tractor alternator

[cmackay]

Does anyone have a wiring diagram for converting an old tractor wiring system from 6v (dynamo) to 12v (alternator)? Thanks

[cmackay]

Does anyone have a wiring diagram for converting an old tractor wiring system from 6v (dynamo) to 12v (alternator)? Thanks

[John]

Why do you want to do it twice? ;-)

[Weatherlawyer]

Boy, are you in the wrong forum. IIR anything, the positive becomes negative to start with and then you have a big deal with the earth wires.

There was also something about heat sinks and rectifiers -or was that just the good old days?

[The Natural Philosopher]

No, because just about everything will change

- the ignition system will need a new coil, if its petrol

- all the bulbs in it will need changing

- the starter motor will need changing

- if its diesel, the glow plug(s) will need changing.

- the dynamo and regulator and battery will need changing.

- most of the fuses will need looking at.

If there is anything else electrical on it, apart from tehe odd switch, that will probably need changing as well.

[Conor]

Is he hell. It's something commonly done to classic cars, especially Morris Minors.

No you don't. You don't understand electrics at all do you?

[Mark]

You haven't said what tractor you have, but I converted a BSA 3wheeler without too much trouble. You will need a new starter motor, finding this may be the hardest part of the conversion. Wiring info

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[Harry Bloomfield]

cmackay formulated the question :

The dynomo will certainly use one of those old electro mechanical charge two or three bobin regulators. That will need to be removed and the wires isolated. Modern 12v alternators are all pretty much the same...

Built in rectifiers and regulator. A ground terminal/casing, a warning light output and the main +ve output. The later needs to go to the battery +ve.

Battery, starter motor, ignition coil, all lamps, instruments etc. will have to be changed to 12v versions. It might be possible to have the starter motor rewound to suit 12v, lamps should present no problems. It might be possible to get instruments to work correctly by inserting resistors into their 12v supply.

Other than the above, any modern car circuit diagram will provide enough clues.

[Weatherlawyer]

That's why I reposted it from UK.d-i-y.

If I ever did, it was a long time before these things became classics. And You are right, I don't remember much about it -but then it was an awful long time ago.

So long ago I don't recall the name of the voltage control doo dah that was the last thing I ever messed with on one of those things from the pre alternator days.

That's why I reposted it to uk.rec.cars.classic. You dip****!

*******

Is there anyone here that actually has an answer for the OP?

[John]

Dead easy but I can't draw it out here. Most alternators have 3 terminals. The BIG one is obvious and goes to battery +. The sense terminal also goes to battery +. The two are seperate so that the sense senses battery voltage regardless of the volt drop on the big wire. However, for a tractor, they can be simply comnnected at the aternator. The ign terminal connects to the ignition through a warning light, typically 2.2W. You will need to change the battery to negative earth. The ignition coil and the bulbs will need changing but the 6V starter will be OK. It will crank quickly but won't overheat unless you are stupid and crank for ages. Glow plugs will also need changing if it's diesel. If the thing is 6V, it's so old there's not much more to worry about. My Ferguson T20 is converted to 12V and there's no problem.

John

[Rob]

When you fit an alternator - basically most alternators have a built in regulator so the output goes to the positive of the battery. You may have to fit into the circuit a indicator lamp (low watts)which comes from a live pos feed and goes to the alternator small terminal - this is the excite the diodes in the alternator to make it work. (this also is dependent on the make of alternator)

So all wires are from the pos terminal of the battery. The old voltage regulator removed - wires are soldered together.

Hope this makes sense!

[Dave Plowman (News)]

You can usually use a 6 volt starter on 12 volts.

[Andy Dingley]

Charity shop, get a Haynes manual for anything '70s - preferably something with the same maker of alternator. Just copy it.

Lucas alternators are rubbish. Fit a Bosch. Japanese alternators are great, but not weatherproof.

It'll be negative earth afterwards and it might have been positive earth beforehand. If you replace both battery and dynamo/alternator together then you've sorted it out anyway. Ammeters and voltmeters might care too, other gauges generally won't.

Alternators come in two sorts - regulators inside, or separate regulators. Nearly all of them outside the USA are external. The installation difference is trivial (one extra wire). Regulators aren't interchangeable, so keep the one that came with the alternator. Replace the wire between alternator output and battery with something suitably heavy (recycled from the donor car might work, if long enough).

Wire the charge warning light according to the alternator circuit and use the right bulb. If it's an old Lucas ACR alternator, then this bulb is a crucial part of the circuit and _must_ be the right rating! (usually in a red holder in the dashboard, not black or white like the rest).

Discard any ammeter. Add a voltmeter if you wish (more use with an alternator).

Electronic rev counters (which I doubt you have, unless it's a Yank) need replacement.

All bulbs change to 12V, as does the indicator flasher (if fitted).

Dashboard fuel / temp gauge might need replacement, or else a solid state regulator (a 7905 and a couple of resistors, AFAIR) added to its existing voltage regulator.

The ignition coil should be replaced, which is probably a good thing anyway. Don't use a ballasted coil where there's a resistor in the feed to it (or a Ford coil).

Diesel pre-heaters can be left alone, but don't leave them on too long. Replace them with 12V if you do break them.

The starter can stay, but you might change its solenoid (it may not even have one on a tractor, and I assume it's a helix not a pre-engaged starter). Or else just ignore it and fix it if you break it. Ford used to be the easiest source for a separate solenoid, as they kept using them for longest.

Vehicle Wiring Products (webbable) are your best source for parts. Get a decent crimp tool for non-insulated crimps and don't use the pre-insulated sort if you care about reliability. Some silicone grease too.

[Andy Dingley]

Have you sobered up yet from the other night?

[Dave Plowman (News)]

They're often identical from the '80s.

[Andy Dingley]

Basically, avoid the old Lucas designs (especially the ubiquitous ACR). The more recent stuff was nothing like as badly designed.

Bosch build quality was rubbish when they were supplying it to Rover. There was an attitude that "the Brits would accept anything" that they'd never have tried on with VW. Alternators weren't too bad, but the starter solenoids were ghastly (I did one of the test rigs). As for the actual factory location for stuff from the '90s it's pretty hard to tell, but generally anything that looks like Lucas was obsolete and anything that looks like Bosch was well-intentioned but shoddy.

[Dave Plowman (News)]

The ACR fitted to my old P6 Rover simply didn't work as intended. It claimed to be 45 amps output but couldn't even balance a 40 amp load. I ended up designing a new regulator (based on an earlier Lucas design) and fitting it eternally. Had a pot to set the output voltage. No more problems after that.

The 70 amp one fitted to my SD1 is ok though and has lasted well. It's one of the ones which could be either Bosch or Lucas and they appear identical.

[adder1969]

Did they used to be 6v?? My Mini Minor had a dynamo but it was 12v (pos earth)

[Chris Bacon]

Gosh, that'll make Japanese cars very unreliable, then.

[The Natural Philosopher]

That would be due to the loose nut involved in the installation then?

Rover cars are like Victorian pine floors.

Most people simply throw them away, but there is always someone somewhere who thinks that spending more man hours on them than were ever spent on their original construction will turn a sows ear into a lambswool mitten...