View Single Post
Old 10-01-2009, 11:39 AM   #13 (permalink)
Batman Junior
MetroMPG's Avatar
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,999

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

MPGiata - '90 Mazda Miata
90 day: 53.56 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: 57.1 mpg (US)
Thanks: 3,638
Thanked 6,459 Times in 3,344 Posts
Sounds to me like a classic "unbalanced pack" problem.

The old batteries had a much lower capacity than the others, so they were depleting faster than the newer ones. When they "blew", I suspect that was the result of a cell reversal - the voltage in an individual weak cell was drawn down to zero, at which point it reversed and started being charged by the neighbouring cells. ... At 100+ amps, or whatever the current was while you were driving!! That much current will generate a lot of heat and gas, and a BANG! isn't out of the question.

I'm a firm believer that all EV's need pack monitors: either passive (by computer, with appropriate warning methods) or active (some kind of array of gauges the driver can keep tabs on).

The battery pack is usually the most expensive component in the car, so it just makes sense to monitor it in a more sophisticated way than a single "state of charge" voltage gauge.

EG see:

You can also get commercial versions of that: Pak-trakr is one.
Latest mods: 3-cylinder Mitsubishi Mirage. EcoMods now 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