Newbee, need some advice!

[vietnamezerice]

Hey guys, I'm new to the site and pretty new to Xmods... anyways I recently did a FET upgrade along with a PN Racing "01" motor and 6 cell conversion... I'm using regular alkalines and I don't see much improvement as far as low end torque can you guys tell me if this sounds right? here are pictures of my FET install, please let me know if you see something wrong with it thanks!

6 cells just flat out suck. alkalines suck even worse. Thats your problem right there.

a 4 cell with a good set of rechargeables would be better. Lithium would be even better yet. That motor probably requires more battery than the alkalines can feed it.

Also your car does work? pin 3 from the left on the first stack is touching that other metal.. im surpised that doesnt cause a problem...

[vietnamezerice]

you're talking about the second picture stack on the left? third pin? yeah i know! I was comparing mine with other ones I found online and mine is for some reason like that... the flat metal surface leads to that pin... i don't understand... so you think even if I got some NiMH batteries it will help the low end torque?

[Donziikid]

Originally Posted by vietnamezerice

so you think even if I got some NiMH batteries it will help the low end torque?

Nickel-Metal Hydride batteries (NiMH) offer a higher discharge rate than Alkaline batteries, which will in theory help your low end torque because power is supplied faster to your electronics.

[vietnamezerice]

hmm... I just picked up some Energizer 850mAh rechargables... I'll let you guys know how it does

do you guys think it'll be ok if I run the MiMH 6 cell or just leave it at 4 cell?

[Donziikid]

Running six cell NiMH (1.2V x 6 cells = 7.2V) is safe as long as you run properly. An excessive trigger finger could lead to overheating of the FETs and your motor, causing some problems either then or later on down the road due to an overly used motor.

In my opinion, six cell will add a little bit of speed, but the added weight will certainly slow down it's agility. I'd stick with four cell unless you really want that extra one or two mph and lose some track agility.

Also, if you're going to run six cell, make sure you never switch back to Alkaline. At 1.5V each that adds up to 9V which will fry your board.

Cheers,
Kyle.

[BART]

I think he stated in the first post that he already has a 6 cell and has been running it with alkalines. Your point that alkalines have such a weak discharge rate is probably the only thing that has saved his board. We have done 6 cell with nimh on 4 of out cars and i think the improvement is quite substantial and well worth it.

[vietnamezerice]

yeah, when I tested my alkalines it put out about 1.4 volts x 6 and I had 8.4 volts going to my board... I'm sure there were some minor voltage drops along the way... is there supposed to be a certain voltage when power is supplied to the motor?

[BART]

Not sure what your asking but if you understand fets, when they are wide open, or running on the closed side of the square wave, full battery voltage is supplied to the motor, the amperage draw is dependent on motor speed and load.

[vietnamezerice]

well, when I tested the voltage going to the motor at full throttle it was at about 5v is that normal? or should it have been the full 8.4v?

[BART]

Originally Posted by vietnamezerice

well, when I tested the voltage going to the motor at full throttle it was at about 5v is that normal? or should it have been the full 8.4v?

If your measuring the voltage at the motor with it hooked up the voltage should raise as motor rpm increases. Ive never measured the exact voltage at the motor.

[kendallcschm]

me personally if you have 8.4 volt batts and your getting 5 volts at the motor then you have a problem with the resistance... mesure in ohms... (resistance) of one ot the wires you have connected to the motor.. tell me how many ohms.... and 0 ohms is good... :-)

[vietnamezerice]

so I need to set my multimeter on Ohms and put one lead on the neg terminal and the other on the motor neg side?

[BART]

If you had enough resistance in the 3 inches of wire from your board to your motor to consume 3 volts it would be pretty obvious. you would have melted wire and burnt insulation. If your really curious as to what voltage your motor is receiving unhook your motor and measure the voltage at the motor wires at full throttle. Although this will not really tell you anything as there is no load/hence no current flowing. when an electric motor is under full load the voltage will be very low and the current will be high, as motor speed increases voltage will raise and current will drop. Voltage and amperage work like a seesaw. when one is high the other is low exponentially.

[vietnamezerice]

hmmm thanks for the info I'll check it out tomorrow