Experience with ZTW SEAL 200 Amp 8s ESC

[plinse]

Hi,
most ZTW-Threads cover the topic on how to get them to work by calibrating them to the RC.

I am actually interested in another topic.

Several chinese ESC have worked out to be reliable and capable of quite high currents (Turnigy 180A V2, Flycolor 150A and labled versions of that one, ...). They can be pushed very hard when you run them disciplined in SAW operation, perhaps modify them with some caps and better cooling...

I have seen some different technical ratings of the ZTW Seal 200A:
https://www.offshoreelectrics.com/pr...200-6200200-v2
https://www.ztwoem.com/product/ztw-s...0a-sbec-8a-8s/
Both say 200A continuous current but OSE and some other vendors rate 300A burst current while the manufacturer says 1200A burst.

My observation so far is that for example the flycolor 150A gives a technical rating of 900A burst (10s) and 150A continuous and when you crosscheck with the MOS FET-Rating this is challenging but there are reasons for it .
My experience is that pushing these ESC to 500A burst is no problem when modifying them slightly with some cooling improvements and caps , you will not need burst for 10sec anyway.

The ZTW200A Seal are capable of 8s but they are also much more expensive (about 4 to 5 times more expensive) so just trying out is a different topic

Is there a reason why Manufacturer and vendors have so much different ratings on burst?
There might be more experience on the 300A Seal. It is the same there:
https://www.offshoreelectrics.com/pr...tw-300-6300400
The vendors rating says 300A continuous and 350A burst while the manufacturer says 1800A burst (same ZTW link as above).

I have not read about dying ZTW a lot so they should be quite reliable?

What do you think about the differences of vendors-rating and manufacturers rating?

Regards, Eike

[koen]

In the manuel of ZTW they said seal 200 burst rate 300 A and for the seal 300 burst rate 1000A,they are maybe more expensive but very reliable and very well made, i have a 150HV,200A,300A to full satisfaction

[Alfa Spirit]

I order 2 x ZTW SEAL 150A High Voltage, price is 90 Euros each esc.

[plinse]

I have issues with mine having a strange startup. Few motors work somehow (starting at constant speed and going to regulated mode very abrupt after 1-1,5sec).
The motors that don't work show no problem being driven by a ZTW300Seal which is strange to me as they are supposed to be very similar. All the motors that don't work at all have no issue with Flycolor 150 or YEP controllers either.

I copied the settings from the 300A seal as they obviously work with ZTW software but it did not help either.

I love the mechanical way the 200A ZTW are made but I am afraid I have to return them.

[Alfa Spirit]

I received two ZTW SEAL 150A High Voltage today, they are very small and very light

[plinse]

I have a brief update on my ZTW200A

I received a softwareupdate and this solved the startup-issue. I planned to use the ESC in a different boat but needed a replacement in a 4th hand HPR C5009 I am just sorting out other problems on.

This gave me the opportunity to do another test run on the new boat.

• In the first 2 runs the servo died. New Servo, new linkages.
• In the 3rd run I had a flip which caused the tape to fail in the cold with lots of water in the boat. This killed one ESC why I needed replacement.
• Today I had run #4 to #6, all of them were stable runs. The new propellers that just arrived work very well (Doctor Props Tornado 4516, again Alex send me really cool propellers ).

After all it was nice to spend some time outdoors after a busy week in homeoffice.
Now I have a good basis to continue improving the setup on.
The video shows the 2nd run today:


This boat was made for SAW and all the reinforcements made it quite heavy, also the Neu1527 definately are powerhouses.

4516 Propellers are a good basis for fun, the potential of the boat is to go for more but not in todays weather. It was quite windy. Still this setup was a good test for the ZTW200A. The peak current slightly exceeded 300A, at top speed it was ~180A. The ESC deffinately got warm but they handled it. In summertime it might be tough. Keeping this setup I would definately install a cooling pump but let's see. The ESC were planned for a different boat...

At first the support from ZTW was good and solved the startup problem. Also the ESC worked well in a quite demanding boat.

