Peak Voltage of 72v 20a controller

I was not willing to open up my controller yet but wanted to know what the maxium voltage input is on a Crystalyte controller. I currently have the 36v-72v 20a small version controller. Below is a picture from poweridestore.com:



I've wanted to try some high top speed but hot off the charger the dewalts are at 66v I wanted to add another 8v or so. Would it take or am I going to blow the controller?

you'll be fine. my controller (same as yours) have 72v worth of NIMH, which at full charge is 87v. actually my crystalyte controller is only stated to go up to 48v!!

p.s. a good tip for coolng is mounting the controller upside down because then the hot chips are stuck to the top surface and the heat can go up in to free moving air instead of up into still air inside the controller box.

Oops, wrong thread, Plz Ignore Me!

I"ve had mine up to 97v peak full charge.. ( Dips to mid 80's under load right away. )

As long as the " Fresh off the charger " voltage is below 95v, you should be ok, but it's Dangerous teritory, nothing for certain above 90v, each unit has it's own tolerances .. :wink:

I think the parts are rated for 100v.

they use either IRFB4710 or IRFB4310 fets. both are rated for 100V.

The IRFB4710 have a fairly high turn on resistance and tend to get quite hot at elevated voltages. this has proven to be a reliability problem.

that is why the newest units have switched to IRFB4310which have a lower resistance.

IT WORKS GREAT!

Thanks for all the help guys! I added a 5s 2p module of a123s to my 20s 2p setup. My system is now trying to hold me at above 33mph and sucks 1800w at the start. System voltage is now a nominal of 82.5v. The only problem is now I eat up the batteries riding full bore in 15 minutes despite the additional watt hours. Thanks again guys!

It's been talked about alot in the past, and found that in most cases, adding power results in the same range.. you just get there faster !

Ypedal said:

in most cases, adding power results in the same range.. you just get there faster !

Click to expand...

If he had a 40 amp controler, would his distance be roughly halved if used same throttle? Or does it not work that way, :? I never quite understood amperage.

recumbent said:

Ypedal said:

in most cases, adding power results in the same range.. you just get there faster !

Click to expand...

If he had a 40 amp controler, would his distance be roughly halved if used same throttle? Or does it not work that way, :? I never quite understood amperage.

Click to expand...

Easiest way is to remember that power in and power out will always balance. It's the variables such as wind resistance, etc. that can change the outcome in a noticeable way.

So if you had a 20 amp controller running 72 volts, that's basically 1,440 watts of power maximum you can throw at the motor. If you have a 40 amp controller running at the same voltage, that double it to 2,880 watts of power to send to the motor. What you have to keep in mind is that it doesn't always take maximum power to run the e-bike.

If a 20 amp and 40 amp controller e-bike were riding side by side, given the same bike setup, same motor, same battery voltage, battery AH, etc. The only difference would be resistance. So, if both bikes were going 20 mph down a level road, they would use the same power because neither has hit it's maximum to maintain that speed. But, if both e-bikes were to go up a steep hill, say over a mile long, all of sudden, the 20 amp controller is maxed out and can only maintain 10 mph up this steep hill, while the 40 amp controller e-bike has power to spare and tears up the steep hill at 20 mph.

So basically, you are using twice the power to cover the same distance in half the time. But in the end, the distance is the same, it's just a matter of how fast you got there. So if you can burn out your batteries with a 40 amp controller in 15 minutes and cover X amount of miles, in theory (given a perfect world), the 20 amp controller would cover the same distance, it would just take twice as long.

So think of the amps as the force needed to maintain a certain speed and the voltage as the controller of such and such speed. More voltage, wheel spins faster, etc. More amps, wheel spin speed doesn't change, just how much torque is behind that wheel spin.

Another way to think about it.

If you have 4 different people, each can run 20 MPH, that wouldn't mean that if those same 4 people were to carry a heavy box that they should be able to run 80 mph right? Of course not, it doesn't make sense to add up their top speed that way. What the 4 people can do is carry a heavy box faster than a single person, but only up to their top speed. Same thing when talking about volts and amps. Sure, the volts give you the speed, but without the amps you have nothing to push with.

What it really boils down to is wattage. Amps and volts are really not the right measurement to be deal with when you talk power to hold speed. Heck I could run a motor at 4v 400amps or 80v 20a but both, if geared correctly should be able to push me at a max of 1600 watts. When you pushing wind it takes watts to keep you moving not just amps or volts alone. Look at electric cars they run like 360v at 300 amps and do that to save on many levels, ie cost, weight, design. I believe the common thought with electrical design is amperage cost a lot in many ways.