Stromer ST2 - Technical review

[PTFC Brian]

Hi Brian,

There are few minor differences in the CYRO drive vs SYNO drive. First, the thru-axle system is little different and 2nd, the way power cable exits the motor is also different.
Even though the top speed is similar ~28mph, SYNO drive has little more Copper mass and hence gets upto speed quicker. I don't pictures for the internals of the motor but since the platform is same, it wouldn't look much different.

If you get the 814 Whr battery, upgrade the lights to Supernova and upgrade the grips/pedals you will have ~85% ST2 at a much nicer price point.

Hello Ravi, thanks for your response!

Glad to hear that the motors very similar, with the removal of the controller the bike is much more balanced, and the heat dissipation is greatly improved from the ST1 (I also have an St1 elite). I purchased the ST1x with the 814wh battery, and will be installing a Supernova fixture if it's compatible.

You are researching a great field of study, and at a very good time in history. I also have an EV, and I closely watch the changing technology. I'd love to hear your thoughts regarding battery tech! Maybe that's for another discussion, but the recent articles from Dr Goodenough's work on solid-state glass electrolyte battery could be the next evolution of energy storage. I hope it is, and it would trickle down to eBikes as well.

 

[Ravi Kempaiah]

Hello Ravi, thanks for your response!

Glad to hear that the motors very similar, with the removal of the controller the bike is much more balanced, and the heat dissipation is greatly improved from the ST1 (I also have an St1 elite). I purchased the ST1x with the 814wh battery, and will be installing a Supernova fixture if it's compatible.

You are researching a great field of study, and at a very good time in history. I also have an EV, and I closely watch the changing technology. I'd love to hear your thoughts regarding battery tech! Maybe that's for another discussion, but the recent articles from Dr Goodenough's work on solid-state glass electrolyte battery could be the next evolution of energy storage. I hope it is, and it would trickle down to eBikes as well.

Thank you @PTFC Brian. I hope you enjoy the ST1-X immensely.
As you know, batteries are constantly evolving. There are lot of interesting things going on that could trickle down to eBikes very soon, like 20700 batteries instead of 18650, Smarter BMS etc.
Prof. Goodenough is a hero in the electrochemical research community. The fact that he hasn't gotten a Nobel prize speaks ill of the Nobel committee. I recently did speak to couple of Professors regarding his solid state electrolyte work and they think it might work for Grid-scale energy storage with lot of improvements but not for the EVs.

 

[PTFC Brian]

Thank you @PTFC Brian. I hope you enjoy the ST1-X immensely.
As you know, batteries are constantly evolving. There are lot of interesting things going on that could trickle down to eBikes very soon, like 20700 batteries instead of 18650, Smarter BMS etc.
Prof. Goodenough is a hero in the electrochemical research community. The fact that he hasn't gotten a Nobel prize speaks ill of the Nobel committee. I recently did speak to couple of Professors regarding his solid state electrolyte work and they think it might work for Grid-scale energy storage with lot of improvements but not for the EVs.

Thanks!

Is your assessment that battery technology will be a gradual evolution of Li-Ion, or do you see bigger leaps over the next 10 years?

 

[Ravi Kempaiah]

Thanks!

Is your assessment that battery technology will be a gradual evolution of Li-Ion, or do you see bigger leaps over the next 10 years?

Honestly, I do not have deep insight into situation this but all the reliable sources indicate that Li-ion will prevail for at least next 10 years. Gigafactory and Panasonic folks just invested a lot of money in building a new factory. There is enough lithium supply for the next 50 years. If you have time, you may want to watch this video.

Re: ST1-X bike, I suggest you put something like a tire liner in the rear tire. It is no fun fixing a flat on a heavy hub motor bike.

 

[PTFC Brian]

Honestly, I do not have deep insight into situation this but all the reliable sources indicate that Li-ion will prevail for at least next 10 years. Gigafactory and Panasonic folks just invested a lot of money in building a new factory. There is enough lithium supply for the next 50 years. If you have time, you may want to watch this video.

Re: ST1-X bike, I suggest you put something like a tire liner in the rear tire. It is no fun fixing a flat on a heavy hub motor bike.

I'll watch the video this evening, thanks!

