Alternator problems again/still

Lucas, right? :)

Which one? Battery to chassis or chassis to engine block? Have you checked all the earth bondings? It doesn't take much resistance. factions of an ohm, to drop a volt at a few tens of amps...

Have you had the battery checked? Might have sufficient to start up the vehicle but starts to cause problems when getting a charge. Sulphation of the battery comes to mind.

Absolutely, can you borrow a battery off a mate and then take a reading?

Try a jump lead directly from the body of the alternator to battery to backup the earth straps as a test.

Mike

On or around Mon, 17 Nov 2008 00:17:59 +0000, puffernutter enlightened us thusly:

plenty of bigger alternators around but they might not fit.

The biggest obvious one is the 100A from the 300TDi, but you'd need different pulleys and so on, and it'd not drive well from a single 10mm belt, either.

other options include the later DI tranny, at 95A, but that's a poly-vee as well.

I trust you're using a known good voltmeter? If you're using the one on the vehicle, make sure *its* connections are sound.

In article , puffernutter writes

Three years ago I had quite similar symptoms from Marge: volts down a bit when the engine was running and reluctance to start. 'twas the old engine so not a good starter (200TDI is brilliant!).

It turned out to be a weirdly duff cell in the almost new battery. It passed the short circuit 'big spikes' tester they had at the battery place, but they had a new, more sophisticated tester that failed it. The replacement has shown no signs of problems since.

It was dragging the volts down on charge, and, like you, I changed the alternator. It didn't cure it.

Have you got a battery you can swap-in for a while?

Regards,

S.

PS: BBC4 ran an excellent prog on the last days of steam last night.

This weekend I have mainly been......

1. Connecting the alternator directly to the battery using a spare jump lead (I used a red one instead of black, but I don't think it affected the electrons!), it certainly had no effect on the charging voltage - still down around 13.1 - 13.3v even on a fast idle.

1. Changing the battery for a known good battery - same effect as above (nil!)

Looks like a new alternator.

Thanks for all the advice.

Cheers

Peter

Did you also connect the other side of the battery direct to the engine block?

Dave,

In a word, no :-)

I had a new +ive (alternator - battery) that I laid in permanently last time and over the weekend I connected the alternator body directly to the battery -ive.

Voltage readings were taken using a digital multimeter on the battery terminals. So basically, using two new (good) wires the alternator was connected directly to the battery.

What difference would connecting the battery to the engine block have made?

Cheers

Peter

It would give a good earth route from alternator to battery. thereby isolating a bad earth strap as the cause of your problems.

Mike

In article , puffernutter writes

Under those circumstances (direct cabling both ways), little or nothing.

Did you check the regulator/diode block connections were good? They often plug into the back of the alternator. Also, IIRC, don't some of them have a failsafe mode to prevent the voltage rising massively?

I still think it's a bit odd that you've managed to get through two of them in quick succession.

I double checked last night and as the 200TDi engine came without an alternator, I put the one from my 2.5TD on it.

So it's the same alternator as before (not the second, my mistake). I found the other one last night, so I will do a swap and see what happens.

Cheers

Peter

Well that is what has been done with alternator body to batt neg. I asked 'cause it wasn't clear in the post this morning which side of the battery connection had been by passed with the jump lead over the weekend.

As Simon says it might be worth looking for an iffy connection in the alternator but we are talking resonable power levels and something dropping a volt at 50 amps is going to get rather warm rather quickly and burn out.

The alternator replaced a couple of weeks ago and "on charge" showed to be around 13.5v. (Fast tickover). It would drop to around 13.0v on load. Not brilliant, but much better than the other one!

BUT!

I went to a dog show yesterday at Ryton on Dunsmore (Best Puppy in Breed and Best Dog in Breed :-) and, on the way up the voltage indicated at the lower end of the scale (I'm going to fit a scaled meter rather than the high/low colours) but seemed to hold its own as far as charging went.

However, just to satisfy my curiosity, on the way back I attached a simple battery condition/alternator meter - the battery indicator was red/yellow/green LEDS (good charge, medium charge, low charge) and the alternator was yellow/green/red LEDS (low charge rate, satisfactory charge rate and over charge rate).

So, on starting the engine I had no LEDSs on the alternator part lit and red, yellow and green on the battery. I also had a reasonably bright charge warning light on the dash (not promising!) No lights or any other power being taken. On putting on the headlights there was no change to the LEDs. I did notice that on tickover the yellow alternator light would flicker, but go off when the revs increased! (Weird!)

We were travelling back from Ryton on Dunsmore down the Fosse via Worcestershire to Trowbridge. As we turned on the Fosse we lost the Green LED on the battery indicator (still no LEDs on the alternator charge state)...and I thought that Defender lights were poor with full volts! Even a a reasonable speed, there was no sign of the alternator charging, but at leas the yellow LED stayed lit! In Moreton on the Marsh (possibly after hitting a small pothole) we had the green battery LED back, shortly followed by the yellow alternator LED and the alternator warning light dimming slightly. As the journey progressed we had the green alternator charge light lit which stayed lit for the rest of the journey and the charge light gradually got dimmer and dimmer, but never actually went off totally (although very dim - could only be seen in pitch black).

So, even though I tried a separate earth, the above leads me to wonder if I still have a poor earth? Did the alternator provide enough voltage at low revs when a little current was being taken? (Hence the flickering light at tickover?) As the revs increased, so did the current and the voltage dropped?

I reckon my next job is to either re-check, or just fit new, battery to engine and engine to body earths.

Are there any other things that I may have missed?)

Cheers

Peter