x88x EV saga, v1.0: Honda E15 Magna

Quote:

---

Originally Posted by Technochicken

Good points. I've seen their cylindrical cells on Hobbyking, but they are 18$ per cell! I should be able to get my hands on some next year, though, as A123 is affiliated with the university I will be going to.

---

...aaaand, there you hit it on the head. ;) Through universities is how the majority of the interesting cells I see used are sourced. That being said, I do know a guy in China who builds M1 packs and sells them for, last I saw, ~$12/cell+shipping assembled. ..you know, if you get bored of getting them for free through your university. ;)
http://www.emissions-free.com/

Quote:

---

Originally Posted by Technochicken

Thanks for the spreadsheet, that will definitely come in handy! Good to know about the nano-techs as well. I've been leaning towards the regular Turnigy's, just because they are so cheap (relatively speaking), but I may have to reconsider.

---

If you want info on using Turnigy batteries in small EVs (scooters, ebikes, etc), the best resource I know is the forum over at endless-sphere.com. Now let me temper that recommendation...make sure you've got your tin foil hat and fireproof shorts on and take anything said that isn't directly backed up by hard data/proof with a moderate sized grain of salt. There are a lot of very post-active people over there with no actual experience with the stuff they're talking about, just repeating second-hand information over and over, sometimes misinterpreted and/or misunderstood. ..I admit, for a little while I was one of them, until I realized wtf I was doing and shut the hell up... :P Once you dig through the piles of crap, though, and find the probably ~40-50% of the members who do actually do stuff and have first-hand knowledge and experience on what they're talking about, I don't think you'll find a larger group of people who have used those batteries for exactly the application you're talking about.

Quote:

---

Originally Posted by TLHarrell

My brother in law was building an EV conversion of a K-1 Attack kit car (Honda Accord donor engine usually). He ran on hard times and had to sell it when it was nearly complete. He was using an AC Propulsion drive and A123 cells, and hand assembling packs from individual cells. Might be worth looking up his worklog. Lots of good insight there.

More on the project here: K-1 Attack EV Conversion @ Attackforums

---

Ouch! That's an expensive powertrain! And rare...AC Propulsion and A123 are both legendary in the EV community for basically telling DIYer to f*** off, we don't want your business...unfortunately, they're also known to make very nice products...really annoying combination, that...

I'll check out his log, see what he's got to say.

Quote:

---

Originally Posted by TLHarrell

I have a great interest in electric vehicles, but still sitting on the sidelines until the technology gets to where it needs to be.

---

Out of curiosity, in your opinion, what is that point? Not being facetious, I'm honestly curious. A lot of people have very different requirements...and hey, we might be there already, you just don't know it yet. ;) Obviously they've passed the threshold of viability for me or I wouldn't be doing this project. :D I don't think I mentioned yet; this is to be my daily driver during the riding season. That's why I really need to get that range.

Ran into a bit of a problem dropping the engine. I had Ichbin helping me and we took the side frame piece out and got the engine free-floating, but cannot for the life of me figure out how to get it out of there... Problem is, since the engine is wider than the frame, even with that section out, it still needs to move to the side before it can get free...and it doesn't help that the mufflers are rusted on to the accumulator...I may end up just taking an angle grinder to the accumulator if I can't work it out; it's mostly rusted to hell anyways, so I'm not trying to salvage it and if chopping it up lets me get the engine out then chop away.

w00tz! Finally got the engine out!

I cut off the mufflers (rather, cut through the accumulator before the mufflers...mufflers are actually in decent shape), but still ended up having to drop the bike on its side to get the damn thing out. Finally out though, so it's all good. :D

Got measurements, now I just need to figure out what I can fit in there.

Ok...so, I ran some numbers, sized some stuff, and...LiFePO4 ain't gonna fit...even headways...damn.. Hmmm, well, I'd been playing with the idea of LiPo anyway, since it would cut ~100lb off the pack weight. I guess the frame made the decision for me. ...now to nail down how to do this without killing myself...

Please don't die. :P Nice naked frame you got there ;)

Quote:

---

Originally Posted by x88x

Awesome! ...buildlog? :D Come on, I showed you mine, now you show me yours. :P

---

Here you go:

http://www.thebestcasescenario.com/f...306#post357306

Been off on ES for a bit, working out what I want to do with the batteries. I've come to peace with the batteries I'll be using (5S 20C 5Ah Turnigy packs), and am working on the battery module design.

From design thread there:


Ok, starting on actually designing the modules (intro here) for a ~11kWh lipo pack I am building for my electric motorcycle conversion. Pack will be 25S and at least 24P (as wide as I can make it, basically), constructed from a crapton of 5S 5Ah Turnigy lipo packs. These packs will be formed into 5 modules, each module being a load of packs in parallel. These 5 modules will then be connected in series to complete the pack. Each module will contain one of methods' LVC/HVC boards, managing the cells in the module.

I'll see what I can put together in sketchup tomorrow, but for the moment a text description will have to do.

Basically what I'm envisioning is 3 rows of packs, with a copper bus bar down each side, and one down between each border. Like so:

Each pack will be connected to the adjacent bus bars with ring terminals, and the leads shortened as much as possible to minimize the resistance between the pack and the bar. I'm currently thinking 3/16x3/4" copper bar for the bus bars. This should give me a conductor cross-section area of between 3/0 and 4/0, so I'm thinking that should be fine. ;) Currently thinking 2/0 for the inter-module links.

For the shell, I'm thinking some sort of high density plastic, held together with bolts. I ordered some 0.5" HDPE and some M6 socket flat head bolts to experiment with, so we'll see how that goes. In the mean time though, I wanted to put together a cheaper, lighter, easier to modify mock-up to get an idea for what I'm looking at. Enter foam-board.

I found an arts and crafts store near me today and went to pick some up. Found some nice 0.5" stuff for not unreasonably much, so picked up a few sheets of that to work with. Based on my measurements, I came up with this:
(turned out a little short, thus the little bit tacked on the end)

Pack in box:
(yes, I know it looks too wide; box is designed for 5S, that's a 6S)

I'm hoping to be able to cut a bit off the top; gonna pick up some aluminum bar tomorrow the see what I can work out.

Comments/concerns/recommendations/etc are welcome and appreciated.

###########################

Since then, I have received the HDPE sheet I ordered....and realized how strong and tough the stuff is...and heavy...and placed a new order for a couple sheet of 1/4". Really nice material though; I'm sure I'll find something fun to do with it. :D

Oh, and the motor's on the way! :D :banana:

I hope you're planning to add some sort of over-current/short protection in your bus system. I'd hate to see a short with all the packs involved. That'd really ruin your day. No matter how careful you are, there's always some chance of an errant screw or a slipped tool that lands in just the wrong spot. Always good to engineer as much safety into a system like this as possible.

As for the HDPE, I'd keep the 1/2" stuff to hold the fasteners better. You can always rout out some of the material to lighten it up. Make a nice template in MDF and run a flush cut router bit, cut 3/8" deep.