The Dangers of a Full-Face Helmet and Low Battery

[Marty Backe]

When I took my Tesla up into the mid-20's (GPS speed) I was wearing my latest gear, including the full-face helmet. Imagine my surprise when I was processing this video and discovered the 3rd alarm blasting away. I didn't hear a thing.

At this point in the ride the Tesla was at no-load 50% battery. Clearly as I was pushing the wheel the power drain was such that the 3rd alarm was sounding. I'm glad I didn't go for higher speeds (which the Tesla is more than capable of with a full battery).

I don't ride with tilt-back on because I never ride at maximum speeds. But I have to remember this lesson. When the battery is not near-full, don't assume that the wheel can achieve its maximum speeds. If I had decided to go ahead and push it to 27+ mph I may have had a cut-out 

Two lessons:

• You can't hear a damn thing with a full-face helmet when traveling fast
• Maximum speeds are substantially reduced when at 50% or less battery

 

 

[steve454]

19 minutes ago, Marty Backe said:

When I took my Tesla up into the mid-20's (GPS speed) I was wearing my latest gear, including the full-face helmet. Imagine my surprise when I was processing this video and discovered the 3rd alarm blasting away. I didn't hear a thing.

At this point in the ride the Tesla was at no-load 50% battery. Clearly as I was pushing the wheel the power drain was such that the 3rd alarm was sounding. I'm glad I didn't go for higher speeds (which the Tesla is more than capable of with a full battery).

I don't ride with tilt-back on because I never ride at maximum speeds. But I have to remember this lesson. When the battery is not near-full, don't assume that the wheel can achieve its maximum speeds. If I had decided to go ahead a push it to 27+ mph I may have had a cut-out 

Two lessons:

• You can't hear a damn thing with a full-face helmet when traveling fast
• Maximum speeds are substantially reduced when at 50% or less battery

 

 

I was getting worried with the constant beeping, but figured since you were accelerating fairly slowly, even though the speed was high the load was not too high.  The beeping was not very loud, at that speed you might not have heard it even without a helmet, due to wind noise.

You weren't getting buzzes on the pebble from spikes I guess.  There must be some way to transmit the beeps to your helmet, perhaps install a miniplug jack and wear an earbud, but that would be a lot of work.

I guess like you said, just keep it under 22mph with less than full battery and it's good.

Cool telemetry on the camera.

[WARPed1701D]

Sound advice... Your conservative view on speed probably saved you from testing that helmet.  But before people opt away from a full face because of this it should be noted that not all full face helmets are the same. My Switchblade is vented and has vents right by the ears. I notice very little loss of situational awareness with it on. The same helmet can be different for different people too. @Scatcat also has a Switchblade but seems to lose a little more sound than I.

Maintaining situational awareness is why I don't like the idea of a motorcycle helmet for lower speed riding (although recommended for >25mph). It's also why I don't use headphones. 

 

[steve454]

20 minutes ago, WARPed1701D said:

Sound advice... Your conservative view on speed probably saved you from testing that helmet.  But before people opt away from a full face because of this it should be noted that not all full face helmets are the same. My Switchblade is

Spoiler

vented and has vents right by the ears

. I notice very little loss of situational awareness with it on. The same helmet can be different for different people too. @Scatcat also has a Switchblade but seems to lose a little more sound than I.

Maintaining situational awareness is why I don't like the idea of a motorcycle helmet for lower speed riding (although recommended for >25mph). It's also why I don't use headphones. 

 

Just a small drill bit, make a vent, and viola.  Or an amplifier in only one ear.

Imagine riding at high speed, near the limit of power, and all of a sudden, you hear, HELLO, KINGSONG!

[Rehab1]

2 hours ago, steve454 said:

Imagine riding at high speed, near the limit of power, and all of a sudden, you hear, HELLO, KINGSONG!

You have a excellent idea! There is no reason why EUC manufacturers could not develop software to transmit an audio and/or vibratory alert to your phone via Bluetooth. 