Yes, the dreaded rear hub-motor/flat tire challenge (the only real flaw of the hub-motor design). Funny you should mention this. I had a few rear flats on my ST1 elite, then added a tire liner and Slime tube. I wanted to see how good the Big Ben Puncture Guard tires are without the added protection, and that wasn't a good idea. Took a 1" ring nail through the center of the tire, and unfortunately my pump failed to function, and I had to call my wife to pick me up.

As you noted, The Cyro Drive is similar to the Syno Drive, and a lot better than the ST1 motor. It's much easier to remove, and there are no rear zip-ties! The early reviews and photos showed a rear zip-tie, but the final design excluded it. There is just a power wire and controller wire to unscrew, and remove the through-axle, that's it. Since then, I put heavy-duty Slime tubes on both wheels, and kevlar tire liners.

 

[bluecat]

I wonder how you arrived at that understanding.

Hi Ravi, I've no doubt you did proper scientific research and the outcome was robust. My concerns are around the question: Can results (from any lab test) be transferred on the ST2 battery? I see three aspects:

1st: I'm suffering on a lack of information. The 18650 cell size is clearly identified. But how are they used? Tech guys from Stromer told me, the depth of discharge is the major battery killer. Therefore, Stromer set the 0% value above of the value which the cell manufacturer gives as standard endpoint of discharge. On the other end, I don't know, if 100% are the max. value which the tech specs of the cell allow - or is 100% somewhat below this value? I see figures from 0 to 100 on the ST2 display, but how are the values behind? I agree, they must be 2900mA cells, but what current can they handle? Will cells with low Amperage have different aging for such with high current?

2nd: I've overviewed several battery-related articles. All together, I've got the impression, the advice were a legacy of the experiences with batteries from RC toys. Typically, the charges for such batteries are unmanaged. This means, the full charging current is active all the time - until the user disconnects the battery pack. Once again, I miss several informations: The charging characteristic remain unknown; was the current reduced for the final 20% of capacity? What current was used - the max. allowed or a reduced one? How was the discharge managed? In terms of the ST2, the max. output of the charge is 4.5A / 54.6V. But are 4.5A really in use? Regardless of this question, the max. discharge during the daily commuting is four or five times higher. Additionally, the surrounding conditions on the road are much tougher as in my living room. This brings me to the conclusion, the active use of the battery causes stress, not the smooth charging.

3rd The strongest argument is the economical. Stromer grants one of the best (or the very best?) warranty on the battery of the whole electric bicycle industry. They recommend to charge as often as possible and to charge always upon full capacity. Would they ever do this, if the 100% charging of the ST2 battery would damage the battery?

 

[smitty]

All very interesting...it is the weakest link in the chain so to speak in regard to e-bikes, but I'm thinking that improvements cannot be that far away. In the meantime, while the Stromer battery is pretty heavy, it is really powerful, I'll take it for the job it does!

 

[Polycarp]

Yes, of course.

For me, 80% charging is not an improvement of battery lifetime but will result in a lack of performance of the bike. What's about a silent office/living room charger or a lightweight travel charger? How would a State-Of-Charge indicator on the charger be rated?

Hi bluecat,

I fully agree on those improvements: smaller form factor, and lighter is always better, and definitely silent/fanless. Also, perhaps a digital indicator of % charged or other metrics.

 

[Polycarp]

My sole advice is: Charge only at room temperature.

A timer is enough patient to wait until the battery is cooled down from sunshine or warmed up from the icy winter. In fact, the charger works with full load up to approx. 80%, then he reduces the current until the battery is fully charged. During this final phase, the fan is usually inactive. With other words: If you prefer the partially charged battery, program the timer as necessary.

You're right, we have broad and high skilld discussions at stromerforum.ch about the battery. I can't do proper translation of all the outcome. But I'll tell you a different aspect: "Battery - 75% of capacity within 2 years" This might be the best warranty in the whole electric bike industry! They would never grant such thing, if a degraded battery would be more than a rare exception. The daily riding causes much higher demands on the battery as the charging ever could do.

Thanks for the explanation of why you use the timer. That's a good idea. I find that usually after my rides, I just bring it inside, and then it's a few hours before I go to bed, and I go plug it in to charge right then - it's reached a better temp. Perhaps that's a Stromer charger improvement opportunity - one that detects if the battery temp is outside the recommended ranges and delays to start charging until proper temperature is achieved, or allows for the owner to manually override.

