Begode Master 134V 2400WH Suspension

[MTurcotte]

Should we charge our wheels at 100% all the times?

Of course not.  All Lithium Ion batteries degrade and it is well known that the more you reach their limits, the more they degrade faster.  This is why Tesla cars recommanda not to charge more than 90% unless you are going for a road-trip.

In the past, I have been monitoring the charging of my Rockwheel S16 and unpluging it with the help of a timer.  I was using its original charger.  But I kind got tired of monitoring it like a baby and setting up alarms to remind me to check the charge level every now and then.

Since I installed my solar system, I got used to charge its LiFePo4 (Litium battery) at a specific voltage.  So I wanted to do the same with my EUC.  So I ordered a Variable Voltage & Variable current power supply.  Here is the link:

https://star.aliexpress.com/share/share.htm?image=A5bbacd13f1294559aaf0fc6bd901ac7bO.jpg&businessType=ProductDetail&title=US %2488.20 10％ Off | Digital display Switching Power Supply 1000W Adjustable transformer AC 220V 110V To DC 12v 24v 36v 48v 60v 80v LED Laser Driver&platform=AE&redirectUrl=https%3A%2F%2Fwww.aliexpress.com%2Fitem%2F1005002957280615.html%3F%26srcSns%3Dsns_More%26tid%3Dwhite_backgroup_101%26mb%3DoajGONgmMjkwzeK%26businessType%3DProductDetail%26spreadType%3DsocialShare
(Sorry, Aliexpress has those horrible links).

I chose the 0-160V, 0-6.5A.

What I like about it (other than using it for various projects) is that I can decide how fast I charge my wheels (amperage) and when to stop (voltage).  To help us find the voltage, we can use the following graph:

After removing the left part of the graph that spikes up, we can safely use 4.1V (at rest for a fully charge battery cell as seen in the graph above).  And to determine the lowest voltage before the rapide voltage drop on the right of the graph, we find a linear slope varying from 4.1V when full to about 3.4V on the right.

For the Begode Master, I will set the following voltage to my power supply:
99% charge = 131V (32 x 4.1V)
90% charge = 129V (90% x (4.1V -3.4V)) + 3.4V) = (32 x 4.03V)
80% charge = 127V (80% x (4.1V -3.4V)) + 3.4V) = (32 x 3.96V)
70% charge = 125V (70% x (4.1V -3.4V)) + 3.4V) = (32 x 3.89V)
60% charge = 122V (60% x (4.1V -3.4V)) + 3.4V) = (32 x 3.82V)

Trick:  The Begode Master charger is ‘smart’ and avoids sparks when connecting the power into the wheel.  To achieve the same goal with a ‘dummy’ power supply, simply set the Amperage very low (like 0.5A) when you plug it in and increase it to the desired Amperage after it is plugged in.

For slow charges, I will choose 3A (which is 30% of a standard charge rate for the Samsung 50E cells).
When I am in a hurry, I will charge at 6A (60% of a standard charge rate) (6A/(4x2.5A)).
And for maximum charge rate I will use 9A (at 143.4V) (90% of a standard charge rate using both my variable charger & Begode’s Master 3A charger).

Addition:  A blogger reported that Begode stated there is an internal 10A fuse protecting the charging circuit of this wheel.
I presume this 10A fuse protects the total charge capacity of both 2 charge ports.

Why charge at reduced voltage and reduced speed?
Because it produces less heat while charging and heat is the main factor that cause battery degradation.  So I try to keep my wheels around 60-70% charge between rides and I charge them only as needed depending on how far I need to go on my next ride.  Additionally, I don’t like fires and I do not feel comfortable charging those wheels at 100% every time, not to mention that my wheel will last longer and will be safer to ride and consequently will be less likely cut off on any given ride (I like to keep my limbs intact).

Important point noted by another member:
this charging logic must include a 100% full charge to allow the battery packs to balance their cells (regardless if the packs have their own BMS with active balancing or not).  A FULL charge/balancing until the light is green should be done about every 20 cycles for slow riders and up to every ride for insane riding styles.

Also note that reducing the voltage will take longer to charge to the final voltage
(because in the end, there will be less voltage differential to push the charge).
Just add some time to your charge time when charging at reduced voltages.

I hope this helps some of you.

