Mten4 announced!

[chanman]

3 minutes ago, BKW said:

I should expect 80% efficiency at 32F

I don't know how much stock you should put in the 80% number, if you're drawing lots of current it could be substantially less. 

It's possible the internal connections aren't good and you're only on one parallel group effectively, which you should find when you charge the wheel. Either the power meter measurement of energy drawn from the wall, or without one just the charging time given the charger output amperage would be a good indicator.

If these are Begode supplied packs it's also potentially possible the pack is functioning as intended and what's in there is not actually legitimate Samsung 40T cells with maybe worse cold weather performance or less than stated current capability or capacity.

[BKW]

8 minutes ago, chanman said:

I don't know how much stock you should put in the 80% number, if you're drawing lots of current it could be substantially less. 

It's possible the internal connections aren't good and you're only on one parallel group effectively, which you should find when you charge the wheel. Either the power meter measurement of energy drawn from the wall, or without one just the charging time given the charger output amperage would be a good indicator.

If these are Begode supplied packs it's also potentially possible the pack is functioning as intended and what's in there is not actually legitimate Samsung 40T cells with maybe worse cold weather performance or less than stated current capability or capacity.

is there anyway I can take a reading and see what volts it is to tell me if anything is off?

is there a way i can take a reading and see if one of the batteries are ineffective? Any other reading I can do to check if things are off?

[chanman]

5 minutes ago, BKW said:

is there anyway I can take a reading and see what volts it is to tell me if anything is off

The voltage reading alone won't help you, there's still the 20 cells in series so the voltage will read as expected.

Actually you could try something like record the initial voltage, charge for a fixed amount of time, say 30 minutes, disconnect the charger and record the final voltage. This would give a good idea of the effective capacity of the pack given some math and the charger current output, but really the power meter simplifies things.

Edited March 9, 2023 by chanman

[BKW]

20 minutes ago, chanman said:

The voltage reading alone won't help you, there's still the 20 cells in series so the voltage will read as expected.

Actually you could try something like record the initial voltage, charge for a fixed amount of time, say 30 minutes, disconnect the charger and record the final voltage. This would give a good idea of the effective capacity of the pack given some math and the charger current output, but really the power meter simplifies things.

yeah, i'll just ride the wheel back down as low as i can write down the Wh at this stage. Then write down the Wh at 100%. Ewheels has asked I do this and report back to them.

What if I get similar results? Should I send the batteries/wheel back? None of this seems right to me, and everyone is telling me on facebook I should get much more range under similar circumstances.

I'm wasting too much time on this right now though. I'll take the readings at report back when i have the time

[chanman]

If you find the capacity is more likely to be 300Wh then you definitely don't have what you paid for and should send the wheel back, presumably for a battery pack replacement, or maybe consider doing the replacement yourself if you don't want to mail the wheel.

If you find the capacity is more likely to be 600Wh, then you probably have what you paid for, but the cold weather range for you isn't good enough, so if that's an issue for you maybe you should send it back. 

(Hopefully not offensive, but do you happen to weigh like 250+ lbs?, that's the last thing I have on the list for bad range number causes that I didn't see addressed)

[BKW]

5 minutes ago, chanman said:

If you find the capacity is more likely to be 300Wh then you definitely don't have what you paid for and should send the wheel back, presumably for a battery pack replacement, or maybe consider doing the replacement yourself if you don't want to mail the wheel.

If you find the capacity is more likely to be 600Wh, then you probably have what you paid for, but the cold weather range for you isn't good enough, so if that's an issue for you maybe you should send it back. 

(Hopefully not offensive, but do you happen to weigh like 250+ lbs?, that's the last thing I have on the list for bad range number causes that I didn't see addressed)

i weigh closer to 178 lbs. I did this range test in 34F with avg speed of 12mph and top speed around 20mph. roughly 8 miles.