[Mrd777]

10 hours ago, Rehab1 said:

You have a excellent idea! There is no reason why EUC manufacturers could not develop software to transmit an audio and/or vibratory alert to your phone via Bluetooth. 

Both Darkness bot, and Geometrics have this feature. I get a vibration alert on my phone and watch at the speed I set that alarm for. It saved me several times from going too fast.

[Rehab1]

3 minutes ago, Mrd777 said:

Both Darkness bot, and Geometrics have this feature. I get a vibration alert on my phone and watch at the speed I set that alarm for. It saved me several times from going too fast.

I was not aware. Many thanks! 

[Marty Backe]

3 hours ago, Mrd777 said:

Both Darkness bot, and Geometrics have this feature. I get a vibration alert on my phone and watch at the speed I set that alarm for. It saved me several times from going too fast.

 

3 hours ago, Rehab1 said:

I was not aware. Many thanks! 

This reminds me. I need to add the 3rd alarm to my Pebble watch because I always can feel the buzz on my wrist.

[dmethvin]

Man that's scary. Even with a bike helmet and some nearby traffic noise I've had problems hearing warning beeps. The Firewheel has an urgent-sounding voice that says "Take care!" when you're right at the limit but it's not loud enough. Good idea there but bad execution.

[Scatcat]

17 hours ago, WARPed1701D said:

Sound advice... Your conservative view on speed probably saved you from testing that helmet.  But before people opt away from a full face because of this it should be noted that not all full face helmets are the same. My Switchblade is vented and has vents right by the ears. I notice very little loss of situational awareness with it on. The same helmet can be different for different people too. @Scatcat also has a Switchblade but seems to lose a little more sound than I.

Maintaining situational awareness is why I don't like the idea of a motorcycle helmet for lower speed riding (although recommended for >25mph). It's also why I don't use headphones. 

 

Yes, I've learned to hear the bloody alarm anyways. But when going close to a busy road it is really hard...

To compensate I keep in mind what my current battery status is, and my experience is enough to know how hard I can push at my current level.

[Smoother]

Spending over 1,000 miles on a wheel with a 340Wh battery I soon became acutely aware  of the dangers of voltage sag on a significantly depleted battery.  Anything less than 60% and caution was the key until I could get it home for a charge.

just another reason to order a massive battery.

even now on my 840Wh wheel, I go into my own caution mode at 60 % even though 60% of 840 is more than 100% of 340.

That's  why King Song reduces available speed at reduced power; because they know the consequences of excessive speed on a depleted battery.  They are going into caution mode for you, in case you forget, or can't hear the beeps.  Many hate this, but it's there for your protection.

Now, why they reduce speed at the same % regardless of battery size is a mystery. As my 840 vs 340 reference, points out; there's no reason to limit a wheel whose large, reduced-power battery still has more available power, than a smaller battery that isn't limited at that same, or smaller Watt-hour level.

[The Fat Unicyclist]

25 minutes ago, Smoother said:

Now, why they reduce speed at the same % regardless of battery size is a mystery. As my 840 vs 340 reference, points out; there's no reason to limit a wheel whose large, reduced-power battery still has more available power, than a smaller battery that isn't limited at that same, or smaller Watt-hour level.

But if the bigger wheels (battery, not diameter) have bigger motors (with a bigger draw), shouldn't that be the case?

[Smoother]

1 hour ago, The Fat Unicyclist said:

But if the bigger wheels (battery, not diameter) have bigger motors (with a bigger draw), shouldn't that be the case?

Regardless of the potential power of the wheel, it still takes the same amount of energy to do the same work.  12 to 18Wh per km seems to be the quoted power draw on flat ground.  More for hills.  A 14b and a Monster side by side with same overall weight and wind resistance will require about the same energy ( although differences in internal inefficiencies will skew the actual used, a bit).  If they both accelerate from 15kph to 20 kph at the same rate, again the same amount of energy is needed.  Same for climbing a hill.  The bigger wheel, will only put out the energy needed regardless of its potential to give more.  So a 1600Wh battery at an actual 50% charge is still way more safe that a 340Wh at 100% (800Wh vs 340Wh). Or am I missing something? 

