I'm perhaps slightly atypical on this particular forum in that I'm not planning to turn this bicycle into a motorcycle. For me, the whole point of transitioning to bicycle commuting isn't to save money or satisfy some notion of ecology, it's simply to force myself to get some damn exercise on a daily basis. So I'm not looking to have the bike do everything for me, I just need it to be able to act as a force multiplier and allow me to crest some of these inclines without giving myself a stroke in the process.veloman wrote:If you don't want to go above 25mph, get the 10T. The 8T will handle the 8-10% grades okay, but there's no need for the extra speed (30mph) on 48v, if you only want 25mph top speed. Better to have that extra torque.
And I can guarantee you that you will be blown away how much faster off the line and up hills these geared Mac motors are than a basic DD on the same 'commuter power' of around 1000w.
Well, I'm a realist and I understand that mechanical parts wear out even under the best of circumstances. The one thing that kind of bothered me just from looking at the emissions-free.com website is that there's no mention of spare parts availability. Granted, the motor/wheel kits are cheap enough that I could just order two and keep a spare on hand, but I'd feel a lot better knowing that common service parts are available.o00scorpion00o wrote:There are new clutches on the way, though you might have to wait a while. They can fail. Mine did by running far more power than I should have been!
I don't think that range will be a problem, assuming that the new system is not significantly less efficient from what I've been running. The 36v 10Ah LiMn battery that Amped sells has historically been sufficient for my range needs, as I do try to do most of the pedaling myself, using the electric assist only as needed.o00scorpion00o wrote:The battery is also a good choice, though you might find 11.5ah a little on the low side if you are riding up a lot of hills, depending on how much you are willing to pedal, and how far you have to go!
Well, that's part of the problem I'm having with the system I have now.dogman wrote:But in fact, a 72v 20 amp controller on your existing motor might make you very happy. You won't be crazy fast, but fast when it would fit your needs, like approaching those steeper hills.
If your battery can handle it, just upgrading your existing voltage to 40 amps will perk up the hill climbs too. Nothing you are doing requires special stuff unless it's a really long 15% grade.
Like I said, money isn't a huge concern here. I'd far rather spend $1k on a nice bike and another $1k on a proper drive system and have something that I really like than go half-arsed just to save a few bucks. And, as I mentioned above, the current drive system isn't operational at the moment to begin with. I'd been contemplating upgrading the bike for some time, and the recent loss of the drive system is what really gave me the motivation to just go ahead and jump.dogman wrote:Your real reality check is this. Upgrade your bike first. Get a nice full suspension frame, or complete bike if possible on the used market. It doesn't have to be a DH monster bike. Just a decent suspension bike with a fork better than a cheap pogo stick. The bike might cost more than you planned for a choice one, so you might need to ride your existing kit another season.
Don't take any MPH figures I've quoted as etched-in-stone. I put that out there in the first post because I knew if I didn't that would be the first question asked, but I hate giving numbers such as this because then some people might start interpreting them as hard-and-fast requirements. Given that the primary power source under normal operation (particularly on the flat and downhill) is me, and that I'm expecting the motor to really strut its stuff on the hard climbs, I'm far less interested in meeting any specific speed target than I am satisfying the "must be able to climb a 15% grade for 100 yards without stalling / lugging / overheating / exploding" target.dogman wrote:Replacing just the motor with a Mac 10t or the 2810 9c would get you up those hills better, but you will not hit your target speed of 25 mph unless you run more than 48v with the slower motors.
Indeed that's why I suggest a temperature sensor.veloman wrote:Regarding motor temperatures, I see very little mentioned about ambient temperature. It makes a pretty big difference, even 65 vs 85 degrees F. If I run my 8T Mac at full speed on 1200watts on fast roads, it won't get warm at 65 degrees temp outside for at least 10 miles. If it's 85+, then the motor can't shed it's heat nearly as well.
