mm high power brushed and other ?'s

so i got a slash yesterday and instantly replaced spedo with mm. what is high powered brushed mean for the mm, i see the wiring is all crazy 3 wires to positive and negative to the battery. i thought it was a joke high powered BRUSHED mode, whats it for

also i have a hyperion 0610i and will be charging of a 1:1 car battery while camping; how often should we be starting the car, charging at 4 amps, it a ford explorer. basically how many batteries (2s 4000 mah ) should i be able to do before the 1:1 battery dies?

and last has anyone else had trouble getting their mmm or mm to stop the beep at the beginging, other setting are taking but they both still beep at me and i hate it

thanks all

[BrianG]

The MM has 18 fets.

In brushless mode: At any one time, a 3 FETs are channeling battery + to the motor and 3 FETs are channeling battery - to the motor. The current rating is limited by the combined amperage rating of those 3 FETs.

Brushed with reverse: Similar in concept as above, except one phases is not used.

High power brushed: This hookup does not have reversing, but 9 FETs are on all at once going to the motor + coil. While the - battery goes directly to the - motor. This effectively triples the amount of current available to the motor compared to the other two hookups. This might be useful if you want to drive 2 or 3 motors at the same time.

[Pdelcast]

Originally Posted by BrianG

The MM has 18 fets.

In brushless mode: At any one time, a 3 FETs are channeling battery + to the motor and 3 FETs are channeling battery - to the motor. The current rating is limited by the combined amperage rating of those 3 FETs.

Brushed with reverse: Similar in concept as above, except one phases is not used.

High power brushed: This hookup does not have reversing, but 9 FETs are on all at once going to the motor + coil. While the - battery goes directly to the - motor. This effectively triples the amount of current available to the motor compared to the other two hookups. This might be useful if you want to drive 2 or 3 motors at the same time.

Hi Brian!

The MM actually has 30 FETs. 18 on top, and 12 on bottom of the main power board.

So in reversing brushed there are 5 FETs high side, and 5 FETs low side driving the motor (and they are in series -- so it doubles the FET loss)

In high power brushed, there are 15 FETs driving the motor, and only on one side. But no reverse...

[BrianG]

30 FETs? Hmm, I wonder where I got the 18 number from. Did the MM always have 30 FETs? Anyway, at least my answers were "proportionally" correct.

[Pdelcast]

Originally Posted by BrianG

30 FETs? Hmm, I wonder where I got the 18 number from. Did the MM always have 30 FETs? Anyway, at least my answers were "proportionally" correct.

Well, the really early MM had 36 FETs, but when we went to the SO8FL package (leadless FETs) we had to make a little more room, so we reduced the FET count to 30. However, the new FETs had lower resistance at 30 count than the old FETs had at 36.

The MM Pro will have 18 FETs, but the FETs are significantly better than the FETs used on the MM -- so it will have about the same resistance as the MM.

Patrick

[BrianG]

So, I guess I forgot to count the ones on the bottom.

On the MM Pro, couldn't you piggyback the FETs directly on top of each other? V-drop would be less (and therefore heat). I understand this would raise the price, but should be fairly easy to implement if the FET package leads are long enough.

[Arct1k]

Gives you limited heat conductivity though... better than mounting on the bottom of the board though...

[BrianG]

Yes, but if there is less v drop (about half) for a given current, each device is dissipating far less (75% less since half the resistance is split across two FETs). And if they are thermally coupled well, the heatsink on the top layer should still function just fine.

[J57ltr]

In high powered brush mode that would be Battery + to the Motor + and the 3 ESC motor wires to the - terminal of the motor, wouldn't it?

Jeff

[lincpimp]

Originally Posted by J57ltr

In high powered brush mode that would be Battery + to the Motor + and the 3 ESC motor wires to the - terminal of the motor, wouldn't it?

Jeff

You also have to put the batt + on the esc +, check this out:

http://www.castlecreations.com/suppo...ng_diagram.pdf