dead battery

In 2022, after nine years of use the battery began to self-discharge due to dendrite formation, indicating it had reached the end of its calendar lifespan. It could still hold a charge, but only briefly. .

The vinyl strapping effectively contained cell swelling throughout its lifespan, with significant physical stress evident upon removal. The plywood base remained in good condition.

Body work continued now off the road.

new front fenders

no before pic

front was out of shape from PO crash

fiberglass vs welding

8 years on the road

 32072 electric miles B-)

replace headliner and stuff

Remove glass to replace headliner. Fix some rust. 

this spot has had it coming for a long time

feels better now

helper is growing fast

rubber cement and binder clips all the way around

there are metal bows inserted in sleeves holding the middle up

interesting wind screen install using the "rope trick"

the silver strip goes in last to tighten the whole deal up

7 years

 Another battery-trouble free year of drivin'!

                            7 years

                            31800 gas free miles

fun accident

The other week dead at a green light, groping about for power, I realized over 5 long seconds that my main contactor had dropped out!

I'd just turned On the air conditioning loading the 12V system down below 10 - ah ha, my 12V battery must not be making good connection! My DC-DC converter can not run so many accessories alone..

I rolled a window down and made a smooth recovery with minimal honking behind.

Back home I confirmed my theory and began to clean the 12V battery connection. With the 12V battery cable in my left hand furiously working it with a wire brush it slipped falling upon the high voltage battery. Zap!

Bitten by my minimalist exposed high voltage battery design!

Death toll:
1 fuse
1 motor controller logic board
12V to 5V USB converter
at least 1 cell monitoring board..

 

The damage was repaired by Manzanita Micro and we should be on the road tomorrow.  :)

6 years on the road

No battery issues in 6 years

29434 electric miles

python

Here is my  python script. Let me know if you have any ideas why it crashes when log_data() is called?

import time
import serial
import smtplib

from email.message import EmailMessage

def log_data(filename, line):
    file_handle = open(filename, 'a+')
    file_handle.write(line)
    file_handle.close()


print('Hello World!')

ser = serial.Serial(
    '/dev/ttyAMA0',
    baudrate=57600,
    parity=serial.PARITY_NONE,
    stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS)

time.sleep(.1)

try:
    ser.write('H\r')
    time.sleep(.25)
    ser.write('2\r')
    time.sleep(.25)
    ser.write('6\r')
    ser.reset_input_buffer()
    kludge = 0
    while True:
        data = ser.read_until('\n', 120)
        if kludge > 2 and len(data) > 12:
            log_data('log.txt', data)
            parse = data.split()
            print(parse[0]
                  + ' ' + parse[1]
                  + ' Amps ' + parse[8]
                  + ' ~ ' + parse[9]
                  + ' Volts ' + str(int(parse[10]) * 9.0 / 5 + 32)
                  + ' ~ ' + str(int(parse[11]) * 9.0 / 5 + 32)
                  + ' degF')
        kludge = kludge + 1

except BaseException:
    # email logged data before quitting
    print("Emailing data...")
    textfile = 'log.txt'
    with open(textfile) as fp:
        # Create a text/plain message
        msg = EmailMessage()
        msg.set_content(fp.read())

    msg['Subject'] = 'The contents of %s' % textfile
    msg['From'] = 'chrisdarilek@gmail.com'
    msg['To'] = 'chrisdarilek@gmail.com'

    username = 'chrisdarilek@gmail.com'

    # Send the message via our own SMTP server.
    s = smtplib.SMTP('smtp.gmail.com:587')
    s.starttls()
    s.login(username, password)
    s.send_message(msg)

    s.quit()
    print('Blow up the spacestation!')


finally:
    ser.close()
    pass

pi

I found a use for an old Raspberry Pi I had. I paired it with a small LCD display and wrote a Python script to poll the BMS for battery data.

I added WiFi to it and now I can SSH into it from my phone to monitor my charge without having to go outside.

My goal is to have the Pi write the data to a file and email it to me when it detects WiFi.

heat

It is getting hot this summer. The AC is working like a champ. I've run out of charge a handful of times over the past 6 years. Each time it was due to my charger turning Off due to high temperature. The model I have appears to need to be reset to recover from this condition. However, if I don't pay attention I do not notice that I'm heading out with less than full charge.

