Begode Master 134V 2400WH Suspension

[Tawpie]

1 hour ago, EUChristian said:

this is my next wheel

if only it wasn't so gosh darn fugly. Black is a huge improvement over the red, but still, for me anyway, it meets the criteria for coyote ugly. And the headlight... I ride a lot after work in the dark, I need a working headlight.

Edited April 15, 2022 by Tawpie

[EMA]

6 hours ago, meepmeepmayer said:

I'm worried that these directly exposed battery boxes (on the Master or EX20S or S22) might be mechanically damaged in a crash. It would be a direct impact. Worst case it's going to kill the entire battery pack.

We'll need 3D-printed protectors, I suspect. Or maybe a one-piece combination of powerpad and protector for the Master would work.

they have already bad crushed this wheel several times and seems fine

3 hours ago, Tawpie said:

if only it wasn't so gosh darn fugly. Black is a huge improvement over the red, but still, for me anyway, it meets the criteria for coyote ugly. And the headlight... I ride a lot after work in the dark, I need a working headlight.

3D printing stuff and mods are always easy with gotway 

like all the other wheels we need a decent real light, don't worry for the front one, it's pretty easy to mod the front mount and makes the light better and tiltable 

i just need to kill the wait...

[Lefteris]

17 hours ago, supercurio said:

requests to make the BMS capable of talking to the mainboard

We don't know yet, when we get one and digg thru the firmware we may find something, so if it "is" there we will know

Edited April 15, 2022 by Lefteris

[Chriull]

9 hours ago, redfoxdude said:

As others have stated, this type of MOSFET has a large thermal connection underneath itself where it is soldered to the copper on the circuit board, and then you would pipe that heat through the bottom of the board to the massive heatsink. 

Just looked at: https://www.infineon.com/dgdl/Infineon-ApplicationNote_600V_CoolMOS_C7_Gold_TOLL-AN-v01_00-EN.pdf?fileId=5546d4625b10283a015b144a1af70df6

There they show a setup with an d2pak-7, thermal vias and a heatsink with a total Rth of 8.5K/W. With 150°C max junction temp, 70 degrees ambient one has a delta T of 80° - possibility to dissipate 80°/8.5~10W.

With some 8mOhm Rds that'll allow an drain current of ~11A. Times 4 gives 44A for continous burdens.

Sounds very nice!

9 hours ago, redfoxdude said:

Hopefully there are good thermal pads between the board and that heatsink, but if not, that's probably going to be a really good potential upgrade

Infineon used for the calculation a "Isolation foil TIM (K10)" with a λ of 0.8 W/(m*K) and a thickness of 0.15mm - seems to be the thing to look for...

[techyiam]

28 minutes ago, Chriull said:

There they show a setup with an d2pak-7, thermal vias and a heatsink

You wouldn't happen to know whether this method of cooling would be a lot more costly to implement than the conventional one?

Edited April 15, 2022 by techyiam

[Chriull]

13 minutes ago, techyiam said:

You wouldn't happen to know whether this method of cooling would be a lot more costly to implement than the conventional one?

No.

But i'd guess it's much cheaper. Thermal vias should be very cheap?

Automated mosfet placing and soldering is cheaper and more reliable.

Placing on the heatsink is one simple assembly step instead of assembling each mosfet with a screw to the heatsink...

[Planemo]

11 hours ago, alcatraz said:

Oxidizing sliders sounds bad. Negligent people are going to simply replace them every few years right? Maybe get them coated or something. 

The careful owners are going to grease them up every year etc.

You should never, ever put grease or in fact any external lubrication on fork stanchions, it will only gather grit and accelerate wear.

Standard practice is to replace the fork seals, internal oil sponges (which lubricate the stanchions) and oil change as per manufacturers recommendation.

Whether this wheel even runs internal sponges or indeed any oil, I have no idea. If it doesn't, it will be a real maintenance headache.

I too have concerns about the integrity of the whole stanchion/slider assembly on the Master. They look awfully skinny to me given the intended use. MTB ones are far more stout and due to the rake of the front end will put far less stress through the fork bushings than the bolt upright ones on the Master. My first thought was that the 4 (albeit smaller) legs on the S18 would be a better solution than the 2 slightly bigger ones on the Master. We shall see..

[EMA]

after watching the disassembly video few times seems to me that the tire change require:

• open the top part up to the board and disconnect the motor wires
• disassembly the bottom part of the wheel
  • pedals
  • screws holding batteries into the lower part
  • release the motor cable
  • the lower part where pedals and kick stand are attached to
• now you should be able to access the 4 screws holding the motor to the frame

[alcatraz]

1 hour ago, Planemo said:

You should never, ever put grease or in fact any external lubrication on fork stanchions, it will only gather grit and accelerate wear.

So just keep them clean then? Isn't there something one can do to inhibit oxidation?

[Planemo]

25 minutes ago, alcatraz said:

So just keep them clean then? Isn't there something one can do to inhibit oxidation?