It's possible that because this 50% charge (per cell) might create  an undesirable condition that is worse than the individual batteries in the 340Wh  cells each being 100%.  But if there is, I don't know what it is.  Others here know much more about batteries and may have more to add.

 

[Chriull]

4 hours ago, Smoother said:

Regardless of the potential power of the wheel, it still takes the same amount of energy to do the same work.  12 to 18Wh per km seems to be the quoted power draw on flat ground.  More for hills.  A 14b and a Monster side by side with same overall weight and wind resistance will require about the same energy ( although differences in internal inefficiencies will skew the actual used, a bit).  If they both accelerate from 15kph to 20 kph at the same rate, again the same amount of energy is needed.  Same for climbing a hill.  The bigger wheel, will only put out the energy needed regardless of its potential to give more.  So a 1600Wh battery at an actual 50% charge is still way more safe that a 340Wh at 100% (800Wh vs 340Wh). Or am I missing something? 

It's possible that because this 50% charge (per cell) might create  an undesirable condition that is worse than the individual batteries in the 340Wh  cells each being 100%.  But if there is, I don't know what it is.  Others here know much more about batteries and may have more to add.

 

The main aspect of higher capacity battery packs is that they quite likeley have more cells in parallel. That gives more current to be delivered if needed and less voltage sag at the same current.

But they still have about the same voltage at similar charge levels.

So a 100% charged 320 Wh (16s2p) battery has more voltage (higher max speed in regard to overlean at the max torque over speed limit) than a ~1300Wh (16s6p) at 50% charge. But still the 6p could provide about 3 times the current as the 2p battery with 1/3 of the internal resistance (voltage sag)

At 65% charge a li ion has ~3.8V (did not find quickly numbers for 50% at batteryuniversity), at 100% 4.2V. so thats 10% less voltage leading to 10% less top speed. Under load the difference will just get a bit smaller, as the 50% charged 6p has less sag than the 100% 2p.

[Scatcat]

54 minutes ago, Chriull said:

The main aspect of higher capacity battery packs is that they quite likeley have more cells in parallel. That gives more current to be delivered if needed and less voltage sag at the same current.

But they still have about the same voltage at similar charge levels.

So a 100% charged 320 Wh (16s2p) battery has more voltage (higher max speed in regard to overlean at the max torque over speed limit) than a ~1300Wh (16s6p) at 50% charge. But still the 6p could provide about 3 times the current as the 2p battery with 1/3 of the internal resistance (voltage sag)

At 65% charge a li ion has ~3.8V (did not find quickly numbers for 50% at batteryuniversity), at 100% 4.2V. so thats 10% less voltage leading to 10% less top speed. Under load the difference will just get a bit smaller, as the 50% charged 6p has less sag than the 100% 2p.

You're correct, but in practice the voltage sag difference will mostly nullify the difference in charge levels when the packs are that different - given they use the same type of cells.

While I haven't checked in detail a 18650 like the sanyo/panasonics used will happily give you 10A until discharged. They can peak at higher amperage, say 25A for a few seconds without damage. As long as you keep within the CDR (The acceptable continuous discharge), the voltage sag is pretty small, but as soon as you go above the CDR the battery voltage drops dramatically. For example a Samsung IMR25R can push as much as 100A for half a second, but as the CDR is 20A the voltage drop at 100A may be as much as half the voltage.

So if the CDR is 10A for each cell, and you have 2p you have 20A without dramatic voltage drop at full charge. Suppose you have 84V and 20A you can push ~15-1600W continuous.

If you have 6p you have access to 60A CDR and even at 3.5V/70V you can push ~41-4200W continuous, while a 4p can push 27-2800W Continuous.

