Alternator terminals +B and W and there uses.

- T
- TVS
  
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posted
19 years ago

Mon, Nov 29, 2004 10:22 PM

Right! Had it on the road for all of about a day and already not happy with it being standard! I've had to fit an alternator off something like a Metro as the original 16ARC (or what ever it was) packed up. The plus side is it's a 55A jobby and has two terminals on the back marked +B and W.. as far as I can remember. Now then, aren't at least one of these for a rev counter? Unfortunately the alternator did have a multi-rib belt pulley, so had to swap this for the V belt pulley which I had to bore out as it had a smaller diameter hole for the shaft! Oh and the tensioner lug was on the wrong side, could have rotated the front end of the alienator but decided it was easier just to make a new tensioner, its now easier to get to anyway. Its a fair point that it took some fitting but it does work a treat! The question is. what sort of output do you get from these other terminals? Is it analogue or digital? Are there any rev counters I can connect straight up to them? Obviously calibration is going to be defiantly out. especially as I've changed the pulley. Otherewise I'll be looking to make something up. Thanks! Toby

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- Simon Barr
  
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posted
19 years ago

Tue, Nov 30, 2004 8:45 AM

The people at Low tension do one intended for Landrovers. It takes it's signal from the W terminal I think. I bought one some time ago but have just not got around to fitting it, it's a nice bit of kit, VDO gauge ISTR. In fact it's been a while since I saw it, I bet it's been 'tidied up' by the missus!

You can find more info at:

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It's also got a pot to twiddle to calibrate it for diesel fitment.

HTH.

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- Austin Shackles
  
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posted
19 years ago

Tue, Nov 30, 2004 9:48 AM

On or around Mon, 29 Nov 2004 22:22:00 -0000, "TVS" enlightened us thusly:

B+ I think is normally the warning light terminal, which may be duplicated in a multi-plug if you have one of those. W is sometimes used for rev counters, and this produces a non-rectified AC output, AFAIK.

On a petrol vehicle, I'd fit a rev counter which runs off the ignition, though, more accurate.

If the pulley is something near the same size as the original, you should be able to get a rev counter to work sensibly. It might be that some of them are adjustable - you can calibrate it by finding a spark-ignition motor with a rev counter, hooking a timing light onto it, and shining that at your diesel crank pulley - run the petrol one at e.g. 1500 rpm, then m,atch the diesel engine speed so that a mark on the pulley appears stationary. It'll also appear stationary at 3000 rpm, of course, but I trust you can hear the difference between 1500 and 3000.