Michel

Edited July 8, 2022 by MTurcotte

[RagingGrandpa]

4 minutes ago, MTurcotte said:

heat is the main factor that cause battery degradation
I do not feel comfortable charging those wheels at 100% every time

You've fallen into the same trap as many well-meaning people before you...

Imbalance (leading to undervoltage) is the most common cause of EUC battery failure.

And EUC's use simple, resistive top-balancing, that only takes effect at the CV setpoint (100%).

If you don't charge to 100%, you never experience the CV setpoint, and balancing never happens. 
Imbalance will build over time, and eventually a cell will become overdischarged during use, go to zero, then to reverse current, and becomes a heater. 

We must avoid this problem. So: 

On 5/6/2020 at 11:41 AM, RagingGrandpa said:

Life can be simple...

"Charge overnight (to 100%) before a ride"

Don't charge after a ride, unless you're going to ride again immediately. (Minimizes storage SOC.)

I truly think this is all that would be needed for most EUC owners to keep their packs happy. If they knew this and nothing else, I think we'd be in a better place than today.

[MTurcotte]

2 hours ago, RagingGrandpa said:

You've fallen into the same trap as many well-meaning people before you...

Imbalance (leading to undervoltage) is the most common cause of EUC battery failure.

And EUC's use simple, resistive top-balancing, that only takes effect at the CV setpoint (100%).

If you don't charge to 100%, you never experience the CV setpoint, and balancing never happens. 
Imbalance will build over time, and eventually a cell will become overdischarged during use, go to zero, then to reverse current, and becomes a heater. 

We must avoid this problem. So: 

You have a good point.  I have not open my battery packs and confirm but I did ear the BMS of other wheels do resistive (aka passive) top balancing.
Cells, as they age and degrade (usually after multiple cycles) loose some of their capacity and get a different voltage compared to their nearby cells.
This degradation is what cause voltage differential between cells.  Additionally, I agree that I omitted to talk about cell aging and cell balancing and because it is important, I should have talked about it: my mistake.

But my interpretation of your wording concerns me.  Cell degradation is a long process and therefore, voltage differential is a long process.
Charging my wheel to 100% every ride to do ‘top passive cell balancing’ in my experience is very much overkill and is also a common miss conception.

My experience comes from building battery packs for off-grid solar projects.  I noticed and confirmed many times that cell voltage differential
Is indeed a very slow process and I am convinced it is tied to cell deterioration.  My solar batteries are designed to reduce their exposure to heat
(the #1 threat to cell deterioration).  And as such, I have observed that their voltage differential remain below the limit of my BMS (limit to 0.015V before active balancing get activated).  So top balancing does not even get activated in my solar batteries even after months (like 6) of usage of about 1/2 a cycle per day.  I was impressed and happy to notice those low voltage differential (currently at 0.005V on one of my solar battery pack; 8 cells in series).

Therefore, from my experience, I will use the charging logic I discussed above and I expect my wheel batteries to remain healthier for longer
and have less cell degradation.  And I will do a 100% full charge every few months (like every 50 cycles) to balance those long term degraded cell.

Because you are pointing on an important point that was lacking my previous post, I will edit it and add a paragraph about cell balancing.  Thank you for helping me and this thread in making it better 🙏.

Note:  I don’t understand your statement about a ‘reverse current’ battery cell.  Perhaps you mean a dead cell with 0V will cause a lose of power through heat?
There is no such thing as a negative current cell in my experience and education.  I do not know what you mean 🧐.
If you mean we should replace a dead cell, then I totally agree!!!  I fell from a cut off on my Rockwheel S16 at 24 mph and I want to avoid them as much as possible and a damaged cell is to be avoided like the worst disease there is.  This is actually why I don’t want to charge them up to 100% every time.  Extra heat gets put on cells when the voltage is above 4.1V /cell which is a to- cause of cell deterioration.

Also note that I use this charging logic not only for my solar battery packs (for 2 years now), but also on my Tesla since 2015 and I did notice the need to top balance every few 3-6 months.

Michel

[Tawpie]

1 hour ago, MTurcotte said:

(… active balancing get activated)

Key detail!

Our wheels, being produced at the lowest possible cost, don't have the luxury of active balancing... at best we get resistive top balancing only. The S22 is the first wheel since the Z10 to give you a view of the individual cell voltages, and this is considered "zowie! amazing! state of the art! an amazing advancement! bravo! buy now!" when it should have been standard practice all along. The S22 doesn't do active balancing as far as I know, but it'll at least let you see when you're going to be needing a very expensive set of replacement parts. You know, gives you time to plan that robbery of the 7-11 to finance it. The rest of our wheels, we sort of just do our best hocus pocus to keep them balanced, hope, and store them in places we don't mind getting burnt down.

