Kraton 6s stuttering at WOT

[Lil Dylan]

Hello all, I have a Kraton 6s

Castle 1650kv---MMX8s, 20-tooth pinion, DX3 with non-avc receiver, Oovonic 100c 6000mah battery, timing 15 degrees, punch 25%. Sometimes when I'm doing a little speed run the car will stutter at WOT. Almost like a rev-limiter and it happens the whole session. This has only happened maybe 2-3 times out of 50 or so runs on this setup. Any ideas on what this could possible be? I thought it might be ripple voltage but the log doesn't show that. Max amperage is 175amp. Also, this happens when the car is fresh so it's not a temperature issue. Thanks

 

[gotnitro]

Could be a plethora of things, got vid?

 

[SrC]

Like stated by @gotnitro ....
First thing that comes to mind is if running that DX3 with AVC enabled. I had similar issues, stuttering, as if it was Amp cutting. Which it could still be.
Just that with AVC it could also be Throttle cutting you as well. AVC is not only a ST gyro, but also does Throttle limiting/cutting, along with it. I could be off here. IDK. But its worth disabling AVC altogether for troubleshooting purposes, if all other possibilities have been looked at. Need to rebind the Rx to properly Disable AVC. Per the AVC/ Rx manual. Merely turning down AVC "Gain" at the radio is not the correct way. And when using AVC, best to keep it at about 10% or lower. All you really need. Many guys turn it all the way up. How you get issues with ST oscillation, etc. Less Gain is more, more Gain is less. Too much just screws it all up.

 

[Lil Dylan]

I updated the original post but the car has a non-avc receiver. I don't have a video but just imagine a rev-limiter type behavior. It doesn't make any strange noises but just kind-of gets inhibited. I believe when it happened the battery was only charged to 3.9v/cell.

 

[gotnitro]

I updated the original post but the car has a non-avc receiver. I don't have a video but just imagine a rev-limiter type behavior. It doesn't make any strange noises but just kind-of gets inhibited. I believe when it happened the battery was only charged to 3.9v/cell.

Sounds like the LVC kicking in.

 

[Lil Dylan]

Sounds like the LVC kicking in.

I don't know why it would do that right off the bat but I will say that both times this has happened it was when I barely charged the battery to just test the car out. Maybe there is something weird going on there.

 

[SrC]

First mistake is not charging the pack to a Balanced full charge. Do that first, test it out again. Need to determine if the Lipo pack is at fault first. Process of elimination. Easy enough to charge the pack first, then try again.
It isn't much of a valid test with a half dead pack.

3.85-3.9v/cell is only 50% charged!

 

[gotnitro]

Battery voltage sag is most likely the reason. How old are your packs and what kind?

 

[Lil Dylan]

Battery voltage sag is most likely the reason. How old are your packs and what kind?

Oovonics 100c 6000mah 6s with maybe 15 runs? I ordered some qs8 connectors in case my IC5 are corroded or something.

First mistake is not charging the pack to a Balanced full charge. Do that first, test it out again. Need to determine if the Lipo pack is at fault first. Process of elimination. Easy enough to charge the pack first, then try again.
It isn't much of a valid test with a half dead pack.

Yeah I'll do a full-charge test. I suspect you could be right.

 

[gotnitro]

Oovonics 100c 6000mah 6s with maybe 15 runs? I ordered some qs8 connectors in case my IC5 are corroded or something.

Yeah I'll do a full-charge test. I suspect you could be right.

I didn't even notice you originally said you didn't charge them up fully.

Voltage SAG is 100% your problem.

 

[Lil Dylan]

I didn't even notice you originally said you didn't charge them up fully.

Voltage SAG is 100% your problem.

Sorry for the spoon-feeding but why would it SAG after a partial charge but not do that say 5 minutes into a full-charge run. Is it because it isn't balanced on the partial charge run?

 

[gotnitro]

Sorry for the spoon-feeding but why would it SAG after a partial charge but not do that say 5 minutes into a full-charge run. Is it because it isn't balanced on the partial charge run?

Could be your batts dude, some batts just are not what they say on the package.

Could be that you simply are nowhere near 3.8-3.9 VPS after 5 min of run time after a full charge too.

 

[Lil Dylan]

I went through my Castle log and noticed that voltage was dropping to 21v during a pull which would average out to 3.5v/cell which is my cutoff. I guess I need to make sure my stuff is fully-charged if I push it hard. Thanks for the help everyone.