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Brands with / without unexpected shutdowns (new buyers look here)


KaleOsaurusRex
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Thank you so much for helping us understand Esa! I'm going to do my best to make this list as clear and thorough as possible.

@esaj, what do you think about the shut downs where afterwards the uni just works again after a normal turn it off then turn it on again?

Would love to hear from everyone, especially manufacturers representatives and salespeople from the companies. This is a deal breaker my friends! Let's get this information right on the table for everyone to see.

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Maybe it's not only manufacturers but also models that should be listed.

I don't know about BMS but my Airwheel X5 Music hasn't shut down without reason.

The reason's it has shutdown is riding uphill with low battery.

I generally ride near 12km/h, the average speed by SportTracker is about 10km/h. I ride just under 12km/h because I don't like the constant beeping and it's not supposed to be driven with constant warnings.

 

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Thank you so much for helping us understand Esa! I'm going to do my best to make this list as clear and thorough as possible.

@esaj, what do you think about the shut downs where afterwards the uni just works again after a normal turn it off then turn it on again?

I can't say for certain, as I don't have experience except with the generic model and Firewheel I have, but I'd suspect that at least in most cases, where the wheel does turn back on (or doesn't completely become powerless, ie. it will still beep or play some message, or show some lights) after cutout, the cutout has been induced by the main board, not the BMS. If the BMS does the cutout, the wheel should become completely turned off, and won't start again when pushing the power button, as I think the BMS cutout is usually latched, and won't reset until the charger is plugged back in, but not 100% if this is always the case.

 

Maybe it's not only manufacturers but also models that should be listed.

I don't know about BMS but my Airwheel X5 Music hasn't shut down without reason.

The reason's it has shutdown is riding uphill with low battery.

I generally ride near 12km/h, the average speed by SportTracker is about 10km/h. I ride just under 12km/h because I don't like the constant beeping and it's not supposed to be driven with constant warnings.

I'd expect the models from one manufacturer to use same batteries and BMSs, but again not sure. So probably if one model of the manufacturer has the problem, all the others do all so (at least if they were manufactured around the same time), or vice versa.

At least hobby16 has pictures of shunting an Airwheel X8 and "some other" Airwheel in the BMS problem-topic, so apparently they do have the problem, but the voltage where the BMS cutout occurs could be different between different brands (different BMS), so it may not be as sensitive as with some other wheels. Also the Airwheels are slow(ish), so the cutout is not as dangerous as with faster wheels (Gotway 14" or Firewheel), and the faster wheels must draw more power due to higher speed and faster acceleration, so probably the variation in voltage is also larger, and can trigger the BMS cutout more easily in those wheels.

If the wheel still turns on after shutting down going uphill with low battery, I'd expect the shutdown to be caused by the main board logics and not the BMS, but not sure.

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The reason's it has shutdown is riding uphill with low battery.

So, Airwheel X5 is confirmed to also exhibit unpredictable shut downs. This should never happen, not uphill, not low battery. Never.

 

If the wheel still turns on after shutting down going uphill with low battery, I'd expect the shutdown to be caused by the main board logics and not the BMS, but not sure.​

So it seems that this thread would better serve folks from a practical perspective, if it were to encompass both BMS-related unpredictable shut downs AND main board related unpredictable shut downs.

@esaj, would you expect that the main board type shut down, which I am beginning to think may be the culprit I've encountered in Airwheel and generic/tg t3, could be filtered by brand as well? Or would you expect that this an inherent feature of the technology regardless of brand? 

Edited by KaleOsaurusRex
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So, Airwheel X5 is confirmed to also exhibit unpredictable shut downs. This should never happen, not uphill, not low battery. Never.

 

So it seems that this thread would better serve folks from a practical perspective, if it were to encompass both BMS-related unpredictable shut downs AND main board related unpredictable shut downs.

@esaj, would you expect that the main board type shut down, which I am beginning to think may be the culprit I've encountered in Airwheel and generic/tg t3, could be filtered by brand as well? Or would you expect that this an inherent feature of the technology regardless of brand? 

