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GW MCM4 is Unsafe?


Jason McNeil

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I bought my Gotway MCM4 6 months ago.  I use it for daily commute (6miles) and have not had a single power cutoff.  Since safety is the number one concern for commuting, I try to avoid the potential danger by (1) keeping the battery level more than 20% all the time; (2) accelerating slowly at the beginning; and (3) reducing speed when climbing. 

The three tips came from my own experience using Wheelog: the power consumption is high during the initial acceleration and during climbing steep slopes.  On flat surface, the power consumption is not quite as high even going with high speed (up to 20mph, without wind of course).

I charge the wheel once in a couple of days.  By the end of the second day, the battery level drops to 30% - still enough reserve for normal riding.  I hope this is the optimal charging schedule - a tradeoff of low charging frequency for longer battery life and enough battery capacity for safety.

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22 hours ago, EU_commuter said:

I charge the wheel once in a couple of days.  By the end of the second day, the battery level drops to 30% - still enough reserve for normal riding.  I hope this is the optimal charging schedule - a tradeoff of low charging frequency for longer battery life and enough battery capacity for safety.

I was doing the same thing, to "save" charging cycles. It actually works for mobile phones, because they use the battery all the time and you can avoid micro-cycles of charging. 

However when it comes to electric unicycles... it's actually better to charge your wheel when the battery is above 50%. I didn't know this until I read this article:

https://www.electricunicycles.eu/all_you_need_to_know_about_rechargeable_batteries-c__224

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3 hours ago, Bat said:

I was doing the same thing, to "save" charging cycles. It actually works for mobile phones, because they use the battery all the time and you can avoid micro-cycles of charging. 

However when it comes to electric unicycles... it's actually better to charge your wheel when the battery is above 50%. I didn't know this until I read this article:

https://www.electricunicycles.eu/all_you_need_to_know_about_rechargeable_batteries-c__224

The article is a bit copied all together what is known for care abput batteries, without bringing it to conclusion!

First it states just discharge down to 50%...and then charge full again...but you have to read on...later it says not to charge more than 80-90 full!

both is true, and good for longer batterie life. Its just a bit unrealistic to stay alltime between 50 and 80%, as this is a bit less for riding then!

Its a good middle to say, you maximize your batterie life when keeping the batterie between 20/30 and 80/90 percent!

what is really totally wrong...is to put the EUC  on the charger after every ride and fill it up to 100%.

Also bad is not using it for longer time after you did a 100% charge. LiIon 18650 optimale want to be stored between 20-50%. To balance your seriell batterie system, it is enough to do a full charge all 10/20 rides...

 

 

 

 

 

 

 

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On 4/7/2017 at 0:48 AM, Trey Lewis said:

A lot has changed since the old MCM4. It is the popular wheel in my area and I have yet to see or experience a cut-out. I personally ride one for short trips. Sounds like it used to be a scary wheel though. I never feel unsafe on it at 30km/h despite being rather heavy.

Yeah, pre-December 2015 production was the 'high-torque' version MCM4, had a low cut-out threshold of around 25kph; since then the HS version seems to be pretty decent.  

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On 07/04/2017 at 7:49 AM, EU_commuter said:

a tradeoff of low charging frequency for longer battery life and enough battery capacity for safety.

I haven't yet seen any reliable source suggesting that Li-Ion batteries suffer from frequent charging (as it was the case with previous generation type batteries). Li-Ion batteries suffer from keeping them at high charge values for most of the time (in particular at high temperatures), which could be a consequent of frequent charging. However, frequent and short charge cycles which keep the battery between, say, 30% and 70% are supposed to increase battery life (in overall Wh) by more than a factor of four compared to full cycling. 

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On 4/8/2017 at 1:28 PM, Mono said:

I haven't yet seen any reliable source suggesting that Li-Ion batteries suffer from frequent charging (as it was the case with previous generation type batteries). Li-Ion batteries suffer from keeping them at high charge values for most of the time (in particular at high temperatures), which could be a consequent of frequent charging. However, frequent and short charge cycles which keep the battery between, say, 30% and 70% are supposed to increase battery life (in overall Wh) by more than a factor of four compared to full cycling. 