1 hour ago, MTurcotte said:

I don’t understand your statement about a ‘reverse current’ battery cell.

I believe he was referring to a characteristic of Li Ion that when over-discharged, it can reverse polarity. When that happens, the other batteries in the pack will attempt to 'charge' it, but since it's totally borked what happens instead is it looks like a short circuit to the rest of the cells. They dump current into it, everything heats up mui pronto, and in short order the fire brigade is necessary.

Edited July 8, 2022 by Tawpie

[omshree]

Somebody states that Begode answered to him, can't use the 10A chargers

https://imgur.com/a/IiBE8OF

[redfoxdude]

1 hour ago, omshree said:

Somebody states that Begode answered to him, can't use the 10A chargers

https://imgur.com/a/IiBE8OF

The Begode EX20S doesn't have the same boards as the Master, however. I don't know if things have changed, but Ecodrift found a 15A fuse on the charging board in the Master during their teardown. Not sure if the rest of the circuit and wiring is up to that or not.

Edited July 8, 2022 by redfoxdude

[Chriull]

8 hours ago, MTurcotte said:

But my interpretation of your wording concerns me.  Cell degradation is a long process and therefore, voltage differential is a long process.
Charging my wheel to 100% every ride to do ‘top passive cell balancing’ in my experience is very much overkill and is also a common miss conception.

Under normal conditions I'd agree. Unfortionately cells in EUCs are consistently mistreated.

So imbalances occur and balancing every 20-100 cycles did not help.

Could have been not so good/bad cells from the beginning, bad welding spots destroying cells over time, uneven heat build up, or what not else.

Could be that in some cases top balancing would not have helped at all.

However Weak cells gets easily and quite fast beaten to death by motivated EUC usage.

The master with a 4p config could be borderline stressing the cells with motivated riding.. 9.8A per cell average burden will happen for some times. 14.7A per cell maximum non continous current is easily exceeded.

A Master can be ridden so that battery cells are burdened well within their specification and still have (enough?) fun. So different charging recommendations for different usage patterns?

From my very personal impression from reports of "battery not charging too 100% anymore" low parallel cell configs appear more often.

Maybe charging recommendations should be changed to something like the lower ones battery capacity, the more burdening/motivated ones riding style is, the more often one should charge until the green led is showing up. If one discharges ones wheels battery regularly below 20% prayers are strongly recommended, too.

8 hours ago, MTurcotte said:

My experience comes from building battery packs for off-grid solar projects.  I noticed and confirmed many times that cell voltage differential
Is indeed a very slow process and I am convinced it is tied to cell deterioration.  My solar batteries are designed to reduce their exposure to heat
(the #1 threat to cell deterioration).  And as such, I have observed that their voltage differential remain below the limit of my BMS (limit to 0.015V before active balancing get activated).  So top balancing does not even get activated in my solar batteries even after months (like 6) of usage of about 1/2 a cycle per day.  I was impressed and happy to notice those low voltage differential (currently at 0.005V on one of my solar battery pack; 8 cells in series).

So i'd be very cautious to transfer any of such deterioration  experiences to EUC batteries..

There is no such thing like trying to minimize heat exposure. Also series circuitry of cells tend to imbalance more by higher cell counts - there should be a huge difference between 8s and 32s...

9 hours ago, MTurcotte said:

Note:  I don’t understand your statement about a ‘reverse current’ battery cell.  Perhaps you mean a dead cell with 0V will cause a lose of power through heat?

Under burden once a cell in a series circuitry is (about) dead and does not provide (enough) current anymore it gets reverse charged to negative voltages. So it's charged with a negative charge current and discharges with a negative current.

[Freestyler]

1 hour ago, Chriull said:

Under normal conditions I'd agree. Unfortionately cells in EUCs are consistently mistreated.

So imbalances occur and balancing every 20-100 cycles did not help.

Could have been not so good/bad cells from the beginning, bad welding spots destroying cells over time, uneven heat build up, or what not else.

Could be that in some cases top balancing would not have helped at all.

However Weak cells gets easily and quite fast beaten to death by motivated EUC usage.