​Someone who knows electronics and/or dc motor driving better would probably be more suitable to answer this, but I suspect that the mainboard cut out is always there, in all wheels. It could be fairly well justified, if it is to protect the mainboard electronics from too high current, which would fry the components:

-If the current is too high, the main board will cut the power to the motor, to save itself, and you will fall

-If the current is too high, and the mainboard will NOT cut the power to the motor, the mainboard will fry, and you will fall, plus your wheel mainboard will break

With lower voltage, a higher current is needed to produce the same power to the motor as with higher voltage.

Another thing is that the motor will need a certain voltage to keep turning, and it will be way higher than 1V or such. About a decade ago (2004 I think), I attended an embedded systems class, where I built a temperature-controlled computer fan controller. It was done with an Atmel ATMega -chip, and I used the reference programming board schematics as base to create my own board, with a few temperature sensors and mosFETs controlling voltage from a separate 12V line for the fans (the voltage affects how fast the fan will run). I milled the board with circuit board milling machine, soldered the components to it, added an LCD to show voltages/temperatures/settings for the fans etc,  and then wrote and tested the software. What I found out was that the fans would not turn if I dropped the voltage below something like 6V or 5.5V using the mosfets (the way to control the fan speed is PROBABLY similar to what the wheels use, the PWM (Pulse Width Modulation) outputs of the chip were connected to the control -leg of the mosFET, and using different pulse widths, I could control the voltage passing through the mosFET from the 12V line between 0 and 12V.). So the wheel cannot keep driving the motor, if the voltage is too low, you'd only get a huge current running through the mosFETs, and they'd probably burn.

EDIT: So while the mainboard cut out is there, and there's probably nothing we can do about it, it's still SAFER than the BMS cutout. The mainboard logics will give you a fair warning (beeps, voice messages, pedal tilt back etc) before the cutout occurs, and it (usually) occurs only at high speeds or climbing, whereas a BMS cutout can happen totally unexpectedly, without warning, and especially on lower temperatures, at any speed or time...

Edited by esaj
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So, Airwheel X5 is confirmed to also exhibit unpredictable shut downs. This should never happen, not uphill, not low battery. Never.

​So you want a wheel that does not stop when going uphill with low battery.

Good luck finding.

Low battery in my situation means it has already beeped "low battery" and slowed down twice and I had powered it up again (twice) so the battery was about 10% left(estimate). Airwheel stops first at about 30% battery and I drove it for two beeps.

Edited by MarkoMarjamaa
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With lower voltage, a higher current is needed to produce the same power to the motor as with higher voltage.

...

EDIT: So while the mainboard cut out is there, and there's probably nothing we can do about it, it's still SAFER than the BMS cutout. The mainboard logics will give you a fair warning (beeps, voice messages, pedal tilt back etc) before the cutout occurs, and it (usually) occurs only at high speeds or climbing, whereas a BMS cutout can happen totally unexpectedly, without warning, and especially on lower temperatures, at any speed or time...

Would it be correct to say the main board cutoff is only experienced in low battery conditions? If so, it seems that by allowing the battery to only be drained to a certian percentage one could avoid the problem altogether. The Chevy Volt manages its battery in this manner for the sake of longevity. 

Thus, perhaps manufacturers need to not just warn the rider of low battery conditions, but actually act as though they are fully drained earlier, not allowing themselves to be turned on at all. This might seem like a hassle, but wait until these things start rolling into traffic! We might not be riding at all after that.

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​So you want a wheel that does not stop when going uphill with low battery.

Good luck finding.

​Hi Marko, to be more precise, KaleOsaurusRex was talking about "unexpected shutdown", and not about "stopping".

Any wheel which has a shunted BMS will "stop", ie will incline the pedals and force you to climb down. But it won't shutdown, never ever, that makes a huge difference.

The only exception being Gotway, which does NOT implement any pedals incline and only warn you by loud beeps (it's a horrendously dangerous wheel for deaf people, lol).

Let's be very clear, some wheels may seem not to cut, yet. But if they have the cut off circuit (if there are 2 or 3 mosfet transistors they do), they will cut sooner or later, when it's cold, when the battery is aging, when one single cell doesn't deliver...

