Help Needed- Charging problem

[seabee]

I have a Willys MB that I purchased 18 months ago. It has been changed to 12 volt.

It starts up first time when the battery is fully charged.

Over a period of weeks the battery seems to lose its charge. (It starts up ok, I take it for a drive, but once it is switched off it will not start without a jump or push starting, then it runs alright until I have to stop again)

I thought it must be the battery so I purchased a new one, but the problem is still there.

According to my meter there is voltage coming from the dynamo - is it possible that it could still be set up for 6 volt charging through the voltage relay? Any help would be appreciated.

 

Cheers

Chris

[fv1609]

Chris

It's either not charging or it is charging but there is some circuitary causing it to slowly discharge. To test the latter, turn of everything electrical, disconnect one battery lead connect an ammeter to the lead & connect the other end to the terminal you removed the lead from. See if any current flows then if you are using a multimeter go down the current range until you can measure less than one amp or even 0.1 amps. Should still read zero even a drain of 0.01 amps after a week or so can significantly discharge your battery. But remember don't turn on any switches with the ammeter in a low current setting!

 

To test if it is charging with the ammeter on a high range 20 amps say, with the leads reversed see if the battery is being charged as you rev the engine. But put this in the lead from the regulator not in the wiring that supplies the starter motor otherwise you will bust the ammeter.

[seabee]

Thanks for that information- I shall give it a try.

 

Much Appreciated.

Chris

[Pete Ashby]

It has been changed to 12 volt.

Over a period of weeks the battery seems to lose its charge. I thought it must be the so I purchased a new one, but the problem is still there.

According to my meter there is voltage coming from the dynamo - is it possible that it could still be set up for 6 volt charging through the voltage relay? Any help would be appreciated.

 

Cheers

Chris

 

 

Chris

 

what voltage are you seeing form the generator at around 1500 engine RPM ?

 

Pete

[seabee]

Thanks for the info guys.

 

 

I think it must be my dynamo charger that is not working.

There is no drain on the battery that I can find- the battery seems to be at 11.7 constantly when the engine is running. If I take a lead off, the engine stops instantly. I did however find a bad earth connection and have replaced the negative lead from the battery. When I checked the voltage from the charger/dynamo, that was again 11.7, sop I assume I was getting a battery reading.

 

Thanks Again

Chris

 

[fv1609]

Chris

Your dynamo should have two terminals F (field) & D (dynamo output). Check that the voltage regulator is supplying the field winding with 12 volts or so. This is to provide the magentic field for the armature to rotate in. The regulator controls the voltage to the field winding which in turn determines the output from the dynamo at D.

 

If with the engine running there is no voltage at F. Turn off & trace back to the F lead to the regulator & see if you can pick up a voltage. Then maybe clean up the contacts on the regulator.

 

If there is a reasonable voltage at F with the engine running see if there is output from D. If nothing then very likely your carbon brushes are worn out.