The master with a 4p config could be borderline stressing the cells with motivated riding.. 9.8A per cell average burden will happen for some times. 14.7A per cell maximum non continous current is easily exceeded.

A Master can be ridden so that battery cells are burdened well within their specification and still have (enough?) fun. So different charging recommendations for different usage patterns?

Agree. I had my Inmotion V11 for around 1500 kilometers.

I was always monitoring the pack voltages (within the app), and the difference was around 0.05v.

At around 1200km I was getting really comfortable with the wheel and was trying some max accelerations getting very close the cutoff limits.

4500w, 60-65a current. Those little stunts alone from that day made the imbalance closer to 0.1v between the 2 packs.

Even with balancing the voltage differential did not reduce. (I don't think v11 balances between the 2 packs, they are independent) 

 

So yeah, my anecdotal experience says that the more you stress the wheel, the more likely you'll need balancing.

50 cycles on my current wheel with around 80km of range is 4000km. That is absurdly long to wait before balancing the batteries.

I don't remember the exact numbers, but I know that the balancing resistors bleed such a little power that it will take more and more time the more imbalanced the batteries get. (in the realm of hours - days)

If you don't charge your wheel to 100% regularly (for me every 2-3 charges), you are also missing out on range.

I'd rather use 100% of my range and slowly let it drop in the course of 2-3 years, than always lose the top 10-20% from the first day of owning the wheel. (and you will also lose some capacity anyway due to aging regardless if you charge the batteries or not).

 

Also, if you don't regularly charge the wheel at 100% and checking the voltage, what other tool do you have to somewhat monitor the health of the batteries?

Without individual cell monitoring, we are mostly blind.

Edited July 8, 2022 by Freestyler

[MTurcotte]

8 hours ago, Chriull said:

Under normal conditions I'd agree. Unfortionately cells in EUCs are consistently mistreated.

So imbalances occur and balancing every 20-100 cycles did not help.

Could have been not so good/bad cells from the beginning, bad welding spots destroying cells over time, uneven heat build up, or what not else.

Could be that in some cases top balancing would not have helped at all.

However Weak cells gets easily and quite fast beaten to death by motivated EUC usage.

The master with a 4p config could be borderline stressing the cells with motivated riding.. 9.8A per cell average burden will happen for some times. 14.7A per cell maximum non continous current is easily exceeded.

A Master can be ridden so that battery cells are burdened well within their specification and still have (enough?) fun. So different charging recommendations for different usage patterns?

From my very personal impression from reports of "battery not charging too 100% anymore" low parallel cell configs appear more often.

Maybe charging recommendations should be changed to something like the lower ones battery capacity, the more burdening/motivated ones riding style is, the more often one should charge until the green led is showing up. If one discharges ones wheels battery regularly below 20% prayers are strongly recommended, too.

So i'd be very cautious to transfer any of such deterioration  experiences to EUC batteries..

There is no such thing like trying to minimize heat exposure. Also series circuitry of cells tend to imbalance more by higher cell counts - there should be a huge difference between 8s and 32s...

Under burden once a cell in a series circuitry is (about) dead and does not provide (enough) current anymore it gets reverse charged to negative voltages. So it's charged with a negative charge current and discharges with a negative current.

When I look at the cell spec:  https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/INR21700_2D00_50E-Cell-Specification_5F00_V1.0_5F00_180711.pdf

For a wheel with 4 series of cells in parallel, I find:  continuous of (4 x 9.8A) = 34A.  34A x  116V nominal (32s x 3.63V) = 3900W (continuous cell capacity).  And a peek cell capacity of (4 x 14.7A) = 58.8A.  Which is 6821W (116V nominal x 8.8A).

I might be wrong, but as far as I know, this wheel beeps and does cut off.  It has a spec motor of 3500W (spec: http://www.begode.com/productinfo/770685.html).  Those 3 facts (motor spec and battery spec mixed with beeps and designed cut offs), I like to think (and optimistically hope) that Begode did ‘the right thing’ and implement those beeps and cut offs according to the cell spec (and BMS and wiring around it) and I would think the cell are protected and will not be abused.

It is hard to know for sure, considering Begode lie (about range, capacity and who knows what else), but I will trust that the beeps and the cut off will make sure the 3900W/6821W the battery cells can provide will be well above what the beeps and cut offs are implemented.  That is an 11% margin protecting the battery cells (3900W cell nominal /3500W motor.  with a peak of 6821W cell peak / 3500W motor = 195%).