I have one TG that cuts off very often, once leaving me a painfull faceplant (shunted), and another noname-wheel that does not cut off (not shunted, yet).

If you don't shunt a faulty BMS, no matter the wishfull thinking, it will cut off and you will faceplant, sooner or later, that's as inevitable as tax or death !

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@KaleOsaurusRex

You can add the SML brand too. It's a very dangerous brand because its BMS triggers the cut off and and the main board trigger the cut off at high speed too.

It combines the craziness of most BMS cut-off  and the Gotway's high speed cut off. Hell !

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Any mechanism for preventing it from turning on with a low battery would be totally pointless. It will have run the battery low whilst you are riding it so unless you happen to turn it off when you have already ridden it to a dangerous condition it would never have an oportunity to work.

@hobby16  Gotway have the setable blutooth vibration warning to  cater for the deaf. :)

Edited by Gimlet
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I don't have experience with the others, but the Firewheel should always, definitely be shunted. I wouldn't call a shunted Firewheel "safe", more like "a wheel that doesn't do much to prevent you from killing yourself". There's no tilt-back to warn you of overspeeding (at least that I know of, I've hit the 31.5km/h max speed without noticing any tilt back, on the other hand, I think hobby16 once said his FW has tilt-back, so it could be it won't occur until higher speeds, as hobby once mentioned doing over 35km/h). The volume of the audio-alerts is so low, that wind or any other noise can easily cover them. What is done good, is the low battery warning, the wheel will decelerate, tilt-back a little, prevent you from accelerating and start shaking, repeating "Power is low", "Power is low" and if you don't believe it, your speed drops to a crawl and the shaking becomes more stronger. There's no way you could miss that.

​Here is what I can tell you from my experience on my version of Firewheel, maybe with more riding, you can confirm the same on yours (IIRC, vee has replaced your mainboard and it's more recent than mine) :

At high speed (>31km/h), I don't have a tilt back but a short but vigourous acceleration, largely enough to warn you to slow down. The first time it happened, it was frightening but I end up loving it a lot since I can cut the buzzer and ride securely without risking any overspeeding. Maybe if I maintain that very high speed, it will result in a tilt back but I doubt anybody can on normal road condition. I will definitively not try that on everyday life use, since I only wear a helmet.

Just tried yesterday : on 35% steep hill, climbing up with a 2/3 empty battery (full charge then 15km trip at full speed), buzzer restored for the test. The Firewheel does not go fast because of the hill and I heard no warning at all. Maybe with a near empty battery, I will hear the "take care" warning like you did. So from what I know, I maintain that the warning voices are at fixed speed thresholds.

Be aware that at low battery, you will have the tilt-back, the "power is low" voice, ok but if you insist enough (it's possible since the tilt-back is moderate compare to Solowheel or Airwheel tilt-backs), the Firewheel mainboard will CUT OFF ! Well, it's not a very smart feature but it's rather harmless since the wheel is already at very reduced speed. It's not nearly a fraction as dangerous as an unexpected cut off at high speed by the BMS (most generics) or by the mainboard (Gotway).

Edited by hobby16
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​Here is what I can tell you from my experience on my version of Firewheel, maybe with more riding, you can confirm the same on yours (IIRC, vee has replaced your mainboard and it's more recent than mine) :

The mainboard was replaced sometime late December 2014 or early January 2015, so I'd expect it's from a November or December 2014 batch.

 

At high speed (>31km/h), I don't have a tilt back but a short but vigourous acceleration, largely enough to warn you to slow down. The first time it happened, it was frightening but I end up loving it a lot since I can cut the buzzer and ride securely without risking any overspeeding. Maybe if I maintain that very high speed, it will result in a tilt back but I doubt anybody can on normal road condition. I will definitively not try that on everyday life use, since I only wear a helmet.

