hv maxx and lipos

[mwe-maxxowner]

I found an old hvmaxx ESC with the 6.5 motor in some old stuff. I'm thinking about trying it in a slash 4x4 with revo sized wheels and tires on it.

Is this ESC capable of running 4s lipos? It's already been re wired for one battery pack.

If memory serves me correctly, it will require an external lvc, right?

Any ideas how it should be geared in something like this?

[Arct1k]

Required an Lvc. It can run 4s but only in dual battery config. The internal BEC runs off one of the two batteries only else you will blow the intern BEC.

[mwe-maxxowner]

Ahh dangit. What if an external bec is used?

I have a ubec in my spare parts bin.

[_paralyzed_]

Originally Posted by mwe-maxxowner

Ahh dangit. What if an external bec is used?

I have a ubec in my spare parts bin.

That's fine then. Just be sure to pull the red wire from the esc > receiver connector.

I wouldn't gear for more than 35-40mph. I know it's smaller and lighter than a maxx, but with revo sized tires that is some big rotating mass. Tire size (weight) drastically effects the load on the esc, and that's a fairly weak esc to begin with.

When I retired my hv-maxx to move onto bigger and better things I put it in a rustler.

Just be sure to watch temps as with any new setup. Have fun man!

[mwe-maxxowner]

Thank ya sir! If it doesn't work out well, its back down to pede tires and a velineon system. I may try to piece together a hobbywing system over time. It was recommended to me to start with stock 4x4 slash gearing and adjust from there?

I'm a little embarrassed, but I really don't know how to use the ubec. I can research that later, but tips there would be greatly appreciated!

[Arct1k]

Disagree with paralyzed.

In IMO you still risk blowing the internal esc - the internal BEC will be getting 4s. even though its only powering the internal of the esc it could fail.

Novaks always seemed more seanitive than castle.

[_paralyzed_]

I went digging around the traxxas forums before I responded to make sure I was giving correct advice. Arct1k is absolutely correct, you do still run the risk of blowing the internal bec, which kills the esc. But the guys over at traxxas have ran these esc's with a single lipo, and running an external bec is how they did it.

To run the bec you just wire it to your esc plug, black to black and red to red, then when you plug in the battery it will be powered. If the voltage of the bec output is selectable, choose 6v. Then you simply plug the other end of the bec into any open port on your receiver. Now the bec will power the receiver and servos.

On a side note, the search engine on the traxxas forum SUCKS. I ended up googling to find the info.

[_paralyzed_]

Also, stock gearing will be wayyyyy off. The velineon at 3s is spinning 38850 rpm. The 6.5 at 4s is spinning 50320 rpm. You would have to gear down for that rpm difference alone. Add to that the increased diameter of the revo wheels and you will have to gear wayyyy down.

You should learn how to use this tool > http://www.scriptasylum.com/rc_speed/top_speed.html

It's a speed calculator made by this forum's own BrianG. You simply plug in the appropriate values and it will show you the speed you will get with different tire sizes/voltages/gearing etc. It can be found in the brushless section here at Rc-M stickied at the top.

The kv (rpm/volt) of the 6.5 is 3400. Plug in your values and shoot for 35-40 mph, and that will tell you the gearing you need.

[mwe-maxxowner]

I will use the bec, and give it a shot. I might even try it first on 3s, but I imagine it would be underpowered like that. I'll play with that calculator and figure it out. That would be very useful on all of my vehicles.

On a side note, if the ESC fails but the motor is still good, I could purchase one of the ezrun 80-150 amp escs and still run the motor as unsensored, correct? Then once I get a little extra cash I could upgrade to a low kV motor.

If I were running the original 2 battery configuration with 2 2s batteries, is there still the risk of blowing the internal bec? Or does that have something to do with the single battery setup?

Never mind I answered my own question. With two 2s packs the internal bec only uses 2s from one pack.

[_paralyzed_]

suicideneil says it's okay to run a single 4s with a bec, and he's like an encyclopedia of maxx knowledge. But yes, 2x2s is guaranteed to work.

Yes you can run the motor unsensored if the esc fails, but hobby king has some pretty inexpensive sensored esc's if you so desire.

Just google for values if you need to for the calculator, like diff ratio and what not.

[mwe-maxxowner]

I would like something similar to the mmm but not so expensive. Less tuneability is fine with me.

Does anyone know what the largest spur is for the 4x4 slash?

[mwe-maxxowner]

What are the opinions on the xerun 150 amp ESC? I read somewhere it does not do 4 pole motors.

[mwe-maxxowner]

Originally Posted by mwe-maxxowner

What are the opinions on the xerun 150 amp ESC? I read somewhere it does not do 4 pole motors.

http://www.hobbyking.com/hobbyking/s...dProduct=18395

What is the opinion on this thing? Would it run a 2200 kV motor?

[_paralyzed_]

The xeruns are pretty decent esc's, and they absolutely DO run 4 pole motors. They were sold in combos with 4 pole motors.

That hobby king esc you linked to has some bad reviews on it right there on hobby king's site.

I would recommend the xerun over the hobby king.

[mwe-maxxowner]

Thanks for the help. What about the kV limit on the ESC? Is that an absolute rule? That would mean it can't run the 6.5 motor.