SL Range Extender 'Range' Considerations

[Stefan Mikes]

Disclaimer: Everybody is different. At exactly the same Assistance Level and Max Motor Power, the same SL e-bike model, the same riding conditions, a person with stronger legs is expected to get a shorter range but higher average speed than the weaker rider. All data here pertain to rides on the plains in early Spring condition, on closed loop routes and with acceptable wind. And, the most importantly, the data refer to my legs and riding style, Vado SL 4.0 EQ.

I'm going to continually update this table. Brand new SL Range Extenders, always ridden from 100 down to 5% of charge with no main battery use.

Assistance Level % (SL)	Max Motor Power % (SL)	Range [km]	Elevation Gain [m]	Battery Consumption [Wh/km]	Average speed [km/h]
100	100	18.5	46	8.46	23.4
80	80	23.6-25.5	164	6.65	19.5
70	70	28.5	70	5.34	20.2
55	55			3.75
35	100	42	115	3.69	19.1

Note: Below 20% charge, one can feel gradual reduction of assistance. In the range of 10...5% of the RE charge, the assistance becomes greatly reduced.

Feel free to provide your own data if you have recorded your ride data on Range Extender only.

 

[Elkman]

Air drag for the rider increases with the square of their speed so an average speed of 22 km/h takes 4 times as much energy from the rider and the motor as riding at 11 km/h. No way of knowing what the power efficiency profile is for the motor used and the motor can change year to year.

With my bike the battery drain rises disproportionately with a power setting great than 30. I now have Eco at 30% and Sport at 50% and 90% of the time I am in Eco mode. I use Sport only when there are strong winds to overcome and the pedal assist helps a great deal.

The motor draw from the RE is no different than it is from the internal battery.

 

[e-levity]

Here are some data from a couple of different rides on my Vado SL. Both used the Main Battery and Range Extender. The first is a long climb and descent using 30% Assist with Peak Power set to 100%. The second is a shorter, easy recovery ride with some hills using 50% Assist and 100% Peak Power. Both rides include 10-20% off-pavement sections that reduces efficiency somewhat. No excessive wind on either ride. Assistance Level % (SL) Max Motor Power % (SL) Range [km] Elevation Gain [m] Battery Consumption [Wh/km] Average speed [km/h] 30 100 90 1870 4.8 21 50 100 36 538 6.6 24

 

[Stefan Mikes]

The motor draw from the RE is no different than it is from the internal battery.

I do totally agree. Using the RE alone means it is easier to get consistent results for range test rides as the RE will get empty after relatively short ride distance.

Air drag for the rider increases with the square of their speed so an average speed of 22 km/h takes 4 times as much energy from the rider and the motor as riding at 11 km/h.

It is even the cube and the power demand is 8 times for your example. It is because the square relationship is only for the air drag but the cube function is for the power demand to overcome the air drag.

No way of knowing what the power efficiency profile is for the motor used and the motor can change year to year.

We need to trust Specialized the Max Motor Power (mechanical) of the SL 1.1 motor is 240 W, and we can read the electrical power delivered when the motor is maxed out. 240 W mechanical and 303 W electrical give the efficiency of 79%.

Here are some data from a couple of different rides on my Vado SL. Both used the Main Battery and Range Extender.

To understand fully: Is your range given for both batteries used together? If yes, let us only look at the Wh/km figure.

• It is very interesting to see how much the elevation gain affects the range
• You have been using the "flexible assistance" with the 100% Max Motor Power. I quess it is a major factor for limiting the range (nothing wrong, though).

See this comparison:

Rider	Assistance Level %	Max Motor Power %	Elevation gain	Average speed [km/h]	Battery Consumption [Wh/km]
e-levity	50	100	538	24	6.6
e-levity	30	100	1870	21	4.8
Stefan Mikes	55	55	244	20	3.75

It was @Nubnub to draw my attention to the fact the Max Motor Power is the primary factor affecting the range for SL e-bikes.

 

[e-levity]

Two factors contribute to “high” battery consumption in the rides I reported in Table 2 above:

1. Elevation gain. The rides I listed above have 15 and 21 m/k gain whereas the rides listed in the first Table by @Stefan Mikes have 2.5m/k gain. No distance is given in the third Table above, but the total elevation gain is only 244m.

