I've been messing with the Cougar controller today. I have an accurate resistance measurement tool - a Micro Ohmeter, or Ductor - and have checked the resistance of each leg of the MOSFETs to the B- busbar and to the M- busbar.
The results are confusing for me.
I had assumed that one leg of each MOSFET was connected to the M- and the other leg was connected to the B- copper bars. When M- is connected to B- through the MOSFETs, current flows from the battery pack + to B+ to Motor+, through the motor, to motor -, to M-, through the MOSFETs to B-, and on to the battery pack -
I have MOSFETs that during one set of measurements appear to have a poor connection to B-, but the same MOSFET has to good connetion to M-.
Table of measurements below. MOSFETs 1 and 3 have had their leads cut - scorch marks were a good hint that they had failed. But not just them!
Resistances are listed in milli-ohms
Code:
Measure resistance from B- to MOSFETs
MOSFET Middle Right
1 dead dead
2 >200 14.7
3 dead dead
4 3.9 10.1
5 8.4 0.7
6 3.8 2.6
7 3.7 9.6
8 3.7 22.7
9 2.8 1.7
10 3.8 16.4
Code:
Measure resistance from M- to MOSFETs
MOSFET Middle Right
1 dead dead
2 >200 >200
3 dead dead
4 2.4 9.3
5 7.0 4.6
6 0.6 50.0
7 0.5 6.4
8 0.5 19
9 0.5 1.7
10 0.5 13.0
I'm not sure what I was expecting. But whatever THAT was - THIS does not match it!
I took the Cougar out to my battery pack, put a resistor in series with it, then connected it first across 4V, then 8V, 12V, 16V and on up until I ran out of batteries. There was no current measured except for charging the caps. I was expecting current to flow somewhere. 12V was not connected to the Cougar at the time.
I disconnected the pack and just connected 12V to the controller. I checked for heat on each resistor. Nothing. I checked for voltage across the resistors that drive the MOSFETs. Nothing.
Paul - what am I doing wrong here?