Good point about the Stromer warranty. Again, it's why I had asked (in another thread) about using any potential approaches or technologies which may void that warranty! I see that it is safest and wisest just to use only Stromer charger!

 

[Ravi Kempaiah]

Hi Ravi, I've no doubt you did proper scientific research and the outcome was robust. My concerns are around the question: Can results (from any lab test) be transferred on the ST2 battery? I see three aspects:

1st: I'm suffering on a lack of information. The 18650 cell size is clearly identified. But how are they used? Tech guys from Stromer told me, the depth of discharge is the major battery killer. Therefore, Stromer set the 0% value above of the value which the cell manufacturer gives as standard endpoint of discharge. On the other end, I don't know, if 100% are the max. value which the tech specs of the cell allow - or is 100% somewhat below this value? I see figures from 0 to 100 on the ST2 display, but how are the values behind? I agree, they must be 2900mA cells, but what current can they handle? Will cells with low Amperage have different aging for such with high current?

2nd: I've overviewed several battery-related articles. All together, I've got the impression, the advice were a legacy of the experiences with batteries from RC toys. Typically, the charges for such batteries are unmanaged. This means, the full charging current is active all the time - until the user disconnects the battery pack. Once again, I miss several informations: The charging characteristic remain unknown; was the current reduced for the final 20% of capacity? What current was used - the max. allowed or a reduced one? How was the discharge managed? In terms of the ST2, the max. output of the charge is 4.5A / 54.6V. But are 4.5A really in use? Regardless of this question, the max. discharge during the daily commuting is four or five times higher. Additionally, the surrounding conditions on the road are much tougher as in my living room. This brings me to the conclusion, the active use of the battery causes stress, not the smooth charging.

3rd The strongest argument is the economical. Stromer grants one of the best (or the very best?) warranty on the battery of the whole electric bicycle industry. They recommend to charge as often as possible and to charge always upon full capacity. Would they ever do this, if the 100% charging of the ST2 battery would damage the battery?

@bluecat

1. Re:

   Tech guys from Stromer told me, the depth of discharge is the major battery killer. Therefore, Stromer set the 0% value above of the value which the cell manufacturer gives as standard endpoint of discharge. On the other end, I don't know, if 100% are the max. value which the tech specs of the cell allow - or is 100% somewhat below this value?

   
   Most battery manufacturers do this by default. Bosch, Yamaha, BMZ etc have built-in LVC (low voltage cutoff) and HVC. They may tweak it a little bit but more or less, most battery packs come with this. If Stromer claims 814Whr pack and limits the LVC and HVC significantly, then it would reduce the total energy density to < 750Whr.
   
   

2. The charging characteristic remain unknown; was the current reduced for the final 20% of capacity? What current was used - the max. allowed or a reduced one? How was the discharge managed? In terms of the ST2, the max. output of the charge is 4.5A / 54.6V. But are 4.5A really in use?

   
   That's right. The last 10-20% charging on most battery packs are slower. Even on the ST2, the first 80% happens (Orange light) via critical current (CA) and then switches over to critical voltage (blinking green). I have also noticed on my Haibike that the last 20% is slow (trickle charge). So, the charger doesn't pump in 4.5A always.

Most eBike battery manufacturers are aware of this and BMS does handle it well. But none of them have employed capabilities where you can control the charge rate (1A vs 5A) or limit the SOC. I guess they all want their customers to have the best range possible at the expense few cycles less. That's ok. But, if you get a 984Whr pack and then use only 800 whr or so with SOC limited to 4.05V/cell, one wouldn't have replace the battery for at least 3-4 years, even with heavy use.

The strongest argument is the economical. Stromer grants one of the best (or the very best?)

I am not sure if Stromer has the best warranty. But recently, BMZ (supplier of battery for Brose systems and many other brands) announced 4-year warranty for their batteries, which is great.



My point is, none of the eBike companies have taken steps to implement such smart charging methods. May be they think it's a very small difference and the technology would have changed so much in 3 years and they want their customers to get the maximum out of their ebike batteries.

 

[Nebster]

Or, maybe, they're not particularly well-incentivized to optimize for battery lifetime.

