How low can you go? (battery question)

[orbajosbrother]

I ride an 84V 1600wh MSX. Yesterday I went on my longest ride. 24.5 miles. I started with 90% (had one or two 3 mile trips on it already), once EUC world started reporting singe digit battery levels under load, I returned home. After settling for a few minutes EUC world reports 29% and somewhere in the neighborhood of 72V. It seems like the wheel should not be ridden any further without charging since if the battery level hits 0% under load, it's all over, right? Would enabling the EUC world battery level averaging feature be a safer bet? 

I'm feel that I am getting pretty poor range compared to others. I don't accelerate hard (IMO) and I don't even ride that fast. I have my EUC world alarm set at 25mph and I try to keep it right around there. Sometimes I overshoot it and have to slow down, it's pretty easy to do on the MSX. I weight 175 lbs + gear. So maybe 185lbs max on the wheel.

Thanks!

[Chriull]

28 minutes ago, orbajosbrother said:

once EUC world started reporting singe digit battery levels under load, I returned home. After settling for a few minutes EUC world reports 29% and somewhere in the neighborhood of 72V.

Charge % as reported from the wheel is just computed from the battery voltage. While riding/charging this number is just inaccurate/wrong. Battery voltage sags under burden (as it gets positive "bias" while charging) and needs time with no load to settle to it's "normal/internal state". Once the voltage settled suffuciently the charge % computed from voltage are (more) accurate again.

28 minutes ago, orbajosbrother said:

It seems like the wheel should not be ridden any further without charging since if the battery level hits 0% under load, it's all over, right?

Hopefully not. But the wheel will give warnings, start to tiltback and finally shut off, once the battery goes too often too long too low.

But i don't know the detailed behaviour of the GW MSX.

36 minutes ago, orbajosbrother said:

Would enabling the EUC world battery level averaging feature be a safer bet? 

It should show the battery charge left more accurate as the normal charge % computed "directly" from the voltage.

37 minutes ago, orbajosbrother said:

I'm feel that I am getting pretty poor range compared to others. I don't accelerate hard (IMO) and I don't even ride that fast. I have my EUC world alarm set at 25mph and I try to keep it right around there. Sometimes I overshoot it and have to slow down, it's pretty easy to do on the MSX. I weight 175 lbs + gear. So maybe 185lbs max on the wheel.

You have inclines at your tracks? They eat up battery. Headwind? Colder temperatures?

Maybe you're just not standing as "smooth" on the wheel while riding so it needs more power to balance you?

Different tire pressure?

You are charging you wheel really full? About 1/2-2 hours after the led went green.

The wheel shows not only 100% charge but also some voltage around 84V?

Your charger delivers 84.xV without load?

If you measured the charger, which accuracy has your voltmeter?

....

There are about countless points that influence in any combination the range...

 

[meepmeepmayer]

You can ride the wheel until it throws you off for low battery (beeps and ultimately tiltback). Maybe be a bit careful and don't stress hard at lower battery.

You should charge to (nearly) full after every ride if you know/expect you'll use the wheel again soon. No reason not to. Higher battery charge state is always better when riding.

24.5 miles at 25mph... starting at 90%... seems to be a very normal range. There's a lot to be gained by charging to 100% or even above (keeping the charger in for a few hours after it goes green adds another ~10% to the overall energy on Gotways, because 100% voltage isn't actually full, you can charge to 111% by their math but it won't show as more than 100%).

Also you can see how much range you get if you ride it down to the battery beeps, might be a bit more as you didn't do that.

So, charge to full (or a high charge state like 90%) after each ride, and maybe do a range test. Everything seems absolutely normal.

Edited May 29, 2020 by meepmeepmayer

[meepmeepmayer]

In addition: you should charge to full (100% and keep the charger in for a few hours then) regularly, maybe every 10 charge cycles or so (adding another 100% to the battery state counts as one cycle, no matter in how many increments). The fine balancing of the battery cells only happens at full battery and should be done regularly. If you never do that, you get reduced range and can ultimately (ultimately, don't worry!) even harm the battery.

No harm in charging to 90% or full after each ride (just don't store the wheel for weeks/months at full, that stresses the battery).

[orbajosbrother]

Thanks for the info! The wheel when fully charged does show 84V. I think 84.3V to be exact. I've not tested my charger with a multimeter but since the wheel reports 84V I think it's fine. I have left it charging overnight so the green light has been on for at least 2 hours. I just did not think it was necessary to charge it after the 2 short trips I made the day before. The temperature yesterday was in the mid 70's so I thought it would be ideal for range. I do not think there were many, if any, notable inclines around here. I did increase the tire pressure in an attempt at better range. It's now somewhere around 38 PSI. I have slimed the tire. The fan was running when I turned the wheel off.

My stance is something I had not considered, and might need improvement. Rather than lean to accelerate, which I do a little, I try to instead shift my weight toward the front of the pedals. I tend to stay up on my toes with knees bent, this helps absorb bumps. The center of my foot is just about in the center of the pedal, if not a little forward. I ride in hard mode because otherwise my pedals dip in hard turns and this is unsettling. I have not calibrated the gyro, maybe I should.

