Methodology proposal to establish the assistance levels in an E Bike

[AntonioAlfaro]

As I mentioned earlier, my first experience with an ebike was with an Orbea Gain D50 with a rear hub motor, based on the Mahle X35 system with a 250WH battery and a 40NM motor. The total weight of the Orbea is around 13.1 Kg. Rear hub motor ebikes have some particular characteristics that make the riding experience somewhat unnatural. Nevertheless, they are an excellent option, and I have no complaints about it.

Motivated by curiosity to experiment with a mid-drive ebike, I acquired the Domane + SLR 6, which is equipped with a 360WH battery and a 50NM motor. The total weight of the Domane+ is around 13Kg. Based on the data records for each ride I have made on the same route with both ebikes, and trying to maintain the same travel times with both ebikes, I want to show some qualitative results of energy consumption (WH) and efficiency of one system over the other. Please see attached graphs. On average, for that sample of 10 routes (500KM), the Domane+SLR 6 turns out to be 8.14% more energy-efficient compared to the ORBEA Gain D50. This quantitative result is valuable to me from the perspective of future route planning with the Domane+.

In addition to the quantitative data, there is a very different riding experience on the Domane+ compared to the ORBEA Gain, and this experience is a very pleasant and natural feeling when traveling with the Domane+. Although both ebikes have the same levels of assistance programmed, the intrinsic characteristics of each system influence and require a different pedaling style from the cyclist. Let's see why,

Rear Hub System:

1) Independent of cadence

2) Assistance power goes directly to the wheel

3) Independent of gear ratio

4) Linked to cyclist's speed

5) Not suitable for steep inclines.

Mid-Drive System:

1) Linked to cadence

2) Independent of cyclist's speed

 

[rdv]

Antonio, thanks for expanding the Domane+ SLR knowledge base.

Post #41provides reassurance that the TQ motor and overall system are efficiently tuned. The overriding point I get from your post #40 is that battery charge consumption might go a bit under-reported early on, it ends up on the mark. It adds to my confidence in the 'battery remaining' feedback that I rely on.

I've taken a slightly different approach to monitoring battery consumption (no extender): I have summarized key factors (length, ascent, max grade,% consumption [by assist level]) for my August rides and have a pretty good idea of what to expect on similar future rides. Most of my riding falls within a comfortable zone of about 50-60% consumption at ~1.4~1.6% per mile. I'll keep tracking to deal with possible aberrations and outliers.

I have also started recording charge times (with a countdown timer) to better predict how to go from X% to Y%. Would like to target X>20%, Y~80% to extend the battery's life, but charge to 90 or 100% for longer or unknown rides.

I'd liked to use Average Ascent Grade as a telling metric, but don't know how to strip away the descending and flat mileage that render the overall average grade rather pointless in assessing relative steepness. Anybody know of a practical means to determine an average grade that includes only uphill segments?

 

[AntonioAlfaro]

Hello Rob, I'm glad to hear that you started to enjoy the Domane+ SLR. Collecting data from our rides is crucial to understanding the Domane+/HQ50 system. This knowledge will enable us to use the battery efficiently, resulting in longer and more challenging trips.
I like the approach you're developing!.
I wanted to mention that the GXP files exported by the TREK app contain some valuable but incomplete information since the app only records about an hour of the ride. From that GPX file, you can perform analyses and draw interesting conclusions because, in addition to geolocation data, TREK includes fields such as motor power, cyclist power, slope, velocity, cadence, assistance mode, altitude, and time. You can convert it from GPX to Excel and then perform your calculations from there.
I think achieving what you're looking can be done easily (I believe). I'd like to know a bit more about the details and the input data you have.
Feel free to reach out to me. Regards.

 

[rdv]

I get more feedback than I need from the Karoo2 through the PC based Hammerhead dashboard, including battery % charge at start, end, and amount consumed at each level (except that it thinks E is lvl2, M lvl 4 and H lvl 7). I don't rely on max grade: stepping the bike over a curb throws it way off.
If you are inclined, check it out if you haven't yet, and let me know how it compares with the Trek GPX file.
I use RWGPS to dive in on specific segments on occasion.

 

[AntonioAlfaro]

I've taken a slightly different approach to monitoring battery consumption (no extender): I have summarized key factors (length, ascent, max grade,% consumption [by assist level]) for my August rides and have a pretty good idea of what to expect on similar future rides. Most of my riding falls within a comfortable zone of about 50-60% consumption at ~1.4~1.6% per mile. I'll keep tracking to deal with possible aberrations and outliers.