What does this all mean?
I feel comfortable believing the Begode Master wheel is designed to protect its cells and will not let them run out of their limits and therefore will unlikely damage those cells and keep the risk of fire very low even if this means cut offs will occur to protect the wheel.

You have a good point saying the wheel BMS is not as smart as solar system battery packs.  And I will revise my suggestion to fully charge the wheel more often than every 50 cycles.  And now we will be guessing (for a lack of guidance from Begode) and we should fully charge our wheels like for slow riders maybe every 20-30 cycles and every 2-3 months minimum.  And for fast rider, it does depend how much you push your wheel.  If you abuse it like an horror movie with regular beeps and cut offs, then a full charge could be at every charge in those extreme insane limits.

I bought this wheel because I was riding my Rockwheel close to its limits (22 mph) way too often.  I did not trust that Rockwheel S16 and I wanted a wheel that has way more capacity than I need so I could feel safe and not be cut off again.  I do not plan to have any cut offs ever with my Master.  And all the rides that I have plan have a variety of range from 5 to 45 miles with a handful around 45-50 miles.  I will charge my wheel usually to 90% when I know I only need 50% range.  I will charge to 100% every month or so or when I exceed a 35-40 miles planned ride.

Good luck to all of us and let’s keep our limbs in good standing.

Michel

Edited July 8, 2022 by MTurcotte

[conecones]

43 minutes ago, MTurcotte said:

I feel comfortable believing the Begode Master wheel is designed to protect its cells and will not let them run out of their limits and therefore will unlikely damage those cells and keep the risk of fire very low even if this means cut offs will occur to protect the wheel.

Is there any specific reason(s) you feel this comfortable? Is this based on a teardown of your packs? Given Begode's history and Ewheel's move to only provide 3rd party supplied batteries, you'll find the general consensus is that they cannot be trusted unless proven otherwise.

 

41 minutes ago, MTurcotte said:

 I do not plan to have any cut offs ever with my Master.  And all the rides that I have plan have a variety of range from 5 to 45 miles with a handful around 45-50 miles.  I will charge my wheel usually to 90% when I know I only need 50% range.

Factoring your intended use mileage should also be a consideration. For example if the intent is to use is semi-regularly then the added battery degradation from always charging to 100% is likely insignificant as you will likely never even come close to reaching the 500 charge cycles or whatever is specified for these cells. With how fast tech is moving, it doesn't seem realistic to keep a wheel more than 3 years anyways. 

[Chriull]

1 hour ago, MTurcotte said:

Those 3 facts (motor spec and battery spec mixed with beeps and designed cut offs), I like to think (and optimistically hope) that Begode did ‘the right thing’ and implement those beeps and cut offs according to the cell spec (and BMS and wiring around it) and I would think the cell are protected and will not be abused

Maximal motor current is about 200A-220A. Whatever this number means - lets assume its about the 3 phase rms current.

This 200 A have to come from the battery. It's only short pulses, as the controller pwm's the battery voltage/current. I did not see any specificationd for pulse burdening of such li ion cells.

If one takes some simplified equivalent schematic circuit of the battery, controller and motor like in 

https://forum.electricunicycle.org/topic/7549-current-demand-versus-battery-voltage/?do=findComment&comment=104078

and has the logged pwm duty cycle, battery voltage and motor current and a value for the motor coil resistance calculating the average battery current is easily possible. Maybe we get some logs to see "real" values.

[MTurcotte]

1 hour ago, Chriull said:

Maximal motor current is about 200A-220A. Whatever this number means - lets assume its about the 3 phase rms current.

This 200 A have to come from the battery. It's only short pulses, as the controller pwm's the battery voltage/current. I did not see any specificationd for pulse burdening of such li ion cells.

If one takes some simplified equivalent schematic circuit of the battery, controller and motor like in 

https://forum.electricunicycle.org/topic/7549-current-demand-versus-battery-voltage/?do=findComment&comment=104078

and has the logged pwm duty cycle, battery voltage and motor current and a value for the motor coil resistance calculating the average battery current is easily possible. Maybe we get some logs to see "real" values.

200A-220A must be a mistake. That wheel cannot handle that much power (that would be above 23232W = 116V x 200A).
The motor on this wheel is rated 3500W.  3500W with 116V is 30A.   200A would melt any normal wire in a fraction of a second.