I'll let the wheel tell me when it's had enough then, instead of focusing so intently on the EUC world battery level. If there are 20 cells in the MSX, then 72V would mean ~3.6V in each cell, which is still quite a bit if Gotway lets each cell go down to 3.0V (is this correct?). The EUC World WearOS app does not show voltage like it does on the phone so I have not seen what it reports under load. Battery level averaging sounds like it might report a more accurate battery level, or at least less wildly fluctuating as I ride.

 

 

[Chriull]

10 minutes ago, meepmeepmayer said:

and maybe do a range test

And make second range test with "just" 30km/h - you'll be surprised.

[orbajosbrother]

Oh by the way, if tilt back is disabled on the MSX will it still do it in response to a low battery condition?

[meepmeepmayer]

The voltage measurements on all wheels are quite inexact (+/- 1V can happen). Don't trust the too much.

13 minutes ago, orbajosbrother said:

I have not calibrated the gyro, maybe I should.

No reason to calibrate unless you get pedal dipping in curves or want another default angle. Never change a running system, especially a sketchy one like a Chinese EUC

13 minutes ago, orbajosbrother said:

Gotway lets each cell go down to 3.0V (is this correct?)

4.2V is full, 4.1125 is 100%, 3.3V is 0% and it won't let you go lower (at 15% the battery beeps start and below 0% you always have massive tiltback).

Edit: That is why, even at 0%, you still have some good safety reserves on Gotways, and why they will let you speed until the battery beeps start.

11 minutes ago, orbajosbrother said:

Oh by the way, if tilt back is disabled on the MSX will it still do it in response to a low battery condition?

Yes it will (as far as I know). You would only disable the speed tiltback (tiltback is just another speed alarm).

12 minutes ago, Chriull said:

And make second range test with "just" 30km/h - you'll be surprised.

True!

Edited May 29, 2020 by meepmeepmayer
number

[Chriull]

11 minutes ago, orbajosbrother said:

Thanks for the info! The wheel when fully charged does show 84V. I think 84.3V to be exact. I've not tested my charger with a multimeter but since the wheel reports 84V I think it's fine.

+1

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I have left it charging overnight so the green light has been on for at least 2 hours.

+1

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I just did not think it was necessary to charge it after the 2 short trips I made the day before. 

Just you have less capacity left for this next ride

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The temperature yesterday was in the mid 70's so I thought it would be ideal for range.

+1

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I do not think there were many, if any, notable inclines around here. I did increase the tire pressure in an attempt at better range. It's now somewhere around 38 PSI.

+1

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My stance is something I had not considered, and might need improvement. Rather than lean to accelerate, which I do a little, I try to instead shift my weight toward the front of the pedals. I tend to stay up on my toes with knees bent, this helps absorb bumps. The center of my foot is just about in the center of the pedal, if not a little forward.

This should have about no influence. I meant if one stands very "insecure/wobbly" on the wheel this could need more "balancing power".

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I'll let the wheel tell me when it's had enough then, instead of focusing so intently on the EUC world battery level. If there are 20 cells in the MSX, then 72V would mean ~3.6V in each cell, which is still quite a bit if Gotway lets each cell go down to 3.0V (is this correct?).

Afaik 3.3V. if they did not change this lately. 3.0V is(?was?) with KS wheels. Many/some KS stop at 3.15V.

9 minutes ago, orbajosbrother said:

Oh by the way, if tilt back is disabled on the MSX will it still do it in response to a low battery condition?

FYI - the "overlean limit" is direct proportional to battery voltage (and "burden"). So have fun with high(er) battery levels and do more relaxed riding once the battery lowers.

[orbajosbrother]

9 minutes ago, Chriull said:

And make second range test with "just" 30km/h - you'll be surprised.

Hah. I don't know if I have it in me, but in the interest of science I'll probably try it eventually. I tried riding my 14D the other day after being accustomed to the MSX. Almost immediately I hit the speed limit and get tilted back. At least the tilt back on that wheel works now. Ever since my 14D tilt back malfunction crash I have been very wary/scared of tiltback. Another reason I got the MSX, so I could turn it off. I know some people say tiltback works by accelerating to bring the wheel in front of you, and there is evidence to support that, since if you pick up the wheel and exceed the max speed it will speed up even more before shutting off. But my gyro issues on the 14D also make it seem like it may be more than just raw acceleration, the gyro seems to also actively make the pedals tilt back also.

[Chriull]

14 minutes ago, orbajosbrother said:

I know some people say tiltback works by accelerating to bring the wheel in front of you, and there is evidence to support that,

Yes. As while balancing the rider the wheel is constantly acc- and decelerating to keep one upright.

14 minutes ago, orbajosbrother said:

since if you pick up the wheel and exceed the max speed it will speed up even more before shutting off.

Yes, but that's not the evidence. Tiltback is not and cannot limit the speed. One can always "ride the tiltback" until one reaches the wherls limit and overleans.