Hello Rob, I hope you've made progress with your battery consumption estimation model. Please, tell us about it. I'm a data addict, and I have detailed records of all the trips I've taken since I bought the Domane+SLR2023. The file generated by the TREK app has a lot to analyze. I've developed Python code to simulate different approaches to estimate consumption, but to be honest, I'm still not satisfied. The consumption estimation model that comes closest to reality is based solely on ascent. My input to the program is meters of ascent, and the program returns the estimated battery consumption percentage (see screen image attached). However, it still has some considerations to keep in mind, so I'm still wracking my brain on how to improve it. I'd like to have everything, or almost everything, perfect to share it on this forum. I don't know when that will be.

 

[rdv]

I've tracked battery usage through September and the patterns are holding. Most of my rides fall into a1.2 to 1.6 ( % depletion / mileage) range so that 80% consumption will allow me to go 50-60 miles along local topography, which encompasses nearly all of my rides. Put simply, I don't have to think about it much unless it's a new ride in new territory.


On occasion I'll do a short hillier ride, which result in outliers. An interesting phenomenon is the impact of grade. A short recent 27 mile ride on a typical course with1750' of ascent ended with a short steep climb of 14% which pushed the consumption rate to 1.7. However, an older 25 mile ride, with 1720' of ascent yielded a 2.2 rate of consumption. The difference is that the earlier ride included not only the same 14% climb, but a short one of 21% and a couple more at ~10%. My hypothesis is that the steeper grades require the motor to do more work (duh!), but that nothing is gained back on the subsequent downhill, whether descending at 5% or 15%. More work uphill, no difference downhill for the motor.

A similar circumstance pertains to speed. I ride with two groups that move at different speeds. The slower can sustain bursts of 16-18 mph, while the faster can sustain bursts of 20-24 mph. The higher speed draws down the battery noticeably faster in covering the same distance.


I've also kept track of the charging. I keep the max charge below 100% to preserve battery life, so it's topped off at 80-85% if the next ride is ~45miles, 90-95% if 50~60 miles. Up to 90% charged the rate of charging is steady and predictable at 1% per 1.2 minutes, so if I want to charge from 25% to 85% simply set a countdown timer at (85-25=60 > 60x1.2=72mins=1hr12mins).

Regards, Rob.

PS: The missing metric.
There's one piece of data that I wish I could tap into, which could provide an informative correlation to battery consumption: average incline (or climbing, ascent, uphill...) grade. Not the useless average grade of total ascent / total distance. Rather the sum of the vertical gain on all segments at > 0% divided by the sum of the corresponding segment lengths. Is there any app out there that does that?

 

[AntonioAlfaro]

For those who like real data, I conducted a test on the Domane+ SLR 2023 until the battery was completely depleted. Two purposes; 1) To determine at what battery percentage the assistance disconnects, 2) To determine the total battery capacity in Wh. During the test, I thought I would be notified in some way when the battery reached 15% remaining, but that didn't happen. The system continued to work normally regardless of the level of assistance used, and I reached 5% remaining without any issues. However, just as I passed to 4% remaining battery, the assistance cut off. The e-bike started to function like a regular bicycle. The display showed 0% battery. This is an important piece of information to consider when planning a new ride and wanting to avoid surprises. So, remember the magic number: 5%. Back at home, I started charging the battery until it was back to 100%, and the energy required for that was 335 Wh. This data is equally important in planning new routes, as it represents the actual maximum available capacity (not 360Wh as we might be tempted to think). I hope this modest measurement is useful to you. Regards.

 

[AntonioAlfaro]

I must say that before conducting this test, I was searching for information on the web, and the only thing I managed to find was an FAQ document from Trek, which is on the Domane+SLR 2023 page in the Service section. In that document, there is a very interesting answer that says: "
Are there any other special instructions for the battery?
Please note that the battery will only last to about 15% capacity the first time it is depleted. So
don’t be alarmed if the range on your first ride is a little shorter than expected. After the first
full depletion and subsequent charging, the battery management system will “learn” what it
needs to know and will deplete all the way to 0% on future rides.
Also note that any time the battery reaches less than 10% charge, the motor output will be
reduced to 110 watts. The battery level indicator will flash to indicate Low Battery mode.
".
It seems that in the first deep discharge, the system cuts off before reaching 0%, but in subsequent deep discharges, the system reaches 0%. This aligns with what you report having observed.

 

[AntonioAlfaro]

Full Discharge, Second Test: As you may recall, the purpose of the first discharge test was to verify the discharge percentage at which the TQ system would cut off during the first deep discharge. The cutoff was confirmed at 5%. Today, in the second deep discharge test, we aim to determine the percentage of discharge at which the system cuts off (TQ says ....the battery management system will “learn” what it needs to know and will deplete all the way to 0% on future rides). This second test confirms that the system cuts off when reaching 0% discharge, thus aligning with the manufacturer's specifications. With this verified data, you can now plan your journeys with accurate final values. Regards.

