TSD2 range ?!

[Simon Knight]

Hi,
I have recently fitted a TSD2 to my recumbent trike and am presently trying to assess the range I can achieve. At the moment I have been using it in mostly Eco with occasional use of Tour, the lowest two assist modes. I have a large battery 15Ah at 48v, which I hoped would give me fifty plus miles but it appears to be giving quite a bit more.

So far I have ridden over sixty miles from a full charge and the battery indicators on both the battery and the display are both reading full. Is this typical and should I expect the battery to rapidly decline and or can the indicators be relied on to give an indication of battery status?

S

 

[Bonzo Banana]

That's a huge battery capacity of over 700Wh so very decent there and the Tongsheng isn't the most powerful mid-drive motor either and its power is controlled by the torque sensor so it only really pushes high amounts of power when you are going up steeper hills plus you have been using ECO so I think your range will be impressive to say the least.

It's quite common for the battery level indicator to give a false indication of remaining range though and give you too optimistic a viewpoint on remaining battery capacity. I think typically you would use from about 10Wh to 25 Wh per mile so that would give a range of about 30 miles to maybe 75 miles but there are so many variables on how you ride, your weight, how many hills etc. It could well be you could achieve over 100 miles range.

Some riders spend so much time above the assistance speed i.e. 16mph or more that they rarely use the motor at all and get ridiculous range out of a battery which they only really use for hills.

 

[Simon Knight]

That's a huge battery capacity of over 700Wh so very decent there and the Tongsheng isn't the most powerful mid-drive motor either and its power is controlled by the torque sensor so it only really pushes high amounts of power when you are going up steeper hills plus you have been using ECO so I think your range will be impressive to say the least.

<snip>

Some riders spend so much time above the assistance speed i.e. 16mph or more that they rarely use the motor at all and get ridiculous range out of a battery which they only really use for hills.

I went for the large battery because when compared to a bike my trike is quite heavy, however, on the plus side it is probably has less aerodynamic drag than most uprights (upwrongs!) . I have also found myself working quite hard to keep the speed above motor cut off because speeds of 16 and 17 mph are such a novelty.

I think I may be in the market for a device that measures the discharge of the battery in Watts, if such a device exists, to give a better indication of battery health.

 

[Nealh]

Range with the tsdz2 does appear to be very good , more so above the cut off. In my experience the sytem /motor rides nicely without power and unless one is going up hill the non assistance isn't noticable.

 

[Woosh]

So far I have ridden over sixty miles from a full charge and the battery indicators on both the battery and the display are both reading full. Is this typical and should I expect the battery to rapidly decline and or can the indicators be relied on to give an indication of battery status?

The battery indicator shows a voltage between 41V (completely empty) and 54V (completely full) in 5 bars, each roughly corresponds to 20% or 13V/5=2.6V.

You can see the voltage drops when climbing a steep hill, you lose a bar or two during the climb and recover after the climb, although the state of charge does not change much during the climb.

The amount of energy is higher for the first bar (54V-51.4V) than the last bar (43.6V-41V) because energy = voltage * current. On your 48V 15AH, the first bar (the rightmost bar) has roughly 54V *3AH = 162WH in energy, enough for about 20 miles, compared to the last bar (leftmost bar) 43.5V * 3AH = 130WH. So you can do more miles out of the first bars.
You will do a lot fewer miles if you ride on throttle. The average battery consumption on pedal assist torque sensing bike is around 8WH per mile, on throttle alone about 16WH per mile. Battery consumption is also less if you spin the cranks faster because the back EMF is higher, less current will flow through the coils.

 

[Bogmonster666]

I am not too surprised given my experience. My 480wh battery has lasted me over 50 miles and wasn't fully depleted. That is on a mountain bike in a hilly area and included a couple of ascents from Somerset levels to the Mendip plateau. I'm not much of a cyclist and was often on tour or speed and for the most part was not trying too hard. Also, my gearing needs adjusting. So yes, I can see that a larger capacity battery on flatter ground may well get 100 miles+

I believe the lion's share of my consumption was on the long uphill sections. Lower gearing will allow me to input a greater percentage of assistance and will help my range quite a bit, obviously with a bit of a speed penalty.

C

 

[Simon Knight]

Thanks for all your responses. I'm amazed at the potential range of my system. Before purchase I was worried about riding power off and what sort of extra range the system would allow me to achieve. Riding power off is not an issue and I usually start out without power just to decrease the time it takes to warm up. On my unassisted trike a longish ride would be twenty five to thirty five miles and I hoped I could achieve sixty miles assisted. Based on my first few rides it seems that I am going to go much further on a charge : I'll report my total miles per charge once I have completed a greater distance.

Also I have not noticed any roughness or jolts at the transition between assisted and unassisted that has been reported on some forums.

My only issue is some knee pain which I am attributing to pushing to hard when pulling away in a high gear; I really must learn to change down before coming to a stop.

 

[Woosh]

If you have knee pain, start off using the throttle then pedal.