Ok, I have misunderstood then, there is no tilt-back at all. Didn't really put my trust into that there was anyway ;) . Mine does not have the sudden acceleration, or then I just hadn't noticed it accelerating myself. The motor makes much more noise (not loud, but powerful "whirring" sound) when doing over 30km/h and I can feel some vibration (probably from the motor) in the pedals and the shell (if I clench it) at those speeds, so even if I hear no warnings, I know I'm going near (my) top speeds. I don't know if it could be pushed even faster, but haven't tried on purpose to go over 30km/h lately. The 31.5km/h is still the highest speed I have ever attained with my FW.

Just tried yesterday : on 35% steep hill, climbing up with a 2/3 empty battery (full charge then 15km trip at full speed), buzzer restored for the test. The Firewheel does not go fast because of the hill and I heard no warning at all. Maybe with a near empty battery, I will hear the "take care" warning like you did. So from what I know, I maintain that the warning voices are at fixed speed thresholds.

Yes, I tried it a little yesterday, I didn't ride the battery to empty (about 20% left when I got back), towards the end of the trip, I could get the "Take care" to come out around 26.5-27km/h going on level straight, so a little below the usual (usually with fuller battery I'd say it comes somewhere between 27.5-28.5km/h). When the battery is nearly depleted, it can come very early (I have once got it coming around maybe 20-22km/h on slight uphill, but that was something like 300m before the battery run out entirely with the "Power is low"-warning).

Be aware that at low battery, you will have the tilt-back, the "power is low" voice, ok but if you insist enough (it's possible since the tilt-back is moderate compare to Solowheel or Airwheel tilt-backs), the Firewheel mainboard will CUT OFF ! Well, it's not a very smart feature but it's rather harmless since the wheel is already at very reduced speed. It's not nearly a fraction as dangerous as an unexpected cut off at high speed by the BMS (most generics) or by the mainboard (Gotway).

​Yeah, I don't doubt you CAN overlean or cause a main board cutout if you don't believe the warning, and the tilt-back is very slight, but the warning is done so good and is so noticeable that at least I don't believe anyone could outlean it ACCIDENTALLY, as the warning is done very well in my opinion  :)  (Unlike the speed warnings ;)

 

Would it be correct to say the main board cutoff is only experienced in low battery conditions? If so, it seems that by allowing the battery to only be drained to a certian percentage one could avoid the problem altogether. The Chevy Volt manages its battery in this manner for the sake of longevity. 

Thus, perhaps manufacturers need to not just warn the rider of low battery conditions, but actually act as though they are fully drained earlier, not allowing themselves to be turned on at all. This might seem like a hassle, but wait until these things start rolling into traffic! We might not be riding at all after that.

The main board cutoffs seems to be caused only by low battery conditions and too high speed (over speeding). If I remember correctly, the Firewheel will start the "Power is low" -warning when the battery voltage has dropped below 56V (so around 3.5V per cell) for a while, and if it stays there after restart (the battery voltage doesn't go up after waiting for a while), it will begin the warning immediately when you turn it on, and you really can't ride it. That's the only warning in FW that's done really well  ;)  I once got the warning going uphill, carried it on top of the hill, waited a while and could turn it back on (the battery voltage had raised a bit after recovering from the high load caused by the climb). I then rode another 1.3km or so very slowly to not drain much of the battery, until it then did again, and wouldn't let me ride at all anymore. Had to carry it home the rest of the way (this was the time I was trying the max range).

Edited by esaj
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@hobby16  Gotway have the setable blutooth vibration warning to  cater for the deaf. :)

​I haven't try that in real conditions. Supposing the bluetooth connection is reliable (I found that at high speed, the connection tends to be lost, probably because of more electrical noise due to switching high powers), does the phone vibration work really ? I mean, the vibration thresholds are at fixed speeds but the cut off can occur at much lower speeds when climbing a steep hill or when battery is low.

If our deaf has vibrations programmed at 28km/h, you have a faceplant, a dead phone or a dead deaf. :wacko:

Anyway, vibrations, ON THE PHONE (I thought it was by the wheel when I bought it, grrrr !). Come on Gotway, what a sad joke !

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​Hi Marko, to be more precise, KaleOsaurusRex was talking about "unexpected shutdown", and not about "stopping".

Any wheel which has a shunted BMS will "stop", ie will incline the pedals and force you to climb down. But it won't shutdown, never ever, that makes a huge difference.

