rtbcomp
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A friend of mine is having problems with the Lucas E418L dynamo on his 1925 Rover.
The brush arrangement according to what I can find on the net and in "The Modern Motor Engineer" (5th ed. 1955) is thus:
Basically the field coil is earthed through the 3rd brush which sits at a small positive voltage above earth, as the dynamo speeds up this voltage increases, reducing the field current thus cancelling the increase in output voltage from D+ due to the increased speed, i.e regulating the output voltage. It wasn't a great system so the switched resistors were provided to give, summer (3), normal (2) and winter (1) charging settings.
But, according to his workshop manual and the dynamo fitted to the car, he has this set up:
An extra resistor is wired in series with the field coil in the form of some resistance wire wrapped on the outside of the field coil and the 3rd brush is connected to D- (earth). This has two implications 1) there is no regulation and 2) the armature windings between the D- and the 3rd brushes is shorted out.
The symptoms he's getting on the car is that the charging voltage reaches about 16v, which isn't good for the battery. The plan is to convert back to the 1st scheme, but we were wondering whether anyone on here has had experience of this system?
EDIT 17/1/2019 - see posts #17 & #18
The brush arrangement according to what I can find on the net and in "The Modern Motor Engineer" (5th ed. 1955) is thus:
Basically the field coil is earthed through the 3rd brush which sits at a small positive voltage above earth, as the dynamo speeds up this voltage increases, reducing the field current thus cancelling the increase in output voltage from D+ due to the increased speed, i.e regulating the output voltage. It wasn't a great system so the switched resistors were provided to give, summer (3), normal (2) and winter (1) charging settings.
But, according to his workshop manual and the dynamo fitted to the car, he has this set up:
An extra resistor is wired in series with the field coil in the form of some resistance wire wrapped on the outside of the field coil and the 3rd brush is connected to D- (earth). This has two implications 1) there is no regulation and 2) the armature windings between the D- and the 3rd brushes is shorted out.
The symptoms he's getting on the car is that the charging voltage reaches about 16v, which isn't good for the battery. The plan is to convert back to the 1st scheme, but we were wondering whether anyone on here has had experience of this system?
EDIT 17/1/2019 - see posts #17 & #18
Last edited: