I'm new here (as you can tell by my post count) but I've been reading for a while and I'd like to tackle something new to me, an EV conversion project! I'm blessed by the fact that I have a 9 mile commute each day (4.5 one way) so when the weather is nice, a car for a daily driver does not make a lot of sense. You can do a lot of wear and tear to an internal combustion engine doing a lot of "short hop" commuting where the car never gets to warm up, so I've been looking into alternatives. Of course, a motorcycle immediately sprung to mind but then you run into the same problem of warmup. This is where the EV idea sprang from. Our office also has 120VAC 20A outlets in the parking lot for golf carts that we no longer use, so I can get a solid 8hrs of charge in each day, provided I go with onboard charging. The outlets are in a "open" area of our parking lot but the facility is not exposed to the "public" so vandalism/theft should not be an issue.
Being quite familiar with internet forums, I took the advice from the sticky in this section
and have started my "intro thread"
Your skill level with auto mechanics and fabrication
The range you are hoping to get (how many miles/charge)
- Quite skilled in auto mechanics, somewhat of a neophyte fabricator. I've been playing with cars and wrenching on thing for many years. I can run a soldering iron, build a wiring harness from scratch (Thanks Dr. Lucas) and I know how to use a set of dial calipers correctly. I can handle pretty much any automotive task thrown my way provided it does not require specialty tools and I have clear enough instructions. The family comes to me when they need their brakes and oil changes looked after I have no problem swapping and engine or doing a set of chassis bushings in a couple of weekends. I'm no welder but I have friends with the tools and experience. I believe in using the right tool for the job and I prefer to learn from other peoples mistakes and do it right the first time.
What level of performance you are hoping to get
- Technically 10 miles would be a minimum, but I see no reason not to shoot for 20~30 miles per charge.
How much money you are willing to put into your project
- Most of my commute is in town/country roads so 25/35mph would be an average. Maybe 45mph top speed but only for short bursts.
What parts you've already considered, if any.
- I'd like to keep the budget around $2000~$3000 all in.
My plan, in the broadest strokes, looks something like this:
- 200-400cc bike frame (availability & insurance cost dependant)
- Motenergy ME-1004 or ME-0708 motor
- Alltrax AXE 4844/4845
- Magura Twist Grip Throttle
- DC/DC converter (headlights, blinkers, etc)
- Onboard charging
I've been going back and forth between PB (Optima AGM) and something like CALB LiFePO4 for batteries. Here are my thoughts and the numbers I've found so far:
Pricing out a set 4 of 55Ah AGM bats as used in the above linked article (4S) puts me at like $3.65/Ah @ 12v, so $14.60/Ah @ 48v, so we are talking a shade over $800 in batteries. Pricing LiFePO4 from someone like evsource.com
requires 15 cells (15S) to get my 48v (3.2v nominal) and 60Ah comes out to $1.37/Ah @ 3.2v, so $20.55/AH @ 48v. That's $1230 total in LiFePO4.
For PB/AGM, it looks there there are no shortage of $50-150 chargers available for bulk charging at 48v. As for the LiFePO4, things get a bit ...complicated. I'm familiar with the volatility of LiPo from playing with multirotors and while I understand that LiFePO4 is supposed to be better, it still seems to require a managed BMS and a lot of additional hardware to the tune of 3-5x the $ cost of charge equipment for PB/AGM. Everything I've been able to find tells me that its fidgety, heavy, and not exactly "onboard charge friendly" for something like a motorcycle. That alone seems to kill LiFePO4 for this particular project.
As for weights, AGM comes to 174lbs and LiFePO4 tips the scales at 66lbs. That's 38% of the weight and 153.75% increase in cost. Seeing as I'm on a "$" budget and not a "#" budget, I'm thinking AGM might be the way to go, simply due to ease of implementation.
Anyway, that's where I'm sitting in this particular case. I'd love to hear some input from folks who have built EV motorcycles or recommendations for other resources. I've poked around a bit on elmoto and endless sphere but I figured this looked like a pretty good places to start. Thanks all for documenting and sharing your ideas!
Edit: I took another look today at my 9 mile commute on Google Maps and discovered that by adding 1/2 mile to my route I can completely avoid the 1 mile section of highway and the need for speeds above 45mph. I'm feeling a bit more confident about 48v now, so needs can be adjusted accordingly.