Can someone explain S and P in 3S1P

[JEB123]

I'm guessing 3 series packs and 1 in parallel to increase current only? How many cells are actually wired and how are they wired? How does this compare to only 3S packs? What should I run in a TRex 450SE V2 with a Scorpion HK2221-8 and 45A Scorpion commander? I'll be doing mostly scale flying (Hughes FG fuse) so I want more torque than speed.:confused:

[beeflyer2]

3S1P is the same as 3S, there are 3 cells in series.

[JEB123]

So what is the 1P?

[JEB123]

Beeflyer2, you're right, but I mean as in 3S2P. Now I see it's 3 cells in series and two packs of 3 in parallel to double the current at the same voltage. With series voltage is summed and current remains the same, in parallel current is summed and votage remains the same. I guess my question really is what's a good balance for a scale 450 bird to have a good amount of flight time without too much weight?

[beeflyer2]

3S1P is the standard size for T-Rex 450. I prefer 4S1P however, as you can get much better power and/or duration from the extra voltage.

It's not very common to see anything higher than 1P. When multiple cells are in parallel, you sum the capacity of each cell. The more common way to get higher capacity is to use larger cells.

[JEB123]

Sorry Beeflyer2, but I'm an old nitro plank guy and a newb to EP helis. I'm an electronics tech so I know a little about the subject. I read a post yesterday that someone smoked his motor with a 4S battery. How do you determine the output voltage of the ESC based on input voltage? I know my Scorpion motor has a max current of 45A and 450W which means 10V are being put across the motor, but does that's under max load. I imagine the voltage must drop as the battery gets weaker, but these motors don't spec a max operating voltage! How do you know what it can handle voltagewise?

[ualdrivr]

3S is 3 in series and 1P is one in Parallel. You charge a pack like that as a 3S pack.

[JEB123]

Right, but what about the last question I posted? How do you know max voltage that will be applied across the motor so as not to fry it?

[beeflyer2]

Generally, the motor does not have a max voltage spec, the ESC does. However, any motor for the T-Rex 450 will be fine with 3S.

[JEB123]

Actually, most motors do. Look at this link for the Align motor, it's no. 1 at the top of the specs:
http://www.deeteeenterprises.com/NS.T.Rex.Align.Brushless.430L.3550.php
There has to be a max E (voltage) spec. Power is the result of voltage times current, so E is one of the three determining factors in how much power is delivered to the motor. My Scorpion motor specs 45A and 475W max which gives you 475/45=10.55V across the motor. If you applied 12V @ 45A (max load) this is 540W which would smoke the motor. Does the ESC calculate the # of cells and apply the output voltage accordingly? This is why I want to know how this guy smoked his motor. It shouldn't have happened since a 4S is 14.8V which is exactly at the top end of the Align spec and the motor only draws the current it requires. i would like to know the limitations of my motor to prevent any stupidity on my part.

[RTDillon]

S = series
P = parallel

3S1P is a 3-cell pack with all cells in series. You multiply the cell voltage by the number of cells to get pack voltage. (~3.7vx3=11.1v pack)
Current rating is the same as the rating of the individual cell. (If the cell is 2100mah the pack is 2100mah.)

4S2P is a 4-cell series pack in parallel with another 4-cell series pack. In this case you multiply the cell voltage by the number of cells to get pack voltage. (~3.7vx4=14.8v pack) You next multiply the mah rating of each series string by the number of series strings (P) to get the total current rating. (2100mah x 2 = 4200mah pack)

Current adds in parallel and voltage adds in series. Think of voltage as pressure in a hose and current as the size of the hose.

There! This should be clear as mud. LOL As the writer this all makes sense, as the reader. let me know if it helps. :-)

[JEB123]

Thanks for your reply, of course, this is basic electronics. I'm an FCC licensed electronics tech for 29 years, and series and parallel were my first suspicions, just wanted to confirm that. I'm new to BL e-flight and it's terminology, that's why I asked. However, look at the last post before yours. This is what I'm trying to get answered. What determines the voltage OUTPUT of a ESC? Does it detect the no. of cells and change accordingly?
Maybe you can answer this.