I am working on versions with 4115 fets and higher voltage caps and I am looking into the feasibility of using IRFP4568 as well for even better performance (and reliability).
Since these fets are rated for 150V, we should be able to comfortably push at least 130v.
John in CR wrote:Of course there's a performance advantage using higher voltage, which is a different topic. The point I was making is that for a given rpm and torque a given motor gets the same signal from a controller regardless of pack voltage. It may be broken up into different size pulses due to pwm, but what the motor "sees" is a relatively constant supply. That means we don't get a benefit in the form of reduced I2R losses by using higher voltage for the same power. Yes, power input is volts X amps, but volts and amps have to be looked at separately...current for torque (acceleration/thrust) and voltage for rpm (speed, though there's a torque component with speed since the load of overcoming wind resistance increases geometrically.)
Regarding promoting the use of 100V limit equipment with packs that are 100V fresh off the charge, regardless of anecdotal evidence of people getting away with it, it should be discouraged. Those who get away with it are pushing light loads and use easy to drive motors, but even then failures are too common, and no one pushing real performance has gotten away with it without popping plenty of controllers. Since you're a vendor I'm trying to do you a favor. We've had only one vendor on ES who promoted the use of 24s packs with 100V limit components in the controllers, and he quickly went out of business. Absolute reliability is pretty easy even at extreme performance, and that is accomplished best by staying well away from current and voltage limits of any component in the system.
Powervelocity.com wrote:If there is no benefit in higher voltage, we should be all getting 12v packs with 1000A discharge rates and be happy with all the torque we can get from it.
I will choose my 24s over 20s or 18s in a heartbeat, as the difference in performance is substantial.
And I have no concerns overheating my 18Fet controller running at 100v and 100Amps. The motor MXSUS v2, however, does overheat after 3 minutes running at 9kw but that's expected as that's 3x of its rated power.
John in CR wrote:Using higher voltage to reduce I2R losses for the same power only applies between the battery and controller. Regardless of pack voltage for the same torque and rpm (power) the motor gets the same thing from the controller. Our controllers are buck converters to change the DC coming from the battery to exactly what our motor needs. I use higher than necessary voltage for a different reason than you plan, to get higher torque (greater acceleration) all the way through my usual top cruising speeds. That higher performance resulting from higher torque does have a cost in terms of more motor heat, but riding around using the same performance I would with a lower pack voltage has no cost in motor heat. There is more heat in the controller though, which warrants using a beefier controller like you plan. There's some interesting discussion on this topic here https://endless-sphere.com/forums/viewt ... 30&t=79229.