Unfortunately this project has stretched to over a year longer than intended due to starting a business, consulting people and having a girlfriend, etc. Couple that with the fact that I don’t own some of the metalworking equipment I need to build my battery enclosure and holders, and time just runs away.
Because of that, the batteries sat in a box in my apartment.
So, one thing I was a little weary of over the last 6 months, is the health of my 180 cells. I charged them about 4-5 months ago one-by-one with an RC battery charger. They had never been charged before that and didn’t apear to be consistently charged from the factory. After charging, they all had basically the same voltage (I know SOC isn’t a real accurate measurement of SOC, but at the top/bottom, it’s fairly accurate).
Last night, dreading the chore, I measured all 180 of my batteries with a handheld multimeter. Not one was below 3.28V and they only varied about 0.06V amongst all of the cells. No dead cells. None had a large self discharge. I didn’t record the starting voltage for each cell bar-code, but I’m really happy with the fact that these things can sit for months and months and have no problems. When I do make the pack, I’ll start things slowly and not hammer on them too much just to wear them in properly.
Since it’s winter time, I’ve got some more free time, and I’m starting to work out the electrical system. A friend of mine is taking my extra frame and we’re going to make some mockups of the battery pack. We were considering spray foam, that way we can cut it away as needed and fiture out the final dimensions of the pack. He’s a welder so we should be ok on the enclosure side of things.
So Adrian finished working on the discharger. I’ll need to mount the last module, driver boards, fuses and some fans to the ends for cooling, but it looks like the mechanical is finished. Picking it up tonight! Adrian and his guy did a great job.
No more CBA-II for discharging batteries….. I’ll be using this discharger and a data logger that I can actually calibrate for free (unlike the CBA, where you have to pay more for a calibrated version).
So I took a little time this last couple months to set up my business and got a couple clients, which is great. I can start to work a little on the bike and side projects. One of the side projects involves designing a battery discharger for high amps. I get customers that want me to test a cell, but I can only discharge to 150A continuous. With some of the new batteries, I need something with a higher discharge ability. I’m working with a friend of mine on this project.
I realized that testing is something that not many people are doing, and it’s something I’ve gotten used to doing for friends. I’d like to be able to test larger batteries and different setups. I like my discharger setup, it’s just gotten a little small for needs beyond my own. It’s been great for testing my Headway 38120S cells.
Basically, we’re using 6 Darlington pairs (DP) in dissipative mode, rather than full on or full off. This basically makes the DP’s resistor that can be varied externally with an analog signal. Each DP has it’s own shunt for a feedback loop, so the control board can control the current going through the DP based on a set-point. I divided into 3 different groups. Each group has 2 DP’s, 2 Shunts one contactor and a driver board. This allows some redundancy. If one group fails, it’ll drop out on it’s own, and signal the others of the fault. This also helps, because the contactor and fuse can be rated at a lower current. The DP’s should be able to do about 1000W each, but we’re derating that to ~500W each for now, so ~1000A total. This will all go back to some sense boards that measure the current, temperature and voltage of the cell(s) under test. My mechanical friend is assembling the device. Me and my buddy are working on the driver boards that will drive the DP’s.
Here’s a couple pictures showing the device so far:
Haven’t been up to much on the motorcycle besides getting the shop cleaned up and getting some help with the battery pack
Got my forks rebuilt last week and drilled out my triple clamp to attach a bar riser I found to mount some Spiegler superbike handlebars. Only 1 problem, the brake line isn’t long enough, so I need to order some new lines. Kind of a bummer, but now I can upgrade to braided brake lines quick would be good since I’m running with 25+ year old lines.
Got me thinking about just replacing the front master cylinder too. They’re harder to get parts for. Since I don’t NEED anything immediately, I’ll let things go until I get the bike running because I’ll probably want to rebuild the front and rear brake slaves, replace brake lines, replace pads and put new brake fluid in there. It’l be a good nice weekend project in the spring.
But at least it’s back together. I’ll throw the old bars on there for now until I get the lines. Probably be a couple months because I don’t really feel like rebuilding the brakes right now. At least I can get back to the battery pack I keep putting off. The forks were rebuilt last week as well, so the bike is now a rolling chassis again. I sketched up some ideas for the battery pack and think I’ve got most of it sorted out. I didn’t want to start doing a bunch of work, then have to take the forks off, rebuild them and halt the work. I’d rather do it now and not have to do it again.
So here’s the current state:
Lots going on behind the scenes I guess. A few weeks ago, I ordered a friend a 1238-7601 and AC20 combo and he mentioned that he wanted to make a heatsink for it. He found a good price on a heatsink that mostly fit the controller and told me he was going to mill it down and fit it to the controller once he got it in his hands. I asked him if he could order 2 and mill an extra for my bike (I was already going to do this). When it arrived, it only took him a few days to get his milled. Then he confirmed with me, milled it and shipped it. Let me just say, this thing is beautiful. I kind of want to anodize it!
I also drove to Seattle for some consulting I’m doing with an old buddy of mine. Pretty cool projects. I’m helping a little bit on the electrical side. On the way back I picked up my old motor and old 28Ah batteries from the guy I sold them to. He’s moving and can’t finish the project. I figured I can use the SLA’s for a nice test bench at home. Got some 72V to 12V dc-dc converters and some spare VFR parts too. I got the old motor and agreed to sell it for him, I’m sure it’l find a place.
Also, since I’ve started the consulting company, I’m trying to get that all sorted. I’m not in a hurry and I’m not rushing it. I need to get a website up soon though. I worked on it this weekend and met with Jason (he’ll be working with me), so now I’m a bit freed up to work on this project. My GF moved an hour away, so that means a little more spare time during the week. Hopefully I can get some more done this weekend too. REALLY need to get that battery pack laid out.
That’s it for now.
Time for a little update, but this time it’s not about the electric motorcycle.
For the last couple years I’ve helped a ton of people figure out what system they need for their vehicles, sold batteries and BMS and helped with technical support. I’ve also worked with some OEM’s in helping them with their vehicles as well. I’ve recently started testing batteries for various people. I was doing this all as an independant contractor as a side job.
So late last month I decided to start my own company, Electro Motive Force, LLC (EMF), so that I can funnel work through it. I’m not leaving my day job, but I want this gig to be a little more official and have the benefits of having a business. I’ve asked 2 colleagues of mine to help and they’re onboard and I’ve partnered up with several other businesses. We’ll be doing pretty much the same thing as I’ve been doing with the addition of a few things. Currently working on getting a website up and running. I don’t want to give more details right now, but I will say that this next year is going to exciting!
This shouldn’t take time away from me finishing the motorcycle, it might actually help speed it up!
Uncategorized | Travis | 
December 7, 2011 9:32 am | 
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