Limitless ESC amp rating vs number of supported Lipo cells

[nathanlow]

Hello!
Out of curiosity and for my understanding, have a question on esc amp ratings.

Hobbywing XR Plus, 200A: support 2-6S lipos.
Hobbywing XR Pro, 200A: support 2-4S lipos.
Hobbywing Max 6 : 160A : Support up to 8S lipo
Ztw Beast pro : 220A: support 2-4S lipos.

Questions: Why some of the 200A esc can only support up to 4S where most 150A esc can support to 6S?
Even within the HB Xerun series, same Amperage but diff Lipos supported.

Anyone have any clue why this is? Thanks guys

 

[Grimbles]

S rating tells you how many cells in series (I.e. voltage) an ESC can take. Amperage rating tells you the motor draw in amps that the esc can take (sometimes given on a continuous and/or peak basis).

 

[nathanlow]

S rating tells you how many cells in series (I.e. voltage) an ESC can take. Amperage rating tells you the motor draw in amps that the esc can take (sometimes given on a continuous and/or peak basis).

yeah but...doesn't make sense that a 160 A esc can take up to 6S, whilst a 200A esc can only take up to 4S..thats what im scratching my head about..is it that the internal design , mosfets and heatsink designs are different, and Xerun esc are made for competition use, and can last longer on races without overheating/over amp, thats why 200Amps, but limit to 4S?

 

[Grimbles]

yeah but...doesn't make sense that a 160 A esc can take up to 6S, whilst a 200A esc can only take up to 4S..thats what im scratching my head about..is it that the internal design , mosfets and heatsink designs are different, and Xerun esc are made for competition use, and can last longer on races without overheating/over amp, thats why 200Amps, but limit to 4S?

So the formula for amps is Watts divided by volts. Amps is not the same as volts is not the same as Watts. Take two examples:

4s esc (arguments sake let's call this 16v) @ 200A. The power output (watts) is 16x200=3200w

6s esc (arguments sake let's call this 24v) @ 160a. The power output (watts) is 24x160=3,840w

So the 6s esc has a greater power output over a lower amperage.

 

[nathanlow]

So the formula for amps is Watts divided by volts. Amps is not the same as volts is not the same as Watts. Take two examples:

4s esc (arguments sake let's call this 16v) @ 200A. The power output (watts) is 16x200=3200w

6s esc (arguments sake let's call this 24v) @ 160a. The power output (watts) is 24x160=3,840w

So the 6s esc has a greater power output over a lower amperage.

Awesome..thanks so much @Grimbles. Never thought of calculating the Power (W).
Now it makes sense.
Cheers!

 

[rotauq]

Little sidenote that the ZTW beast pro 220A does accept 6S.

Whiles cooling is mostly matched on watts. Amp limit is set on the wattage of the highest voltage.
Voltage restriction mostly comes from caps, mosfets and voltage regulators. These don't scale nicely, so size and specs like (ESR) will become less optimal.

A racing esc optimized for 4S competition will do slightly better on 4S than a 8S capable esc running on 4S (+ extra size/weight)

 

[nathanlow]

Little sidenote that the ZTW beast pro 220A does accept 6S.

Whiles cooling is mostly matched on watts. Amp limit is set on the wattage of the highest voltage.
Voltage restriction mostly comes from caps, mosfets and voltage regulators. These don't scale nicely, so size and specs like (ESR) will become less optimal.

A racing esc optimized for 4S competition will do slightly better on 4S than a 8S capable esc running on 4S (+ extra size/weight)

Thanks @rotauq for the correction on the Ztw. Now, i get it. Before this, i was looking only at the amp limits, and wonder why some 150A can use 6S while the 200A esc can only use 4S. (max8 vs xr8 pro).

So,
XR8 pro : 200A x 4S x 4V = 3200 Watts
Max 8/Spektrum150 : 150A x 6S x 4V= 3600 Watts
XR8 Plus : 200A x 6s x 4V = 4800 Watts
Max 6 : 160A x 8S x 4V = 5120 Watts
ZTw beast pro 220 : 220A x 6S x 4V= 5280 Watts (suprisingly small esc for this power)
Ztw beast pro 300 : 300A x 12S? x 4V = 14,400 watts ( is this even logical?)

 

[rotauq]

Castle xlx 600A+ x 8S x 4V = 19,200W+

Most big and heavy 1/5 rig will have plenty of power with 6-8kW

Once speed comes into the equation demand for power grows exponential.