dogman dan wrote:Nominal voltage, as explained above, is 3.7v. Most in the bike industry have settled into the standard for 48v being 13, 3.7v cells in series. This charges to 54.6v.
Others prefer a bit more speed, a tad more wattage, and run 14s. This charges to about 58.8v,, or some will undercharge a 14s, and go to somewhere around 57-58v.
Most 48v controllers have an absolute max rating of the capacitors inside of 63v. Open your controller, see 63v on the little cans inside,, there you are,, your max is 63v. Of course,, some push that some,, after all, your battery will sag a few volts as soon as you apply throttle. So with some risk, folks are known to run 15s,, or even 16s, especially if they also undercharge a tad.
And by the way,, if you are looking at power tool batteries, like mowers and trimmers, ,, they tend to go by 4.2v,, and call a battery 50v,, instead of 44v.
As for your motor itself,, its a 28 mm wide magnet direct drive. I've briefly run those at 4000w,, 40amps controller and 96v nominal. At 3000w,, usually a 72v 40 amps controller, you can run out about 10 ah worth of battery before the motor starts to damage itself. About an 8-10 mile ride full speed of 40mph.
A better, longer lasting plan for those motors is not to try to get 45 mph out of them. Let your full speed be around 30 mph or so, and run 48v 40 amps controllers. At 2000w it will ride very perky, and only risk overheat if you seriously overload one and ride up hills.
If you want 3000 or more, then you really must go to a much wider motor, with a lot more copper and wider magnets. then go for 5000w.
Now,, as for your battery plan,, bleah,, those holders I mean.
Assuming your current controller is 22 or 25 amps,, you need enough cells in parallel to put out 25 amps continuously.
A good rule of thumb for that is take the cells max amps rating, and cut it in half. So say one cell says it can do 4 amps,, calculate at 2 amps,, 25 amps will require about 13 cells in parallel. But you wont pull 25 amps continuous with that controller,, so figure on about 18 amps to cruise full speed, at 25 mph or so. For this example,, 18 divided by 2 amps,, you need 9 cells in parallel. Your cells might be better, or worse,, but at least 100 cells sounds about right.
That's the minimum,, if the cells are not real great,, 20 ah is a bare minimum. 30 would be my suggestion, unless they are top of the line cells.
OK, now I understand a lot more about exactly what the bikes can take power wise, that it's not just cut and dry, and why. That helps a lot.
My confusion with the necessary AH's to run my systems came from seeing some vendors selling 15 AH batteries for the 1000w, and then there is the guy on youtube running a 9ah for his 1000w and getting about 20mi out of it. I was just about to the point of thinking I need to just build something small and try it and see for myself what happens but, the info on this thread seems pretty reliable.
So, as long as I could go fairly small, I'd probably try the removable battery route, but 100 batteries minimum, or even 50 per pack if I divided it, are just too many batteries to deal with that way.
Its just that I hear all kinds of things about balance systems maybe not doing their job, something going wrong in there and the user not being able to determine if there is even a problem with a fixed system like that. Does anyone here recommend a more conventional non balanced system? I mean not something like I had planned but a fixed system where everything could be checked manually... I'm sure some of you have seen the "Balancer or no balancer" videos...that's what I'm talking about.
As for the way I'll be riding the bike, I'm kind of old so, especially on the three wheeler, 20mph is fast enough, as I can see serious problems with possibly flipping that thing or something close with a muck up at higher speeds. In my Sidewinder two wheeler, about the same speed seems safe but I can seem myself getting comfortable with it and maybe wanting more speed, but not much more. I do have to say, when they both were running right on electric power, they were pleasure to ride so, cant wait to get the kinks worked out, and as I say, get mor comfortable with em'. I think I'm still a little afraid of them. Several motorcycles, but until now, haven't been on any bicycle for probably 50yrs or better. I was actually wondering if I'd remember how to ride, then I remembered the obvious.
As far as amperage, I can tell you, the three wheeler, will blow a 25 amp fuse with anything extreme, like accidentally leaving the emergency brake on, and 30 amp seems to be working well for it. That should render some clue about the amperage....I guess.
On some of the details you mentioned, Dan, that's what I'm looking for, what most people do. So unless I run into a another situation where I can get a lot more good batteries quickly for under a buck each, I'll keep up the tedious task of gathering about 25 more batteries and go with the 100 battery/20ah pack recommend. I knew there was a thing about total amps necessary but am more clear on that now, and why the larger packs are a must for me. Thanks for that and everything else there, Dan.