They shouldn't be rusting in the first place is my answer. Thats the whole point of using chrome plate.

But any decent MTB fork won't be using chrome anyway - they all have gone over to friction-reducing coatings which have the added bonus of preventing corrosion from the outset.

If I DID have anything left that was still chrome, yes I would just keep it clean and dry as you say.

[Tawpie]

5 hours ago, Chriull said:

But i'd guess it's much cheaper. Thermal vias should be very cheap?

Yes and no. The vias are 'inserted' as part of the standard automated bare board assembly, but to be effective you need a heat plane made of thick copper added to the board. This isn't expensive, but adding a heat sink to the board really complicates what's called the solder schedule (soldering profile). You have to warm the heatsink or it'll cause the solder to freeze 'early' leading to low quality and potentially unreliable joints. The thick copper heat plane can also cause warping issues because copper expands and contracts at a different rate than fiberglas/epoxy. All very manageable but care is required.

The real challenge is getting the heat out of the PCB and into the air. That requires careful thought, modeling, and measurement. Again, very manageable.

But real life is the only 'test' that matters. Lab tests are confidence builders, but real life is always surprising and usually not in a good way.

Edited April 15, 2022 by Tawpie
typos. can't typ

[redfoxdude]

4 hours ago, EMA said:

after watching the disassembly video few times seems to me that the tire change require:

• open the top part up to the board and disconnect the motor wires
• disassembly the bottom part of the wheel
  • pedals
  • screws holding batteries into the lower part
  • release the motor cable
  • the lower part where pedals and kick stand are attached to
• now you should be able to access the 4 screws holding the motor to the frame

I'm not sure you even need to go that far, I think it may even be possible to:

1. Open the top to access and disconnect the motor wires
2. Remove the screws retaining the motor cable clips on the slider
3. Remove pedals (maybe not, if compressing the suspension gives enough clearance)
4. Remove the battery adjacent to the motor cable, unless it can be snaked out (can't quite tell if there's enough clearance)
5. Air out of the shock to fully compress the suspension (make the motor screws accessible)
6. Remove the motor screws and drop the motor out

Either way, much better than working on previous generation suspension EUCs. I'm really looking forward to checking out the Master in person.

Edited April 15, 2022 by redfoxdude

[BleepBloopBlop]

I was doing more comparisons between the 40T and 50E in terms of ride time. It looks like unless your average amp draw is over 10A there isn't a mileage advantage to the 40T cells. I think it's rather unlikely to draw over 10A on average for the duration of a ride.

[0000]

33 minutes ago, BleepBloopBlop said:

I was doing more comparisons between the 40T and 50E in terms of ride time. It looks like unless your average amp draw is over 10A there isn't a mileage advantage to the 40T cells. I think it's rather unlikely to draw over 10A on average for the duration of a ride.

Something to bear in mind when you are doing these comparisons is there is a significant performance difference between generations of Samsung 50E and 50E2 cells. I don't know if all new Samsung cells coming in the master come as 50E2 or if the charts you are using are of 50E or 50E2, but here's one test showing the difference:

 

So the 50E2 = would be a decent amount less voltage sag and more range over the older 50E.

source

[EUChristian]

I just want to say...although I have zero clue what half of this means at this point...have electrical engineers, scientists and insane hobbiests who know circuit board technologies and the physics of suspension sliders MAKE MY FING DAY. If I was Gotway I would have half of you on retainer. 

[EUChristian]

On 4/14/2022 at 11:38 PM, Tawpie said:

if only it wasn't so gosh darn fugly. Black is a huge improvement over the red, but still, for me anyway, it meets the criteria for coyote ugly. And the headlight... I ride a lot after work in the dark, I need a working headlight.

I have to admit, the older I get the less I care how it looks and the more I care "how it drives and how reliable it is".

 

I am becoming my Dad. Lord help me. 

[DavidB]

I like this one. The engineering seems streets ahead of the Gotways of not so long ago. It even looks like it will be not too difficult to custom mod if you want, and I am not talking just a different shock.

When the Hero came out I was concerned about the lack of torsion rigidity like fbhb and was completely unsurprised when Kevin's Hero arrived with a bent suspension tube. The Master has way beefier tubes and the battery cases seem ali  not plastic like the Hero but if it is not enough (for Mike Leahy types) it looks like it would be pretty easy to add some ali or carbon support stays in front and behind the batteries. Don't like the head light? Looks pretty easy to bolt on an Aliexpress alternate a la Adam Wrongway. There is no lower surround to restrict whatever shape you want.

Suspension? Yes you could change the shock but it would not be too difficult to change the linkage and progression rate. Hell if you want and had time and money on your hands you could even change the whole set up. Leaf springs? Citreon type air suspension? Torsion bar spring? Even a rubber ball between top of sliders and the top frame.

