[B]If I have 12 6v batteries and want to run 2 series of 6 parallel at start and swap to all 12 in series for faster top end what can do this ?
Or do I have this all wrong ?[/B]
why would you do that? Are you using a controller? If you are, the controller decides the power that the motor gets… you just throw the bats on there and off she goes. The cap bank inside helps with low end current. My motorcycle bats put out 80, controller puts out 350 to the motor.
if not, you’re going to need some HUGE contactors.
[B]Yeah I’d be using a controller, just I was reading that for a stronger take off you need more current right now. If I was to have 2 packs of 6 12v batteries that would be 72 volts but at double the AH…
But to get good top speed one needs a higher voltage and you use alot less amps… all 12 12v batteries 144v but you have the AH capacity of what ever one battery has.
I just thought if you could switch from 72v until you needed higher speed to 144v…
Thought I was thinking in the right direction ? Or can a controller do this on its on ? If so How the heck do you wire the batteries and what controller does this ?[/B]
I’m using 12, 12V batteries right now, 2 packs of 6 wired to the controller… but I’ve tested at 144V and the power is the same at take off.
Basically, when you start to push the throttle, the PWM only a small percentage of 100%. Say the duty cycle is 10%, during that 10% you’re connecting the batteries AND the capcitors inside the controller (there’s a cap bank inside) right across the motor for 10% of the time. The other 90% the batteries are charging the caps back up.
As stated, power is power. If you have 144V at lets say 50Ah, that is the same as 72V at 100Ah. Same power. The controller will pretty much do the rest.
My bats run 80A output, the controller, at the same time, puts out 350A… voltage on the pack side is constant, the “average voltage” on my motor side is VERY low, but high current.
Controllers do this on their own, thats what the caps inside are for, to keep the DC bus charged. Most controllers do this, some do it better, due to the size of the cap bank. When you do this, just wire all 12 bats in series as 144V to the controller… the thing is, you need a 144V controller, which costs a TON more than 72V controllers.
We (synkromotive.com) make one, 156V 600+A, USB programmable, has built in precharge resistor, contactor drivers for Main and the Forward/reverse contactors, Fault dash light and built in fault logging. Its pretty slick. MSRP is around 1500, but we’re doing a Beta test program where you can get some of the first off the line for wholesale price.
Curtis used to make one (it wasn’t on their site a week ago), kelly says they make one, but they’ve had issues. Logisystems makes one, but its spendy, and not programmable, and there’s the Zilla, way overkill.
[B]
I was looking at the 1000 amp Zilla actually. But I’m still learning how to pick the right motor, controller for a certain size EV… I still need to learn more “and get up the money” to build my first ride.
So you are part of a manufacturer that makes controllers ? Hmmmm can I buy you a beer or two ?[/B]
well, you have a motorcycle, whats the weight? Start from there. Figure out weight + rider. Figure out the acceleration you want to get out of it, figure the speed you want to get out of it.
Acceleration, gear ratio and weight will allow you to calculate the torque needed from the motor. the speed and gear ratio will allow you to calculate the RPMs of the motor and the voltage of the system.
Always work backward with EV’s. You might end up throwing alot of money away because you just want it to haul ass… but it’l haul ass just fine without all the extra amps. Zilla on a motorcycle would be for drag racing… but it would be pretty fun too.
I am one of the engineers (mostly system design and applications, not circuit level stuff)… for Synkromotive. Just starting up, but we’ve got their controller in my motorcycle, and it rocks.
[B]I will be building a Trike, I will build a custom frame as the stock one just isnt right for alot of batteries, I have a front and rear end for now and when I can get all of my batteries I’ll build a frame around them, mount the motor right onto the rear axle with a short chain.
From what I can gather 10 group 24 batteries will be approx 600 pounds.
Rear axle 200 pounds, rider 200 pounds, the rest of it 200-300 pounds.
So at the most it will be 1300 pounds.
Top speed 55 mph or so.
Range 20 miles would be all I would need.
As much accel as I can get with the limits and/or goals above.[/B]