The only exception being Gotway, which does NOT implement any pedals incline and only warn you by loud beeps (it's a horrendously dangerous wheel for deaf people, lol).

Let's be very clear, some wheels may seem not to cut, yet. But if they have the cut off circuit (if there are 2 or 3 mosfet transistors they do), they will cut sooner or later, when it's cold, when the battery is aging, when one single cell doesn't deliver...

I have one TG that cuts off very often, once leaving me a painfull faceplant (shunted), and another noname-wheel that does not cut off (not shunted, yet).

If you don't shunt a faulty BMS, no matter the wishfull thinking, it will cut off and you will faceplant, sooner or later, that's as inevitable as tax or death !

​Yes, when a battery was low, and Airwheel had already stopped one or two times with beeps and I've restarted again, and then driving uphill, it suddenly  shut down but I could turn it on again so maybe it wasn't BMS.

And I've been riding for 7 months now and it hasn't shut down when driving normally. When driving normally and hitting unexpexted obstacle, I've basically just taken a couple of running steps and no faceplant.

My point is you just can't say "my device did this and that = every device of that manufactures does the same". You cannot make a gallup when n=1. We need more data.

 

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​Yes, when a battery was low, and Airwheel had already stopped one or two times with beeps and I've restarted again, and then driving uphill, it suddenly  shut down but I could turn it on again so maybe it wasn't BMS.

 

This is the problem. ​No amount of education is going to stop people from riding with unsafely low battery levels, because they feel soooo confident. I know you were probably riding in a safe area, but this is what's going to happen if we don't figure this out: electric unicycles are going to get very popular, very fast. Then someone is going to do exactly what you did, in a city. A bystander is going to get hurt, or a unicycle is going to go tumbling and cause a car accident. Then we won't be able to use these as transportation anymore.

 

Any mechanism for preventing it from turning on with a low battery would be totally pointless. It will have run the battery low whilst you are riding it so unless you happen to turn it off when you have already ridden it to a dangerous condition it would never have an oportunity to work.

 

You're exactly right! That's why we need to make sure that when the battery level is unsafe, if there's a chance of main board shutdown, the unit won't let you ride at all. It slows all the way down, forces you to step off and won't turn back on until it is charged.

Not enough range? Get a bigger battery.

 

If I remember correctly, the Firewheel will start the "Power is low" -warning when the battery voltage has dropped below 56V (so around 3.5V per cell) for a while, and if it stays there after restart (the battery voltage doesn't go up after waiting for a while), it will begin the warning immediately when you turn it on, and you really can't ride it.

This sounds exactly like what we need all manufacturers to do. The low battery behavior needs to trigger very conservatively, or else this problem is going to ruin it for everyone.

If these are going to be popular because of us early adopters, it is our responsibility to make sure no normal end user after this generation of unis knows this was ever a problem.

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My point is you just can't say "my device did this and that = every device of that manufactures does the same". You cannot make a gallup when n=1. We need more data.

 

​Hi Marko,

No offense but I must strongly disagree. The BMS cutoff is by design. A faulty design, where mosfets cut off are implemented, when they should never ever have been because we are dealing with unicycles. So if my device cuts off, every devices of the same manufacturer does the same, only with some tolerance, as long as the design is the same. Millions of cars have been recalled based on the same principle, for much less risk of harm to users than this BMS horrendous blunder. I don't know for recent Airwheels but your 7 month old Airwheel does have a BMS that need to be shunted, for sure. Many users have been faceplanted by X3 & X8 and have had to shunt, see my post on the French forum. It's not a matter of speed or lo bat only, it can happen anytime, even after 5m with full charge and the risk that WILL happen increases with battery aging.

BTW, a wheel that can restart after cutoff is not always evidence that the BMS is cleared. On the SML for example, the BMS can cut off then restore power without having to plug in the charger (how nice !).

No matter what, no monowheel should ever ever trigger any power cut off, whether by the mainboard or by the BMS, wether at low speed or high speed.

