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Alternator queries 110 200TDi


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Have had a few problems recently with battery charging - Odyssey Red Top starter and Tayna./Enduroline deep cycle leisure battery being fed through an IBS split charge system. Not charging very quickly and the other night having an unexpected adventure in a blizzard in the middle of highland nowhere I noticed headlights and internal lights were pretty dim which suggested an alternator glitch.

I fitted a rev counter a few months back and set it to idle at 800 odd rpm using a strobe, but in the last few weeks have noticed its readings are wildly optimistic - bimbling along in 5th at 55mph was returning 3500rpm and redlining when accelerating. Which seemed way off base (given disco gearing I have and sound of engine was not stressed nor racing).

Yesterday I put a simple alternator tester on the batteries and did as the instructions suggest and tried to put rpms up to 2000, headlights on full beam, etc and noticed that although engine revs audibly increased the rev counter needle wasn't moving at all, and at that point the charge indicator on the tester didn't light either. A few stabs at the accelerator got the needle to move occasionally and with it the tester lights came on. So it appears there's some intermittent fault with current delivery from the alternator. Checked alternator belt tension and its fine.

Alternator that on there now is probably 15 years old and I've not replaced it and with the additional loads of twin batteries and other stuff I have it seems an upgrade to a better alternator is maybe a good idea. Not sure if mine is 45 or 65 amp, but I see there are 120 amp upgrade kits available and my question to the knowledgeable is:

Are my symptoms consistent with a failing alternator? (do they swoon off gradually or just suddenly die, or can it vary?)

Are these uprated ones a straight swap? Is the physical size of the uprated ones the same as the standard fitment so they fit in the existing space? (Pretty sure mine is three bolt version, not four)

There are kits on ebay and John Craddock with uprated cable like this which I presume are ok. Although this is (apparently) britgrot part (or maybe its just the drive belt?) I've seen comments in forums that they're actually Denso or Marelli - anyone know for sure who does make them?

Or - can you suggest alternative supplier of quality uprated ones (not OE Land Rover at £300 please!)

Thank you very much.

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Uprated cable is just a cable with a bigger cross sectional area nothing more. I always try and fit the biggest cable I can in anyway. You've got a proper Defender 200TDi haven't you?

Yes its the proper Defender 200tdi fitted in place of old 19J, definitely not a disco 200. Aye familar with the cable sizing (from my forays into solar recently and voltage loss over distance and cable cross sections etc!)

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A 65amp alternator will be ample.

Rebuilding them is very easy. Just done mine for 20 quid with bits from evilbay.

Yes? Thanks Vulcan - if 65amp will be fine that's good to know. They are lot cheaper and from known makers too.

I've just been out a few minutes ago (now the deluge has stopped) and run the engine, all lights on and the alternator tester shows OK with the rev counter needle moving as it should.

However.....I switched on the heater fan on full and immediately the alternator tester took a dip and showed a charging problem, the rev counter needle stopped going past 1000 rpm and the IBS split charge automatically linked the two batteries to charge them.

So is all this consistent with a failing alternator output?

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I'm assuming that your rev counter runs off the W terminal on the alternator? The W terminal outputs an unrectified AC voltage, the frequency of which is proportional to the alternator speed. If originally set correctly and now reading low/intermittent then the alternator is either not turning as fast as the engine/pulley arrangement should or the rectifier could be damaged, causing an iregular waveform to be output.

Even with an irregular waveform, the rev counter should increase with revs, although it may not be accurate. Silly question, if the belt is OK is the pulley firm on the shaft?
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I'm assuming that your rev counter runs off the W terminal on the alternator? The W terminal outputs an unrectified AC voltage, the frequency of which is proportional to the alternator speed. If originally set correctly and now reading low/intermittent then the alternator is either not turning as fast as the engine/pulley arrangement should or the rectifier could be damaged, causing an iregular waveform to be output.

Even with an irregular waveform, the rev counter should increase with revs, although it may not be accurate. Silly question, if the belt is OK is the pulley firm on the shaft?

Hi AMB - just checked it all out and the belt is tight and pulley is rock solid and without any hint of play. Yes rev counter runs off the W terminal. Under 'load' conditions - headlights on full beam, radio on, and fan on high, with engine revving, the rev counter wont move beyond 1000 rpm (indicated). Once load is off the rev counter resumes its arc of movement but does not seem consistent with estimated (by ear) rpm, certainly not when driving where its indicated 4000rpm when accelerating (but not sounding like its going beyond 3000rpm).

Been speaking to Paddocks just now about a 65 amp version and they say that the 65 amp version is NOT a straight swap that the bolts are different and a mounting kit is required. Is this correct? I thought the 45 and 65 units were interchangeable. Anyone know for sure?

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Don't listen to Paddocks....

Your other option is to recondition what you have... Any local autolecky should be able to do it... There's a company in Rugby called Autolec for instance.

Try the likes of Land Rover Direct, Britcar, LR Series or even my local place called AMD 4 Wheel Drive.

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Bit more experimentation today.

Engine ticking over, alternator tester shows full charge current being delivered (although red warning for 14V is showing). Blip throttle and rev counter flicks up.

Switch on heater fan at full, all still the same.

Switch on headlights, alternator tester starts to flicker warning for low current delivery from alternator, but rev counter still flicks up.

Headlights on full beam (with two additional spots) and alternator tester goes off so no current is being delivered to battery, rev counter wont flick over, heater fan audibly slows, and IBS split charge monitor lights up 'Auto Battery Link' light to indicate the relay has tripped in (low voltage on aux battery)

Oddly, I have a solar controller (Morningstar - good quality) which has led lights to indicate aux battery status. It shows green for full charge, but switching on a load eg Eberspacher heater causes the yellow light to come on very quickly indicating low voltage, iro 11.95V. This is on a new battery, recently replacing one I thought was a problem but it turns out may be a victim (somehow) of the alternator. (I'm guessing!)

The Eberspacher has a cut-out function and fault logging. It's been cutting out regularly recently and when I interrogated it it showed the last five shut-downs were because of 'low voltage' so some gremlin is loose in the works.

Anyway got a new alternator ordered - 65amp and will fit that and see what happens!

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UPDATE:

Ok got a new 65Amp alternator and after a bit of blowtorching and serious wrestling with a long bar managed to get the old pulley and fan off the old alternator (mainly because - in case you don't know - the cost of a new pulley is a mind-numbing £45 to £90 depending on brand, and the fan is £15 or so!).

So got them off and fitted, alternators swapped and its outside running now and so far I can switch on everything, heater fan on high, radio, healdights and spots on full etc and the alternator tester shpws no drop in current delivery and the rev counter (which was dying when revs were applied with a load on the alternator) is now flicking up and down as it should and appears to be on the nail re accuracy.

In hindsight since the 200tdi was installed I've been plagued by electrical oddness - Eberspacher proving overly voltage-sensitive and cutting out with 'low voltage' warnings, batteries not charging properly, windscreen wipers 'creeping' sometimes and I had this odd feeling that the heater fan wasn't always blowing as hard as it could, often in winter seeming 'slow' when starting off then later on getting more vigorous. Seems I was right - the fan is now whirling like a dervish and sucking in so hard on the wing intake I nearly lost my hand!

So I'm guessing that the alternator was goosed, or the voltage regulator was, since the engine was installed.

Will see how it pans out over the next few days as it gets used in earnest.

Thanks for your help, again, folks!

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