 

[bluecat]

My point is, none of the eBike companies have taken steps to implement such smart charging methods. May be they think it's a very small difference and the technology would have changed so much in 3 years and they want their customers to get the maximum out of their ebike batteries.

Ok, I see.

As stated in the beginning, my doubts are if an isolated cell test could be transferred onto the daily life of the ST2 battery . Let's do the following: Take a half dozen ST2 batteries. Place them in a climate chamber where summer sun and winter snowfall is simulated. Connect them to a strong discharging device and alternatively to the ST2 charger. Run a simulated commuter ride with all elements (from regen to full load) using 60% of the capacity. Do this 400 times. Three batteries will always be fully charged, so the cycle is 100% - 40% - 100%. The other 3 batteries will always be 80% charged, so the cycle is 80% - 20% - 80%.

What's the outcome?

Regarding the value of the BMZ warreny:

They pack cells to make batteries, BMZ is not a cell manufacturer. I could not find any information regarding the capacity which must be claimed by the warranty. Without a guaranteed value of remaining capacity, the whole warranty is useless (because a battery is a consumable, degrading is part of its nature). Rotwild (Brose eMTB) grants 70% after two years. This is not so far from Stromer, but the calculate with much less stress for the battery as the eMTB is used for leisure only (on a few sunny weekends). A strong competitor (in the field of commuter eBikes) grants 60% after two years.

BMZ also announce the new, bigger 21700 cell. They claim 12 years lifetime for this cell. But obviously, they are seeking for investors. That's why such announcements are made. Nevertheless, the 21700 cell will come. But probably not in eBike batteries. The big size will limit the possible arrays. The dead volume will be to big.

 

[Ravi Kempaiah]

Ok, I see.

As stated in the beginning, my doubts are if an isolated cell test could be transferred onto the daily life of the ST2 battery . Let's do the following: Take a half dozen ST2 batteries. Place them in a climate chamber where summer sun and winter snowfall is simulated. Connect them to a strong discharging device and alternatively to the ST2 charger. Run a simulated commuter ride with all elements (from regen to full load) using 60% of the capacity. Do this 400 times. Three batteries will always be fully charged, so the cycle is 100% - 40% - 100%. The other 3 batteries will always be 80% charged, so the cycle is 80% - 20% - 80%.

What's the outcome?

Regarding the value of the BMZ warreny:

They pack cells to make batteries, BMZ is not a cell manufacturer. I could not find any information regarding the capacity which must be claimed by the warranty. Without a guaranteed value of remaining capacity, the whole warranty is useless (because a battery is a consumable, degrading is part of its nature). Rotwild (Brose eMTB) grants 70% after two years. This is not so far from Stromer, but the calculate with much less stress for the battery as the eMTB is used for leisure only (on a few sunny weekends). A strong competitor (in the field of commuter eBikes) grants 60% after two years.

BMZ also announce the new, bigger 20700 cell. They claim 12 years lifetime for this cell. But obviously, they are seeking for investors. That's why such announcements are made. Nevertheless, the 21700 cell will come. But probably not in eBike batteries. The big size will limit the possible arrays. The dead volume will be to big.

The residual capacity for warranty claim is 60% after 4 years.



20700 cells are already in production and it was showcased in the last year's Eurobike. There has been a lot of news about spec'ing 20700 cells because the internal resistance of this battery is much less than the 18650 cells.

http://www.bike-eu.com/home/nieuws/...ry-innovations-presented-at-eurobike-10127504

 

[Jed Charlesworth]

21700 Game Changer !!!!!

25 months 10000 miles on way home tonight.
I have my 10,000 mile service at The New Wheel on Friday.

 

[Polycarp]

Part 2 with some more slides about the OMNI system and what I would like to see in the version 2 of Stromer ST2.

Chime in below with what you would like to see in the second version of ST2.

Continuing the train of thought about what we'd like to see in the second version of ST2...

