1P or 2P batteries? What does it mean?

[sgomes]

I notice that some batteries specify 1P and some 2P. What does this mean, and which is preferred?

Thanks.

Steve

[mcomet]

Someone please correct me if I am wrong... since I may very well be...

P stands Parallel and S stands for Series... if you are familiar with wiring electronics you will already know what that means. But basically Series means if you have a battery, then wire another one "in line" + to - chaining them up, that is series. Parallel is still wiring together but instead of a chain, both the + and both the - leads are wired together.

So a 3S1P means there are actually 3 capsules or batteries in the real main battery, wired in series, to the connector.

If you had a 3S2P, you actually have -6- parts. 3 in series, then Another 3 in series... and then both those would have their - to the negative connector and + to the positive connector.

I forget which is which but I think one way gives you more power capacity in a burst, the other I think gives more duration. There were some articles on this stuff in some recent RC-Heli magazine issues as well as MHT magazine.

[Probedude]

The number before the S is the number of cells in series to give your pack voltage.

The number before the P is the number of parallel batteries in your pack.

So a 3s1p pack is 3 cells in series, 1 set of these series cells in parallel.
A 3s2p pack is 2 sets of 3 cells in series.

Some packs, to get the C rating up and therefore a higher discharge amp rating, will use mutiple strings of series cells in parallel to boost the current and C rating of the pack.

You can do the same thing by paralleling independent packs together (of the same rating). 2 qty 8C packs in parallel give you 16C.

I think the advantage of cells in parallel instead of high C rating cells in series is the overall pack weight can be less. I'm not sure about this though.

Dave

[sgomes]

Michael,

Thanks, and that connects the dots with what I have been reading.

I guess one makes a decision based on battery space?

Steve

[mcomet]

Well decision comes based on the specs of the battery and your power needs. ie: you need t make sure the #amps/volts is correct for your motor and electronics. Obviously too little you won't be flying, too much, and you'll be frying your motor and electronics.

Seems latesly the FP EVO 25C 2170mAh battery is what most people are recommending. I've got two align 2100mah that I am thinking of replacing with these soon.

[xptical]

So, let's say an average cell is 700mah at 3.7v.

A 3C1S pack would be 2100MAH@11.1V.

Series would boost MAH and parallel would boost volts.

You still won't get much over 2100mah, but you might get a higher discharge rate.

I run a 40A ESC. At most, I can use 19.something C. Any more than that, and my ESC fries. The Align 35A ESC could take 1.6C.



I would think, at our level, anything over XC1S would be overkill. Once you progress to the 600+ helis, you will see XC2S and bigger to provide higher discharge rates.

[Probedude]

Series would boost MAH and parallel would boost volts.


It's the other way around. With parallel you add the mAH and Volts stays the same. In series, you add the volts and the mAH's stays the same.

Overall the total wattage you can pull from the pack is the same since wattage = A * V

[Pinecone]

A 3S1P of 700 mAH cells would still be 700 mAH. A 1S3P pack of these cells would be 2100 mAH, but only 3.7 volts nominal.

A 3S1P pack will be 11.1 volts nominal.

And higher C than you can use means that you are running your packs less hard, meaning cooler and they will last longer (number of cycles). If you have a max draw of 30 amps and use 15C 2100 packs, you are running them pretty much at their limit (max 31.5 amps), but if you switch to 25C packs, and still only draw 30 amps max, you are only run the pack at 60% of its max amp draw, so the pack will run much cooler and under less stress.

A system will not draw any more amps than the motor/pitch/gearing causes it to draw. A higher C pack will not deliver any more amps than the system will draw.