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Gotway ACM 1600 Autopsy and Mods


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2 hours ago, Hunka Hunka Burning Love said:

:lol: I think I'll wait until you successfully get your ACM back together and functioning before I let you do unnecessary surgery on my 'bot!

Clear your calender for 2020! The GWEx (Experimental) should be done and your bot will need some nips and tucks!

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2 hours ago, Hunka Hunka Burning Love said:

:lol: I think I'll wait until you successfully get your ACM back together and functioning before I let you do unnecessary surgery on my 'bot!

I almost missed that subtle insult - sweet :laughbounce2:

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No insult intended :innocent1:.  Rehab's quite a capable practitioner of the Gotway surgical arts.  Heck the guy has put together experimental helicopters so I think an EUC shouldn't be too huge of a task for him to beef up.   The missed screw thing was a little worrisome though I do admit :whistling:, but hey we've all been there.

Taking bets on how many "extra" screws will be found after reassembly!

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Then, when the heat can be very good, the printed circuit board to kill a sudden spike in the power under heavy loads. It is not even a good cooling help at all.
We need a well-designed and made of a circuit board.
Those not yet anyone done.

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12 hours ago, Rehab1 said:

Thank you! Great info and an easy fix! Did you modify yours? :thumbup:

I had the pedal magnet come loose on my Monster.  It was a really quick fix with some Gorilla Glue and some Gorilla Tape for good measure.  That is one less item I need to be concerned about:-)  If you are in there it is a worthwhile preventative measure.

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4 hours ago, EUC Extreme said:

Then, when the heat can be very good, the printed circuit board to kill a sudden spike in the power under heavy loads. It is not even a good cooling help at all.
We need a well-designed and made of a circuit board.
Those not yet anyone done.

I concur! Unfortunately building an improved board with spike or surge protection is beyond my adroitness. Is there anyone on the forum up to the challenge.... @esaj ?

In your opinion when do spikes generally occur?

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7 hours ago, Rehab1 said:

I concur! Unfortunately building an improved board with spike or surge protection is beyond my adroitness. Is there anyone on the forum up to the challenge.... @esaj ?

In your opinion when do spikes generally occur?

Making a (separate) current limiter for the motor shouldn't be complicated (electronics wise), but it will likely need a large heatsink when it starts to limit the current and the wheel controller still wants to run faster and faster, unless it's the kind which shuts down the power from the motor completely :P  Easier way to do it would be to handle it in the firmware.

For voltage spikes, TVS diodes with suitable (larger than maximum battery) voltages could suffice, although I'm not sure if they're needed anyway (I think the boards are already protected, otherwise they'd be blowing up all the time? ;)).

 

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Before I begin pulling out the 16 awg main motor wires to change over to a larger 14awg wire (hopefully) I took a few photos of the current installation method. 

The thin insulative sleeves that are  currently slid over the soldered connections would not be my choice as I could see a few strands of bare wire already beginning to poke through the sleeve. If the upgrades I am performing work and the 14 awg silicone wires do fit down through the shaft I will be using aircraft grade shrink wrap as a insulator. 

There just might be enough room for 14 awg wire with a protective sleeve.

Struggling just to slide the 16 awg wire up and down the axle opening! Not a good indication for a larger wire! 

One guy wanted to know about the side profile of the temperature logger in the ACM so here is a photo. If anyone is interested I purchased the logger through MicroDAQ.com for $55 USD. Model # HOBO MX 100. 

I believe @EUC Extreme mentioned that Gotway does not produce their own motors. We may need a hieroglyphic translator but here is a stamping I found on the wheel hub. It might be a clue to who actually does produce the motors. 

 

 

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1 hour ago, Rehab1 said:

Before I begin pulling out the 16 awg main motor wires to change over to a larger 14awg wire (hopefully) I took a few photos of the current installation method. 

The thin insulative sleeves that are  currently slid over the soldered connections would not be my choice as I could see a few strands of bare wire already beginning to poke through the sleeve. If the upgrades I am performing work and the 14 awg silicone wires do fit down through the shaft I will be using aircraft grade shrink wrap as a insulator. 

There just might be enough room for 14 awg wire with a protective sleeve.