The max speed is of course affected anyways, as the max voltage affect the max torque speed, but the wattage is still incomparably better with more parallel packs. This in turn means that the 2p pack will be more dangerous uphill even if fully charged, just as the overlean risk is higher with 2p than 4p or 6p.

[Chriull]

59 minutes ago, Scatcat said:

You're correct, but in practice the voltage sag difference will mostly nullify the difference in charge levels when the packs are that different - given they use the same type of cells.

With the above example 16s2p at 4.2V and 16s6p at 3.8V the voltage difference is 16*.4V=6.4V

At a load of the CDR of the 2p pack (20A) and an internal resistance of one cell of approx 40 mOhm the voltage drop of the 16s2p would be 6.4V, with the 16s6p 2.13V. Thus reducing the difference to 2.13V.

Quote

...

So if the CDR is 10A for each cell, and you have 2p you have 20A without dramatic voltage drop at full charge. Suppose you have 84V and 20A you can push ~15-1600W continuous.

Should be about 8V (so ~10%) drop.

Quote

If you have 6p you have access to 60A CDR and even at 3.5V/70V you can push ~41-4200W continuous, while a 4p can push 27-2800W Continuous.

The max speed is of course affected anyways, as the max voltage affect the max torque speed, but the wattage is still incomparably better with more parallel packs. This in turn means that the 2p pack will be more dangerous uphill even if fully charged, just as the overlean risk is higher with 2p than 4p or 6p.

Yes.

Just for the files, as requirements are very different for each rider - "more dangerous" is relative - for light riders who don't need much range and are not using up every km/h of the max possible speed 2p packs can start out to be more than sufficient.

With 4p pack and their continous power delivery ability one should be already above or at least reach about the thermal capabilities of the wheel design (mosfets, etc) for continous operation.

Dangerous and quite irresponsible is imho the lack of any warning related to the max torque over speed limit (overlean limit) in the wheels firmware.

Edit:

Ps.: Almost forgot another main advantage of parallel packs - less current per cell increases the usable capacity (range) and this less "stress" per cell should also increase their lifetime (have to look through batteryunivetsity once again, if i can find facts for this second idea/feeling)

So with a 6p pack more than 3 time the range can be reached than with a 2p pack. With the more of a difference, the higher the burden/load is.

Pps.: breaking capabilities would also be an important aspect for more cells in parallel

[Scatcat]

3 minutes ago, Chriull said:

With the above example 16s2p at 4.2V and 16s6p at 3.8V the voltage difference is 16*.4V=6.4V

At a load of the CDR of the 2p pack (20A) and an internal resistance of one cell of approx 40 mOhm the voltage drop of the 16s2p would be 6.4V, with the 16s6p 2.13V. Thus reducing the difference to 2.13V.

Should be about 8V (so ~10%) drop.

Yes.

Just for the files, as requirements are very different for each rider - "more dangerous" is relative - for light riders who don't need much range and are not using up every km/h of the max possible speed 2p packs can start out to be more than sufficient.

With 4p pack and their continous power delivery ability one should be already above or at least reach about the thermal capabilities of the wheel design (mosfets, etc) for continous operation.

Dangerous and quite irresponsible is imho the lack of any warning related to the max torque over speed limit (overlean limit) in the wheels firmware.

You are of course correct, the rider weight is crucial.

Myself, I ride on a GT16 which has 20s4p in the packs. At 90 kilos I take it very easy at any charge below 60% - easy as below 25 kph.

But the firmware in the GT16V2 is pretty good. It warns and even tilts back if you try to push beyond what's safe at the current charge level. The 80% warning and tilt-back is not something you can turn off, while hard speed limits can be tinkered with at you wish.

It is a sign of the current Wild West/Snake Oil/Cut Throat mentality in China, that they don't bother with good manuals to tell people what is safe and not. Any warnings and advice are lackluster and more of a liability avoidance than true care for the customers.