I picked up a Manzanita Micro PFC20 charger with forced air cooling. It's the green box at the bottom of this picture. The previous charger only had fins for cooling.

Sure enough, this charger overheats as well. At least it continues to charge, only at a lower rate. The BMS is wired to give it the Off signal when charge is complete.

My water cooled motor controller is overheating as well. I may need a bigger radiator.

My battery has been at 120 degF by the time I get home from work lately.

disc flexin' once again

I'm now on my 5th flex disc in just under 6 years. The Meyle brand lasted almost 1 year. That's an improvement from the last candidate. Again I'm switching brands, finding one that is slightly more expensive this time.
I'm beginning to believe the issue is the high starting torque of the DC motor. I don't use 1st gear because it is very jumpy. I start out in 2nd gear and usually nail it.
I can tell the unit goes under a lot of force. The grade 5 bolts in the pic below were new 1 year ago. Notice how a shoulder has been worn on the ones at the bottom. I lost the 8th bolt on a turn, that's how I knew it was time to swap a new one in.

mirror failure

My driver's side mirror fell off underway. I was able to turn around and retrieve it. The part that it holds onto the door with had worn away and no longer provided a purchase.
I fabricated a replacement for this part in aluminum and made a gasket from inner-tube.

patching a hole where the rain gets in

The carpet on the driver's side is always wet when it rains. I pulled it back to see why.

It's a bit perforated. I found a sheet of metal in my scrap and cut a patch for it.

5 year aniversary

This post marks my 5 year anniversary! 25,000 miles total. No battery issues! I estimate I have saved $3250 worth of gas at $2.60 per gallon, have paid $832 in electricity at $0.10 per kWh, and have 458 cycles on my battery.

Refresh EV grin

Step 38: refresh EV grin. Closing out my 5th year of driving I decided to upgrade my motor controller to a Zilla. At 1000A this will double my HP (but not affect my top speed).

The Zilla is a high-side switch so I had to run a new power cable from the controller in the trunk up to the motor. While I was under there I inspected my brushes. They look brand new.

I spray painted the power cable orange like the others. The Zilla is liquid cooled. I'm using a PVC pipe for a reservoir, a 12V pump, and a radiator for a power steering cooler located under the trunk.

I also added a little wall to mount the reservoir and to protect my rig from groceries.

window crank

This window crank broke in half.  I fixed it several times but in the end could not get epoxy to stick to the metal.  I gave up and got one off ebay.

more flex disc'n

The last flex disc lasted only 9 months.  The 3 that have been eaten were M/T brand.  I put a Meyle brand on this time. 

New driver training

Front brakes

Old car stuff.  I knew the front brake calipers were from a ‘75-‘83 BMW 320i, and the brake lines were for a 2002tii booster, but I didn’t know the hubs were from a BMW 2002 standard. I replaced the rotors, one of them had warped.

Brake job

I was driving my friend home when the brake pedal went to the floor.  Where did the brake fluid go?  A failed slave cylinder.

Instrumentation

For four and a half years I've been operating without any battery instrumentation.  Professionally I work in the field of battery charge estimation, algorithms that decide whether to light 1 LED or 5 LEDs.  My cousin recently gave me a ride in his Tesla Model S and pointed out the irony to my lack of battery charge gauging.  I simply make sure I don't drive more than 40~50 miles on a charge.

When in a pinch I have read the voltage of a single cell with a voltmeter to get an idea, when fully relaxed these voltages are directly related to state of charge.

I've run out of charge only 2 times so far.  One time because I forgot to charge the night before.  And the other time is still a bit of a mystery.  I thought it was perhaps due to running the air conditioning over lunch break but that would not account for how much charge I lacked to get home.  Both times I simply called AAA and was done.

There is a communication port on my battery management system and I've used it for diagnosis using a laptop and to log data using an iPhone.  The iPhone was really too small to be practical and was abandoned.  My family recently upgraded from an old iPad to a Kindle Fire and I've adopted the iPad with cracked screen to up my game.

As a security feature it hides nicely under the passenger seat.  With this I can monitor and log voltages, temperatures, and current.  The app I'm using is called Get Console and is basically a HyperTerminal for iPhones.  I hope to do some more data collection and efficiency calcs soon!