How can I measure if it is utilizing only 300wh instead of 600wh? I opened the wheel already and confirmed it's the 600wh pack. I don't know how to check if it is only utilizing 300wh of the 600wh, etc. I don't know what to check or what to look for or how to do it

Edited March 9, 2023 by BKW

[chanman]

20 minutes ago, BKW said:

How can I measure if it is utilizing only 300wh instead of 600wh

We went over this with the power meter I thought, measuring the amount of energy drawn from the wall for a full charge. You're not going to get exactly 300 or 600, there's a little more due to inefficiency from the wall and the charging, and a little less because the battery pack will not be completely 100% drained, and the manufacturer numbers are a bit inflated to begin with, but you'll probably get something closer to one of the two.

Edited March 9, 2023 by chanman

[BKW]

1 minute ago, chanman said:

We went over this with the power meter I thought, measuring the amount of energy drawn from the wall for a full charge. You're not going to get exactly 300 or 600, there's a little more due to inefficiency from the wall and the charging, and a little less because the battery pack will not be completely 100% drained, but you'll probably get something closer to one of the two.

OK. Like I said, I'm dumb when it comes to this stuff. I'll do that then and check it out. Thanks again

[chanman]

4 minutes ago, BKW said:

Thanks again

No prob. I see you have some other wheels, you can also try this process with one of those with a known good pack and use that as a reference. Like if you get 1400Wh on your 16X for instance doing this you know to expect a little lower than actual reading, although that's a little trickier to get drained as much as possible.

[BKW]

Btw, Ian from Speedyfeet got 10 miles at 700wh on his mten4 in his range test (timestamped):

 

[Paul A]

Disconnect one battery and see if there is still power?

Then reconnect the battery, and disconnect the other battery, and see if there is still power?

Could this determine if one battery is not functioning properly?

[rebeuc]

3 minutes ago, Paul A said:

Disconnect one battery and see if there is still power?

Then reconnect the battery, and disconnect the other battery, and see if there is still power?

Could this determine if one battery is not functioning properly?

It's not two separate packs; there is only one power connector.

[chanman]

6 minutes ago, Paul A said:

Disconnect one battery and see if there is still power

We determined there's only one pack connection apparently, but kind of 2 packs internally. The question is if there's an internal problem or if this is just the true cold weather range for this person's use. The 10 mile range test seems to suggest it's not unreasonable if you're pushing the wheel hard or in cold temps, but it's also possible they have the same problem.

Edited March 9, 2023 by chanman

[BKW]

5 minutes ago, chanman said:

We determined there's only one pack connection apparently, but kind of 2 packs internally. The question is if there's an internal problem or if this is just the true cold weather range for this person's use. The 10 mile range test seems to suggest it's not unreasonable if you're pushing the wheel hard or in cold temps, but it's also possible they have the same problem.

Ian is known to get the worse-case range tests, so 10 miles with 700wh 50E pack is likely the worst-case range. He did said it was cold out, not sure how cold though. He also weighs more than me and is known to push wheels hard.

[Chriull]

1 hour ago, BKW said:

but given the datasheet I provided it says I should expect 80% efficiency at 32F.

Capacity! Efficiency is something different.

Capacitance as given in the datasheet is measured with low currents.

If one measures the capacity at the very same conditions but with a higher current the result is less capacity. So the higher the burden, the less capacity is available.

One reason (?the main reason?) for this effect is the internal resistance.

With lower temperatures internal resistance increases - so the ratio of "low current capacity" and "high current capacity" gets worse.

This is what i meant with "efficiency" in this context.

[BKW]

34 minutes ago, Chriull said:

Capacity! Efficiency is something different.

Capacitance as given in the datasheet is measured with low currents.

If one measures the capacity at the very same conditions but with a higher current the result is less capacity. So the higher the burden, the less capacity is available.

One reason (?the main reason?) for this effect is the internal resistance.

With lower temperatures internal resistance increases - so the ratio of "low current capacity" and "high current capacity" gets worse.

This is what i meant with "efficiency" in this context.

