TSDZ2 48v 750W + 13S3P Samsung 50E?

[Aprvtcav]

Hi,
Been wanting to convert one of my bikes into an ebike for many years.
Now it´s time. Live in Sweden and are planning on sourcing a TSDZ2 + battery from pswpower and hopefully reasonable delivery time.

Having difficulty deciding what battery to choose. Would like to build my own battery in the future but will hold of on that now due to other projects in life that need more attention.

Found a batterypack with 13s3p (15Ah) 21700 Samsung 50E (300USD). According to datasheets they have a max discharge of 9,8A, which would give me 29,4A of current. As far I can tell the TSDZ2 controller draws 18A.
It felt like a done deal.

Went down the rabbit hole(endless sphere) where they discuss cell longevity and my interpretation is that there is a risk that the 50E cells would be a bit to stressed in my use case with voltage sag and shortened cycle life.

Thinking that I am futureproofing with a 21700cell battery because they will probably be replaced with different cells with the same formfactor in a couple of years when I have sourced a spot welder, nickel strips and all other bits and pieces needed.

Found a local unused 52v 14s4P (11,6Ah) 18650 Samsung 29E cells (400USD), more expensive than the 50E cell battery pack and also have relatively low discharge rates and seems like an even poorer choice..

Thoughts? Samsung 50E 13S3P, good enough battery? Any battery recommendation from a reasonably reputable seller with decent delivery time?

 

[matthewslack]

Pragmatism: 300USD is a cheap battery pack, doing is the best learning, data is a good teaching tool. I'd not worry too much about the battery, I would spend a bit on data collection - cycle analyst seems to get mentioned a lot, I'm sure others on here know if there are other options - and just get riding and looking at your data.

Then you will be able to answer questions like what is your average and maximum power draw and therefore current, what is your average energy per km, your range, your preferred ride length and all of that.

Then you can build the bike you really want from a position of knowledge!

 

[Nealh]

3s or 4s requires 15 or 20a rated cells, any cell chosen ideally one should be looking at 50/60% of the cell current rating for usage so as not to stress the cells. The top end current rating of a cell is ok for temporary use but even the very good cells will age quicker used nearer their top end rating.
For my Bafang G370 buit bike I'm using 12s2p but chose the 20a LG hg2 as my cell for a max 40a discharge, as it is I'm using a max 22a rated KT controller so the cells if the max current was applied would be less then 60%.

The 29E is a very good value cell but not up to it in 4p, so one needs a good 10a or higher rated cell for 4p or opt for another battery, the issue at the mo is a battery with quality cells which are scarce.

I was going to look at the BAK 20a 18650 as a bargain build but even they are now out of stock, so looks like after xmas I will have to pay double the price and go back to plan A of using the reported excellent 25a Molicel P26.

 

[Nealh]

I'm also looking at the tsdz for my cargo bike next year, for me usage is only local so a 2p or 3p 6- 9 ah battery is perfect. I know the 12s2p will suffice but will also look at 12s or 13s 3p with 2500mah 20/25a cells.

 

[Nealh]

For good quality cells one will have to think of allowing approx. 300 - 380eu for a battery.
Have a look at enerprof.de hard and soft packs with 21700 cells in 3p using the likes of the Molicel P42a or the Panny NCR2070C cell, both use higher rate discharge cells.

48V (13S) Batteries | ENERprof#

Softpack Battery 48V 10.50Ah NCR2070C in Enerpower Bag | ENERprof

 

[Aprvtcav]

Thanks for your help, both of you above.
Matthewslacks pragmatism really hit home. Finally ordered the kit and battery with S50E cells.

I get where Nealh is coming from, but for now I went cheap and hopefully will get riding in the foreseeable future.

Intrigued by building a 13s2p pack with high discharge cells and converting to a lighter and more stealthier build later on.

Best regards