Regards, Eike

[plinse]

I have an update on this ESC - not such a good one

As you can see in the video above I ran the ESCs in a ~100mph setup. This requires certain lakes and during summertime we have people swimming, ... and only very few lakes where you can run really fast boats. Long story short: I did not run the boat for several month.

When I wanted to run it this weekend it looked like the ESCs had forgotten the throttle calibration. Ok, repeat it and go.

I had 2 runs that were just normal. The third one convinced me to replace these ESC and not to risk my material or even casualties by running them again.
The boat just behaved strange, I did one slow circle of perhaps 15m to get my boat back and when I opened it there was smoke inside. Not a lot of smoke but some smoke. On the first view everything looked fine. On the second view I found the burned RX-cables as you can see in the attached picture.

The setup in the boat was pretty simple:

• Two separate drives, each having 6s LiPo
• No connection between the LiPo, If one ESC fails and burns it can only kill one LiPo and not both.
• As the ESC have BEC and 2 BEC in parallel might cause electrical oscillation I connected the RX-cable using a Y-connector that does not connect the plus on the RX-side. I use a separate RX-batterie. In high power application this makes sense anyway.

The damage is also described pretty quickly:
The minus-wires going to the RX are burned, plus and impulse are fine, the burned wires end in the Y-connector. The minus-wires of the Y-connector on ESC-side are also fried, on RX-side the wire is completely fine. This tells us where the uncontrolled current flow was. It was going from ESC to ESC on the RX-minus-wires. Kind of a ground-loop obviously.

Analysis today: I replaced the RX-wires and both ESC work fine. I just tested one at the time. The BEC also works fine, at least on 2s as 2s was the batterie I just had to hand.

I don't run such fast boats that often due to availability of big lakes AND safe conditions at the same time. I have to guess but I had about 15 runs on it, 2 runs on Saturday without a problem, I changed nothing, just charged the LiPo and then it burned the wires on the third run.


So lets sum up:

1. The firmware on delivery had some strange startup with multiple motors tested (SSS, Surpass, Lehner). I don't know on which basis ZTW thought te ESC would work but they sold it to the customer. An update could fix that.
   It is not just me having this issue, just watch this board...
   https://forums.offshoreelectrics.com...TW-200-amp-esc
   And based on this thread I had at least 2 PNs asking for the firmware.
2. Bringing a motor to high rpm the ESC causes high EMC disturbance. This dusturbance is so high, it caused rushing noises when recording videos with my Samsung smartphone. As I had the firmware-issue I discussed this with my vendor using WhatsApp and videos. This is why I found out about the EMC-disturbance. ZTW claims that the ESC fulfills CE and RoHS. It would be interesting whether that is true
   
   You can see the strange startup with the old firmware and the disturbance of soundrecording in this video, talking is in German language though.
3. The ground-loop is the next topic. It happens by chance. As I had no intended connection between the two 6s LiPo I expect it to be a switching-issue which can be no problem sometimes but it can be a problem like I experienced without you knowing it before.
   What I am doing now is brainstorming of an electrical engineer but when the ESC operate synchronously (synchronous switching of the FET) I would expect to have no (only little) current flowing, which would be no problem. If switching would be inverse orientation there might be high current flow due to inverse voltage ripple that could burn wires that are only dimensioned for signals.
   My startup-procedure is always the same. I connect the 6s LiPo, then I switch on the transmitter, then I switch on the receiver which usually arms the ESC synchronously. it looks like this worked out about 15 times but not the last run. I don't know what made the difference.
   On the other hand this should not be an issue anyway. I have at least 5 Boats with a twin setup and I never had such issues running them over years using YEP, Flycolor and Schulze-ESC. On some of the boats I have more then 200 runs. They all have the same general setup (2 separate drives and the receiver operated with a separate RX-batterie). This is my first boat using ZTW ESC and it looks like it will be my last.

1. Lousy software
2. Lousy electrical design / EMC-concept
3. Lousy testing

Just imagine I had operated them on 2 different receiver-channels not using a Y-connector. Then you have the high currents inside the receiver burning the internal connection. Melting wire-insulation can also cause a short circuit on the receiver batterie and make the whole RC system fail - hopefully the boat is not running at high speed at that moment.