Sorry, I have to be careful with the words I used here (I used it without thinking it through). When I meant by "efficiency" is, basically, 80% expected range when comparing it to 100% at optimal conditions

Edited March 9, 2023 by BKW

[Chriull]

1 hour ago, BKW said:

Sorry, I have to be careful with the words I used here (I used it without thinking it through). When I meant by "efficiency" is, basically, 80% expected range when comparing it to 100% at optimal conditions

I'm sorry - my thoughts above should (hopefully) fit for some high capacity cells, but as it seems not for the 40T.

Just looked in the linked datasheet - at 0°C the 80% capacity are stated for 10A discharge current!

Don't know your wheels battery config (?20s2p?), but with comfortable riding these about 80% of "normal temperature" riding should be reachable.

Best to check the battery packs!

[BKW]

I just came back from a 8.61 mile trip with the mten4 starting at 100% charge. Temps were 38F. Avg riding 11.3 mph and top speed 20.4 mph.

At 8.61 miles I now have 33% battery left. Last time I went out I had roughly 8 miles with 12% left.

Someone in facebook suggested I check the tire pressure. I think this street tire has max PSI for 50psi. I pumped it up to 45 PSI. The PSI is what I think saved me 25%+ battery life. I rode it stock PSI from ewheels without checking pressure. But I think my last test it was 16 PSI or under.

I wasn't paying as close attention to the range this time and I think I might have reset it somehow in the app early on, so I'll go out with 45 psi again another day and test it again.

 

I used 67% battery doing 8.62 miles. So, theoretically, 67%/8.62miles = 7.77% per mile. Therefore, 100% battery / 7.77% per mile would give me 12.87 miles total if I kept at the pace I was going and battery is to stay the same throughout (it won't).

12.87 miles given 178 lbs rider weight, 11.3 avg mph, 38°F and using lower capacity 40T cells sounds more pluasable?

If 20 miles is expected at 73.4F (ideal temps) with 600wh 40T battery, then at 38F with expected max range of 12.87 miles sounds more plausible? That's a 35.4F lower temp than the ideal temp for 20 miles max range.

Edited March 10, 2023 by BKW

[BKW]

Also, the first time I took it out there was an 11% voltage sag. So when I stopped riding at 1% after a little bit of idling time the battery raised to 12%.

THIS TIME, with higher PSI to 45psi instead of 16psi or lower, the voltage sag was much less -- maybe 3%-5%. So if I stopped at 28%, after idling it rose to 33%.

This makes sense because with lower PSI means the battery is working harder causing more voltage sag, correct? If true, then the battery is working harder at lower PSI causing faster drainage per mile.

Edited March 10, 2023 by BKW

[Chriull]

1 hour ago, BKW said:

But I think my last test it was 16 PSI or under

That about one bar? Afair with my ks16s this was about "empty" and dangerous for the rim when riding up (small) steps/obstacles. Unfortionately it happened as the tube/vent was not really tight.

Pumped up again to about 3 bars it was a bit bumpy, but save again for the rim and nice to ride.

Imho i never really looked in detail at battery consumption but having only half of the range i would have noticed...

Btw - is there a possible difference with your tours? Elevation, accelerations, top speed duration.

Average speed is not very accurate for battery consumption as at higher speeds unproportionaly more power is consumed.

20 minutes ago, BKW said:

Also, the first time I took it out there was an 11% voltage sag. So when I stopped riding at 1% after a little bit of idling time the battery rode to 12%.

THIS TIME, with higher PSI to 45psi instead of 16psi or lower, the voltage sag was much less -- maybe 3%-5%. So if I stopped at 28%, after idling it rose to 33%.

This makes sense because with lower PSI means the battery is working harder causing more voltage sag, correct?

The voltage sag happens by the burden for accelerations, balancing and riding the wheel as power is consumed. Low psi increase this burden.

"Voltage recovery" of a li ion battery after use is normal and the reason why the charge percentage reported by the wheel and shown in the apps is very inacurate - this value is obtained by voltage measurement and directly transformed to charge % (~3V...3.3V, depending on the wheel are 0%, ~4.2V are 100%).

