Conversion armature choice?

[Jerry]

Hi Baggo, Zubbly, Hiker and other conversion folks.

A while back I built a solid steel armatre. This was after a few years of use the stock motor armature.

The stock armature has a great deal of aluminum sandwiched with steel laminet.

In terms of a good flux path it is not as eficient as soldid steel. There is no concern at the armature for eddy currents. If there were the dual rotor disc guys would have a problem glueing there magnets to a solid steel disc. Eddy currents are a stator problem.

Here is the result of a test I did between a solid steel armature and a stock motor armature.

This test was done at 500 rpm with. The load was a 1,100 wat heater element.        The test alt was a 1 HP Garbogen. This is with run windings only.

     Motor armature                                  Solid armature.

      29.4 v, 1.8 amps                                 33.5 v, 2.5 amps

Heater eliment plus 24 volt battery next load test.

      25.7 v, 4 amps                                    27 v, 5.5 amps

No load volt test 500 rpm run windings.

       32.5 v                                             36.7 v.

The above test used the same magnets at the same diameter. There is a noticable improvement in avaible power.

I gues if the disc alt builders mixed in some aluminumin there discs power would be less also.

The soild armature was not that hard to build. The addition of the start windings adds another 50% power.

                        JK TAS Jerry        

[Jerry]

Picture of a stock armature. The magnets in the stock test were not countersunk they were flush.





This is the solid steel armature.

                   JK TAS Jerry

[Jerry]

PS the spool ends on the solid arm. are plexy plastic. No magnetic interfearence.

                       JK TAS Jerry

[baggo]

Hi Jerry,

Interesting test. If I do any larger conversions I will bear this in mind.

On the rotor that I've just done I had to turn a fair bit off as I used 3/8 thick magnets. By the time I'd got down to the right diameter I had turned all the aluminium off anyway and was left with just the steel laminations.

John

[RobC]

Hi Jerry interesting info. On my 5.5hp conversion I cut completely though all of the aluminum to have room for the magnets. One thing I found is that with the aluminum bars gone the laminations wanted to fall apart however there were 4 holes though the armature annd I put allthread though these and tightened it up.

RobC