Struggling just to slide the 16 awg wire up and down the axle opening! Not a good indication for a larger wire! 

 

Wow, all joking aside, I'm really impressed with what you've been doing along with your 'documentation'. I hope it's successful in the end.

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7 minutes ago, Marty Backe said:

Wow, all joking aside, I'm really impressed with what you've been doing along with your 'documentation'. I hope it's successful in the end.

Many thanks! Success can be quantified in many ways! If my sundry list of updates work out as planned that would be a huge success but if not I would still be pleased if some members benefited along the way!

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2 hours ago, Rehab1 said:

Before I begin pulling out the 16 awg main motor wires to change over to a larger 14awg wire (hopefully) I took a few photos of the current installation method. 

The thin insulative sleeves that are  currently slid over the soldered connections would not be my choice as I could see a few strands of bare wire already beginning to poke through the sleeve. If the upgrades I am performing work and the 14 awg silicone wires do fit down through the shaft I will be using aircraft grade shrink wrap as a insulator. 

There just might be enough room for 14 awg wire with a protective sleeve.

Struggling just to slide the 16 awg wire up and down the axle opening! Not a good indication for a larger wire! 

One guy wanted to know about the side profile of the temperature logger in the ACM so here is a photo. If anyone is interested I purchased the logger through MicroDAQ.com for $55 USD. Model # HOBO MX 100. 

I believe @EUC Extreme mentioned that Gotway does not produce their own motors. We may need a hieroglyphic translator but here is a stamping I found on the wheel hub. It might be a clue to who actually does produce the motors. 

 

 

It looks like #14 should work,although you'll definately want to employ a lubricant(have lots of experience pulling wires through tubes having been an electrician since the 70's) might I also suggest beveling the entrance hole in the axle with a larger drill bit or something to lessen the possibility of the metal edge cutting into the larger wires.Have seen many shorts caused by sharp conduit edges.;)

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I know they aren't as flexible, but do you think using solid core wiring rather than stranded might be a better option?   Household wiring is usually solid core and has very tough outer insulation.  Getting it through than axle would be extremely difficult though and may be impossible.   @EUC Extreme used two smaller wires instead of one larger one,  but that would add extra insulator thickness to pass through an already tight axle.

I wonder if that outer protective sheathing that bundles all the wires together is necessary.  It might only be used to help feed the harness through the axle.  If you don't use that you would have a little more room for thicker wires.  Maybe soldering the ends of the six wires together to a length of feeder wire to help pull the group through might help.

Alternatively, cutting a small slot down the length of the axle to allow placing the wires in might be possible.  It would weaken the axle though so only a wide enough slot for the thickness of wire should be made.  Or as per Marty's idea, the other end of the axle could be cored out with a metal press drill or lathe to allow one to feed wiring through the other side.

A larger bearing with larger matching axle and core would make life easier for everyone from the get go.

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It is very difficult to find the original thicker cable. Which would be a thin insulator. As thick insulation takes up too much space.
I solved the case so that the switch behalf of the original cables between.
So I put all the wires double the amount of (non-sensor wires). Without the thick black protective cover. They just fit. But it requires patience :)

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30 minutes ago, Hunka Hunka Burning Love said:

know they aren't as flexible, but do you think using solid core wiring rather than stranded might be a better option?   Household wiring is usually solid core and has very tough outer insulation.

Probably not a good idea.Household wiring is solid because it is cheaper.But in most cases houses are not moving.Solid wiring handles vibration better which is one reason you wont see it used in cars,motorcycles etc.Household wiring is type THHN which is the type of insulation used and is very durable and resistant to heat and is rated for 600 volts.It is also widely available in stranded and any Home Depot/Lowes etc. has it.:)

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One other question - would silver soldering with a propane or butane torch at the motor wire / copper multi-coil wiring junction be best for higher temperature resistance or is regular soldering fine as temperatures don't get that high at that junction?

Also, with the copper winding wire how does it prevent shorting out since there appears to be only a very thin type of coating over the copper?  You would think if a small area was exposed between two wires that would short the circuit out?

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51 minutes ago, Hunka Hunka Burning Love said:

One other question - would silver soldering with a propane or butane torch at the motor wire / copper multi-coil wiring junction be best for higher temperature resistance or is regular soldering fine as temperatures don't get that high at that junction?