It doesn't seem a good idea to go below 30% all the time, but why would you as performance and safety suffer?

The same goes for 100% charging and putting it in the car in the sun for days on end, but what sane person does that with Li-ion batteries?

At the rate EUC develop, most of us will have a new wheel well before the batteries of the old one have reached their end of lifecycle with normal use anyway.

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21 minutes ago, Jurgen said:

It doesn't seem a good idea to go below 30% all the time, but why would you as performance and safety suffer?

Right, the low end of the scale will rarely be a problem in the context of EUCs, as EUCs prevent very low charge values anyways. 

2 minutes ago, Jurgen said:

The same goes for 100% charging and putting it in the car in the sun for days on end, but what sane person does that with Li-ion batteries?

It doesn't have much to do with sanity, but with being informed and it's not so easy to access and judge the reliable information without spending hours on it. I didn't know much about battery life time before I started riding EUCs, and I have gotten rather less sane in the process :) I also had no idea how important the combination of temperature and charge status. 

3 minutes ago, Jurgen said:

At the rate EUC develop, most of us will have a new wheel well before the batteries of the old one have reached their end of lifecycle with normal use anyway.

I agree, that's probably true for full cycling related ageing, though that may not be true for high temperature related ageing. I see regularly posts of people charging their battery always to 100% immediately after they get home and I have seen a few posts about serious battery deterioration.

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On 12/23/2015 at 2:50 PM, Jason McNeil said:

Today @h00ktern & I took the MCM4 & KS14 out to a park to do a range test of the Wheels. Both Wheels were fully charged, I was on the MCM4 (I am about 70kg). We were cruising around the 22-25kph range, the park has no hills or any gradients to speak off. Into 14km of the test (app reported battery still had 70% capacity), the Wheel's power simply cut-out—there was no acceleration or increase in speed, nor was it a brown-out or a recoverable situation.

By way of comparison, I've ridden hundreds of hours on the KS 14C & driven it at least 2x times harder without the slightest hiccup. In my opinion the MCM4 is completely unreliable & unsafe Wheel not to be trusted.  Edit: maybe this opinion is unfair, but when it has an advertised speed of 35kph & gives out at 10kph below the spec speed on nearly a full battery, it's difficult to feel generous towards it.

Sustained injuries were relatively minor, got off with some loss of skin to hand & bruising on the knees. I ought to have been more cautious in trying a new Wheel for cut-outs & strapped on some wrist-guards & kneepads for insurance, hindsight is such a wonderful thing... :unsure:

Edit: had the 'Pedal Tilt-back Speed Setting' enabled.  

IMG_0968.JPG.4b223fde5cf86f03373bef7d04f      567c1b5a329b6_AppSettings.jpg.cec5faed5b

Is this the incident that convinced u so wear wrist guards now?

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3 hours ago, Jack Frost said:

Is this the incident that convinced u so wear wrist guards now?

It is an incident which supports the idea to always and immediately slow down when we hear the last speed warning. Personally, it couldn't convince me to wear wrist guards. In my books, active safety beats passive safety.

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16 hours ago, Mono said:

It is an incident which supports the idea to always and immediately slow down when we hear the last speed warning. Personally, it couldn't convince me to wear wrist guards. In my books, active safety beats passive safety.

@mono. The EUC gods are listening. Its just one wheel and a failure will not allow you to do any kind of pro-active reaction. Its just silence and you go superman mode. Face wrist elbows knees skin donation assured. Be carefull.

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8 hours ago, Carlos E Rodriguez said:

@mono. The EUC gods are listening. Its just one wheel and a failure will not allow you to do any kind of pro-active reaction. Its just silence and you go superman mode. Face wrist elbows knees skin donation assured. Be carefull.

There is just one life and active safety is always preferable over passive safety to keep this one life going. This doesn't preclude to have both. Anyways, you have to do what you have to do B)

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