View Single Post
Old 11-27-2007, 02:26 PM   #448 (permalink)
Batman Junior
MetroMPG's Avatar
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,238

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,796
Thanked 6,656 Times in 3,448 Posts
09-30-2007, 09:24 Pm

Man, I'm getting weary of the hours going into this car... will be very glad when we get our plates. I need a break. This weekend:
  • made up several more cables/lugs (motor cables & other half of Anderson emergency disconnect pair)
  • mounted the ammeter shunt on the underhood platform
  • spent a long time thinking about the best way to mount, orient & wire the low pedal contactor
  • cut & installed strips of rubber for under the battery hold-down angle iron, as requested by my mechanic
  • spent most of my tinkering time Saturday adjusting the motor brush timing... again.
I was reading up on the pile of EVDL messages ripening in my inbox, and came across a message from motor guru Husted about low voltage systems & brush advance. Noted that he said "5 degrees for mild" voltages. Apparently the common "10 degrees for street use" applies to higher voltages (say 120+). So I went out and measured... and the brushes were advanced almost 17 degrees!!

Whoops. For 48v he suggested putting them to neutral.

I now have them near 2 or 3 degrees advanced. According to Jim, the closer to neutral timing = more low end torque and less top end RPM. The motor should run more efficiently too. After making the adjustment (drilled a new set of adjustment holes in the end cap ... with the motor still in the car), I can vouch for the first 2 statements. The car goes up hills better (relatively speaking), but I can no longer wind it out to 4000 rpm before shifting - it just runs out of steam.

And it still won't spin the tires on gravel, before or after the adjustment. I tried.
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown

has launched a forum for the efficient new Mitsubishi Mirage - fuel efficiency info for Geo Metro owners - electric car conversion on a beer budget
  Reply With Quote