Thanks for all your replies.
Based on Steve's suggestions I did some measurements
this evening. The following table shows the voltages
I measured in the different speeds with the transmission
in neutral. I later measured under load and the only
major difference was the armature voltage that caved
in on heavy loads mainly in speeds 1-3, which was
expected.
Speed Armature Field Battery
1 29.8 34.5 37.5
2 30.6 34.4 37.3
3 31.6 34.4 37.3
4 33.6 33.4 37.0
5 35.5 33.2 37.0
6 35.5 11.7 36.7
7 34.7 8.1 36.7
8 34.4 5.5 36.5
I was puzzling why the field current is lower
than the battery. The voltage drop from the
diodes shouldn't be that much (0.7V, right?).
So maybe I should revisit that circuit to make
sure I provide a high enough voltage to the field.
The performance of the tractor while driving it around
seemed a bit better than yesterday. Maybe the field
connector wasn't seated right and had a high resistance.
Running in D2 is now mostly in the yellow area
except when going up inclines.
Markus
Also poor motor performance and large currents is usually
associated
with a weak (or missing) field. You may want to hook up the
voltmeter
across the field terminals and check that it's 36V when in
cruise mode -
actually I guess anything below the field weakening setting
should be 36V?.
These are good points. Too low a field could really be the problem and
I haven't measured the field voltage after I fixed the
diodes, so I think
this is a good thing to check.
Thanks
Markus
SteveS
E20
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