I know this topic has been asked numerous times before.... but there was never a definitive answer from the people in the know.
I'm going to try this myself, however, my electronics knowledge is very fuzzy.
This is what I plan to do. If you think I'm heading for a smoked board, pls warn me.
FETs Pin Configuration
Pin 1 = (N channel) Source
Pin 2 = (N channel) Gate
Pin 7&8 = (N channel) Drain
Pin 3 = (P channel) source - Do NOT connect to board. Connect to +ve of the 5 cells*
Pin 4 = (P channel) Gate
Pin 5&6 = (P channel) Drain
All the pins of the FETs are connected to the board as per normal except for pin 3 *Pin 3 is not connected to the board or it will short out the 5th cell
Notes
The board is powered by 4 cells.
The batt terminal at the +ve end of the 4 cells is connected to the PCB AND the -ve of the 5th batt holder.
The +ve of the 5th batt holder connects to Pin 3 and NOT to the board
The limit to the number of cells is determined by the specs of the FETs.
Pls feel free to comment. I'll be trying it on my OL board after a while (after sufficient time for someone to warn me if I'm wrong), and also after I've confirmed that my MR-02 board is perfectly allright. (btw, if u have a multimeter and an MR-02 board, please help me to measure something . see thread -> . Thanks)
I've wired up the circuit as described above and did some tests with a multimeter. The voltmeter showed that 4 cells were going to the board while the FETs output were higher.
A concern however, is that the FETs were slightly warm after 10 secs of the voltmeter across it (no motor)... so try it at your own risk.
I did not connect Pin 1 (N-channel source) to the board, but straight to the-ve batt terminals, as I plan to connect a 3A motor to it and don't want to risk blowing the PCB tracks.
On the first layer, Pins 1 and 3 were bent upwards to prevent it from connecting to the board and short out the additional cells.
I'm going to connect up the circuit and the conversion kit and bash around and see if something melts/smokes/smells or gets desoldered.
I take back the "FETs were slightly warm after 10 secs of the voltmeter across it" comment. It was fine after I wired up the final circuit, so it could be a prob somewhere with the test circuit.
I had run it around my living room for 1/2 hour. So far, so good. Batteries were slightly warm and so were the motor. No unusual heat or smell.
I didn't touch the FETs as I didn't want to go through the hassle with the MR-02 chassis. (btw, it's an overland PCB). That will be done another day, after I had more runs.
I'll post pics once I'm satisfied that everything's OK
After depleting several sets of batteries, I touched the FETs. They were not warm at all.
So far, things looks positive, but I'd prefer to wait at least a week or 2 before seeing the project as a success
After depleting many sets of batts, I'm comfortable enough to give it the thumbs up. Pictures and brief instructions can be found at the following link;
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