Jrxpro

iTrader: (2)

I picked up a used Kyosho MP10e roller as my first 1/8 scale. Put a brand new Castle Mamba Monster X and 1800kv motor in it.

Using 2x2s RC Juice LiHV 8000mah 100c batteries.

About 5 minutes into the first shakedown run, everything running strong and feeling great, the motor cut out. Steering still worked. By the time I walked over to it, power was back on, and it ran great again for another few minutes until same thing happened again. Steering still working, fan running. I shut it off and took it home. When I put the batteries on the charger to put in storage mode, it said they were still at 80%.

Took it to the track last night for practice, and same thing happened. Cutoff, then start working again by the time I get to it. This time I noticed the ESC was doing a short/long beep sequence. According to the manual that means low voltage? Put batteries on charger and they’re at 86%.

I recalled something similar happening with another car that I ran this same receiver in, so I swapped receivers. Same thing happened. At that point I put it away and ran the truck the rest of the night.

It’s hard for me to believe it’s the batteries. I have several of them, only a few months old, always balance charged at less than 2c, kept in storage mode when not in use. I run them in multiple other cars and they have been great.

I did set the low voltage cutoff to 3.3 when I was first setting up the ESC. Didn’t have my programmer with me last night so couldn’t adjust it. Could the difference between 3.2 and 3.3 really do that? I won’t have time to tinker with it again until next week.

Any other thoughts? If it matters, I’m using a Futaba 4pm with R304SB, Nitropro CT2 servo, BEC set at 7.5v.

thanks for any input.

TurnNBurn

I had something similar happen to me last year - particularly when coming off of low speed, or trying to get going from a dead stop in my touring car.

Not saying it’s the same thing, but have you tried cleaning the connectors to the sensor plugs? This turned out to be my problem, and the person that helped me out told me they need to be inspected/cleaned on a regular basis. I’ve since made pulling them out and cleaning them with a bit of contact cleaner every few runs as part of my maintenance routine. It was an eye opener, especially as someone who was a bit of an expert over 20 years ago before stepping away from the hobby for so long. I hope this helps.

flymetonight

Possible problems

CHECK LIST

A1 -
1 Bad Solderings / 2 Connectors / 3 Or Corrosition.

1 Check all solderings, Make always also sure to do proper soldering job. search how to Solder rc car connectors at Youtube. This is important to know how to Solder properly. It is very easy do mistakes here.
2 Change to new connectors if existing looks have any problems.
3 Cut of bad/corro if it exist on any power cable,, these can be hidden under the Heat Shrink Tubes at connectors from ESC, or Lipos. Cut of about half inch of power wires, , until you see fresh pure cable without corrosition, and solder new connector


-
B1
1 Sand inside tyres , 2 Bad Gear Mesh , 3 Grinding driveline

1 Take of the wheels and feel if they are heavy, wet or sand can makes wheels 2-3x more heavy than fresh wheels
2 After a while of driving, gear mesh can change. Search at youtube How to set proper gear mesh rc car.
3 Check driveline, diffs. Does all wheels spin free ? you may need take off the pinion or adjust the motor of spurgear.
Also hold one side of wheel and spinn the other both rear and front, does diffs feel good? Are all dogbones straight , not wobbling? Hold both rear wheels to ground and lift the front, and spin frontwheels to feel how center diff feels
-

C1-
Gearing, is gearing proper? not too smal pinion? this can make the motor go too high rpm.s alltime, too big pinion? makes heavy load
stock Pinion is 14t in this MP10e
.-

D1-
Are all Bearings ok ? no grinding ?
-

E1
Cooling fans, is everything clean? does the fans run at enough high RPM.s ?
-

F1-
Temps.
You have temp gun?
When it cuts, check fast the ESC and Motor temps.
You can check manually by hold your fingers at the motor , can you hold your fingers 5seconds on ESC and Motor without feel alot heat ?
-

G1
Make sure you have Balance charge lipos, all cells must be full loaded , Balanced , you already know this from what i read
Anyways good info to others, specially beginners who will read this.

Bonus tip. When you remove Lipo battery connectors from ESC. Make sure you pull at the Connectors always with your fingers, never touch/pull at the self cables, This can make Connectors loosen and give bad connection,
or worse it can shortcut when you drive if they get loose totally, and you can risk burn your whole car in worst case.


Goodluck.

gigaplex

iTrader: (2)

If the ESC is triggering low voltage cutout despite the batteries still having "80% charge" (whatever that means, it's the voltage that matters), then perhaps there's a lot of current draw that's causing the battery voltage to sag under load.

You say this is your first 1/8 scale with a new Castle ESC and motor. Perhaps it's not geared correctly? I think that Castle ESC has telemetry support, I'd suggest using that to monitor the input voltage.

Jrxpro

iTrader: (2)

This is along the lines of what I’m thinking. Somehow it’s spiking and triggering the cutoff. And yep I was thinking I need to figure out how to do the data logging and run it again.

Gearing is stock, 15t pinion 45t spur. The drivetrain was buttery smooth before installing the motor.

I am running a lot of connections because I’m running 2x2s hard case batteries with bullets and XT90 connectors to keep the batteries universal for all my cars. I’m confident everything is well soldered. But if it comes down to it I’ll rewire everything and just go straight bullet connectors.

I should have clarified, when I say “80%” I’m referring to my Hitec charger which has a “fuel” screen that somehow approximates the charge level. It has other metrics that I didn’t look at but I will. The general idea was that these batteries were not anywhere near empty.

thanks for the ideas, keep them coming!

Geezatec

Agree with Flyme. Low volts maybe the same as Temp cutoff. Check the temp on ESC and motor, 170 deg about normal, 195deg and higher over 200+ worst. Temp caused by Gear mesh and over gearing. Most manufactures of ESC like Castle, Tekins, and HW set their cut off voltage at 3.3V, I think its more Temp cutoff then low voltage.
What is your Gear ratio?

gigaplex

iTrader: (2)

What motor and battery configuration is that stock gearing intended to be used with? You can't assume that the pinion that came in the kit will work with all motors safely.

Jrxpro

iTrader: (2)

Well I think I figured it out. Did some late night googling and found this:

https://home.castlecreations.com/blo...o-run-hv-lipos

Then figured out how to pull the data log from the last run, and sure enough the voltage cutoff was at 16.7v. So I think the auto cell detection setting was seeing my HV 4s as a 5s.

I turned off auto detect and manually set it to 12.8v (3.2v x 4, right?). Unfortunately I probably won’t be able to test it until this weekend. I’ll report back.

The logging is very cool. Looking forward to digging into all the other data.

gigaplex

iTrader: (2)

A 4 cell LiHV is 17.4V, a 4 cell LiPo is 16.8V and a 5 cell LiPo is 21V when fully charged. I can see why it would think your fully charged 4 cell LiHV was a nearly flat 5 cell LiPo.