Ooops, it has been quite a while since I last updated this blog. This post is intended to summarize what been going on with the lemon.

Time consumers

When we left off I had gotten the Lemon registered and started driving it to work. The car worked quite well for my commute, the lack of A/C was a bit inconvenient in the summer heat, but other than that I enjoyed the car quite a bit. The low end torque makes it a blast to drive.

Tesla and Lemon

Someone had the nerve to park a Tesla next to the Lemon at work. How humiliating! I got to drive that tesla later though so all is forgiven. I want more torque now!

I did run into some problems, like a steering linkage comming loose, luckily I caught it in time. It was quite apparent from the increasing rolling drag that something was wrong. I also had a rear wheel almost fall off after some lug bolts worked themselves loose, caught that in time too. The brake cylinder sprung a leak and had to be replaced.

I was continually tweaking the car and fixing little things that I originally duct taped into place in order to get it running. Expedient sollutions where often chosen in the mad dash to get the car finnished in between taking care of my daugther.

The 12V battery was a continous source of frustration. My battery management system is supposed to go into sleep mode after some inactivity but would often fail to do so leaving me with a dead 12V battery in the morning. Luckily, since it is an EV, jumpstarting it consists of manually closing the open frame relay to the DCDC converter, a trivial task but maybe didn't do much for the reputation of EVs.

The curtis had some issues with getting out of squeel mode under heavy load. It would suddenly loose power, slow down and pick up power again, rinse repeat. It turns out to be the low inductance of the ADC 9" motor that causes this issue. Adding an external inductor solves the problem.

Air core inductor

Here's my test inductor, an old transformer winding. The winding couldn't quite handle the current and started smooking after a while. I've since replaced it with an iron core inductor.

The worst problem was some of the batteries. Most of them worked fine but a few modules had been badly abused in a previous life and started failing rapidly. The failure would show up as high self discharge that got worse with time. I had more than a few incidenses of cell reversal and spent much time with a power supply under the hood bringing up individual cells, but it was a loosing battle.

As summer came and I no longer neede two cars I removed the bad NiMH batteries with the intention of replacing them with some Lithium batteries. I will end up with seven good 12V NiMH modules in the trunk and five 12V Lithium modules under the hood. More on that later...

New Lithium Battery Box