How to prevent the 1717 1650kv from exploding again?

[Lennart]

The last time I drove my 1717 granaded at 127kmh after 5 seconds of full throttle and made the car stop very violently. The front drive shafts are now slightly twisted...

It happened 6 weeks ago and I now wonder how to protect my new 1717. (Next time I will buy a different motor.) EDIT: 1717 1260kv should be better for 8s bashing

What Castle told me: If the motor gets hot the epoxy gets soft and high rpm do the rest.

My motor never got over 54C° before so I guess I want to lower my RPMs in the first place. That day I made several >4seconds passes with around 46K motor rpm .

What I have done:
-Motor cutoff temperature to lowest 49C°
-Improved airflow cooling
-set timing to 0 degrees

How can I reduce the RPM while keep running my 8s batteries?
Should I gear up and reduce the max power output to physically limit it from spinning higher? At like 40k rpm.
Can you limit RPM via software?

 

[gotnitro]

Simply looks like you had a bad rotor. S-happens. Probably will never happen to you again.

 

[Lennart]

I will test if it happens again
Maybe the epoxy was degrading over time, since I was running 8s all year with relatively low load and high rpm...

 

[Garcbomber]

How much runtime was on the motor before it seized and any signs beforehand that it had been compromised?

Can you share the gearing and datalog when the lockup occurred?

 

[LibertyMKiii]

From memory there was a batch of 1717s that had this issue more often than normal.
I believe it has been resolved.

 

[dure16]

I was running 8s all year with relatively low load and high rpm

That’ll do it

 

[Lennart]

How much runtime was on the motor before it seized and any signs beforehand that it had been compromised?

Can you share the gearing and datalog when the lockup occurred?

Sadly the datalog was full due to at-home testing the night before and I forgot to delete it... But the logs from before had the same gearing.
22P 43S and standard vte2 diffs with grp wheels. Full battery 138kmh 50krpm. When it happened 127kmh 46k RPM.

One moment before it happened I heard something strange but before that the motor was running normal.

And it was towards the end of the run so there probably was some heat in the rotor.

I guess I need to lower the rpm...

 

[dure16]

@Lennart what kind of driving is this?

Speed running a 1650kv motor on 8S should be fine. Voltage sag and cooling down between runs help you.

But hooning/bashing a 1650kv motor on 8S might be a recipe for disaster. Others may disagree, but that kv just seems too high to me.

If this is for bashing, check out the 1721 or 1717 in 1260kv form. You can gear up to account for the reduced motor RPM.

 

[yaboyhamz]

@Lennart what kind of driving is this?

Speed running a 1650kv motor on 8S should be fine. Voltage sag and cooling down between runs help you.

But hooning/bashing a 1650kv motor on 8S might be a recipe for disaster. Others may disagree, but that kv just seems too high to me.

If this is for bashing, check out the 1721 or 1717 in 1260kv form.

can confirm blew my 1650kv castle hooning around my typhon on 8s

 

[Lennart]

f this is for bashing, check out the 1721 or 1717 in 1260kv form

Well yes if I think about it maybe the 1717 1260kv is what I want. (1650kv *6/8 = 1240kv I would have equal rpm when I would use 6s on the 1650kv compared to 1260kv on 8s)
The 1721 is too heavy for my build.

For the short-term solution I will gear up to maybe 26P and reduce the esc max power or something. To have lower RPMs with my 8s batteries.

 

[cancelthefuture]

@Lennart what kind of driving is this?

Speed running a 1650kv motor on 8S should be fine. Voltage sag and cooling down between runs help you.

But hooning/bashing a 1650kv motor on 8S might be a recipe for disaster. Others may disagree, but that kv just seems too high to me.

If this is for bashing, check out the 1721 or 1717 in 1260kv form. You can gear up to account for the reduced motor RPM.

Strangely enough, I've read castle actually recommends the 1650kv over the 1260kv for better heat management for bashing. I have no idea why that is and it does not compute.

 

[dure16]

Strangely enough, I've read castle actually recommends the 1650kv over the 1260kv for better heat management for bashing. I have no idea why that is and it does not compute.

It’s because the 1650kv is slightly more powerful. RPM is the enemy in this situation though, I think.

 

[yaboyhamz]

It’s because the 1650kv is slightly more powerful. RPM is the enemy in this situation though, I think.

but wouldnt a 1650kv have higher RPM than a 1260kv all things considered?

 

[cancelthefuture]

but wouldnt a 1650kv have higher RPM than a 1260kv all things considered?

Yeah he's saying that the RPM is the issue and when bashing regularly with 8s it's going to strain the rotor more, even if the motor is more powerful.

 

[Sirkensirlot]

can confirm blew my 1650kv castle hooning around my typhon on 8s

mine too . my new one is staying 6s only

 

[dure16]

but wouldnt a 1650kv have higher RPM than a 1260kv all things considered?

Yes and that’s the problem

 

[Lennart]

So I have ordered bigger pinion gears (up to 29T, currently I have 22). 43 spur.

Could I use the castle max power setting to reduce the top speed? The software actually says % of maximum forward speed... Or is that misleading?

So if the car was geared for 160kmh and I set 80% max power, do I get 128kmh top speed then?
Instead of 47kRPM the motor would have 37.6kRPM at that speed. Should be way better for the rotational forces on the rotor...

 

[Diem Turner]

So I have ordered bigger pinion gears (up to 29T, currently I have 22). 43 spur.

Could I use the castle max power setting to reduce the top speed? The software actually says % of maximum forward speed... Or is that misleading?

So if the car was geared for 160kmh and I set 80% max power, do I get 128kmh top speed then?
Instead of 47kRPM the motor would have 37.6kRPM at that speed. Should be way better for the rotational forces on the rotor...

Yeah, you can do it that way (no, it's not misleading...I used to adjust max power on the fly via the AUX lead, I found it was a good way to get used to new motor, gearing, etc). Or you can adjust the throttle trim on your Tx.

Sorry to see your motor went ALAKABLAMMO. That's always a bummer. There's really nothing you can do that will guarantee that won't happen again other than getting a different motor that has a stainless sleeved rotor. Some 1717s last forever making 8S pass after 8S pass, others grenade below 120mph.

 

[Lennart]

Yesterday I found the onboard footage of the motor seizing up. For the interested people:

Does somebody know if the castle max power setting impacts the car's acceleration? Had no chance to test it yet...

 

[Moirae]

This is wild! I'm surprised to see this is still happening to some people. I have a few builds with the 1717 1650kv and have never had this happen. I guess now that I think about it I've not bashed them on 8s that often. I used to have one in a felony that I bashed on 8s a decent amount but my others are mostly 6s off road bashers.

This is definitely a good time to plug tp motors though. Ive gotten a 4060cm 2080 kv to 240f cause of broken fan and i still use that poop today with zero issues