[Bizra6ot]

16 hours ago, Chriull said:

and has the logged pwm duty cycle, battery voltage and motor current and a value for the motor coil resistance calculating the average battery current is easily possible. Maybe we get some logs to see "real" values.

Darknessbot log provided by Алексей С, phase_current current and power values are/100 https://electro.club/track/45676?time=1656855501.986&csv=1

[Chriull]

2 hours ago, Bizra6ot said:

Darknessbot log provided by Алексей С, phase_current current and power values are/100 https://electro.club/track/45676?time=1656855501.986&csv=1

By looking at the data i've just seen, that it's even easier - one just needs to calculate phase_current * pwm / 100. But in this csv just some low values are given... so max battery current was 0,98A.

For plausibility one can calculate:

u_motor=uvoltage * pwm / 100                                    ......   armature voltage

coil_voltage_drop=phase_current * coild_resistance  ......  something in the range of 0.3 Ohm???

EMV = u_motor - coild_voltage_drop                            ...... motor generated voltage

kv = speed/EMV                                                             ...... kv in km/h/V

kv stayed in this example nicely around 0,76 km/h/V - so maximum speed should be around 134,4*0,76~102 km/h

This battery current corresponds also nicely to the current (not phase_current) in the csv log from Darknessbot. You know if this is by now already directly reported by the wheel (modified firmware?) or calculated within darknessbot? Maybe in the exact same way?

 

[MTurcotte]

Does anyone knows what the 3rd wire of the battery packs is used for?

Obviously 2 wires are used for power.   But what is the 3rd wire used for?   Data?  Status?   Failures?   Balancing?
anybody knows?   Anybody have seen the answer to this question anywhere?

Michel

[The Brahan Seer]

According to Alibaba some more details (albeit vague) on the V2 are: 

The Master V2 has the following upgrades 1. Upgraded the new program and motherboard

2. Upgraded the battery BMS 3. Upgraded air shock fixing screws and metal to be more firm to prevent loosening

https://www.alibaba.com/product-detail/BEGODE-Master-134V-2400wh-3500W-Motor_1600446879006.html?spm=a2700.galleryofferlist.normal_offer.d_title.4fa93014ThBN7j

[Bizra6ot]

9 hours ago, Chriull said:

But in this csv just some low values are given... so max battery current was 0,98A.

.98A is 98A it match with the power value 

69.40 105.80 1.13 0.98 103.68 = 69.40kmh 105.80V 113Aphase 98Abat 10368W

 

9 hours ago, Chriull said:

You know if this is by now already directly reported by the wheel (modified firmware?) or calculated within darknessbot? Maybe in the exact same way?

Idk i guess it is stock FW so an estimated value

[MTurcotte]

1 hour ago, Bizra6ot said:

.98A is 98A it match with the power value 

69.40 105.80 1.13 0.98 103.68 = 69.40kmh 105.80V 113Aphase 98Abat 10368W

 

Idk i guess it is stock FW so an estimated value

This 10,368W is misleading when read on its own.  Indeed, the data (https://electro.club/track/45676?time=1656855501.986&csv=1) shows a wheel that cut-off and crashed.
You can see the Amperage breaching 90A from time 15:38:20.345 @ 93A up to 15:38:21.785 @ 98A.  The current remained above 90A for 1.44sec and was followed by a cut-off (0A).

Then from 15:38:22.204 until 15:38:23.057 when the gps speed went from 72 (kmph) to 2.4 (a hard crash in 0.853 sec).

My point is:  the wheel is incapable of those kinds of powers and 1.44 sec of this excess was allowed before the circuitry decided to abort this abuse before hardware damage.  Hardware damage in those situations are usually melted metal or wire insulation preventing shorts.

Please do not think this wheel is capable of 10.3 kW.  Its motor is rated 3500W which the wheel might be able to sustain.  It is common for electric motors to allow peaks sometimes of twice its rated power for a few seconds (7000W in our case).  This is common when a motor starts spinning.

Conclusion:  This wheel cannot handle more than 90A.  If you try…  you will crash.

I do not know how the motherboard is programed, nor the wire size of the entire wheel, but we know the wheel spec:
      3500W motor with a battery of about 110V (under stress) which gives us 3500W/110V= 31.8A.
So this wheel is designed for about sustained 30A and I am sure allows peaks of 60A and 90A but for short durations… above that it cuts-off.