 

[Simon Knight]

The battery indicator shows a voltage between 41V (completely empty) and 54V (completely full) in 5 bars, each roughly corresponds to 20% or 13V/5=2.6V.
<snip>
The amount of energy is higher for the first bar (54V-51.4V) than the last bar (43.6V-41V) because energy = voltage * current. On your 48V 15AH, the first bar (the rightmost bar) has roughly 54V *3AH = 162WH in energy, enough for about 20 miles, compared to the last bar (leftmost bar) 43.5V * 3AH = 130WH. So you can do more miles out of the first bars.

So to check my understanding using my 1970s school boy physics...
The battery state meter reads 2.6 volts per division in the range 41-54 volts. The 3AH figure is derived by dividing the total battery capacity by the five divisions of the meter 15/5. Plugging the numbers into a spreadsheet implies that the final low voltage zone will allow a range that is 20% lower than the range achieved in the five bars voltage range all other things being equal. Lastly it appears that I have used something like 2.6W/mile so far.

 

[Woosh]

Perhaps not that low 2.6wh per mile, but because you spin the cranks quite fast, battery consumption is lower than average. Next time you put the battery on charge, note the miles since last charge and the time from beginning to the led on the charger goes green. Knowing that the charger delivers 2A, you can work out how good your legs are.

 

[Bogmonster666]

I was quite pleased with my achievements until I went to my neighbours this afternoon. Another neighbour was there and she was a little disappointed with herself as she had cut short her somewhat hilly ride by 20 miles and had just managed a feeble 80 miles unassisted yesterday.

She is also quite an accomplished cave diver so fearless and fit

Ah well, I guess we are all somewhere on the spectrum of couch potato to super athlete.

C

 

[Woosh]

The idea of a very poorly lit cave, freezing water, completely disoriented, all your air in a bottle is just too frightening to contemplate.

 

[Bogmonster666]

The neighbour who's house I was visiting was also a cave diver. They are suffering somewhat poor health now after a triple heart bypass and complications. But he was a pioneer in the early days of cave diving when folks made their own kit. To be fair cave divers often still make to their own rebreathers. Imagine a DIY project to make something as complex as a computer controlled re-breather, image the disappointment of a null pointer exception or a bit of water ingress when you are a couple of hours from open airspace. Makes me feel less queasy about flashing an ebike motor

I like my diving and love my caving but have not felt the need to mix the two...

C

 

[Bikes4two]

Going back to range estimation:

• the LCD battery bar indicators on the VLCD5/VLCD6 are at best a guestimate.
• This is largely due to the voltage/discharge characteristics of Li-Ion batteries in that there is a very small difference in battery voltage between the 90% charged to 10% charged level (maybe around 0.8Vdc depending on the battery cell model).
• There are other methods of helping you to estimate battery range (note the word 'estimate') most of which require 'taping in' to the wiring from the battery/to the motor, i.e. some soldering and maybe changing connectors to something like XT60.
• The first is wiring in a coulomb meter (sometimes called a watt meter - see pic below) which you may or may not wish to mount on your handlebars or else where. This meter will count up the watt hours and amp hours as you cycle as well as showing you the battery voltge on an off load.
• If mounted so that you can view the meter as you cycle, you can then get an appreciation of the different amounts of current/power you're taking from the battery under different assist levels, speed etc.
• A more simpler way of estimating range is to monitor just the battery voltage (a much simpler meter with simpler wiring) as you travel but to understand how this reading might relate to power left in the battery, requires a bit of knowledge about your battery's discharge characteristics and what the battery LVC (Low Voltage Discharge) point is.
• A simpler method of using a Watt Meter is to measure the Wh/Ah used to re-charge the battery by inserting the meter between the charger and the battery. The power transfer from the charger to the battery is not 100% efficient - more likely something around 85%. Thus if on charging you measure 10Ah then the battery is likely to have only required 8.5Ah to get to full (meaning what every type of cycling you did from the last full charge used 8.5Ah)
• Alternatively and much simpler is to just keep cycling over time and get used to what your battery range is giving you. Initially when you think you might be getting towards 'empty', you could always find a local loop of a mile or so and keep pedalling until powered assistance drops of.
• I've done all of the above and I now know with reasonable accuracy what range I can get from my battery under different riding conditions.
• 
• Cost around £20 on ebay or half that from Ali Express

 

[Simon Knight]

The neighbour who's house I was visiting was also a cave diver. They are suffering somewhat poor health now after a triple heart bypass and complications. But he was a pioneer in the early days of cave diving when folks made their own kit. To be fair cave divers often still make to their own rebreathers. Imagine a DIY project to make something as complex as a computer controlled re-breather, image the disappointment of a null pointer exception or a bit of water ingress when you are a couple of hours from open airspace. Makes me feel less queasy about flashing an ebike motor

I like my diving and love my caving but have not felt the need to mix the two...

