VXL ESC Modding
 

Came up with the idea the other day after I thought of running 5s through my VXL if disabaling the over voltage cutoff. Basically what the mod is, is I will take off the (weak) cold soldered 3.5mm female bullet connectors and replace them with direct solder Deans 12awg Ultra wire. Less resistance and less to worry about in terms of the darn cold soldered bullet connectors coming off of the board. I am also looking into replacing the capacitors with bigger 35v 330uf capacitors to handle the power input. Another thing that Im interested in doing is direct soldering a novak capacitor to the input leads on the TRX connector to reduce heat. Not sure which one to use though- http://www3.towerhobbies.com/cgi-bin...ovak+capacitor

This one is what you need - 6.99 on ebay or look in the MM 4s capacitor thread in CC section...

http://www3.towerhobbies.com/cgi-bin...?&I=LXKKN3&P=7

Today I picked up some 330uf 50v capacitors from my electrical engineering class. I know its a little to high of voltage but they should work perfectly. The stock capacitors are 330uf 25v. Im most likely gonna drill out the back end of the VXL case so that the capacitors will come out the back end instead of being directly mounted to the board. I am still a little confused on what I should do to disable the over voltage cutoff. Im was told to do this.

"
Thinking about it a little, it probably has an ADC in there to detect overvoltage/undervoltage. Since they also have something of a LiPo low-voltage cutoff in LiPo mode. In this case what you would be looking for would be a voltage divider (2 high-value resistors in series) across the voltage input, with the output of the voltage divider going to maybe a small capacitor (other side to ground) and then to a pin of the microcontroller or another IC which you could identify as an ADC. Or if you can identify the micro, you can tell if that pin has a (potential) ADC mode. If this is the case it is a simple fix, just replace the high-end resistor on the voltage divider to create a different ratio and "fool" the ESC into thinking, say, 15V is really 9V. There are other ways to design it, but that's the cheapest and most convenient way (IMO) so I think it's what Traxxas would do, so I think that's what you'd be looking for -- two resistors in series attached across the input."

The VXL has two resistors on each input (+,-) Should I remove them and what should I install in place of them so that the ESC will think that it is running in proper voltage range?

All help is appreciated.

Ok thanks for that link. I was confused on which one to get.:wink:

Let me know if that works. I have some VXL controllers that will be modified if it does...hehe. I know the manual says 20V's is the limit so 4 or 5S is not a problem.

There is more to it that v and uf - You need low esr - Are they high temp caps?

Griffin is best placed to comment on caps - You can solder to board - I can't so just added close to board on power leads.

Adding to what Arct1k said, you do in fact want/need low ESR caps. If the ones you got aren't low ESR, then they won't work well as replacements for the stock caps. In some cases you can tell just by the temperature rating: 105 deg C is often an indicator of the caps being low ESR.

Here are the spec's...

Stock VXL Capacitors= 330uf, 25v, 105 celcius capacitors.
Upgraded Capacitors= 330uf, 50v, 105 celcius capacitors.

They should be fine.

Yep those caps are fine. Who gave you the advice about voltage dividers? Sounds like Griffins mind at work there, but if you arent really sure what to solder where, I would suggest some good pictures are required to help identify parts for modding, then maybe he could draw up a 'how to' for you. I think he forgets thatmost of us are but mere mortals compared to him and his electronic skills.... :D

Any other suggestions? If not then Im gonna start on the modding as soon as possible.

Those are words from one of my friends on RCU name "Access". Ill be sure to get pics to you guys very soon.

Ah, sounds like he knows his stuff all the same. Useful people to know, especially in this game.

Ok you guys, here are some pics...

Yeah, a voltage divider may work like you want, but you really have to make sure that the IC pin you are looking at is indeed the v sense pin. Is there a part number on that IC? Many ESCs scratch off the part number on the main brain IC. Not to mention that the brain may just be a PIC and those inputs are programmable. I would definitely wait for Griffin to add his input before attempting anything.

Here what the IC Pin says...

50N025
06 P
Triangle BW
L62k

Maybe you guys can help me grasp what all this means?

Here are some pics of the board...

Those are the FET's, not the control circuitry.

Yes I am aware of that. I just decided to take another couple full pics of the board.:wink:

Datasheet for the FET's:
http://www.vishay.com/docs/73349/73349.pdf

Thanks for pulling that up Skellyo. Do you guys think that if I were to be able to pull of a meraculous fully functional modded VXL that it would be able to handle the power Im going to be putting threw it and drawing from it?

I didn't check the FET specs that closely, but it is rated at 200A, so if you can keep it cool, it may do ok.

Ya I plan to run the Optional VXL Fan over it and not plug it into the ESC fan port but directly to the receiver because if I plug the fan into the ESC something will most likely go wrong.

Well according to the data that Traxxas says on the manual, it should easily handle the 5S and high amp loads of even some pretty big motors like the XL's and Neu's. Would be awesome, since they are so easy to use.

Were exactly does it say this?

I was talking about the 200A C and 320amp max. Those are some pretty big #'s to claim.

Well their proven amp ratings so traxxas is safe...

I think pictures of the brain board are required now, though I cant help much except to offer encouragement... Interesting thought though- I wander if the MM brain could be mated to the VXL power board, assuming it uses the same current to drive the circuitry and has the same number of buss bars joining them together...

I would like to see a velineon esc hooked up to a 1515 neu of around 3000kv. Run it in a truggy geared for 40mph, with 3s 10000mah worth of flighpower 30c lipos. We will see if the esc can handle a 200 amp load. I have a feeling that it will not do it for long before it cooks or turns off.

Does it have 10 gauge cables? 200 amps at 10 volts is a fair amount for the stock wires to handle.

It has 12awg wire...

The MCU they use is from Silicon Labs C8051F330 http://www.silabs.com/public/documen.../C8051F33x.pdf. I spoke to Griffin about this same thing, but I wanted to see someone doing it first. I have found other suitible FETs replacements: ST Micro STD150NH02LT4 (Lower Resistance), On Semi NTD4804NT4G/NTD110N02RT4. There are other DPAK FET out there, but those are really cheap :lol:. Let me know how it works out.

Well since I cant disable the over voltage protection because everyone that I talk to said its most likely installed threw their software which I wont be able to get to. Ill just mod everything else besides the over voltage stuff. Hopefully it will run a little cooler and have a little better preformance.