Also, with the copper winding wire how does it prevent shorting out since there appears to be only a very thin type of coating over the copper?  You would think if a small area was exposed between two wires that would short the circuit out?

If your windings were getting anywhere even close to the 370 degrees Fahrenheit that standard lead/tin solder melts at ( modern lead free solder is even higher) you would have wrecked the magnets well before that as too much heat demagnetises them.

Copper wire windings in coils are usually lacquered to insulate them from each other (that lacquer needs to be scraped off to solder them.) Overheating coils in motors or transformers is a common cause of damaging that lacquer and shorting the coils - so another reason not to use silver soldering!

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4 hours ago, Hunka Hunka Burning Love said:

I know they aren't as flexible, but do you think using solid core wiring rather than stranded might be a better option?   Household wiring is usually solid core and has very tough outer insulation.  Getting it through than axle would be extremely difficult though and may be impossible.   @EUC Extreme used two smaller wires instead of one larger one,  but that would add extra insulator thickness to pass through an already tight axle.

I purchased high temp 14 awg silicone with a 400 copper strand count. Super flexible! I still need to sneak into work tomorrow to try it out. 

 

4 hours ago, Hunka Hunka Burning Love said:

I wonder if that outer protective sheathing that bundles all the wires together is necessary.  It might only be used to help feed the harness through the axle.  If you don't use that you would have a little more room

I agree and will probably eliminate the protective sheath ( better word than sleeve) but I plan to use some form of grommet where the wires enter and exit the shaft. 

 

4 hours ago, EUC Extreme said:

Without the thick black protective cover. They just fit. But it requires patience :)

A few xanax in the morning and I should be good to go!:)

3 hours ago, Hunka Hunka Burning Love said:

 

One other question - would silver soldering with a propane or butane torch at the motor wire / copper multi-coil wiring junction be best for higher temperature resistance or is regular soldering fine as temperatures don't get that high at that junction?

 

 

I have silver solder at work but I am not sure if it will flow properly over the existing solder on the coil wires. I prefer not to cut those wires back. I use a butane soldering gun on my old truck wiring that produces quick pin point heat. The coil is one big heat sink so it will constantly be drawing heat away from my wire spice. The least amount of time I dwell in one spot with high soldering temps the better.

3 hours ago, Hunka Hunka Burning Love said:

Also, with the copper winding wire how does it prevent shorting out since there appears to be only a very thin type of coating over the copper?  You would think if a small area was exposed between two wires that would short the circuit out?

Yes, definitely a concern of mine when I spotted the issue this morning but it should be an easy remedy. I have used various types of high temp aircraft sheaths over my helicopter wires to protect them. To be honest that was one of the more disappointing finds during this rebuild!

 

2 hours ago, Keith said:
3 hours ago, Hunka Hunka Burning Love said:

 

If your windings were getting anywhere even close to the 370 degrees Fahrenheit that standard lead/tin solder melts at ( modern lead free solder is even higher) you would have wrecked the magnets well before that as too much heat demagnetises them.

Copper wire windings in coils are usually lacquered to insulate them from each other (that lacquer needs to be scraped off to solder them.) Overheating coils in motors or transformers is a common cause of damaging that lacquer and shorting the coils - so another reason not to use silver soldering!

Great information! Before I solder the new wires I need to protect the copper windings from excessive using some form of heat sink. Small vise grips might work to help diminish any excessive heat from traveling up the coil to far.

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6 hours ago, jrkline said:

It looks like #14 should work,although you'll definately want to employ a lubricant(have lots of experience pulling wires through tubes having been an electrician since the 70's) might I also suggest beveling the entrance hole in the axle with a larger drill bit or something to lessen the possibility of the metal edge cutting into the larger wires.Have seen many shorts caused by sharp conduit edges.;)

As an electrician, do you think that more windings in the motor might lessen the load?  I mean over building the motor so the stress is less on the control board?  It seems that the manufacturers have used the same motors and increased voltage and battery size, and changed the firmware, but still we see these burnt components.