 

[AntonioAlfaro]

As a continuation of my methodology proposal to establish assistance levels on the Domane+ SLR 2023, today I want to share with you some results of information analysis that I have conducted to validate the theoretical values obtained with the methodology. Please see attached doc.

 

[jlubeck]

I have plans to pick up a Domane 6 + on Thursdays and still have some reservations about motor assist and battery capacity (range).
I am coming from a Creo where I rode with ECO (15/30) or motor off on flats or small climbs and SPORT (30/60) on steeper climbs or playing catchup with faster riders. If I rode at the lowest setting I can achieve 250 miles on a complete charge at ECO setting and 75 miles at SPORT. Also I found that power output numbers (rider only) were a little inflated (5-10%) but consistent.
I have ridden the same floor model Domane on 3 occasions. I have tried to simulate the settings. As the Creo uses a 0-100% assist scale and the Domane uses 25-200%, I doubled the assist level but kept the maximal output the same. ECO is set to 30/72W and SPORT to 60/145W on the Domane. And as others have noted, the power output numbers on the Trek are deflated. I have been riding with power meters for almost 10 years and it underestimates power by at least 25%. So, does the TQ motor use that corrupted power input number to calculate its own output or is there another internal mechanism that is not broadcast?
I did a test ride with the Domane. At the ECO setting I could achieve 150 miles on a charge which is more than adequate and a similar 75 miles on SPORT. At the last ride, I rode about 40% on ECO, 50% on SPORT and maybe 10% with no assist. I recorded the ride on the Trek app with final numbers of 57.3W (me) and 27.6W for the motor. Again, I know that I outputted over 100 watts for the ride. So is the 27.6W output for the motor accurate or similarly deflated? My concern is that if I have to turn the Domane up even higher to equate with the Creo, range will drop even further. I do not want a range extender and never approached the need to use one with the Creo.
On another test, I rode several hilly segments hard and compared them on ECO and SPORT, Domane + vs Creo.
On both the tested ECO assist and SPORT assist segments, times were about 1 seconds faster for the Creo (about 1:50) suggesting that assist levels are close.

 

[AntonioAlfaro]

I have plans to pick up a Domane 6 + on Thursdays and still have some reservations about motor assist and battery capacity (range).
I am coming from a Creo where I rode with ECO (15/30) or motor off on flats or small climbs and SPORT (30/60) on steeper climbs or playing catchup with faster riders. If I rode at the lowest setting I can achieve 250 miles on a complete charge at ECO setting and 75 miles at SPORT. Also I found that power output numbers (rider only) were a little inflated (5-10%) but consistent.
I have ridden the same floor model Domane on 3 occasions. I have tried to simulate the settings. As the Creo uses a 0-100% assist scale and the Domane uses 25-200%, I doubled the assist level but kept the maximal output the same. ECO is set to 30/72W and SPORT to 60/145W on the Domane. And as others have noted, the power output numbers on the Trek are deflated. I have been riding with power meters for almost 10 years and it underestimates power by at least 25%. So, does the TQ motor use that corrupted power input number to calculate its own output or is there another internal mechanism that is not broadcast?
I did a test ride with the Domane. At the ECO setting I could achieve 150 miles on a charge which is more than adequate and a similar 75 miles on SPORT. At the last ride, I rode about 40% on ECO, 50% on SPORT and maybe 10% with no assist. I recorded the ride on the Trek app with final numbers of 57.3W (me) and 27.6W for the motor. Again, I know that I outputted over 100 watts for the ride. So is the 27.6W output for the motor accurate or similarly deflated? My concern is that if I have to turn the Domane up even higher to equate with the Creo, range will drop even further. I do not want a range extender and never approached the need to use one with the Creo.
On another test, I rode several hilly segments hard and compared them on ECO and SPORT, Domane + vs Creo.
On both the tested ECO assist and SPORT assist segments, times were about 1 seconds faster for the Creo (about 1:50) suggesting that assist levels are close.

Hello jlubeck, thank you for sharing your concerns on this forum. I see that overall you are satisfied with the test rides you have done with the Domane+ SRL. Let me express some conclusions and personal perspectives that I have reached through the use of my ebike.