To be honest I am not the first one to experience some ground-loop issues with ZTW-ESC. Friends had issues with ZTW300 in twin setups and the ZTW300 is announced to be opto so this should not be possible. The problem in understanding a problem is that you usually don't talk to electrical engineers and they could not even answer the question whether all DC-wires were connected and whether they had connections between the HV-LiPo of the two drives or not.
This made me think that testing would clarify whether the ZTW200 and my setup would face this issue or not. Perhaps I should have done that testing a 100 times

I will install modified Turnigy 180 V2 again. They were in the boat before, got less hot and don't have this ground-loop- / oscillating current-issue

Regards, Eike

[jkflow]

FYI,
CE marking has nothing to do with electrical noise, neither does RohS.
CE - health, safety, and environmental protection standards
RoHS - Restriction of Hazardous Substances. - basically it's lead free solder

I do not see how a ground loop would even be present. Are you sure that your Y-cable has the positive (middle) truly disconnected? Any other damage on the cable?
It sounds like 2 positive connected by accident, but you have a better overview of the entire setup. Just guessing on my end.

[plinse]

If positive and negative would have had a short circuit it would not be only the black receiver wires of both ESC having melted or close to melted insulation on complete length and all other wires looking like new. The same in the Y-connector. As it is a Y-connector that does not connect the positive wires it is soldered from wires by myself having shrink wrap around each of the 2 soldered connections (all 3 negative wires have a shrink wrap as well as all 3 impulse wires and a big one around all this to make it mechanically more robust) . The positive wires in the Y-connector were removed completely on ESC-side of the connector. There is nothing getting in contact with the positive wires having the BEC supplying power for a theoretical short circuit. And as mentioned before the positive wires would have seen the same current then, they would have melted insulation as well.

Just have a look at the pictures. The wires in the Y-connector were still insulated against each other after the incident.


You won't find a closed loop according to "DC-thinking". In "AC-thinking" you don't need a closed loop. Capacitors and alternating currents don't need a closed loop for driving oscillating currents if there are also inductances involved.
As it worked well for multiple runs before I would expect some topic like the two ESC having operated in a bad phase shift, driving oscillating currents somehow.
Also "interesting" is that you hear inverter-noise when running the boat at partial throttle.
https://www.youtube.com/watch?v=zHwuicTPv1A&t=77s
When the boat passes by closely at partial throttle you can hear some high frequency inverter noise. If you have heard the boat life you can also hear it in the video. It is more constant then ripple from the motors. The best you can hear it from 2:05-2:07.
I never had that with other ESC.

Actually it is brainstorming at the moment. I have not found a short circuit and the boat worked well for multiple runs before.

What I "forgot" to do is a functional test when I opened the boat after the failed run.
It is an automatic reflex of mine to disconnect all batteries when there is smoke.
I had to carry the boat about 100m from the lake to where we were camping, then I had to open the boat (8 screws and tape). This all took time. There was nothing actively smoking any more when I opened it but there was smoke in the boat. The RX-LiPo (850mAh) had 4,1V/cell after 2 complete runs and the third strange one. The 6s LiPos driving the motors had even slightly higher voltage per cell, something like 4,12-4,13V/cell. During the complete run there was no relevant discharge of the LiPo like you would have had in a "standard short circuit". Especially the "stand short circuit" would not stop when you stop operating the motors.

The strange behaviour of the boat was that I could only go ~10% of the speed and then I had a malfunction of the drives.
I expect the oscillating currents were only driven with the motors being under load. I would expect some small percentage of the motor currents, I saw nothing unusual when doing the functional test before the run but that is only a brief check that both ESC are armed, both motors running before closing the hatch with 8 screws and tape. You don't want to do that more often then you have to ... but this test does not put high load on the drives.

A brief explanation of the pictures:

• the brown-red-orange wire is the original one from the ESC
• the black - (red) - yellow wire is from the y-connector
• the receiver-side of the y-connector has all 3 wires, on the ESC-sides the positive wires were removed completely. No chance to cause a short circuit being driven by the BEC in the y-connector.
• obviously only the negative wires on ESC-side are effected. No positive wire or impulse wire has melted insulation.

Regards, Eike