Charging Fault

[charlie63]

Looking for some advice regarding the charging on my Dexta. Ive searched all the related topics on the Forum but havent been able to come up with a definite answer. New loom, generator and control box fitted. It is also fitted with combined key/light switch.
1/ Ive fitted the yellow wire from the solenoid and yellow wire from A on control box to battery on ignition switch as per wiring diagram.
2/ The yellow/white wire from generator warning lamp ive joined with the yellow/white generator wire at terminal D on the control box rather than at the generator end.
3/ Ive put the brown wire that feeds the manifold heater switch on to the coil terminal at the ignition switch as this feed is live when the switch is on.
4/ Generator output and wiring checked at the control box end as per workshop manual and is reading 14.5v when the manual says it should rise rapidly to above 24v. Wiring haas been checked and is okay. Fault with generator??

5/ Open circuit voltage test as per workshop manual is reading 16.5v.
6/ The Amp output test as per workshop manual is only showing 0.4 amps before connecting and once connected does not increase but stays at 0.4amps.

My question is, are the points welded together or is the control box requiring adjusting. I didnt want to start turning adjuster screws in case I damaged something. If it requires adjusting which screw is it as the control box is a sealed unit.


The generator lamp is bright on start up and goes out when revs are increased. Checking voltage across the battery it is showing 12.7v at full revs. Should this not be higher?? Do I have various faults i.e generator and control box or is it all control box??
Appreciate any advise as my electrical skills are basic, give me spanners any day lol.

[blackbob]

I know a lot less than you do but I would have thought your voltage readings were fine... are you sure the '24v' isn't a mis-print?

A modern car alternator runs at 14.5v - if it puts out any higher than that, it will destroy the battery?

[charlie63]

Bob,
Thanks for the reply. It definitely says 24v in the workshop manual I have which threw me with it being a 12v system. My electrical skills just aren't that great. Whenever we had electrical faults on cars etc it was always the auto spark which did the fault finding/repairs so I never got involved in that side of things. What was concerning me was that I didn't seem to get any amp output reading. Sadly I'm away again so the tractor will need to wait for another 4 weeks.

[ianpdexta]

Hello Charlie
Your findings are confusing. But first point, the Fluke is reading 0.4mA not 0.4 Amps, which is 1000 time less, e.g. as good as nothing. Second thing the meter is on an AC range, it should set to dc amps. Next, do you have to plug the test leads into different sockets on the fluke for Current (amps) testing, on most meters like this you do. Was this done and are the test leads in good condition?

I don't want to insult you but need to ask, did you connect the Fluke in series with the dynamo and battery when attempting to measure current? you need to be in series for current, in parallel for volts.

I think the battery voltage should go higher than 12.7 if charging properly, 14v - 14.5v would more like it. My car alternator runs at 14.1 v, it is not harmful to the battery, a dynamo system at high revs could go higher.

You say that you measured 14.5v, from the dynamo, was the dynamo connected to the battery at this point or was it running off load? if it was connected then the battery voltage should have been close to this value, e.g. at least 14. I wouldn't go changing the adjusting screws. I can't say much more at this point, is there someone locally who can look at it?

Regards

Ian

[charlie63]

Ian,
Thanks for the reply. I am currently away again so the tractor has come to a standstill for another 4 weeks.
I am going to get myself an ammeter and carry out the amps check as per the workshop manual and that way I cant go wrong in checking the amps as the Fluke meter can be confusing and I am easily confused ( it seems to be an age thing at the moment lol ). I am alright using it to check continuity on wires etc and voltage. When I was checking the charging rate everything was connected and I was checking the voltage across the battery terminals at full revs and without any electrical load on. Hopefully in 4 weeks time I should have a fresh head and mind to have another look at it.

[charlie63]

Update on the charging fault.
Note to oneself as to leave my tractor and workshop well alone on my last day at home as my mind is usually on other things.
Now I am home and fresh again I have rechecked everything. All the wiring is good, the dynamo is putting out the right voltage as according to the workshop manual and goodness knows how I thought that a 12v dynamo would or should have an output of 24v. All I can think is that I also had a printout from the internet along with my printed pages from the workshop manual and got mixed up. I still couldnt get my Fluke to read amps correctly so found an ameter which I used to check amp output from the control box and it was reading around 10.5 amps which was all good. The cutout voltage for the control box was slightly high according to the readings in the workshop manual so tweaked it very slightly and set it as the meter shows. So glad thats it all sorted now and all screwed together and only the rear lights and number plate light left to wire.

[Mervyn Spencer]

Nice work there Charlie, glad to read that you have sorted your problem out.