Bafang M620 new build.

Hi all,
As Inspired from Andy Kirby ebikes on the you tube channel, I am on a secondary project. i have purchase the following :

Bafang M620 mid drive engine kit .
A bike frame , with the correct mounts for the above engine. ( waiting 12 weeks to be shipped from china.)

I decide to build an 14s4p battery with 48 Panasonic NCR 18650 B. i have used the Vruzend 2.1 solderless kit to construct.

the questions i have :

- what sort of capacity / range will i have ?
- have i picked a decent choice in battery ?
- would i better to have 14S5P ?
- what would be the best BMS to use ?


I am new to the Ebike world , so any suggestions, help would be greatly received.

thanks in advance

Tony

Sounds like a cool build, I like the Bafang mid-drives, here's how I would calculate it:

Looks like the cells are:
3.6V nominal @ 3.4Ah so

14s*3.6 V = 50.4V (48V)
4p*3.4 Ah = 13.6 Ah
5p*3.4 Ah = 17 Ah

The M620 says its rated for 750W at 48V, so current draw at full power is:
750W @ 48V = 15.625 A

So your 4p battery will last a little under an hour at full discharge, and your 5p battery will last a bit over an hour. Also continuous current draw is around 1C for both batteries so that should be fine. I've found some decent looking BMS's on Amazon but haven't tried any personally.

Hope it helps,
Eric

14s 4p is 56 cells- you need another 8. 5 parallel will give you more range and a bit more pep due to less sag, but if you’ve already bought them then don’t worry.

For a data point the older version of the NCR cells was incredibly reliable for me and handled 10A peaks with no issues. 100s of cycles and barely any capacity loss and no bad cells. Charge to 4.1V and don’t go below 3v, and charge at 4A or less for the pack, they’ll be fine.

The red water resistant cheapo BMS work ok, but get more A than you need; if you’re drawing 20A get one rated for 40A. If you want battery health info there are some with Bluetooth

If/when you see an M620 (Ultra) rated at 750w, it's usually with a wink towards being a legal US import. Bafang sets the max amps in the controller at 30a - making it closer to 1500w.

As far as range is concerned, what to expect, many of these are used with 26"x4" tires because of all the power and torque available. Range is not going to be real good with those - not as compared with a 2" or 2.5" anyway.