Alternator not working

[valtraman]

got an old leyland 272 that wouldn't start, battery dead , put multimeter on battery, nothing when stopped and nothing when running so presumed alternator . Put a new one on just now and still no power out the alternator , I have 2 of these tractors and I have tested the good one exactly the same and I'm getting 14 volts to the battery. Am I missing something here or have I got a dud new alternator?

 

[agrimax]

Is the battery/charging light working?

 

[Dave W]

Check there is a power supply to the alternator.

 

[Kevm]

Is there any power in the battery at all, if it is totally flat then the alternator wont have any voltage going to it to get "excited"

 

[marshbarn]

Is there any power in the battery at all, if it is totally flat then the alternator wont have any voltage going to it to get "excited"

Yes this is the most likely , put a battery charger on for a second while engine running to excite the altenator

 

[valtraman]

I have put another battery that was charged and hey presto 14 volts so charging, now I'm thinking waa it the battery at fault originally or was it the alternator and it drained the battery dead.can I charge the possible dud battery up off a set of jump leads enough to see if it holds?

 

[Bloders]

as long as there is a tiny bit of juice in the old battery to get the alternator going it may well charge.
put old battery back on, start tractor, then just out jump leads on for a short while (seconds) to get alternator working then remove jump leads and it will sort itself out most likely

 

[valtraman]

Seems to be nothing in it, ran it for a week bump starting it, I will try it onto the one I robbed battery off and get the jump leads on and see if it will charge up

 

[czechmate]

Not wanting to hijack the thread...

I have an ageing manitou. The battery runs down over a number of days. The light goes out. When I put a volt meter on when it's running it's around 14v, yet it doesn't charge the battery. Seems like the alt gives volts but not amps

 

[Ley253]

Not wanting to hijack the thread...

I have an ageing manitou. The battery runs down over a number of days. The light goes out. When I put a volt meter on when it's running it's around 14v, yet it doesn't charge the battery. Seems like the alt gives volts but not amps

Sounds like dying battery.

 

[DrWazzock]

Not wanting to hijack the thread...

I have an ageing manitou. The battery runs down over a number of days. The light goes out. When I put a volt meter on when it's running it's around 14v, yet it doesn't charge the battery. Seems like the alt gives volts but not amps

If not dud battery, then maybe a switch left on somewhere or a wire shorting to the frame. Favourite on ours is for somebody to accidentally flick wiper switch on as its near ignition switch. It's a rocker and not clear which is off posiiton. Wiper doesn't move as its seized, but it soon drains battery. Had no end of problems with chafed wires on ours as well.

Another problem is corrosion in the fuse holders. This affects alternator control current I think and again caused all sorts of problems. Try emery the fuse holder clips and fuse ends.

Perhaps disconnect a battery connector and connect ammeter in series to see if you have any significant leakage, with everything supposedly "off".

 

[manhill]

Not wanting to hijack the thread...

I have an ageing manitou. The battery runs down over a number of days. The light goes out. When I put a volt meter on when it's running it's around 14v, yet it doesn't charge the battery. Seems like the alt gives volts but not amps

Disconnect a battery terminal overnight, measure its voltage and compare to the voltage next morning.Could be self discharging.
Repeat, without disconnecting this time, and if it's worse some circuit is dragging it down. Then it's a process of elimination.

 

[czechmate]

Disconnect a battery terminal overnight, measure its voltage and compare to the voltage next morning.Could be self discharging.
Repeat, without disconnecting this time, and if it's worse some circuit is dragging it down. Then it's a process of elimination.

To go into a bit more detail. I only just acquired this in November - with the whole farm equip. The previous farmer was quite useful. He had changed the battery, alternator and starter, but it was still the same. He was then habitually disconnecting the battery overnight, which it have continued to do but of course, in the winter, the cold starting soon drains the battery when it doesn't receive charge.
The corrosion in the fuses that the doc talks of sounds a possibility ?

 

[manhill]

To go into a bit more detail. I only just acquired this in November - with the whole farm equip. The previous farmer was quite useful. He had changed the battery, alternator and starter, but it was still the same. He was then habitually disconnecting the battery overnight, which it have continued to do but of course, in the winter, the cold starting soon drains the battery when it doesn't receive charge.
The corrosion in the fuses that the doc talks of sounds a possibility ?

I don't think the thick wire between the alternator and the battery terminal would be fused but any corrosion on this circuit won't help. I would measure the voltage at the alternator field connector (thin wire), this comes from the battery via the ignition switch and charging lamp. It normally measures just a few volts when the engine is not running due to the volts drop across the lamp.This is all that's needed to excite the alternator. With the engine running this voltage will then start to come from the alternator and balance the battery voltage, so there's now no voltage difference across the lamp and it goes out.
Well that's the theory anyway.

 

[czechmate]

I don't think the thick wire between the alternator and the battery terminal would be fused but any corrosion on this circuit won't help. I would measure the voltage at the alternator field connector (thin wire), this comes from the battery via the ignition switch and charging lamp. It normally measures just a few volts when the engine is not running due to the volts drop across the lamp.This is all that's needed to excite the alternator. With the engine running this voltage will then start to come from the alternator and balance the battery voltage, so there's now no voltage difference across the lamp and it goes out.
Well that's the theory anyway.

Ok.

I think

 

[Right-arm fast]

Not wanting to hijack the thread...

I have an ageing manitou. The battery runs down over a number of days. The light goes out. When I put a volt meter on when it's running it's around 14v, yet it doesn't charge the battery. Seems like the alt gives volts but not amps

If the you are getting 14 volts measured across the battery terminals then the battery will be charging as the voltage is created by amperage being put in to the battery. Could be the battery as said or one or more of the diodes has gone in the rectifier letting current drain to earth when the alternator is not generating a current. Can be checked on an oscilloscope if you have a decent auto electrical garage nearby.