kewlnamebro said:
Commute is 13 miles one way and a 45 mph limit the majority of the way. It'll be ridden on country highways, twisties, and the parkway in the mountains (steady climbs everywhere). All in weight, rider + cargo included, ~400 lbs / ~180 kg.
Battery is your big limitation. Motor and controller are easy enough, as long as the motor is capable of the continuoous power dissipation needed to go up the hills and maintain your speed, without overheating. you might need a bigger motor, depending on that. contrller just has to match what the motor asks for.
Motor - QS 3kW V3 Hub motor
Would like to use factory rear wheel, likely 16 or 17 inch rim
I am concerned that a rear hub motor will provide odd handling characteristics
Not really interested in working a mid drive into the frame
if no middrive, then you're really limited to doing that rear hubmotor. motorcycles with front wheel drive have been made, but handling will be "odder" than a rear hubmotor, and has the potential in loose or wet surfaces (anything that culd break traction) of preventing you from being able to steer. if all you have is front wheel steering and front wheel drive, and the rear is just freewheeling or braking, you could have situations you can't recover from (because of loss of traction on front) where if you had power in the rear wheel you have another option of pushing thru into the direction you're left with and correcting, fi ther'es enough unobstructed road surface left in front of you.
the suspension is going to be affected by thehubmotor no matter which end you stick it in, but you hmay have more cheap options for "tuning" the rear than the front depending on the existing stuff on the bike.
handling is going to change regardless, unless you can match the placment of the mass of everything you add to everything you remove. that doesn't usually work, as engine usually weighs more thant he battery that replaces it, even if the battery volume is the same or greater. the motor weight and position is usually different from where theengine stuff was, even with a middrive.
but if you're not used to riding the bike yet anyway, then if it's not a drastic change cuasing problems with riding it in any particular situation, the handling change may not matter.
72v x 60ah is about 4.3kwh
at a guess, with stop/start traffic, hills, etc, at the speeds your'e after, you'll probably use at least 100-150wh/mile, depending on how aero your bike ends up, and how much starting from a stop and hill climbing you have to do. it could be a lot higher depending on those hills.
if it takes 150wh/mile, then 4300wh / 150wh/mile = about 28 miles of range. so it should get you both ways on your commute at least when it's new, though it doesn't leave you much for detours or unexpected headwinds unless you can charge at the destination just in case.
you can look around the web at wh/mile or wh/km discussions of various electric motorcycles to get a better idea of what it will really take, to be sure of your range.
or if you have an idea of the aero factors for your bike (cd, etc), you can go to http://ebikes.ca/simulator and read the entire page so you know what it all is and how it works and how to use it, then setup a custom system with the biggest motor there (or a custom one using the specs of the one you want to use), a custom controller with a current limit equivalent to what you want to use, a custom bike with the weight and cd-figures you have, and a custom battery equivalent to what you want to use. doesn't matter as much if anything but the bike stuff is exact, as the power usage wh/mile as a particular speed on particular terrain is what you're really after.
then you can simulate the various parts of your commute, and see how much each will take, estimate how many miles you have to ride at each wh/mile usage, and then total the number of wh you use on a trip, to have a more precise idea of how many wh your battery has to have to complete the trip.
that way you don't either get a battery taht is too small, nor one that is so much bigger than you need that you're wasting money and space on it.
a second consideration is that the battery has to be able to continuously output the current the controller needs, without sagging too much in voltage and without heatng up internally. tha'ts usualy specified by it's c-rate, which means how many times the capacity in ah it can output amps. if tis'a 60ah battery, and it's rated at 2c, then it could do 120a continous. if it's only 1c, it can only do 60a. etc. the cheaper the battery, for the same claimed specs, the more likely it is made of low-c-rate cells, regardless of the claims of the seller.
the batteyr is the heart of the whole system; if it can't handle outputting the power you need to do something, the whole system either shuts down or underperforms (possibly at a critical moment).
i don't have any specific sellers in mind for ones you could trust, for packs like you need, but others will probably come along to help with that.
Charger - ? (come with battery pack?)
you can usually buy that with the pack, or you can use others as long as they don't exceed the max design charge rate of the pack.'
i'd reocmmend a charger you can build into the bike, so it's with you wherever you are. taht typically means potted and sealed, fanless, so it's heavier bu it's weatherproof and vibration resistant. there are brand name chargers like this i don't recall, but i htink there's one in msjfoto1956's build thread. (which might be a good read for you, as probably would be pretty much any other motorcycle conversion thread here on es)
theres also led psus like the meanwell hlg series, they can be put in series and parallel and adjusted to give whatever charging voltage and rate you need. been using one for a few years now on my small sb cruiser trike, sees lots of vibration/bumps (no suspension) and has been submerged in flash floods a couple times to no effect.
Controller - Sabvoton SVMC72150 350A Phase / 150 A battery
there have been a number of reports on the forum that sabvoton is not the greatest quality anymore, since a few years ago another company bougth them, and various sudden-failure examples have happened. a search on sabvoton and/or mqcon should find these, if it matters.
i don't know which controller would be better for a custom-build, however, since many of the high power ones are not designed to be used by diyers and have no company-provided setup or programming support (and require setup and programming to use at all, like sevcon).
again, someone else should come along and be able to help with that.
