Cogging when Full power?
 

Hi

I have a small problem. When I give my E-maxx almost full throttle from still stand, it is making these small jumps, before finally accelerate. Does anybody know what causes this?

I am using the HV4400 maxx with Maxamps 6000 mah lipos.

Any help is greatly appreciated.

Regards
Jesper

What is your gearing? The hv don't like more than 13 or 14 /66 gearing with 32 pitch

12/70

You could have a power issue. Castle explains that this symptom is most likely caused by weak batteries, but a poor solder joint and/or crappy connectors could do that as well.

Not using the tamiya connectors?

Th HV esc and the Maxamps lipos are connected via deans.

Could it be that the steering servo takes the power before the esc?

The lipos are brand new, and it was their first run. after have charged them full.

What other connectors are you using?( between motor and controller?).

They are wired directly on th HV system.

It may be the lisaver. It is the one on Mikes webshop.

Perhaps the 6000packs aren't up the task. Try it without the LVC and see what happens.

I know this is a long time ago, but today I finally tried without the lisaver, and at fulle throttle the E-maxx landed right on its roof ;o)

Do you know if there may be something in the lisaver, that keeps it from accelerating too fast, to keep it from flipping backwards?

Under high acceleration, the motor can pull a substantial amount of current, which could be causing the lipo voltage to drop below the LVC's threshold. Then it kicks in removing the power allowing the battery voltage to rise again which will make the LVC allow throttle input. This cycle can happen quickly over and over again causing the symptom you are experiencing.

Gearing down more will lessen the load on the motor and pull less current. I would try that and see if the symptom lessens or goes away. If so, the issue is the batteries...

^^ that sounds like the problem. My experience with the 4400 was that it was power hungry, My NIMH's would come out of my E-revo scalding hot, More hot than same batts coming out of my mamba setups

I agree, or in my case when this was happening, the volatge just needed to drop a bit more and it ran no problems.

The batteries simple can't deliver the power needed for the setup; The maxamps 6000 packs are not the best money can buy; they don't hold their voltage very well under high load. Try contacting Austin and ask for an upgrade to 8000 (2P) packs. he is very kind, i think he will take care of you.

Hmmm, I had 6000's and they seemed enough to push my 10xl....just lacked the run time.
But Serum is right, I would contact Austin, who is a great guy.

What LVC did you used Troy?

It was the MM esc. But it also did it with my HV when I had 3800 IB's. Same exact thing.
I did also run the 12020 with a LVC that was not the opto mode and it did it with that as well. When I removed the LVC it seemed better, but still stuttered a bit.

Need to read what I write! Working on two forums here! lol same issues.

Another thing to consider, the HV4400 was lower powered, so it needs current to run hard, thats going to play havoc with all but the best LIPO's. I run NIMH on mine (12 cells) and they would come off so hot i would not be able to charge them for at least an hour, because they needed that much time to cool down

It could also be poor solder joints as well? Have you checked all solder points for quality bond? Lengthy wires might be the culprit too, who knows?

Lipo
 

Hi again

Thanks for all the replys.

I know I should have got the 8000mah. in the first place, but I am still not sure that it is the problem. When I take of the lisaver, there is no problems at all. It just flies away, with no "cogging".

When I am finished driving the lipos are hardly warm, but the motor is for sure.

Could this be a motor issue. Would it help me to replace the rotor with the HV 6,5 rotor (the cheap solution), or should I upgrade to a senserless system?

Best regards
Jesper

If you are using the old non sintered rotor an upgrade might be wise. the new rotor doen't make your motor spin at lower rpm, but it makes it more efficient on partial load.

You can use the new sintered rotor in the old 4400 motor.

Ok, I will try that. Thanks for the reply.

Yeah, anytime. I heard the new rotor works miracles.

It does lower the kv of tth motor, on Novacks site they are now rated at 3100kv

THey seriously need a ~2000kv motor, that would open their market. Better yet, a larger rotor.

a two pole rotor doesn't change the kv. the amount of windings in the can (which isn't replaced) does change the kv.

i think they have got an unloaded and loaded value mixed up.

A larger rotor, that's something i would aim for. they use small rotors and high kv, and we all know what results that leads to.

The power of the rotor will change it, the 5800's have gone down to about 5000 now with the sintered rotor. I would think the strength of the rotor would effect the KV

If it's an unloaded value it simple doesn't.

I wonder how a sintered rotor compares to a slotted/laminated rotor. But the Neu has larger gaps in the rotor between poles, maybe for good reason?

I would think larger gaps would reduce the effect of the magnetic field from adjacent coils from adversely affecting the energized coils. In short, less cross-talk to put in audio terms...

Guys, do you think because I'm using a UBEC, the truck coggs alot?

It does not cogg like crazy lately, but when you hold the truck to the ground and give it some gas, it does cogg.

Maybe I should use a receiver pack, instead.