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Re: (ET) performance logging



It's a pretty simple device. I used a PIC flash microcontroller, RS232 chip, and a dual op-amp to buffer-amplify the signals. Let me straighten it up a bit and I can post the circuit and code. As of now I log to the left-over program memory, which is good for > 1000 cycles and gives about 1 hour logging at 1 sample/sec. This could be improved by 'smart' logging (only log new data when the data has changed by more than some amount), or tossing in a serial EEPROM (proabaly best way). Only three connections to the ET are needed. If there is enough interest we could get a PCB made which is pretty cheap these days. I would guess total parts cost (w/o enclosure) at about $30. The only thing it doesn't do now is log charge current -  I forgot the charge current makes the shunt voltage negative (DOH!). Gotta think about that....
 
One of main reasons I wanted to do this is to log the battery voltage during/after charging to keep on eye on battery health. Wish I had done it earlier,a s I don't knwo how long my charger has been undercharging...
 
- SteveS
 
----- Original Message -----
From: SolidTech
To: 'SteveS'
Sent: Friday, July 26, 2002 8:07 AM
Subject: RE: (ET) performance logging

Steve/all,
  It would be great to have documentation of projects like this posted on the elec-trak.org site for us all to learn from - you know how the second generation device is always (well, almost) better than the first.
 
thoughts?
- - joe

Joseph Rock
E-15 & MagnaTrac Hydro 5000 in Colorado

-----Original Message-----
From: owner-elec-trak cosmos phy tufts edu [mailto:owner-elec-trak cosmos phy tufts edu]On Behalf Of SteveS
Sent: Friday, July 26, 2002 5:04 AM
To: elec-trak cosmos phy tufts edu
Subject: (ET) performance logging

Well, I finally somewhat completed a project for the ET. I built up a little data logger to log voltage and current in the ET. I tried it out last evening and the data is pretty interesting. One can easily see each hill, up and down, mower on/off in the current graph. Voltage, tho' was most interesting as it was in the 36V range. Then I noticed the data while the charger was on - voltage was only about 38V! I thought I seemed to be low on power, even after a charge. So time to troubleshoot the charger - where is that manual?.....
 
 
SteveS
E12S