Interesting Find!

[tcolesen]

Today I was running my newly set-up MGM 120amp controller and Feigao 540 12s motor in my Traxxas Rustler. The 2 battery setups I have are a 3s 4500mah Lipo pack (rated at 50amps+ continuous), and 2 6cell GP3300 packs wired in series (did 3 re-conditioning cycles on them).
With the 3s Lipo pack, I could get as good range with my MX-3 FM 75mhz radio as my eye could see the car. From that distance, I didn't notice any glitching. I strapped in the 2 GP3300 6cell packs using a series connector thingy to see if there was any difference in power. There was definately a difference in the power! So, I started doing some speed runs, and noticed that at about 100ft. or so, the car started glitching. Much further than that and the MGM controller would actually shut down because of the weak signal (which wasn't too good since the car was on my residential street).
I find it very odd that I got such glitching when using the GP3300's instead of the Lipos. My ideas for the glitching with the GP3300's are:
-Extra wire because of the wire coming from the 6cell packs, and then connected through more wire and Deans connectors, and finally to the controller.
-Construction of the packs. I built these myself in side by side using silver battery bars with good solder connections.
-My specific GP3300cells.
-GP3300 cells in general.

The way the 2 6cell packs were mounted was with one on the chassis flat, with the other on top of it (both packs securely secured to the chassis). To the right of the batteries is the receiver, which I had long ago put fuel tubing around the antenna wire, as well as tape under the antenna wire (aluminum chassis). My current thoughts are that maybe the reason why the Novak SS5800 system glitches could be because of the batts! If there is a Novak system owner that gets this glitching problem, he/she should try a 2s Lipo pack and see if the glitching goes away!

[kufman]

It is quite possible that the battery bars themselves act like interference radiators. I guess it would depend on the length of the battery bars and the frequency present on the battery side of the controller. The caps are supposed to supress this "ripple current" but it isn't a exact science unless you use different caps for different situations. One way to test this would be to build a stick pack instead. keep your battery wires close together, kind of like a twised pair. Do the same with the motor wires.

[tcolesen]

I am going to do some experimenting today. I am going to try to put some holes into the shrink wrap that is around the packs so that I can check out the individual cell voltage. I will also try using just one pack at a time to see if the problem could be coming from only one pack.

[kufman]

It could also be a bad battery connection. If there is a bad connection somewhere and it is making and breaking contact, that would cause problems.

[tcolesen]

I tried running the 6cell packs one at a time to see if maybe one of them was causing the interference. Neither of them did! But when I hooked them together with the serial connector, I got the glitching again. So, I twisted all of the battery wires as much as I could, and I couldn't notice any interference! And I don't think that there is a connection with a weak contact, since twisting the wires seemed to work. The guys with the Novak system should try twisting the battery/controller-to-battery wires to see if that eliminates the interference.

[TimisTim]

I had this same problem with my uf 75 and feigao. When I ran twelve cells via a connector and two six cell packs I had bad cogging and glitching, but never with just six cells. I figured it might be overpowering the bec or just trying to push more power so naturally there would be a more powerful cogging effect. It glitched so bad that I was doing a simple turnaround and it went right into a curb which would not be a problem except that with twelve cells it wheelied into the sucker! Cracked my front kickplate on my xxxt.

[OptimaMan]

When running higher voltages, the BEC cannot deliver as much currrent to the receiver and servos. I bet if you use 12 cells and a receiver pack, you won't have that problem.

[SS Pede]

Well, twisting the battery/ESC wires together is something I have not yet tried with my SS5800. I use 6 cell stick packs. There is glitching with both the cheap 2400's and the nicer GP3300's. Perhaps later today I'll try running with those wires twisted.

[ElectricThunder]

Well, since stick packs are welded together with the cheap battery plate things, I'm sure there's some play as those pieces of metal are flexible. That means there could be metal on metal contact, and just from normal driving I'm sure there's plenty of vibration on the chassis, which could vibrate the metal strips connecting the batteries in the stick packs just enough to cause some sort of contact, leading to interference. But the reason optima supplied seems more probable if you're running hand soldered, GPs using battery bars (not those crappy little strips of metal). :eek:

[SS Pede]

Yeah...still glitching. It will not die. If I buy another vehicle sometime that requires a radio, I can get a 75mHz one and try that out.

[TimisTim]

@Optima.....have you had the glitching problem when running high volt lipo's?

[TheSteve]

I've had no glitching issues running 4S(16.8volts) LiPo's with my U-Force's.