan on and current draw drops to -6 amps ish... so the battery is draining with the fan on as expected,

All belts are new and tight on the alternator. I gave the engine a little throttle and amps going into the battery jumped to +6A.

Alternator pulley diameter is 53mm with crank pulley being 128. This should give an alternator speed of 1950 rpm with the engine idling at 800. Which is what the m3 sits at and is non adjustable.

Battery is an extremely small odyssey pc680 which looking today is a 16AH battery... standard 063 battery is 44Ah in comparison,

I have not had time to hook a charge light up but will do.

I can't find a smaller 5 groove pulley

What are my next steps going on the results above?

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gremlin1234

posted on 13/2/17 at 09:05 PM Reply With Quote
quote:
Originally posted by mcramsay What are my next steps going on the results above?

next step: test it with the sense circuit. ie bulb wired in
edit, ps try not to change more than one thing at a time
edit2: also check the battery voltages at each point in the tests

[Edited on 13/2/17 by gremlin1234]

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mcramsay

posted on 14/2/17 at 09:53 PM Reply With Quote
Tonight I have done the following - added the correct wiring so that the alternator excite voltage is supplied through a 2.2w bulb as per the manual. (Just waiting on the bits turning up in the post for the warning light)

Wired the fan controller to its own switched 12v supply. This is only the wire for turning the unit on, and switching the relays, not the main supply cable for the fans.

I had the supply cable for the fans coming from the batt B+ post on the alternator ( along with the charge cable from the alternator) I am going to move this cable so it takes its supply directly from the battery.... I don't know if it makes any difference as the cable ends up terminating at the battery anyway but it will be as the instructions say to do.

I have also got a slightly smaller pulley coming aswell that should as said help the alternator put out a little more at lower Rpms, and I won't overspeed the alternator at higher revs.

This should put the system exactly as it should be and the alternator should cover the power supply required and charge the battery. As said if the alternator is 75A it should be able to make 30a at idle. Which should cover everything....

If not then it must be the alternator. Which even though is new, came from eBay and could be faulty.

On the battery front, of the alternator is giving out enough amps to run the full load of the car the battery should never be run down,

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mcramsay

posted on 16/2/17 at 07:29 PM Reply With Quote
So I had a play tonight.changed the 53mm pulley for a 47mm one, added the charge light and went for it, initially the bulb went out and seemed fine, alternator was chaining output as I switched things on, I could run the lights and fan st the same time. Voltage to the battery was 14.2 volts and dropped to 13.7 when fan kicked in, after 20 mins of working the warning lamp then started to glow dimly, and again I was taking amps out of the battery rather than putting in.

I looked at the engine revs which had dropped from cold fast idle of 1100 to 850ish, things returned to normal with a few extra rpm from the engine.

The alternator must just be falling short of its required rpm even with the smaller pulley. But I think I can do something with the idle speed to sort this... if I put a few turns on the throttle cable I might be able to raise from 850 to 1000 which seems to be the sweet spot.

What has me stumped is that even putting 14.2 volts into the battery the warning light is glowing dimly even though it went off to start with. I am going through the stock BMW wiring loom that goes down to the alternator and looking on the wiring diagram there is a "decoupling diode" in the circuit... I don't know if this is causing the bulb issue.

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gremlin1234

posted on 17/2/17 at 01:56 PM Reply With Quote
what lights are you using?
maybe worth changing headlights to led to reduce the load

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mcramsay

posted on 17/2/17 at 02:02 PM Reply With Quote
Think I've got to the bottom of it, the charge light is glowing because on the ignition side I am seeing 14.2v with engine running but only 12 on the charge light output on the alternator terminal. Phoned the local alternator place who I said output from the alternator warning light post should match the alternator main output voltage. If it's less then there is a blown diode which would cause the 2v difference across the bulb and 33% less power from the altrrnator. So new alt is on order.
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Oddified

posted on 17/2/17 at 02:15 PM Reply With Quote
quote:
Originally posted by mcramsay
Think I've got to the bottom of it, the charge light is glowing because on the ignition side I am seeing 14.2v with engine running but only 12 on the charge light output on the alternator terminal. Phoned the local alternator place who I said output from the alternator warning light post should match the alternator main output voltage. If it's less then there is a blown diode which would cause the 2v difference across the bulb and 33% less power from the altrrnator. So new alt is on order.


A faint glowing ign light is more often than not a sign of a dead diode or two. Be careful swapping pulleys to get a better charge at idle not to over rev the alternator at the rve limit. If it is an A127 alt, anything much over 16,000rpm (alternator rev's) is risky for it's life span. Do a quick calc with the pulley sizes and engine rev limit.

Ian

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mcramsay

posted on 17/2/17 at 02:23 PM Reply With Quote
Already worked out the pulley ratio and it's safe to run, I can't get past 4000 rpm without loosing traction anyway... new alternator is on order
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