• When the thought of purchasing an eBike, especially a road eBike, crosses our minds, it's essential to have a clear understanding of why we are doing it. What is it that we are truly seeking or expecting to gain from the eBike? The answer to that question forms the fundamental basis.
• I agree with many leading manufacturers that, by definition, a "Road eBike" should be as light as possible. This automatically leads to a main battery of low capacity and a very lightweight and compact propulsion system. The true assisted bicycle is the Road eBike since the majority of the energy needed to cover a specific route will always come from the cyclist, and the minimal assistance, if needed, will come from the battery.
• But what happens if our goal is for the majority of the energy to be provided by the battery, with us contributing very little? The answer is that we won't be able to undertake long rides, especially if they are challenging. Disappointments and regrets about the significant amount of money spent on the Road eBike will likely arise.
• In my personal opinion, someone who acquires a Road eBike is an individual who has been cycling for years, maintaining a fitness level beyond the norm that has allowed them to undertake long and demanding rides on a regular road bike. Today, this person uses a Road eBike to supplement that slight energy deficit in very specific and short-duration situations. Typically, this experienced cyclist transitioning to a Road eBike does so due to reasons such as age, recovery from surgery or illness, the desire to do the same activities a bit faster, or to embark on rides that, despite their excellent physical condition, were once off-limits.
• Therefore, with this understanding and if it applies to our situation, we will seek in the market the lightest possible Road eBike. We will remove from our minds large battery capacities and high motor powers. Our goal is different. Our focus will be on how to tackle challenging routes, making intelligent use of the small and lightweight assistance resources available.
• If, for whatever reason, we are not willing to contribute the majority of the necessary energy for the rides, I believe a Road eBike is not the right choice for you. The market offers other solutions that will provide satisfaction.

These thoughts are very personal and are not directed at you; I express them to the entire community. Finally, I want to state that from the performance perspective of the Domane+ SLR 2023, I have no complaints or disappointments. Once the assistance level settings were achieved, I have completed more than 40 rides of varying distances and altimetry conditions without any issues (see attachment). It is a very lightweight and fast machine, as is required for a Road eBike.

 

[jlubeck]

Hello jlubeck, thank you for sharing your concerns on this forum. I see that overall you are satisfied with the test rides you have done with the Domane+ SRL. Let me express some conclusions and personal perspectives that I have reached through the use of my ebike.

• When the thought of purchasing an eBike, especially a road eBike, crosses our minds, it's essential to have a clear understanding of why we are doing it. What is it that we are truly seeking or expecting to gain from the eBike? The answer to that question forms the fundamental basis.
• I agree with many leading manufacturers that, by definition, a "Road eBike" should be as light as possible. This automatically leads to a main battery of low capacity and a very lightweight and compact propulsion system. The true assisted bicycle is the Road eBike since the majority of the energy needed to cover a specific route will always come from the cyclist, and the minimal assistance, if needed, will come from the battery.
• But what happens if our goal is for the majority of the energy to be provided by the battery, with us contributing very little? The answer is that we won't be able to undertake long rides, especially if they are challenging. Disappointments and regrets about the significant amount of money spent on the Road eBike will likely arise.
• In my personal opinion, someone who acquires a Road eBike is an individual who has been cycling for years, maintaining a fitness level beyond the norm that has allowed them to undertake long and demanding rides on a regular road bike. Today, this person uses a Road eBike to supplement that slight energy deficit in very specific and short-duration situations. Typically, this experienced cyclist transitioning to a Road eBike does so due to reasons such as age, recovery from surgery or illness, the desire to do the same activities a bit faster, or to embark on rides that, despite their excellent physical condition, were once off-limits.
• Therefore, with this understanding and if it applies to our situation, we will seek in the market the lightest possible Road eBike. We will remove from our minds large battery capacities and high motor powers. Our goal is different. Our focus will be on how to tackle challenging routes, making intelligent use of the small and lightweight assistance resources available.
• If, for whatever reason, we are not willing to contribute the majority of the necessary energy for the rides, I believe a Road eBike is not the right choice for you. The market offers other solutions that will provide satisfaction.

These thoughts are very personal and are not directed at you; I express them to the entire community. Finally, I want to state that from the performance perspective of the Domane+ SLR 2023, I have no complaints or disappointments. Once the assistance level settings were achieved, I have completed more than 40 rides of varying distances and altimetry conditions without any issues (see attachment). It is a very lightweight and fast machine, as is required for a Road eBike.

View attachment 168215

Thanks for your response and detail. My reasons for purchasing the bike are similar. I just want to extend my road riding as I age while not using much assist. My weekend rides may be slightly longer, occasionally > 100km and I may do 1 or 2 imperial centuries per year. May I ask what assist settings you typically use?

 

[AntonioAlfaro]

Thanks for your response and detail. My reasons for purchasing the bike are similar. I just want to extend my road riding as I age while not using much assist. My weekend rides may be slightly longer, occasionally > 100km and I may do 1 or 2 imperial centuries per year. May I ask what assist settings you typically use?

Let me say that my FTP is 160 W and my weight is 56Kg. , so my settings for assitance are :
ECO 75W max, 112% assist, 70% pedal response.
MID 105W max, 112% assist, 70% pedal response.
HIGH 138W max, 200% assist, 90% pedal response. ( Never used, never tested).

I invite you to take a look of my draft document for a methodology proposal to establish the assistance levels in an E Bike. It is located just at the beginning of this forum.