25.9V pack? 6S or 7S Lith ion

[SolarLeo]

Hello

Im a nubi to the site and I an looking to build a 24v pack for a 250 watt old befang geared hubmotor.

I see a lot of people referring to a 6S pack being 25.9V.
Do you not need a 7S pack for 25.9 V ( 3.7 nominal X7)?

I ordered a hobbyking dc charger good for 8S so I'm not restricted to 6p like a lot of balance chargers.
so at 3 volts its 21 V and at 4.1v its 28.7 volts.

Ordered a 20A infinion controller for 24-48 volts.
Based on the specs I could find for this (old) hubmotor it peaks at 600w and will run 300w continuous, and will run 24 or 36V

i was thinking of building a 10p7S pack from 18650s

Anyone see any issues with the setup?

Some experienced comments would be appreciated!! Thanks in advance.

 

[Jon NCal]

Why not go 10S, 36V? You'll get higher speed.

 

[Ykick]

It won’t spend any time at 3V/cell. 3.5-4.2V or 24-28V for 7S.

I dunno why someone wouldn’t just go ahead and do 8S? 10S if the balance charger isn’t that important?

 

[dogman dan]

I'd at least go 8s, since you have the charger for that. Even if you don't want a lot of speed, more oomph on hills is nice. And if you have no hills, I bet you still have wind sometimes. a good 30 mph headwind means you need a lot of power to move at all.

You also have the option of going 12s or 14s, by splitting the pack.

 

[SolarLeo]

Thanks for your comments Guys!

I see the common theme here is get the volts up by upping the series layout.

And Dogman Dan, your insight on wind is something I had not considered, but its very true. Wind is a huge factor
I'm think i like 8s with the option of a second pac in the future.
I am reluctant to go 10s as this means a BMS and I'm seeing people have a lot of problems with them. I'm also worried about throwing too much power to a little motor.
the bike has 28" wheels , and Im looking for distance, not speed (50KM/32M per day)
Although I did order a CA from Justin so I believe I can control output amps
The 8 s charger ( I think) is all I'll need.
I am still struggling to understand the nominal voltage of a pack and why a 6S pack is coined 25.9 V

Ykick , your comment about 3.5 to 4.2 is noted . I was under the impression you could take an 18650 down to 3.0V.

So my lack of understanding on nominal voltage remains. what would the nominal voltage be for a 8S pack, and how many watts would you estimate with 2200 mah batteries in a 10p8S 18650 pac?

Thanks guys!

SolarLeo