2. Peak Power setting. This can have a large effect as mentioned by @Stefan Mikes and @Nubnub . It is especially true at lower Assist levels when the rider puts in a strong effort and as a result draws more motor power. Limiting the Peak Power to 55% in the third Table above prevents the motor from supplying more than 132W at any rider effort thereby contributing to less battery consumption.

I like to use 100% Peak Power at all Assist settings so motor assistance increases along with my input rather than leveling off at some preset level. Settings of 30%/100% given for ride 1 above work pretty well. I reach the 30% level at 144W (0.6x240W) which is a comfortable effort. Beyond that the motor continues to give me a 0.6X boost until I reach 400W input at which point both the motor and I are pretty much both maxxed out for any sustained effort.

In the second “recovery ride” the settings of 50% Assist and 100% Peak give max motor support of ~240W with 240W rider input (the response is linear up that point). This allows me to cruise along at a good clip with 100-200W input and to get the most out of the motor with a “strong effort” (for me at least!) that I can manage for a short time.

Wind, of course, always has to be considered, and rider weight is a big factor when climbs are involved.

 

[Dazmanturbo]

I managed 56 mile ride on just the extender on Eco the whole way. Was following some old railtrack that have been turned into paths, so nothing much over 2% gradient.

 

[kahn]

I managed 56 mile ride on just the extender on Eco the whole way. Was following some old railtrack that have been turned into paths, so nothing much over 2% gradient.

That sound like great mileage. I only managed 52 miles but with 3,000 feet of climbing on my Creo's main and RE!!!!

 

[Stefan Mikes]

It is an exhilarating experience...

...to own as many as three Range Extenders and using them exclusively for shorter rides (with the main battery kept in the reserve). It is like owning three water-bottles: One of them being "filled up" (charging), and the remaining two ready for the ride. Or, two empty bottles but you still have got one more to be just used! Given the long recharge time (3 hours and 20 minutes for a full recharge), I am always in a position whrn one, two, or three RE's are available for my rides!

The behaviour of "Discharge the Range Extender First" option is, however, unpredictable. Three days ago I left the main battery at 82% of charge. Now, it is the fourth day, and the main battery is at 69%. Does an SL e-bike occasionally draw power from the main battery? Or, it is internal discharge of the main battery there? I don't know!

It is interesting to see the range phenomena in this small 160 Wh model. I started my ride of yesterday against a pretty strong headwind. After 25 km ridden (of which 22 were upwind), 88% of the RE charge was consumed. The remaining 20 km of the ride (mostly downwind) consumed only 60% from the other RE, and I was riding very fast! It looks the tailwind is adding solid watts to your ride! (I only wonder how many watts).

 

[BEC111]

It is an exhilarating experience...

...to own as many as three Range Extenders and using them exclusively for shorter rides (with the main battery kept in the reserve). It is like owning three water-bottles: One of them being "filled up" (charging), and the remaining two ready for the ride. Or, two empty bottles but you still have got one more to be just used! Given the long recharge time (3 hours and 20 minutes for a full recharge), I am always in a position whrn one, two, or three RE's are available for my rides!

The behaviour of "Discharge the Range Extender First" option is, however, unpredictable. Three days ago I left the main battery at 82% of charge. Now, it is the fourth day, and the main battery is at 69%. Does an SL e-bike occasionally draw power from the main battery? Or, it is internal discharge of the main battery there? I don't know!

It is interesting to see the range phenomena in this small 160 Wh model. I started my ride of yesterday against a pretty strong headwind. After 25 km ridden (of which 22 were upwind), 88% of the RE charge was consumed. The remaining 20 km of the ride (mostly downwind) consumed only 60% from the other RE, and I was riding very fast! It looks the tailwind is adding solid watts to your ride! (I only wonder how many watts).

I stopped paying close attention to battery usage/power profiles over the winter. Mostly because everything felt and was less efficient than in warmer weather. And none of my winter rides would tax range limits. My long route has been 19 miles.