Don't get me wrong, that is not an implicit criticism of China per se, we've been there too, Japan was there in the fifties and sixties, Korea and Taiwan in the seventies and eighties, and now it is China's turn. In ten to twenty years they will have turned the corner and be another Taiwan or Korea, turning out the latest and greatest with high quality. You can already see the signs with brands like Huawei that is no worse in quality and performance than brands from other countries.

[LanghamP]

@Marty Backe, yeah no tiltback with no sound gets pretty dangerous but tiltback is pretty bad too unless you practice it a lot. I have to practice about once a wheel at super low speeds, it is pretty easy to crash from a tiltback.

Since tiltback is your only feedback unless you're really good at eyeballing speed, then you have no choice but to leave it on.

My suspicion is tiltback on the msuper is speed instead of battery dependent. 

 

 

[mezzanine]

I've experienced something similar to this with my hood pulled over helmet for winter riding.  In an effort to keep my ears warm, I have a helmet with a kind of ear-muff insert and the hood is insulated with down and dampens outside sound. 

I noted Warp's comment about the Switchblade as I'm looking at full faced helmets and appreciate how important sound is for awareness.  I'm always listening for vehicles coming up behind me.  

[WARPed1701D]

55 minutes ago, mezzanine said:

I've experienced something similar to this with my hood pulled over helmet for winter riding.  In an effort to keep my ears warm, I have a helmet with a kind of ear-muff insert and the hood is insulated with down and dampens outside sound. 

I noted Warp's comment about the Switchblade as I'm looking at full faced helmets and appreciate how important sound is for awareness.  I'm always listening for vehicles coming up behind me.  

The Bell Super 3R also had vents by the ear but I didn't ride with that one so don't know about wind noise. It also isn't downhill rated but being the right fit is paramount and different brands fit different heads better. There are pictures of both in my review thread. 

[Michael Vu]

I noticed this too when I ride with my full face helmet and try to be extra cautious when going at higher speeds on a lower battery. I will also say that it would be better if Gotway included a 2nd speaker (possibly on the other side of the shell) to not only increase volume, but also have redundancy in case a speaker goes out. Kingsong's having 2 or 4 speakers is yet another case why Kingsong's are the best wheel when it comes to safety.

[Michael Vu]

On 1/21/2018 at 11:31 AM, dmethvin said:

Man that's scary. Even with a bike helmet and some nearby traffic noise I've had problems hearing warning beeps. The Firewheel has an urgent-sounding voice that says "Take care!" when you're right at the limit but it's not loud enough. Good idea there but bad execution.

And she says "Take care" twice in a row to try to get your attention. Unfortunately that wasn't enough to prevent my first (and worst) crash I had on an EUC. 

[Marty Backe]

2 hours ago, Michael Vu said:

I noticed this too when I ride with my full face helmet and try to be extra cautious when going at higher speeds on a lower battery. I will also say that it would be better if Gotway included a 2nd speaker (possibly on the other side of the shell) to not only increase volume, but also have redundancy in case a speaker goes out. Kingsong's having 2 or 4 speakers is yet another case why Kingsong's are the best wheel when it comes to safety.

I hope someday they move away from the buzzer and instead use a proper LOUD speaker. And ideally the volume of the sound would vary as the speed of the wheel varies. It would be loudest at high speeds.

[duaner]

The volume should be adjustable by user.  And ideally the volume of the sound would vary as the noise around the wheel varies. Loud wind, loud surroundings (traffic, construction, music, etc) should auto increase the volume from the user's base setting.  User should also be able to adjust pitch/sound somehow -- so when we are riding next to each other I can tell my wheel's beeps from your wheel's beeps.

[WARPed1701D]

I have to say my V8 is very loud. I don't believe I've missed a warning yet. What is cool is that you can adjust the volume (mine is at max) and even set your own sounds. One day my wheel is doing to warn me off a "warp core overload" when I hit a bump at speed.