Hi,
I’m riding a 2013 speed-pedelec (pedal assist up to 45km/h) that uses a Bosch mid-drive engine (first gen, also called classic+). The battery is the original one and is now 3 years old with 18500km on the clock, and I plan to renew it soon. As this system is proprietary, I have basically 3 options:
1) Get a new Bosch battery (same as mine). This is a 36V 400Wh 11Ah 10S4P pack with Samsung INR18650-29E cells (519 euros)
2) Get the Ebike-Vision 36V 468Wh 13Ah 10S5P pack with Samsung ICR18650-26H cells (479 euros)
3) Get the Ebike-Vision 36V 612Wh 17Ah 10S5P pack with Panasonic/Sanyo NCR18650BL cells (669 euros)
Initially I wanted to go with the Ebike-Vision 612Wh pack as it offers significantly more capacity as my current 400Wh. 400Wh has worked fine for me but I’d not be against a bit more capacity.
However, I made some calculation based on the discharge curves available on http://www.dampfakkus.de using the different cells above and looking at the available capacities when discharging the cells only down to 3.0V, knowing that the BMS will likely cut even before that. My engine has a nominal output of 350W but a peak output of 500-550W so I considered that it can draw max 15A, which means 15/4=3.75A per cell in a 4P pack (Bosch), and 15/5=3A per cell in a 5P pack (both Ebike-Vision). The different capacities of the cells at 3.0V and considering the (max) discharge current they would effectively see in real life are:
- Samsung INR18650-29E at 3.0V (3.75A discharge): 2553mAh (linear interpolation based on reported capacities at 3A and 5A)
- Samsung ICR18650-26H at 3.0V (3A discharge): 2538mAh (used the 26F instead since there was no measure for 26H)
- Sanyo NCR18650BL at 3.0V (3A discharge): 2879mAh
If we multiply these capacities by the number of parallel cells, we have:
1) Bosch 400Wh: effective capacity = 4*2.553=10.2Ah (11Ah nominal)
2) EBV 468Wh: effective capacity = 5*2.538=12.69Ah (13Ah nominal)
3) EBV 612Wh: effective capacity = 5*2.879=14.4Ah (17Ah nominal)
What appears striking is that packs 1 and 2 have effective capacities that are very close to the nominal whereas pack 3 has a difference of 2.5Ah compared to its nominal capacity. In other words, there seem to be not so much difference between packs 2 and 3 besides price: pack 2 is 200 euros cheaper!! Looking at these numbers it seems that pack 3 is really not worth it but do these calculations make sense?? Should I consider anything else? For instance, a Samsung 26H cell (in pack 2) has a max discharge current rated at 5.2A whereas a Sanyo BL cell (in pack 3) is rated for max 7A. Is this of any importance for a speed pedelec? It also seems the 26H/F cells have a large voltage drop compared to other cells... And what about the Bosch pack, does it have advantages (e.g. the Samsung 29E have a max discharge of 8A)? Would be glad to have your opinion about these different options.
Thanks
I’m riding a 2013 speed-pedelec (pedal assist up to 45km/h) that uses a Bosch mid-drive engine (first gen, also called classic+). The battery is the original one and is now 3 years old with 18500km on the clock, and I plan to renew it soon. As this system is proprietary, I have basically 3 options:
1) Get a new Bosch battery (same as mine). This is a 36V 400Wh 11Ah 10S4P pack with Samsung INR18650-29E cells (519 euros)
2) Get the Ebike-Vision 36V 468Wh 13Ah 10S5P pack with Samsung ICR18650-26H cells (479 euros)
3) Get the Ebike-Vision 36V 612Wh 17Ah 10S5P pack with Panasonic/Sanyo NCR18650BL cells (669 euros)
Initially I wanted to go with the Ebike-Vision 612Wh pack as it offers significantly more capacity as my current 400Wh. 400Wh has worked fine for me but I’d not be against a bit more capacity.
However, I made some calculation based on the discharge curves available on http://www.dampfakkus.de using the different cells above and looking at the available capacities when discharging the cells only down to 3.0V, knowing that the BMS will likely cut even before that. My engine has a nominal output of 350W but a peak output of 500-550W so I considered that it can draw max 15A, which means 15/4=3.75A per cell in a 4P pack (Bosch), and 15/5=3A per cell in a 5P pack (both Ebike-Vision). The different capacities of the cells at 3.0V and considering the (max) discharge current they would effectively see in real life are:
- Samsung INR18650-29E at 3.0V (3.75A discharge): 2553mAh (linear interpolation based on reported capacities at 3A and 5A)
- Samsung ICR18650-26H at 3.0V (3A discharge): 2538mAh (used the 26F instead since there was no measure for 26H)
- Sanyo NCR18650BL at 3.0V (3A discharge): 2879mAh
If we multiply these capacities by the number of parallel cells, we have:
1) Bosch 400Wh: effective capacity = 4*2.553=10.2Ah (11Ah nominal)
2) EBV 468Wh: effective capacity = 5*2.538=12.69Ah (13Ah nominal)
3) EBV 612Wh: effective capacity = 5*2.879=14.4Ah (17Ah nominal)
What appears striking is that packs 1 and 2 have effective capacities that are very close to the nominal whereas pack 3 has a difference of 2.5Ah compared to its nominal capacity. In other words, there seem to be not so much difference between packs 2 and 3 besides price: pack 2 is 200 euros cheaper!! Looking at these numbers it seems that pack 3 is really not worth it but do these calculations make sense?? Should I consider anything else? For instance, a Samsung 26H cell (in pack 2) has a max discharge current rated at 5.2A whereas a Sanyo BL cell (in pack 3) is rated for max 7A. Is this of any importance for a speed pedelec? It also seems the 26H/F cells have a large voltage drop compared to other cells... And what about the Bosch pack, does it have advantages (e.g. the Samsung 29E have a max discharge of 8A)? Would be glad to have your opinion about these different options.
Thanks
