# 10S4P with Lithium ion battery; Question on the calculation

1. Sep 5, 2014

### marellasunny

I am planning to use the Panasonic NCR-18650 cylindrical cells for a BEV (Battery Electrical Vehicle). As it would be easier to buy ready-made modules, I have found a supplier selling a Li-ion pack that delivers 417 Wh(or in other words 11.6 Ah) at 36 V (something like what this guy uses... http://www.electricbicycleworld.com/36V-11-6Ah-Lithium-Ion-Frame-Bottle-Mount-p/hx-bb-11.6ah-36v.htm ). Upon further inquiry, he says its a 10S4P i.e 10 in series and 4 "strings"(whatever that means) in parellel.

The Voltage and Energy density calculation part is where I get confused:

The panasonic datasheet says that each individual cell has 10.44 Wh of energy and supplies it at 3.6 V.
So,

10 cells in Series → 36 V and 10.44 Wh

IF I arrange these cells in 4 "parallel" rows, I get → 36 V and 41.76 Wh. But, the guy claims 10S4P supplies 417Wh. Where am I going wrong?

2. Sep 5, 2014

### montoyas7940

You are keeping the same watt/hr value despite the increase in number of cells.

P=IE

3. Sep 5, 2014

### montoyas7940

BTW I have an old tadpole recumbent trike I have thought about motorizing as well. I would enjoy watching your progress as you build.

4. Sep 5, 2014

### marellasunny

My build will be from time-to-time be posted in the Automotive engineering forums in Physics forums. I would love to document and share the information online but unfortunately my contract blocks me from doing so. Neverthess.......you'll find me in the AE forum :).

Last question:

What is the difference between connecting the cells in a 10S4P format('TEN' 18650 cells in Series arranged in 4 columns connected in parallel) as compared to connecting the cells in a 40P (all 40 cells in parallel) ?

10S4P-pack gives me 36 V and 417 Wh and 11.6 Ah.

40P-pack on the other hand gives me 3.6 V and 417 Wh and 116 Ah. ( like this pack here...http://www.kreiselelectric.com/en/technology/battery-system/battery-pack/ )

My Brusa HSM1-10.18.13 motor has a specfication of 360 V - 400 V and max RMS current of 300A.

5. Sep 5, 2014

### montoyas7940

I'm not sure what you are asking regarding the difference. But the voltage and current you are considering can be very dangerous. You need an expert.