Michel

[Chriull]

12 hours ago, MTurcotte said:

Does anyone knows what the 3rd wire of the battery packs is used for?

Most likely still a synchronization wire to stop charging with all packs once one cell (group) has overvoltage:

 

[EMA]

finally done some kms on mine Master, really impressed with the overall ride feel. 

[techyiam]

17 minutes ago, EMA said:

finally done some kms on mine Master, really impressed with the overall ride feel. 

Traveling in a straight line, at what speed do you start to feel uncomfortable or uneasy? 

[EMA]

5 minutes ago, techyiam said:

Traveling in a straight line, at what speed do you start to feel uncomfortable or uneasy? 

i'm still riding it "old style" without pad, didn't feel uncomfortable yet, hit 67kmh like nothing. the combination of firmware/motor/power/smoothness is stunning.

i've a kenda k340a on it
but keep in mind i'm familiar with the higher geometry, had an EX for more than 1 year

[Chriull]

On 7/10/2022 at 2:13 AM, MTurcotte said:

You can see the Amperage breaching 90A from time 15:38:20.345 @ 93A up to 15:38:21.785 @ 98A.  The current remained above 90A for 1.44sec and was followed by a cut-off (0A).

Then from 15:38:22.204 until 15:38:23.057 when the gps speed went from 72 (kmph) to 2.4 (a hard crash in 0.853 sec).

My point is:  the wheel is incapable of those kinds of powers and 1.44 sec of this excess was allowed before the circuitry decided to abort this abuse before hardware damage.  Hardware damage in those situations are usually melted metal or wire insulation preventing shorts.

This is not how EUCs work. The firmware does not decide to cut off!At higher speeds the by the motor generated voltage restricts motor current until no current can flow anymore at all (max no load speed).

Maybe the 1.44 seconds wit the ~9xA were enough to melt/fry some wires or components, so the "circuitry" went down...

However this ~98A seem to be about the maximum that can flow ~70km/h. (1)

This ~10kW are about the peak at @70km/h. Peak power for a bldc is reached at half no load speed which should be somewhere about 50km/h? (With full batteries)

So some more power should be possible during "normal" riding conditions.

Gotway (Begode) wheels were always on the edge of selfdestruction - be it melting motor wire insulations (now they have ?fiberglass? sleeves), desoldered motor wires (now they use screws), fried mosfets (the gotway "fuse"). A ?presumption/assumption/guess ? for the reason of the accumulated battery fires of begodes lately could be that the battery nickel strips were now the weakest link and got too hot ...

Hardware cut off by firmware only happens, as written somewhere at around 200-220A - cannot find the link of ? @RagingGrandpa's ? topic with this cut off motor current experiments... (Edit: https://forum.electricunicycle.org/topic/28025-💪-euc-pull-force-test-results-reviewers-please-do-this/ )

 

These high currents can only happen at low(er) speeds and so pwm duty cycle is low and rms battery current "quite low", too. But still the high peak values have to be delivered by the cells in short pulses.

(1) With 105V battery voltage at 70km/h with about 100% pwm (motor armature voltage=battery voltage and battery current=motor current) the current limiting factor is mainly the coil resistance.

With some no load speed of roughly ~100km/h at ~130V the motor should generate a voltage of about 130/100*70=91V. So ~100A with a voltage difference of ~15V give 0.15 Ohm. Which sounds very reasonable as magnitude for the coil resistance.

Edited July 12, 2022 by Chriull

[Chriull]

11 hours ago, Bizra6ot said:

Idk i guess it is stock FW so an estimated value

Ah - ok. That would explain the perfect accordance between motor current, battery current and pwm.

Ps.: Do you know the story to this log? - was it an overlean, a destroyed motherboard or just some high speed riding with "extremely fast" breaking/accident?

Edited July 10, 2022 by Chriull

[Paul g]

On 7/7/2022 at 10:48 PM, MTurcotte said:

Since I installed my solar system, I got used to charge its LiFePo4 (Litium battery) at a specific voltage.  So I wanted to do the same with my EUC.  So I ordered a Variable Voltage & Variable current power supply.

Actually I was watching an interview with Elon Musk, and he was saying that the LiFePo batteries from their China made cars work completely different from the Li-Ion( Ni and/or Cd) ones, as they actually like being charged to 100% and discharged to 0% and they last more cycles that the usual Li-Ion. @MTurcotte hope that helps with your amazing home project.