The more I thought about my minimum voltage yesterday, the more it was bothering me. The battery holds a lot more energy than that. It occurred to me that if the voltage is dropping, but the energy isn't being used, it's probably a loose or high resistance connection somewhere.
The weather was still pretty warm today (and actually sunny and somewhat dry), so I decided to do a decent test run and see if I could figure out what's going on. First I fashioned a temporary front fender out of cardboard. Looked kind of ghetto, but it did help a lot. I rode down Shelburne Rd. and back on the bike path, about half of yesterday's trip. Throughout the trip, I wasn't completely sure, but I did seem to see 2 different behaviors on the instantaneous volt meter. At times it would only drop one bar under full throttle (normal), and other times it was down to half. I also noticed my top speed dropped about 10MPH when this happened.
When I got back, I checked all the connections, and sure enough, I found the culprit. The connection between the battery and the battery management system (BMS) was still a cheap, standard crimp connector. It was not too hot to touch, but definitely pretty warm. When I pulled it apart I saw a little bit of charring around one of the contacts. Going to replace this with a Power Pole connector.
Accidentally reset my power stats when I was changing the watt meter over, but enough said/noticed to satisfy me on this. Round trip was about 8.5 miles.
One of the neat things we got as part of our Christmas haul is a Crock Pot. I've been wanting one for a while, and it was really perfect timing. We've already made quite a few dishes in it, and it's been going very well. One thing that kind of sucked was that one outlet in the kitchen (apparently) doesn't work, and it took an hour to find out that the Crock Pot wasn't cooking. There is no power light on the device anywhere, and the only way you know anything is happening is by the surface getting hot, which either takes a long time to do so, or is so hot that it will burn your hand. Besides these lengthy guessing games, it's a safety concern when there is no visual indication that the thing is so hot you can't touch it. Not really ideal.
To complicate matters, I also invested in a simple outlet timer that would shut off power to the cooker in case no one was home to do so. The timer I got also lacks any sort of on/off indicator, so it's even more difficult to tell whether the crock pot is functioning or not.
A number of possible solutions came to mind, but I finally decided that the slow cooker/crock pot should really just have a power light.
Today I took the bike out again after a (supposedly) full charge. I decided to do an errand run downtown, normally a medium difficulty run in the summer because of traffic, etc. During the winter it was slightly higher difficulty due to the high winds and mud (from melting snow). I really need to get a front fender. My face was covered with brown polka-dots when I got back.
I guess the slightly concerning thing was that my pack voltage was lower than it should have been. It seems like perhaps it didn't get a full charge. A 12 mile ride is generally not anywhere near enough to drain the pack, and by the time I got back, it was close to the cut out voltage. The overall juice consumption seemed reasonable for the ride, but it seemed like that was about all that was in the pack.
Stats after ride:
42 minutes round trip.
Amp Hours Used: 8.431 AH
Watt Hours Used: .403 kWH
Pack voltage minimum: 45.35 minimum (this is really low for only 8.4 AH!)
Sitting at 52.8V
So tomorrow I'll take it for another run and see if I can figure out why my performance is being hit.
One of the amazing things about winter in Vermont, at least a normal one is that we typically get a January thaw. Almost like clockwork, the second week of January will give us a quick break from the brutality of cold, snowstorms, and short days. Today was one such day, and I decided to venture out on my e-bike once more.
For a while now (long before the invention of the Nest Thermostat (which is an awesome accomplishment in its own right), I've had the idea of building a smart heat management system for my house. Here are some of the issues that prompted me to consider doing this.
Susannah was talking about snow-shoeing today, and I got the idea that it might be neat to try to make some. From a pure practicality standpoint, at worst, it would be nice to have something to help the occasional trek out to the storage shed when the need arises. At best, I might actually try doing some real snow shoeing (in a place where I won't be judged by some yuppie with their $300 designer L.L. Bean, carbon fiber jobbies). I decided to use any of the million scrap pieces of wood in the garage.