So, your climate has a big influence on how much you can push your motor too. Although, at ~1000w, I'm told then handle it fine even in hot weather. Lots of variables though. LOTS.
I wouldn't have thought that such a small change in ambient temperature would make such a large difference.veloman wrote:Regarding motor temperatures, I see very little mentioned about ambient temperature. It makes a pretty big difference, even 65 vs 85 degrees F.
Cell-man is the best person to ask that, he supplies higher rated bms's maybe it would be worth it to get that ? I would have thought it better not to run components at their max specs for long. As far as the cells are concerned, they are rated for 70C continuous, so 30 amps on the pack that would be just under 3C at 30 amps, maybe 4-5C peak. So your pack would have a very easy life! cell-mans triangle battery and bag might be worth the extra money if your triangle can take it ?Joe Perez wrote:My primary concern in mentioning the battery was in whether the 11.5Ah battery using a 30A-rated BMS would be sufficient for a controller operating at 30A. In other words, am I likely to damage the battery or BMS by subjecting it to a continuous 30 amp discharge? (see next section of message for why I am particularly sensitive to this concern.) It's well within the specified c-rating of the cell themselves, and assuming that This is the BMS used in that pack, I believe that the notation of it having a "50-80A Protection Current Rating" means that there will be a sufficient margin of safety (and I'd likely fuse it at 35-40A anyway), I just wanted to ensure that this specific area was not a cause for concern.
The 12T would run the coolest, and also be the slowest, It's always better to volt up a slower high torque motor than to run a fast motor with lots of amps, it just means a bigger battery for the extra volts. That's why the 8T is brilliant for me because I like my battery to be light as possible because I like to pedal to keep fit, it also gives me the speed I need for fun and can climb steep hills when I need to and the temp sensor will allow me to find the limits of the motor without killing it. I don't know yet how much of a hill it will climb and for how long!Joe Perez wrote:It would be nice if it were fast (I very much enjoy being able to pass the more serious-looking Armstrong Jr's on the uphill sections) however it would be devastating if I wound up with something that was very fast on the flat sections and yet unable to scale the hills that I really need it for. So if a 10T motor is ballsy enough for the climbs, then I'd pick it over a 12T. But if a 12T is what I really need to make the hills without destroying the motor / controller / battery, I'll gladly sacrifice top-end speed for that.
Chroot, this video is the single most convincing thing I have seen thus far. That is actually similar to the area in which I live, although our hills are not quite as severe. If a 10T motor can climb that incline on 48v at 1,5kw (which would make it a 30A current draw) then I suspect this is probably the motor / controller combination which I need. Thank you.chroot wrote:Here another MAC 10T tested by Hightekbikes at 20% grade hill in SF so 12T will be more faster climb up the hill at ease than on 10T MAC. Here the video show
Well, I'd like to leave my options open for the future. And, to be honest, the difference in efficiency between the 4110 and the 3077 should be so trivial as to be immeasurable.GMUseless wrote:If you are staying under 60V, you really don't need the 4110 fets...the 3077s will run better (less heat) at that voltage....and they cost less.
Huh, I didn't even realized he offered one. I planned to take the measurements of the triangle battery with me when frame-shopping, however. Worst-case I can always go with a rectangular pack and hang it off the front tree or beneath the rear cargo basket.o00scorpion00o wrote:cell-mans triangle battery and bag might be worth the extra money if your triangle can take it ?
Well, I have no first-hand experience with it, as I've never been an R/C enthusiast. My knowledge of LiPo basically consists of:o00scorpion00o wrote:How would you feel about LiPo ? IF you don't know much about it I would stay clear, but the reason I asked is because the 12T would probably give you only 15 mph on 48 volts, so I would go with 60 volts.
Well, the video that chroot posted on that subject seems fairly convincing, assuming that the data presented in it is true.o00scorpion00o wrote:The other thing about the 10-12T is how fast will it actually go up the hill is what you need to ask cell-man or someone who actually has those motors, you might find that 48 volts is awful slow while climbing!