It's totally, utterly crazy ! There is absolutely no technical reason to do it (if there were, I would like to know), no difficulty to avoid it and no excuse to condone it. We should all remind that relentlessly to prospective buyers to pressure manufacturers to change. Otherwise like KaleOsaurusRex said, we will all end up with a bad reputation, tons of regulations and interdictions, with subsequent price hikes.

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Major reframe of the top post. I BEG YOU ALL, PLEASE TEAR IT TO SHREDS! The truth is out there  :ph34r:

No matter what, no monowheel should ever ever trigger any power cut off, whether by the mainboard or by the BMS, wether at low speed or high speed.

It's totally, utterly crazy ! There is absolutely no technical reason to do it (if there were, I would like to know), no difficulty to avoid it and no excuse to condone it. We should all remind that relentlessly to prospective buyers to pressure manufacturers to change. Otherwise like KaleOsaurusRex said, we will all end up with a bad reputation, tons of regulations and interdictions, with subsequent price hikes.

Edited by KaleOsaurusRex
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There is absolutely no technical reason to do it (if there were, I would like to know), no difficulty to avoid it and no excuse to condone it.

I don't know if it's really a factor, but I thought that maybe the reason for the mainboard cutoff was to prevent the mainboard from breaking due to high temperatures/currents. To produce the same power (watts) with lower voltage, you need higher current, ie P = U*I, I = P/U:

500W of power @ 67V = 500W / 67V = about 7.46A

500W of power @ 60V = 500W / 60V = about 8.33A

500W of power @ 56V = 500W / 56V = about 8.93A

500W of power @ 52V = 500W / 52V = about 9.62A

etc., higher current for same wattage at lower voltage. If the mosfets were to burn, you'd faceplant anyway, plus the mainboard would break. But I would like the wheel to give you a clear warning when the temperature is about to skyrocket (I believe that Gotways do have temperature alarms?) and the components could also benefit from active cooling (cooling fins & fan, like what Vee76 modded to his GW MSuper to prevent it burning with LiPos pumping high currents through the mosfets). Also higher quality/larger/more power mosfets would probably withstand more heat/current, but push the unit price up.

Edited by esaj
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Probable Solution: An electric Unicycle must NEVER, EVER, EVER turn itself off unexpectedly. Ever. This phenomenon must be designed out of the equation.

​It would be nice having a wheel that never shuts off no matter how far you push it. I guess the only way to acheive this is to design a EU that is so fast and powerful that it can handle western riders at any speed (until stopped by air resistance) riding upwards on a bumpy surface :) It would probably be very expensive and weigh a lot...

The safest wheels you can ride are the slow ones where you can just walk off when they shut down, but as many want fast and cheap wheels there will be some limitations. IMHO Gotways are safe to ride as long as you pay attention to the warnings and react to them. 

Edited by Lorents
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I want to thank the contributors who are offering anecdotal reports of safety. We are all happy to hear you haven't had an unexpected shutdown yet.

However, please take into account confirmation bias. In the near future, when the rider numbers are much, much larger, when most riders do not read the forums, unaddressed unsafe electrical designs will cause absolutely avoidable injuries. Now is our chance to change directions and hold the manufacturers' and distributors' feet to the fire.

The argument of "there will never be an electric unicycle that's perfectly safe" is an absolute copout.

The BMS shutdown design will go away first; that design is already on it's way out of style.The next problem going forward is going to be mainboard thermal overload / shutdown.

There is no reason the controller/mainboard couldn't modulate motor performance to avoid mainboard thermal overload. There's no reason the computer couldn't force a safe and gradual complete low battery shutdown while maintaining enough charge to avoid an absurd unexpected shutdown.

Yes, these solutions might add some cost. Yes, the solution might reduce the usable range of a given battery size. However, this is not optional. It is our responsibility.

There will be other problems to be addressed, but for now the two main known issues are entirely solvable. We will solve them by using the power of the almighty dollar, to make sure the manufacturers and distributors can ignore this problem no longer.

Edited by KaleOsaurusRex
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If you want the thrill of the angry wheels you need to accept the risks . But do you believe your m 18 super high tork is safer than the high speed Gimlet?

Edited by Luiz
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