is my math right?

[evst 360]

ok guys I am planning on getting an LRP 13.5t bl motor, and I am in need of an esc. According to tower, the motor draws 180 watts at 7.2 volts. If my math is correct, this is 25 amps (watts/volts=amps). That doesnt sound right, because my mamba esc from my rc18b is rated at 25 amps constant, 50 amps surge. I find it hard to believe that, according to the numbers, I could use the lrp with the mamba esc. If this is pushing the limit of the mamba, would an esc rated for anything above 25 amps work with this particular motor? Or could I use the mamba with no problems?

[Grizzbob]

ok guys I am planning on getting an LRP 13.5t bl motor, and I am in need of an esc. According to tower, the motor draws 180 watts at 7.2 volts. If my math is correct, this is 25 amps (watts/volts=amps). That doesnt sound right, because my mamba esc from my rc18b is rated at 25 amps constant, 50 amps surge. I find it hard to believe that, according to the numbers, I could use the lrp with the mamba esc. If this is pushing the limit of the mamba, would an esc rated for anything above 25 amps work with this particular motor? Or could I use the mamba with no problems?

I don't think that'd be a good idea. I don't have exact numbers, but I can tell you that Novak's 13.5 can draw as many amps at low rpm as many mod motors, & from what I've read & heard, the LRP one is about the same that way. Even stock brushed motors might AVERAGE a certain amount of amp draw, but at very low rpm & anytime a big load is placed on them(like when slamming against a barrier, for example), they can draw as much as 80-90 amps(I know because I've seen this on my Robitronics dyno), which would toast any ESC like the Mamba25(that's what the 50 amp surge rating is about, how much they can handle at low rpm & in spikes like those that occur in a collision). And the same applies to brushless motors, overall they may be more efficient, but they can still draw a LOT of amps(in fact, that's why we're now seeing the return of using caps on the reeiver, to help it maintain a proper running voltage when the motor draws so many amps it's giving the ESC's BEC system problems sending power to the radio system), so I'd expect one would blow up any micro ESC in a hurry....:cool:

[evst 360]

I don't think that'd be a good idea. I don't have exact numbers, but I can tell you that Novak's 13.5 can draw as many amps at low rpm as many mod motors, & from what I've read & heard, the LRP one is about the same that way. Even stock brushed motors might AVERAGE a certain amount of amp draw, but at very low rpm & anytime a big load is placed on them(like when slamming against a barrier, for example), they can draw as much as 80-90 amps(I know because I've seen this on my Robitronics dyno), which would toast any ESC like the Mamba25(that's what the 50 amp surge rating is about, how much they can handle at low rpm & in spikes like those that occur in a collision). And the same applies to brushless motors, overall they may be more efficient, but they can still draw a LOT of amps(in fact, that's why we're now seeing the return of using caps on the reeiver, to help it maintain a proper running voltage when the motor draws so many amps it's giving the ESC's BEC system problems sending power to the radio system), so I'd expect one would blow up any micro ESC in a hurry....:cool:ok, thanks. It turns out I wasnt able to get a good deal on it, so it might be a while before I get it. But I'll save up my money for a better esc. Got any suggestions? Would a mamba max esc be able to run this motor, being (I believe) a sensored motor, and the mamba max motors being sensorless?

[Grizzbob]

I don't believe a Mamba Max can control a sensored motor properly(heard rumors that they could with a software update, but haven't heard anything to verify that & personally I wouldn't risk it when you spend that much on a motor & ESC), so I think your best bet would be either one of LRP's speed controls(any of the versions of their Sphere ESC should work), or Novak's GTB or XBR(& the XBR is likely the best deal you'll find, can be found for around $180 at the online shops). Also, the XBR has the advantage of being able to run either brushless or brushed motors(10.5 turn limit with BL, no limit on brushed motors), can auto-detect either kind of motor & set itself to run it(the GTB can run either but you have to go through a lengthy & slightly irritating proccess to switch from brushed to brushless or vice-versa), & best of all the XBR also has LiPo voltage cutoff circuitry(I think Novak calls it Smart Stop), so it'll be very LiPo friendly should you choose to run those later.....:cool: