I drove my car to the monthly Minnesota Electric Auto Association meeting last night. Its bitter cold here in Minnesota so I used the new heater and it worked well. After the meeting, on the way home, I got about half way and I could see my pack voltage was trending close to trouble, despite the fact that the BMS said I had 50% capacity remaining. I was running out of juice. I pulled off the freeway and onto a side road. I coasted to a stop and was able to park the car while keeping the pack voltage above the minimum safe voltage. I called a family member and got towed home. It was annoying, embarrassing, and dangerous because it was 9:30PM and only 14F (-10C) outside.
In total I drove 25.1 miles. I think I have learned my lesson that I need to take the time to balance all the cells in the pack to maximize the range. 25 miles doesn't cut it! I plan to start that this weekend. I have also been working on some circuits to drive the gauges in the dashboard that I will publish soon.
Hey Kurt!
ReplyDeleteI've been following your blog since you starred on Hackaday.com; and it's unusual for me to comment :)
I just wanted to let you know how interesting I find your conversion. The blog write-up is great, the effort you're putting into it is appreciated (and I'm certain will be something you'll look back on in years to come!).
But stay safe man! That really could have finished with a very different story... :O
What's the car insurance like for you where you live? In the UK, the insurance companies start getting quite jittery when you've swapped out engines etc, let alone completely converted something to electric!
Do you think the cold weather makes the batteries discharge at differing rates? (i.e. if some are better "insulated" [and therefore warmer] due to their location in the car, they discharge slower?)
Don't be embarrassed though - truly, truly awesome achievement. Irrespective of whether you broke down or not :)
Thank you for the kind words Wally. The insurance company does not know anything about the customizations to the car. All they know is that its a 2002 Porsche 996 C2. If it gets totaled, I assume they won't provide me anything more than the book value of the stock Porsche.
ReplyDeleteThe cold weather definitely increases the batteries' internal resistance which reduces the max current I can get out of the system. Many of my friends in the MN EV association do use battery boxes with insulation and heaters to keep their batteries at optimal temperature. I didn't go that route because I planned to only drive it during the warmer months of the year...