(ET) Lost responses...

[Allan <allanhv worldnet att net>]

I tried to post these ideas in response to several questions / ideas,
but they didn't get out to the mailing list, so I'm trying again...

1) As far as a converter from 18VDC to 12VDC for jump-starting, I have
seen low current "conversion" using diodes in series to provide the
appropriate voltage drop. At 0.7V per diode, just use as many diodes as
necessary to reach, say, 14VDC. Of course, the diodes would have to be
very high current for a jump start, and I'm not sure how effecient this
would be. For long term use, the power dissipation might be more than
the diodes could handle. But, if it would work, it would be simple!
Anybody care to comment on this idea?


2) I use a Tenma AC/DC clamp-on current meter, which handles 600 ADC and
only
cost $50. The catch is that it has no display. It must be hooked up to a

voltage meter, to which it outputs 1mV/A. It seems to work fine, and is
rated
at +- 2% +- 2A. Of course, the error of the meter must be added to this.

If interested, it is a Newark brand, and can be ordered from Newark
(1-800-463-9275) using part number 52F7508. Newark didn't list this in
catalog #116, but it was still available. Personally, I'm not a big
Newark
fan, but the price is right!


3) Using the above clamp-on current meter, I found the following...

I measured the following on an E20 (BA, I think), and also on an E16
(they
performed very similarly). I plan(ed) to use the data to develop a new
controller. I, too, am curious to hear what others have found.

Note that loading was moderate, probably not the maximum load possible
(although
I did get my belt to slip!) and that the peak current was measured on a
DMM with a slow refresh, taking the highest reading seen in 5 - 10
trials. All
measurements were with a fresh charge, but I'm not sure exactly what the
voltage
was. (Around 36V, I expect).

The mower currents below do not include the current used by the motor.

Motor:
    16A no load all gears
    50A peak (to start) (approx, using a slow DMM)
    50A loaded
    75A peak loaded (to start)
    100A peak loaded w/ top speeds (i.e. with reduced field voltage)
    1A field current (approx)

Lawn Mower
    22A no load
    200A peak (to start)
    40A loaded (This was difficult to measure, since it required a
moving
tractor, grass to cut, etc.)