V2.0: Inside the AC15 motor

So I talked with my motor mount fabricator the other day, and we looked over the AC15 motor a little. It appears that the motor is quite a bit longer than it needs to be. He asked me to take apart (which I wanted to do anyway), so that we could see if things could be integrated more. We want to do some drawings of the main part of the motor and see how a motor mount/bearing holder could be built. Not sure if we’re doing it just yet, but it helps to have it apart to see how feasible it is. From first glance, it looks like there may be some room for a couple lengths of copper tube for cooling. Here are some pictures of the motor disassembly:

So hopefully this week I’ll have a better idea how the motor is going to be mounted. In the meantime, I can at least plan for the motor to be in a specific spot on the frame. I’m going to try and mock-up some battery stuff this week.

Still contemplating purchasing a CBA-II to test the batteries. I found a used CBA and Amplifier online. I’m waiting to hear back from the seller. If I get it, I can test the 38120S cells at 160A (16C). This could be very useful, and I could test batteries for other people.

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V2.0: Mechanical planning

So, I was out of town for about 2 weeks for Christmas. I got to see family, some friends and my girlfriend’s friends….. in NJ, Virginia and DC. It was tons of fun, but I’m kinda glad I’m back. I should have more time available to do some stuff on the bike.

Last week, I decided to go ahead and throw a small pack together with the BMS boards installed and take some pictures. I need to get an idea on how much room I need. I used one positive, one negative and one mid board. There are 3 physical connections to the actual batteries per-board. Each board balances 2 cells. There is also a communication connection between boards (1-wire), and on each negative and positive board, it goes back to the  controller. I need to order connectors and see if I can get some communication working the next few weeks, but the BMS will be one of the last things to setup, I’m more worried about getting things put into the bike. Here are some pictures of a 6s2p pack with BMS installed:

I went to Home Depot this last weekend and got some Pink insulation foam. Its about 1.5″ thick and pretty sturdy material. I plan on cutting pieces of foam to mockup the space inside that I can use for batteries and controller. I’m getting to the point where I can start to really get a good idea on how I want to mount things.

Last night a friend came over and we went over the chassis. It sounds like he’s going to help me out with the motor mounting, and maybe a cooling plate for the controller. I’m going to disassemble the motor so we can look at it to see if there’s any way to reduce the motor length and mass. We need to see how it mounts to the end plates so we can figure out a way to mount the motor efficiently inside the frame. I also realized, that the chain position was wrong, and the motor could shift down and back about an inch, which would put it closer to the pivot point. That gives me another inch for batteries, which I’ll need. I wanted to shift the batteries backwards anyway.

Motor mount will be aluminum. Battery case might have an aluminum frame for mounting strength, but the sides will likely be hard plastic, so things don’t rub and short. I saw a 192-cell pack of headways sitting on a bench on Tuesday. It was about 22″ tall, 10″ wide and 12″ deep. Huge copper busbar (which I will implement as well) really made the pack rugged. The funny thing, I have 10.5″ wide, 13″ deep, and 22+ inches tall, so I think I can actually fit my 192 in my bike without much modification.

So, agenda:

• Dissasemble motor and take pictures and measurements for the motor mount
• Get mockups of controller, motor and charger and decide on placement
• Use foam to fill the empty space where batteries will be installed
• Use the mockup of empty space to design a mattery pack
• Fabricate motor mount and battery case

This should get me to a point where I can assemble the bike and get the main system working to test. Then I can move forward on getting the 12V system working, as well as make sure the keyswitch, contactor, kill switch all function the way I want them to. Finishing the bodywork, headlight mounting and dashboard will all come last.

Its taken a while, but its really starting to come together. Its my first time really doing any sort of mechanical design, but I’m having fun learning. It’l pay off in the end.

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V2.0: Batteries and BMS

Its been a busy season. I went to Ashland, OR to visit Brammo and Barefootmotors (will write about that this weekend hopefully). The weekend after that I went to Spokane, WA for Thanksgiving with my relatives. I haven’t had a ton of time to sit and do stuff on the battery side of things.

Last night, I brought my batteries inside from the garage. The temperatures have been very low this last week, and I feared the batteries might get damaged. I sat down for about an hour and measured each and every battery. Out of 195 batteries that I had sitting there (6 more are at Synkromotive, 1 in my car), one was 2.8V, two were 3.19V and 2 were 3.22V. The rest were between 3.28V and 3.33V. Not bad for sitting almost 3 months.

So my plan this weekend is to make some progress with the batteries. I want to put small batches in parallel to equalize, and bring them all up to ~3.65V with a 3.7V DC-DC converter and power supply I’ve got. After letting them charge, I’ll disconnect and let them all balance between eachother and settle. This will ensure a balanced pack before building. If it isn’t pre-balanced, the BMS will take a long time to balance the cells by itself. People often make the mistake of not balancing the pack before assembly, which can cause them many problems down the road.

Hopefully I can finish equalizing cells this weekend. If I do, I’m going to see if I can borrow a CBA-II from Phil Hochstetler (to do a 3-4C discharge on each cell to make sure they’re all in good shape for the pack. I can log each battery and save the graphs. It’l help knowing how each battery (barcoded) progresses over time.

