Re: (ET) Solid state controls

[Jim Coate <jbc_shop coate org>]

Bill and all -

I too have thought about this.  An electronic speed controller is a
little more expensive than the relays but is actually much simpler to
wire and would provide a nice pedal interface for precise speed control.
I'm looking at units such as an E-Z-Go (Curtis p/n 73144G, 36 volt, 250
amp), but haven't yet confirmed this to be a good match (and what
matches my E20 motor may be different from what would match your E12
motor). One of the issues is if a standard sep-ex controller can drive
the compound wound Elec-Trak motors ok.

For the readouts, I'd suggest a "Link 10" meter (the product formerly
known as "e-meter"). See
http://www.xantrex.com/Products/Inst_Acc/link10/link10.html 
This is microprocessor based and can show pack voltage, current, a-hrs
used, estimated run time remaining, etc. Note that to be accurate, you
must properly program the meter with the correct information for your
battery pack. The deluxe version has an rs-232 port if you want to be a
geek and hook up a laptop computer to record the data stream it produces
every second. It is in a standard sized meter package, so drops directly
into the existing 2" hole for mounting. I might put a good quality (i.e.
Westberg) voltmeter in the other hole (with a 270 degree scale of say
30-50 volts) as an analog meter is indeed easier to read while driving
and doesn't wash out under bright sun.

If you want to go all out, you could make something like Lee Hart's
Battery Balancer (as described on the EV list). This uses a
microprocessor and small relays to monitor the voltage of each battery
and then shuttle extra power to whichever battery is the lowest. You
could add programming to display any information about the batteries you
might like. However... that might be overkill for the application. 

A more economical way to monitor individual batteries would be 6 LED's,
each hooked up to one battery with a zener diode with the values chosen
such that the LED goes out when the battery voltage drops below say
5.3(?) volts.  This would give you a quick visual indication of which
battery was weakest by which light started dimming first under load (and
would also tell you when to back off on the "gas" pedal...). So maybe an
e-meter in the first meter hole, and a little panel with 6 LED's
arranged in the same pattern as the batteries are installed in the
second hole.

So many ideas, so little time!


wilbett earthlink net wrote:
> I want to make some electrical improvements to my E12 which I
> think most Elek-trac owners would also want. These are things
> GE would probably have done if they'd had today's
> technology in 1970:
> 
> 1. A solid state speed control.
> 
> 2. LCD voltage readouts


_________
Jim Coate
1992 Chevy S-10
1970s Elec-Trak E20
http://www.eeevee.com