C

I went caving once as part of a training course I was on. At one point we had to fully submerge to wriggle under a rock wall between two chambers. Never did it again for reasons of cold, wet, dark, mud and the continuous risk of flash flooding from unexpected rainfall up on the moors. Mind you if it floats your boat..... Agree about the null pointer exception etc you really have to know the hardware you are using over and above writing bullet proof software.

she had cut short her somewhat hilly ride by 20 miles and had just managed a feeble 80 miles unassisted yesterday

It always seems to happen - you bag three Munros in a day and sit down in the pub next to a group who have bagged five. Your friend probably frets that she ought to be doing 400km audaxs https://forum.cyclinguk.org/viewtopic.php?t=134997

Personally having e-assist means that I am using my bikes and trike more frequently. I don't always use the power but its nice to know its available if needed. I'm looking at e-assist as a way of reducing my car usage and avoiding ever having to buy an electric powered car which in their present form are, in my opinion, rather hopeless.

best wishes
S

 

[Simon Knight]

• Alternatively and much simpler is to just keep cycling over time and get used to what your battery range is giving you. Initially when you think you might be getting towards 'empty', you could always find a local loop of a mile or so and keep pedalling until powered assistance drops of.

Thats where I have started but I was surprised how long the battery was lasting. This thread and others has reassured me that the battery is unlikely to suddenly drop from five bars to empty. I will probably use the battery down to 1 bar on the display before recharging.

Mind you I do like the idea of collecting extra data so a power meter like the one described above will be an interesting addition.

S

 

[Bogmonster666]

Personally having e-assist means that I am using my bikes and trike more frequently. I don't always use the power but its nice to know its available if needed. I'm looking at e-assist as a way of reducing my car usage

This is why I converted my bike. Tbh I don't really enjoy cycling that much, but I really don't enjoy driving so it's the lesser of two evils for me. I get plenty of exercise with other pursuits so I'm quite comfortable being an ebike user. I still get moderate exercise cycling and if I build up some more cycling stamina then that is a positive side effect.

 

[Bikes4two]

Mind you I do like the idea of collecting extra data so a power meter like the one described above will be an interesting addition.

• So if you do get a power meter, you can take it's use further by creating a dummy load to discharge a fully charged battery into.
• If you do this periodically then you'll gain an appreciation of battery performance over time as any battery only has a finite number of charge/discharge cycles.
• If you do go into making something like this, then care will be needed in making up the dummy load to ensure the load, e.g. power resistors, are correctly rated so that they don't burn out. I only run my discharge testing at 4 Amps and the load resistors (3 of them in parallel) are in and on a heat sink as they run very hot.
• Battery packs are often quoted as having 'x' cycles - this is only an estimate, albeit a good one, and cycles are generally counted until the power of the battery drops to 80% of it's new value.
• There are ways of extending the life/cycles of a battery but that's not for this post although if you are interested in such things, this article HERE from the Battery University website is informative.
• 

 

[Simon Knight]

#Bikes4Two - thanks for the diagram and links which I will file away for future reference. I would prefer not to have to fit a "Watt Meter" just to assess battery charge state. As it happens I remembered I have a similar meter that I purchased with the idea of fitting to a different bicycle. Mine claims to display the average watts since the last screen update which occurs once every 0.4 seconds. Given that, if I remember correctly, a watt is defined as 1 joule per second I wonder what it is displaying.

I completed another ride yesterday raising the milage on a single charge to seventy six miles. The battery level on the display has finally reduced by one segment i.e. five out of a total of six. However, the four LED display on the battery is showing two: one red and one green. I believe the battery display rather than the VLCD5 and interpret as my present battery capacity is somewhere between 25% and 50% capacity. If I call it a third charge then my max range is somewhere in the region of 110 miles of riding with low assist (eco/tour) on flat terrain. This matches what Bogmonster666 has experienced with his Tongsheng system.

I have ordered a waterproof volt meter which, once fitted, I hope will give me a better idea of battery state.

 

[Bogmonster666]

This has got me thinking about how to increase my range further. I think 3 simple steps to start with:

Lower geared cassette so I can contribute a higher percentage to the overall load on steep hills. It's not that the motor can't get me up the hills today, it is just working quite hard to do it.

Make myself a bit more aerodynamic to reduce the overall load and keep me above the cutoff for longer. I tend to cycle in baggy clothes with massive panniers and quite upright. I think slightly better fitting clothes (not full Spandex ), lose some of the bags when not needed and drop the handlebars an inch or so may have quite an impact. At 18mph I understand air drag is ~80% of the load. Given how windy it can be here, 50+ mph winds forecast later, then I think modest improvements in aerodynamics will have a big impact.

Keep cycling and get fitter. I am moderately fit for a 50+ but not cycling fit. The only way to fix that is to get cycling and the torque sensing motor allows me to do attempt reasonable distance, hilly rides whilst still getting a reasonable workout.

Ideally I'll reach a point where a bike with a small motor and battery, or no electric assistance at all will meet my needs. However, in the interim I'm very pleased with the tsdz2 and what it already allows me to achieve. And I suspect I will always want to retain a bit if a workhorse bike for this supermarket trips.

C