Project: The Electric Booger (budget EV conversion - '92 Mazda MX-3)

[jray3]

Yup, I'd bet those two recover allright. Twould be good to run em through a few cycles to 'wake em up' before putting the whole pack back in use. You've discovered why those who tried 'distributed charging' 8-10 years ago abandoned it. Without an alarm to notify you when one of the many chargers fails, it's too easy to kill a battery, or worse.

[mechman600]

Originally Posted by jray3

Yup, I'd bet those two recover allright.

They just went to float - after 14-1/2 hours @ 10A!
I just separated the [hopefully un-murdered] pair and will let them sit for half an hour and then check each battery's voltage to check for internal discharging/damage. After that I will put them on charge again to float them until after work tonight...or maybe tomorrow morning.

Twould be good to run em through a few cycles to 'wake em up' before putting the whole pack back in use. You've discovered why those who tried 'distributed charging' 8-10 years ago abandoned it. Without an alarm to notify you when one of the many chargers fails, it's too easy to kill a battery, or worse.

Like I said, I normally rely on my Kill A Watt to make sure everything is good:
1070W when I plug it in after my commute to work.
1000W when I plug it in after my commute home (deeper discharge).
But with no Kill A Watt I will have to plug in my battery monitors when charging to prevent this from happening again.

EDIT: I let the two batteries sit for 10 hours and measured their voltages: 12.84V and 12.88V. I reconnected them and turned the charger on and they instantly shot to max charge voltage and after two minutes went to float, so it appears that they have recovered!

[mechman600]

After work at midnight I decided to finally find out the "performance" figures for the Electric Booger on the way home. Not exactly accurate as I was looking down at a stopwatch while I accelerated (really safe, I know!), but still, ball park figures to get an idea.

0-30 mph: 12 sec
0-40 mph: 22 sec
0-50 mph: 35 sec
0-60 mph: 55 sec

THAT'S RIGHT! 60 MPH IN A 72V EV!

It probably would have gone faster, but I didn't want my little motor to turn into molten lava, especially with the big hill I still had to climb on the way home.

[MetroMPG]

0 to 60 in 55 sec... speed demon!

I'm glad you're not around here to intimidate me with that overpowered monster.

FYI... the last I checked, the ForkenSwift took around 21 seconds to sprint to 50 km/h / 30 mph. Big 3 electric car questions: How fast? How far? How much? - ForkenSwift.com

How did you shift?

[bennelson]

Fun/Scary doing speed testing isn't it?

While I was never an agressive driver in the Electro-Metro, it was a little crazy the time that I hooked up a BIG RED BYPASS BUTTON that disconnected the motor controller and then connected all the batteries in series PLUS two additional ones!

It made enough power to push me back into my seat a bit!

In retrospect, I shouldn't have done it in 5th gear!

[mechman600]

Originally Posted by bennelson

Fun/Scary doing speed testing isn't it?

While I was never an agressive driver in the Electro-Metro, it was a little crazy the time that I hooked up a BIG RED BYPASS BUTTON that disconnected the motor controller and then connected all the batteries in series PLUS two additional ones!

It made enough power to push me back into my seat a bit!

In retrospect, I shouldn't have done it in 5th gear!

HA! The two extra batteries part is awesome.

My Alltrax controller has a build in bypass. At least that's what I perceive the small bump in power to be when the armature approaches max voltage (motor at max power). But it's a small power pulse, not a two-extra-battery warp mode.

[mechman600]

Originally Posted by MetroMPG

How did you shift?

I shift just as the amps are about to drop, aka at peak HP.
1-2 happens @ 20 km/h (12 mph)
2-3 happens @ 45 km/h (28 mph)
3-4 happens @ 75 km/h (46 mph)

I am thinking 96 km/h (60 mph) could be beat if I shifted to 5th, but my poor motor. My poor poor motor.

I am thinking of EV 2.0 already, using a much lighter glider like a Festiva, but I would definitely get a much bigger motor next time.

[mechman600]

It's time to upgrade my battery monitoring system. Two reasons:
1) My current system is annoying to use. I have to reach over and plug the voltmeter array in while I am driving. Not the safest...
2) One of the voltmeters on my current setup is dead, so it needs work anyway.

So what I have planned is one voltmeter for system voltage and one voltmeter for individual monitoring, both mounted in the dash panel. A six position, two pole rotary switch will be used to toggle between each pair of batteries for monitoring.

Here is the current proposed wiring schematic:

[MetroMPG]

I think a display that shows the relative state of charge of all batteries at a glance is better than one you have to cycle through. And graphical is better than numeric.

No fun, eh?

[mechman600]

I hear what you're saying. However, I rarely use my BMS because my batteries are all quite strong. My system voltage gauge basically tells the whole story, even after a 20 km run. The last time I used my BMS was when I had the charger issue and one pair of batteries went very dead, and I only plugged it in after I felt that something was wrong.

I am also looking around for a new motor - a series wound motor with enough mass to handle my 1-1/2 ton car with ease. Does anybody have one laying around?