1. Development and promotion of the Stromer platform beyond that of transportation, but now onto fitness and health. I believe there are already some manufacturers doing this kind of thing, and I like the idea. Integrate fitness tracking/metrics with OMNI system so that riders can use the system to program "workouts". Monitor heart-rate, and increase or decrease assist levels accordingly, in intervals, etc.. much like cardio machines in the gym. I'm sure there are other great ideas out there, but my point is - let's also see OMNI unlock the potential of expanding on the potential health benefits that intelligent bikes can bring. Especially considering so many (uninformed) people have the perception that eBikes are for lazy people who don't want to exercise. ;-)

2. Give me more access to my own data. With the data we already can see in OMNI (trip, duration, avg speed, etc), I'd like to see access to that data for the owner. Example: Why don't I have a Stromer website to log into which (at least) has the same capabilities of the Stromer OMNI app on my phone? Or, use such a web-based platform for more advanced features such as to update information about my profile, or to see my ride history, or to build a community network of Stromer owners (this Forum proves that many riders are passionate about sharing their Stromer-lives). Frankly, as I was pondering this yesterday, I wondered if I should read the Data Privacy terms and conditions from Stromer? I mean, look, they know everywhere I have ridden since I bought the bike, how much, how fast, how long, etc. As a consumer, do I have the right to delete that data, or insist that it not be stored by Stromer? Anyway, I digress... that was only a thought - not my actual point. My point is, there's a lot of data about how I'm using my bike that is that Stromer can capture "in their cloud". Give the access to the consumer and also open some API's so some creative app developers may create some new applications or integrations which expand the experience, capability and opportunities of the OMNI platform. For example, perhaps an application that pulls Stromer cloud data from my account and integrates it with the Apple Health app, or Fitbit or other popular fitness trackers. I don't know - I'm not the creative type - but I observe that with more data being made accessible, more opportunities for someone who is creative to use that data in creative and beneficial (or simply convenient or cool) new ways. If nothing else, I'd like to possibly have the opportunity to know about my data privacy and have control over that data (such as not retaining ride data for more than x-number of days, or not retaining it at all, or turning off tracking all together).

3. Audible alarm. I like the idea of the theft detection system when the bike has been locked. And yes, it makes sense that a thief would look pretty funny walking down the street carrying a heavy bike with the lights flashing. But what about also putting internal to the bike frame an annoyingly loud, piercing, electric siren or some sort of noticeable audible alarm? Sure, accidentally setting it off would be a little more traumatic for me, so maybe put in a delay before triggering the audible. My point is, it seems that it would be a reasonable addition with a tangible (and marketable) benefit.

Happy riding everyone!

 

[opimax]

Interesting , your avg speed is 35 while mine is 4.7, your hours are 282:23 are my hours 89:31, my mileage is 11,097

I would note that I have had 2 Omni replacements, 1 controller replacement and 1 motor replacement. I believe this info comes from the Omni so the 2 replacements may have made a difference but I can't understand your 35mph avg

I think a high end bike that provides this info should be the correct info or is is useless. upgrade this part please..and I would like to be able to do some resets on everything but total mileage.

Did you do this with one battery , I have 2 currently

 

[George Jetson]

Hello Ravi, thanks for your response!

Glad to hear that the motors very similar, with the removal of the controller the bike is much more balanced, and the heat dissipation is greatly improved from the ST1 (I also have an St1 elite). I purchased the ST1x with the 814wh battery, and will be installing a Supernova fixture if it's compatible.

You are researching a great field of study, and at a very good time in history. I also have an EV, and I closely watch the changing technology. I'd love to hear your thoughts regarding battery tech! Maybe that's for another discussion, but the recent articles from Dr Goodenough's work on solid-state glass electrolyte battery could be the next evolution of energy storage. I hope it is, and it would trickle down to eBikes as well.

You might be interestedin this thread that I started... https://teslamotorsclub.com/tmc/posts/2105598/

 

[Jed Charlesworth]

My mileage is correct I do get crazy WH numbers and the speed number is also off.
I started using Strava when bike was 4or 5 months old have 7810 miles their. I use to leave bike locked in garage in lock mode caused a lot of crazy numbers.
Jed

 

[Jan]

Part 2 with some more slides about the OMNI system and what I would like to see in the version 2 of Stromer ST2.

Chime in below with what you would like to see in the second version of ST2.

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Most informative post ever. . . . I hope you do this when you get your ST5

 

[Ravi Kempaiah]

Most informative post ever. . . . I hope you do this when you get your ST5

Thank you @Jan Doc . Hope you are enjoying your ST2-S