I have no idea, just brainstorming here, but that looks like a good idea about beveling the edges.  Electrician is something I wanted to do, but while going to school I woke myself up one day, yelling, But where does the current go!:w00t2:

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My wish is that Gotway is following this thread and ends up commisioning a new motor for their future wheels with larger bearings in the motor covers along with a matching axle that has more room in it for thicker wiring.  If they changed out that bottleneck I bet we wouldn't be seeing these wire temperatures ending up melting connectors and shorting out.

If they want to make "Monster" EUCs it would be nice to see beefier motors that can keep up with the larger battery capacities.  There is that 40A MicroWorks control board out there.  If they can get MW or whoever they use to engineer a heavier duty controller that can handle voltage spikes better and maybe incorporate automotive standards for connectors a lot of our problems would be eliminated instead of requiring end users to troubleshoot.

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2 hours ago, steve454 said:

As an electrician, do you think that more windings in the motor might lessen the load?

Generally speaking,more windings = more load,so no.

 

2 hours ago, steve454 said:

I mean over building the motor so the stress is less on the control board?

You would have to down size motor power to lessen the stress on existing components or upgrade them to more efficiently handle power demands.AFAIK there have not been problems with control board failures in as much as the problems with conductor and or connector failures.The weak link seems to be the wires between the board and motor itself.So if the wire size is increased like @EUC Extreme apparently has done to some of his wheels,you could apparently illiminate or lessen the source of a lot of the failures that have shown up in Gotways.KingSong tends to limit their wheels' power with software to avoid the problems like Gotway is having while being constructed with similiar components.So the end result is,if you want the most powerful wheels,Gotway is pretty much the only choice.And if Gotway were to suddenly scale back the power of their wheels through software,they would lose one of the biggest incentives to buy a Gotway;power!

 

2 hours ago, steve454 said:

 Electrician is something I wanted to do, but while going to school I woke myself up one day, yelling, But where does the current go!:w00t2:

My dad was an electrician,and he discovered that it was easier to put me in the attic when I was 10 year old and run the wire than it was for him to do it.I've been doing it ever since.:w00t2: 

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Since you guys are talking about the motor windings, here a theoretical question:

Would it make a difference to make the windings (defined here to be all the parts made from copper wire as seen in the photos) from one solid block of copper (via CNC or whatever)? Would that produce a better motor?

(I don't care how expensive that would be)

[Having no working EUC atm due to EUCs being not good enough yet, I'm fantasizing about how an optimal EUC would be constructed]

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3 hours ago, meepmeepmayer said:

Would it make a difference to make the windings (defined here to be all the parts made from copper wire as seen in the photos) from one solid block of copper (via CNC or whatever)? Would that produce a better motor?

I don't think that would help. If I recall my high school physics and industrial arts classes, I think the whole electromagnetic force works when there are several windings to allow current to move around a metal core which generates a magnetic field that interacts with the poles of the magnets nearby.  If there was one solid turn of copper going around it would not generate enough of a field as the current needs to repeatedly circle the core (solenoid).

http://science.howstuffworks.com/electromagnet.htm

 

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Update on Mosfet/ Heatsink attachment:

@KingSong69 had a question on the Mosfet attachment and interface in one of my previous photos so here is some clarification. 

There are two types of  Thermal Interface Material (T.I.M.) used on the GW ACM 1600. I am sure other GWs use this material as well.

T.IM. Is described as any type of material that is inserted between two parts to enhance the thermal coupling properties between the two components thus increasing heat dissipation. My ACM uses both thermal pads and thermal grease for the T.I.M. 

There is a silicone thermal pad T.I.M. inserted undeneath the upper and lower bank of Mosfets along with screws that contain plastic insulating shoulder washers.

The top bank of (6) Mosfets are attached to an aluminum bridge of sorts that is fastened with (4) screws to the main aluminum heat sink. Gotway uses a different T.I.M. in this area called  'Thermal Grease'. 

Thermal Grease does not have any mechanical bond properties. It is purely designed to increase heat dissipation between the two surfaces especially if there are any small imperfections on either surface.

The existing thermal grease will need to be cleaned off and a new application applied before assembly.

I hope all of this makes sense! What an education! 

Here is a view of the mosfet attachment screw and shoulder insulating washer. 

 

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