Something to consider for sure. I'm not sure what the single-block BMS options for such a battery would be- I need to figure out with certainty if the series-BMS idea is valid. Two 39V packs in series would really be something.Lebowski wrote:If you want speed and hill climbing, get a 12T and a 80 to 100V battery.
To be honest, I've been leaning in the direction of a geared motor for other reasons as well, principally weight and free-wheel ability. I just didn't realize that there were such capable geared motors out there, given that most of the ones I'd seen previously tend to carry rather small wattage ratings.dogman wrote:Very true. Most of the people I have steered towards the 2810 9 continent are running them at 72v, and very happy with 30 mph top speed. And even happier when they have a steep hill to climb. But if you run that motor on 48v, it's too slow for most people, at 19-20 mph. It definitely will climb 15% without any problems, even on a lame 48v 20 amps.
Interesting that you say this, as I've finding the problem to be quite the opposite. There are a number of good bike shops in my area, so it's easy to browse around, sit on bikes, ride them, operate the controls, and get a feel for how they work. (For instance, I rode a bike with disc brakes for the first time this past Monday at one local shop, and I'm absolutely hooked. I'd have never imagined the difference vs. linear-pull rim brakes could be so dramatic!)dogman wrote:The advice about making a really good bike the first priority remains. The rest is an easy solve, the only problem is deciding which slower winding motor to choose, and what voltage to run.
Joe Perez wrote:Well, I'd like to leave my options open for the future. And, to be honest, the difference in efficiency between the 4110 and the 3077 should be so trivial as to be immeasurable.GMUseless wrote:If you are staying under 60V, you really don't need the 4110 fets...the 3077s will run better (less heat) at that voltage....and they cost less.
Looking at the International Rectifier's datasheets for the two devices, the 3077 has a maximum steady-state RDS(on) of 3.3mΩ as compared to 4.5mΩ for the 4110, and the VDS / ID and recovery curves appear virtually identical. So if we assume a constant 30A load, then in a worst-case scenario the 4110 would dissipate 4.05 watts at a forward drop of 0.135 volts vs the 3077 at 2.95 watts at 0.099 volts. (Granted, current in a polyphase inverter is not steady-state, however I assume that the operating frequency of the device is so low as to be functionally indistinguishable from DC to a device whose rise and fall times are well under 100ns, and whose dynamic properties are specified in the Mhz range.)
I think I can live with 1.1 watts and 0.036 volts.
I understand completely.GMUseless wrote:OK, I've got to admint I haven't done the math on this one (like you did!) I was re-stating what seems to be the conventional wisdom here posted by many of the gurus...such as: http://endless-sphere.com/forums/viewto ... 87#p357997 and http://www.endless-sphere.com/forums/vi ... 45#p142287
I sometimes dream of ditching my single Solex progressive carb in my '72 VW bus and throwing an FI megasquirt system in there as others have done. *sigh* Too over my head for now I'm afraid.Joe Perez wrote:I specialize in the Megasquirt family of ECUs
To be quite honest, building a fuel injection system isn't as hard as some people make it out to be. The actual wiring and tuning is extremely straightforward- the only challenges you'd face in converting an engine that was originally carbureted and distributor-based is mostly about hardware; finding or fabricating the correct intake manifolds and injector bosses, arranging a crank-trigger mechanism, etc.pwbset wrote:I sometimes dream of ditching my single Solex progressive carb in my '72 VW bus and throwing an FI megasquirt system in there as others have done. *sigh* Too over my head for now I'm afraid.
Well, think of it this way. As you add weight to your bicycle, it requires more energy to push up a hill, so you need more battery current and more motor power. I think we're all on board with that.GMUseless wrote:Thanks Joe. From your first reply, I indeed assumed the magnitude of the losses (though 25%) must be quite small. But what isn't quite small is the amount of heat generated from these controllers. That's indeed quite sensible. And at face value, you'd think 25% of that would also be significant.