There are little things that bother me. The stand, those rubber lugs should be flush so they don't dig in on the back of jumps. Not too keen on the angle iron nature of the design either. Wouldn't want to get hit with that. The headlight should be recessed a bit so the rubberised foam of the seat provides impact protection. Not too difficult to fix if you move the beeper and drill a couple of holes in the bracket. Pity the display is not further forward though it is better protected where it is.

 

It would be nice if the wheel was less top heavy but unless batteries are redesigned that isn't going to change.

Some have mentioned risk of exposed battery cases. I don't know which is better. I suspect the older plastic shells are safer. Not only will the plastic shell give (and unfortunately crack usually) on impact but Begode packed the batteries in sponge rubber and with a large flat side panels the impact energy of a crash was disipated over a fairly large number of batteries which after all are mostly metal. When I saw a teardown of the Kingsong S20 batteries I  was a little shocked to see no vibration absorbing material between the cells and the ali case. Posters on forums also mentioned the lack of sealing between the battery case and the board. Luckily, it was through those gaps that the S20 battery fire was able to vent. It was spectacular but if the Ali cases had been completely sealed when the cells failed that EUC would have gone off like a bomb. Something Hsiang should think about next time he wants to stand next to a burning EUC.

So as I said, not sure if Ali cases are better (penetration) or plastic (vibration). I'd probably prefer a bonfire to a bomb but I think silicon coated cells in ali cases would be best of all.

 

Edited April 16, 2022 by DavidB

[Chriull]

13 hours ago, BleepBloopBlop said:

I think it's rather unlikely to draw over 10A on average for the duration of a ride

As the master is specified with a 3500W motor >4kW are needed for this as battery power. This number "should" be safely  reachable for some time - although it's marketing and questionable if the mosfets and phase wires withstand it.

So 10A should not be out of the world and not only seldom peak burden.

Most interesting in these diagrams is imho that on of the m50e cut off discharging with 15A after ~10min due to overheat.

Seems from the history it was only a match between mosfets, ?capacitor? or wires to fry/unsolder first - now the batteries are in the game, too...

And i'd assume for this discharge test they were not packed tightly together with 31 more cells with the same burden...

Maybe it'll be hard to find places to burden the master for longer time with >4kW. That'll need something like a 10% incline with 50km/h or 20% with 40 km/h... (for 3kW motor output - guestimated to >4kW battery output...)

[onkeldanuel]

20 minutes ago, Chriull said:

Maybe it'll be hard to find places to burden the master for longer time with >4kW. That'll need something like a 10% incline with 50km/h or 20% with 40 km/h... (for 3kW motor output - guestimated to >4kW battery output...)

And at this Point the Mainboard gets hot way quicker than the batteries and Kicks you Off at 80 Celsius......before batteries get dangerous warm

[Meserias]

There any telegram/WhatsApp group dedicated to this exact model (Master) ?
please let me know in private or post here

[The Brahan Seer]

 

[Adel]

When comparing Samsung 40T versus Samsung 50E, it seems the cycle life of the 40T is much worse:

Samsung INR21700-40T:

Capacity ≥ 2,400mAh @ after 250cycles
(60% of the standard capacity @ RT)

Samsung INR21700-50E:

Capacity ≥ 3,802mAh @ after 500cycles
(80% of the Rated Discharge Capacity @ RT)

So start off with less capacity to begin with, and degrade it over time at twice the rate of the 50E ? I'm trying to decide between the 2 options and want to see what is practical benefit of the 40T,for example is the firmware and components different to take advantage of the extra capability or is it just potential performance that is not tapped fully. For non-agressive riders (cruising between 25-35 mph), is there any benefit to the 40T.

[chanman]

1 hour ago, Adel said:

 

So start off with less capacity to begin with, and degrade it over time at twice the rate of the 50E ?

it's a bit misleading. The 60% at 250 cycles number for the 40T is with 35A continuous discharge and a fast 6A charge, which is a much more rapid discharge than you would need with these in a 4P configuration and is pushing the limits of the cells. The 50E 500 cycles to 80% number was with much gentler cycles, 1C (5A) discharged and charged at 0.5C. 

I would like to see a more real world for our use case cycle life test for the 40T, 0.5C charge and 15A discharge perhaps, which i think will look much better.

Edited April 17, 2022 by chanman
Added charging info as well

[alcatraz]

A 50E buyer could "upgrade" later by swapping out one or more of the battery modules with high current modules.

You don't have to swap all four modules.

With 2x50E and 2x40T you get like ~2160Wh.

As long as the wheel has a good way of indicating when modules are going bad so we can swap them in time before, and as long all the extra bmss' work as they should. More complexity = more failure modes. Let's hope they nailed the bms quality and intercommunication.

[chanman]

Mixing 40T and 50E packs is possible but I wouldn't personally recommend it, you get the 40T packs trying to both charge and discharge faster than the 50E packs, and then some current flowing to equalize the voltage, the 50E packs recharging the 40T packs as you discharge with the 40T's providing more of the current to the motor.

Overall just seems like introducing more failure modes and additional wear on the cells that can easily be avoided by sticking to one cell type.