Voltage measurement for state of charge only works somewhat accurate if the li ion cells have some resting time after use!

So most of the times the shown charge % are just "irrelevant" values! Like your 1% or 28% directly after or still during use.

The 12% and 33% after some resting time are already somewhat more accurate, waiting for 15 minutes, half an hour or an hour would make the values even more accurate.

There is also a systematic failure by this voltage to charge % calculation - it is not really linear. A full battery going from 4.2V to 4.1V provided more energy than an empty battery going from 3.3V to 3.2V. Still the wheel will report the same charge % difference...

And there is a second systematic failure by directly translating charge % to left milage. 

To keep one riding at some distinct speed an empty battery needs more current as a full one.  So capacity in mAh is consumed faster.

If your trips allow it it's best for the batteries and your "safety" to stay with the charge% as high as possible - performance/safety margin is much better the fuller the battery is. And burdening an empty battery can get some cells at dangerous low voltages. The cells are not all perfectly identical and get more and more different over time. Burdening when empty amplifies these differences and the already weakest cells get drained most to the lowest voltages deteriorating them even more.

[Paul A]

Rough terrain such as gravel trails, will have a dramatic effect on power consumption too.

Smooth paved roads with little resistance will greatly increase range.

[BKW]

Question about tire pressure on the street tire I have for the mten4:

In the attached picture below it reads on the side of the tire "MAX LOAD 190kg(418LBS) AT 350kpa(50p.s.i)"

I was a little confused wondering if it meant the tire is recommended max 50psi? Usually, on tires it'll give you a range of psi with a max psi clearly indicated.

What exactly does the 50psi mean in this instance? Does this mean that this tire is recommending a MAX PSI of 50psi?

[rebeuc]

On 3/6/2023 at 3:38 PM, rebeuc said:

Got shipping notice of mine today; if all goes well I should have it on Friday

Just received my wheel.

As others have reported in came in packaging indicating the 300w battery (I wish ewheels themselves had sent a heads up about this to avoid confusion rather than having to read about it on these forums)

It's also the blue padding and not the black that had been mentioned in one of the earlier updates from ewheels, though who knows how much of that is because Begode messed up their order by sending the 300wh battery packs to degin with.

In any event, I was able to take it out of transport mode with the 5 button press trick and briefly tested it out in my living room; definitely a completely different beast compared to any of my other wheels and I immediately understood why I often see them with that baby foam up near the top; this thing is uncomfortable to mount and I will absolutely be padding the heck out of that top edge.

Unfortunately the weather here is snowy, so I will be unlikely to be able to give it a real test ride for at least a few days.

[CrabChampion]

Huge drop on mten4. Crazy that the axle survived. I gotta say I have been babying my mten4 like crazy. Maybe I can be a bit more daring with it

[BKW]

On 3/10/2023 at 1:23 PM, rebeuc said:

Just received my wheel.

As others have reported in came in packaging indicating the 300w battery (I wish ewheels themselves had sent a heads up about this to avoid confusion rather than having to read about it on these forums)

It's also the blue padding and not the black that had been mentioned in one of the earlier updates from ewheels, though who knows how much of that is because Begode messed up their order by sending the 300wh battery packs to degin with.

In any event, I was able to take it out of transport mode with the 5 button press trick and briefly tested it out in my living room; definitely a completely different beast compared to any of my other wheels and I immediately understood why I often see them with that baby foam up near the top; this thing is uncomfortable to mount and I will absolutely be padding the heck out of that top edge.

Unfortunately the weather here is snowy, so I will be unlikely to be able to give it a real test ride for at least a few days.

Nice! You got the 600wh 40T mten4? Curious how the batteries are affected by Michigan cold weather and if it's anything like mine

57 minutes ago, Cobaltsaber said:

Huge drop on mten4. Crazy that the axle survived. I gotta say I have been babying my mten4 like crazy. Maybe I can be a bit more daring with it

Yikes. Nice to know the wheel held up!

Edited March 11, 2023 by BKW