But! The wind! Here in Ashburn, VA a mildly windy spring day means 15 mph. I generally choose my direction based on wind direction. Start out into the wind so it’s helping on the ride back. I can’t be sure since I have no means of comparison, but it seems that the speed difference is greater than the same ride on a calm (winds less than 5 mph) day.

I don’t have the technical knowledge to explain the difference, but it is fun to be casually pedaling in an upright position at 20 MPH. Not even breathing hard. I can’t prove it, but it sure feels like I can go faster with the wind on a ebike than I could without pedal assist. And smile more, too.

 

[Dazmanturbo]

I did a ride last weekend of 60 mile just on Range Extender. This was in UK, where bike is limited to 15.5mph. Mine tend to cut power at 16.2mph and much of the ride I was above this and hence do draw. Still the ride had 2000ft of climbing on a single RE - I was really impressed. Temp wise was 10c

 

[Elkman]

It is being assumed that using the RE battery increases the life of the built-in battery and there is not information to support this. Leaving the main battery at full charge for months at a time may be harmful. Apple with its laptops and iPhones will disallow warranty coverage if the devices are left plugged into power and never discharged by their owners.

 

[Dazmanturbo]

I always try and put all my batteries through a good charge / discharge cycle to keep them tip top. I have 2 range extenders which I will plug in and drain if the main battery is below 50%

 

[Stefan Mikes]

It is being assumed that using the RE battery increases the life of the built-in battery and there is not information to support this. Leaving the main battery at full charge for months at a time may be harmful.

It is not harmful if you maintain the main battery charge at 80%.

 

[Stefan Mikes]

I have recently found that riding at 35/100% SL assistance gave the figure of 3.82 Wh/km, while 55/55% resulted in just 3.75. However, Vado SL kept at 35/100% assistance felt far more flexible as hard pedalling was instantly making the e-bike faster when necessary.

 

[Rider51]

It is not harmful if you maintain the main battery charge at 80%.

As an FYI, I had my Vado SL in a box for over three months while I moved/traveled. When I put it in the box it was at 100%. Three months after just sitting there, I was surprised to see it still had about 65% power remaining.

 

[Stefan Mikes]

I have spotted a strange behaviour when riding with the "Discharge the Range Extender first" option. Occasionally, Vado SL is making use of the main battery even if only the Range Extender should be used.

Yesterday's ride took 166 Wh from the batteries. It was 144 Wh from the Range Extender and 22 Wh from the main battery. Not complaining. I was just expecting the main battery would remain intact!

 

[e-levity]

You might check Mission Control mid ride and near the end to see when it’s drawing from both. it could be that when the RE gets low into the power saving mode the bike begins to draw from the main battery as well so you don’t lose power.

 

[Stefan Mikes]

You might check Mission Control mid ride and near the end to see when it’s drawing from both. it could be that when the RE gets low into the power saving mode the bike begins to draw from the main battery as well so you don’t lose power.

Er, no. It happened in the mid-ride, and the total power consumption for the whole trip only was 166 Wh. Because of the fact the e-bike drew some power from the main battery, I returned with 10% left in the RE. Generally, that part of the ride was done in 35/100 and 20/20% assistance levels. During the final Turbo ride, no energy was drawn from the main battery!

 

[Stefan Mikes]

The Latest Findings...

• The rider with average leg power of 80 W
• No wind
• Flat
• Asphalt only
• Warm weather
• The same Assistance % as Max Motor Power %

Below 50/50% assistance, the Range becomes very long. Linear decrease of Range with Assistance between 50-70%. The Range becomes very short between 80-100%.

Data table:

Assistance [%]	Consumption [Wh/km]	Consumption [Wh/mi]	Estimated range, new main battery [km]	Estimated range, new main battery [mi]	Estimated range, new Range Extender [km]	Estimated range, new Range Extender [mi]
44​	2.48​	3.99​	123​	76​	61​	38​
50​	4.2​	6.76​	72​	45​	36​	22​
60​	5.75​	9.25​	53​	33​	26​	16​
70​	7.09​	11.41​	43​	27​	21​	13​
78​	9.28​	14.93​	33​	20​	16​	10​
100​	9.87​	15.88​	31​	19​	15​	9.6​