High time ebike battery sellers were honest about battery AH capacity

[minexplorer]

Ebike batteries are expensive investments.With each additional AH costing a premium.I think its high time the sellers of them,stopped hiding behind the CELL manufacturers misleading stats.
This will come as no news to some ebikers.However if you ,like myself until recenly, are in the majority,its an eye opener.
Basically, the industry uses a 0.2 amp draw on a cell as a statement of its capacity. At the typical 3amp draw of an ebike motor (higher on higher watt motors) the capacity is considerably reduced.
For example,my 17.4ah battery. It contains 60 samsung 2900mah 29e cells in 6p confguration.60 x2900 = 17.4ah .BUT ONLY AT 0.2 amp.No ebike in existance has a 0.2amp draw.At 3amps its 2580mah x 60 = 15.5ah .This applies to all batteries,regardless of cells used.You can find your own batteries REAL capacity on DAMPFAKKAS site. Specialist manufacturers of ebike batteries are aware of this.But it looks good for them to state as high a capacity as legally they can. But its dishonest.
My point is. If the purpose the cell is to be put to. Is in the construction of an ebike battery. Then the producer /seller of that product should,by consumer law,be required to state its typical capacity for its designed use.
Im not saying it will make batteries cheaper.Im just asking for accuracy and transparency in a product.

 

[flecc]

Ebike batteries are expensive investments.With each additional AH costing a premium.I think its high time the sellers of them,stopped hiding behind the CELL manufacturers misleading stats.
This will come as no news to some ebikers.However if you ,like myself until recenly, are in the majority,its an eye opener.
Basically, the industry uses a 0.2 amp draw on a cell as a statement of its capacity. At the typical 3amp draw of an ebike motor (higher on higher watt motors) the capacity is considerably reduced.
For example,my 17.4ah battery. It contains 60 samsung 2900mah 29e cells in 6p confguration.60 x2900 = 17.4ah .BUT ONLY AT 0.2 amp.No ebike in existance has a 0.2amp draw.At 3amps its 2580mah x 60 = 15.5ah .This applies to all batteries,regardless of cells used.You can find your own batteries REAL capacity on DAMPFAKKAS site. Specialist manufacturers of ebike batteries are aware of this.But it looks good for them to state as high a capacity as legally they can. But its dishonest.
My point is. If the purpose the cell is to be put to. Is in the construction of an ebike battery. Then the producer /seller of that product should,by consumer law,be required to state its typical capacity for its designed use.
Im not saying it will make batteries cheaper.Im just asking for accuracy and transparency in a product.

Whilst I sympathise, it will never happen since the usage rate is under the user's control.

The situation is the same as that with quoted e-bike ranges.

And the same as that with car MPG figures.

The nearest to an absolute in all cases is the minimum possible consumption rate, so legislators are likely to accept that is reasonable.

E-bikes in particular are a special case, since a number of users only switch on power some of the time. I used to ride my Giant Lafree that way. That not only extends the range, it also rests the battery during switched off periods which can improve usable capacity.
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[minexplorer]

Whilst I sympathise, it will never happen since the usage rate is under the user's control.

The situation is the same as that with quoted e-bike ranges.

And the same as that with car MPG figures.

The nearest to an absolute in all cases is the minimum possible consumption rate, so legislators are likely to accept that is reasonable.

E-bikes in particular are a special case, since a number of users only switch on power some of the time. I used to ride my Giant Lafree that way. That not only extends the range, it also rests the battery during switched off periods which can improve usable capacity.
.

Headlamp run times an all eh,80 meters full power 70hrs.... oh no i mean 20 minutes.Yeah i know they never will.I just felt like putting it out there after researching why my actual range is always significanty short. ie,Working out my watt hrs.Then dividing with various opinions on Wh used per mile.

 

[flecc]

I just felt like putting it out there after researching why my actual range is always significanty short.

I know the feeling. An e-bike I bought back in 2006 nominally had a 10 Ah 36 volt battery. But when A to B magazine did some comparative capacity tests on the same model at various power usage levels, with using it to the full it actually only delivered 7.2 Ah. At the other extreme with a powerful rider and using the e-power minimally they did manage to just about get the 10 Ah.
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[Woosh]

For example,my 17.4ah battery. It contains 60 samsung 2900mah 29e cells in 6p confguration.60 x2900 = 17.4ah .BUT ONLY AT 0.2 amp.

are you sure of your source of information?

The datasheet for your cells is here:
https://www.nkon.nl/sk/k/29E.pdf

typical capacity: 2.850AH at 0.2C 2.5V discharge
that's 0.2 * 2.9A * 6P = 3.48A going through your battery.

I know it's still bordering on the honesty scale but is realistic on a bike going at 15mph on eco mode.

 

[minexplorer]

are you sure of your source of information?

The datasheet for your cells is here:
https://www.nkon.nl/sk/k/29E.pdf

typical capacity: 2.850AH at 0.2C 2.5V discharge
that's 0.2 * 2.9A * 6P = 3.48A going through your battery.

I know it's still bordering on the honesty scale but is realistic on a bike going at 15mph on eco mode.

Im perfectly happy to be corrected if i have misunderstood the tech. As i understood it . If my 350w bbs is running on full power, drawing 18amps .Then with say a 5p battery each string of 10 cells is providing 3.6amp and 6p its 3amp. The dampfakkas site gave the lower capcity of the cells of around 2500mah at this rate. So you are saying then ,that its only the string as a whole thats providing that ampage. Not each individual cell .They are each providing a tenth. So 0.36 & 0.3 amps .And at the lower PAS level, indeed 0.2 amp per cell? So the full stated AH of the battery can be realised,but only on lower PAS?
I thought it seemed odd there was such a vast difference between the manufacturers test figure of 0.2 amp and 3amp .Seems obvious now the larger figure refers to a string and the lower an individual cell.You can start throwing the eggs now...

 

[minexplorer]

Im perfectly happy to be corrected if i have misunderstood the tech. As i understood it . If my 350w bbs is running on full power, drawing 18amps .Then with say a 5p battery each string of 10 cells is providing 3.6amp and 6p its 3amp. The dampfakkas site gave the lower capcity of the cells of around 2500mah at this rate. So you are saying then ,that its only the string as a whole thats providing that ampage. Not each individual cell .They are each providing a tenth. So 0.36 & 0.3 amps .And at the lower PAS level, indeed 0.2 amp per cell? So the full stated AH of the battery can be realised,but only on lower PAS?
I thought it seemed odd there was such a vast difference between the manufacturers test figure of 0.2 amp and 3amp .Seems obvious now the larger figure refers to a string and the lower an individual cell.You can start throwing the eggs now...

What a chump! Just ride the bloody thing an leave off the thinking.

 

[harrys]

In addition to the .2C rate used for capacity of a cell, they also run them down to 2,5 volts for specifications, Most battery BMS circuits will shut down before 2.8 volts to allow for some imbalance. Your motor controller is usually more conservative and shuts down around 3 volts per cell. I will concede that there isn't much power left when we hit the steep tail of the power-voltage curve, but it's probably 5%, maybe higher if your controller is set on the high side of LVC..

Thing is, if all battery makers use this spec, it is consistent. We as users have to account for it.

I'll also comment about wattmeters, the inexpensive Tenergy type. I find them terribly inaccurate for watt-hours on a 30 minute ride. I have several and they give varying numbers, even hooked in series that vary by 50-80%. Where they do seem reproducible is in logging the amp-hours, so I have taken to logging AH per mile.

In the end, the numbers don't matter as we know how far/fast we can go on a given battery most of the time. Add some wind, make it colder, and if not careful, we come home pedaling.