I don’t know if I’ll have time to get much more done before I go visit family in Roanoke, VA for Christmas. I leave the 24th of December and return the 4th of January. Once I get back, I need to contact my welder to get the fabrication started while I do some battery setup and test.

Thats it for now. Should be a fun January and February now that I’ve got pretty much everything.

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TTXGP: Race at Infineon in May

I read about the release of the Mavizen TTX02 motorcycle last week. I had known about the project for a while and had eagerly awaited its release at SEMA. Really slick looking bike based on the RC8. After reading a little about the bike, I saw a few other blogs that mentioned something very very interesting…… TTXGP in the US at Infineon.

I looked online, and its about 9 hours from here. I got to thinking, I should go…. and bring my bike. I just need to find more details on the race. Even if I don’t race it, I’m bringing the bike.

Its an exciting time, we’ll see where it goes!

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V2.0: AC motor and Elithion BMS

I know, I know…. you’re all wondering when am I going to get this motorcycle finished. Well, you know how it is…. constantly tweaking things is a trait that comes along with being an engineer. Whether thats a curse or a blessing, I do not know.

One step towards finishing involved ordering my BMS from EVComponents last week. I decided on an Elithion Lithiumate BMS. Its got a main control board that talks to all the cell boards. There are 16 cell boards (one for every 2 cell groups). The BMS also monitors pack current and charger current and will shut off the contactor and the charger relay depending on the cell voltage level. Its all programmable and its got Canbus and an RS232 connection. Its a pretty full featured system that will match very well with my headway pack.

Here are some pictures of the BMS system (hover over for description of component):

So what else? Well, while cruising the EV Trading post, I noticed that Mark Gresens (part of the Barefootmotors TTXGP team) was selling some motors and controllers. I emailed him, and he told me he’s selling a barely used HPEVS/HPGC AC-15 shafted motor and a Curtis 1238-6501 AC Controller (550A 72V)  with the enGage IV digital gauge. We haggled a little bit on price, and I decided to make the plunge.

The way I figure it is, I wanted to go AC from the beginning. And now, with my bike system almost done, I still don’t have a controller. For the cost of my DC motor and getting a DC controller, I can upgrade to AC. Now I’ll have a fully programmable controller that can exist on the canbus network with the BMS, get regenerative braking, control some external devices like lights/blinkers/contactor/etc and have a completely sealed controller.

Here are some pictures of the motor, controller and gauge display:

So, what to do with the old DC motor? Well, I talked to Dave Noble (another guy doing a VFR conversion in Seattle, Wa), because I figured I could at least sell him my motor mount. We talked, and decided that we’d trade my ADC motor and mount for his Jim Husted rebuilt 7″ motor. What will I do with that motor? Well, My buddy Josh Renoe in Portland needs a motor for his go-kart and its a perfect match. Everyone is happy.

So, I said its a 1238-6501 Controller, thats 72V right? You’re all thinking “I though you were doing 96V ?” Well, My friend Eric Cha (a guy I’ve been consulting for in the Portland area) is building an electric tilting 3-wheeler right now.  He had already decided to go with an HPGC AC-31, but was going to do 72V. I called him and said “hey, do you want to order yours with the 96V 550A controller and I’ll pay the difference + some extra cash and I’ll send my controller to be programmed for your AC-31?” He thought about it and figured “why not”…. He already had the 72V charger and his pack can be easily setup for 72V (since they’re headway cells as well). He even put in an order for an Elithion BMS too. Him and I will have essentially the same system (DeltaQ charger, Curtis controller, HPGC motor, Elithion BMS).

So After all is said and done, Dave, Josh, Eric and I all get what we wanted, and can move towards finishing our projects.

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V2.0: Building the Lithium battery pack

So the pack building has begun. It was delayed because earlier last month a few customers at EVcomponents needed some cells ASAP, so I sent them some of my cells since I didn’t need them at the moment. I ended up selling all but 6 cells of my original 200 cells. Well, last week, the EVComponents order came in and Chris Bakken (who is involved with Synkromotive) was traveling up to pick up some cells for a project and offered to pick mine up as well. All 200 cells are on hand, as well as some pack hardware. The extra cells will be used for spares and an aux battery pack.

When I first planned on doing my own pack, I was going to CNC some holders and plates. Once I saw the building blocks from headway, and the 4-hole buss plates, I decided that I’d use their hardware to assemble my pack. I had Dave (evcomponents) throw some on my invoice and give them to Chris. I decided to go get them at the Synkromotive shop last night.

I was actually impressed of the quality of the building blocks and buss plates.

I found that the fit was a little tight on the positive end of the cell, so I cut about 1/2″ of the heat shrink off the end of the positive end. The fit was great. I need to heat it up to see if the shrink tubing pulls back at all. Here are some more pics of the 6-cell sub-pack being built:

I also got a 200W 48VDC power supply along with a 75W 48V to 3.7V DC-DC converter. This will serve as a charger for a single sub pack to ensure all my batteries are charged to the same voltage. I can also use it later to bring up any low sub packs if they go too far out of range.

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