bbellfly

My Feedback: (2)

What is the difference between a 3 cell 3s and a 3 cell 4s pack. What does S messure?

thanks
bbellfly

jdetray

Hi bbellfly-

This is from an earlier post of mine, so it may be more info that you need, but here goes....

This nomenclature tells you how many individual cells are in a battery pack and how they are connected. In theory, you can describe any type of battery pack this way, but it's most often used to describe lithium-polymer packs.

The first number (the "S" number) tells you how many cells are connected in Series (S for Series). From this, you can determine the voltage of the pack.

A single lipo cell has a nominal voltage of 3.7V. So a 3S pack is a bank of 3 cells connected in series and has a voltage of 3 x 3.7 = 11.1V. A 4S pack is a bank of 4 cells connected in series and has a voltage of 4 x 3.7 = 14.8V. A 5S pack = 18.5V. A 6S pack = 22.2V, etc.

The second number (the "P" number) tells you how many of these series-connected banks are connected in parallel (P for Parallel). The larger the number of banks connected in parallel, the greater the capacity of the pack.

Examples:

A 3S2P pack has two 3-cell banks connected in parallel, a total of 6 cells. The voltage is 11.1V, and the capacity is twice that of a single bank of 3 series-connected cells.

Let's assume you are using cells with a capacity of 2000 mAh.

Then a 3S2P pack will have a voltage of 11.1V and a capacity of 2 x 2000 = 4000 mAh.

Using the same 2000 mAh cells, a 3S3P pack (9 cells) will have a voltage of 11.1V and a capacity of 3 x 2000 = 6000 mAh.

A 5S3P pack (15 cells) will have a voltage 18.5V and a capacity of 3 x 2000 = 6000 mAh.

Packs with the designation "1P" have only one bank of series-connected cells. So a 4S1P pack consists of one bank of 4 cells connected in series. The "1P" is often omitted when describing packs with only one bank of cells, so when you hear a pack referred to as (for example) "3S" that usually means a pack consisting of 3 cells connected in series.

- Jeff

bbellfly

My Feedback: (2)

Thanks for the information!!!

But I am still confused. On Atlanta Hobby's web site they refer to power supply preferred for the Torque 2814-820 500 Watts As 3 cell 4S. Isn't that contradictory?

Also, the voltage rating is a little confusing. I am looking at purchasing an E-flite's Power 10 BL outrunner vs the Extreme Flight's Torque 2814-820 500 Watts. The Torque refers to 3 cell or 4 cell, but give no voltage range in there specs. The E-flite refers to voltage range from 7.2 to 12. With that thought am I to assume the torque can take 4 cells (14.8 volts) and the E-flite cannot?

I will include the specs from both. See if you can shed some light on the subject.

Extreme Flight's Torque 2814-820 500 Watts

Motor Specifications
Windings: 14Turns
RPM/V (KV): 820
Idle Current (RI): 0.035
IO (@8.4V):A 1.38
Weight: 5.04 oz 143 G
Constant Amps; 28
Max Amps: 37
Suggested Prop:APC 10*7 , APC 12*6
Suggested Pack:3-4 Cell
Max Watts: 518

For best performance use 3 cell 4S lipo and a APC 12*6 prop.


E-flite's Power 10 BL

Specs

Type: Brushless Outrunner Motor
Size: 10-size
Bearings or Bushings: Ball Bearings
Wire Gauge: 16
Recommended Prop Range: 10x5–12x6
Voltage: 7.2 - 12
RPM/Volt (Kv): 1100
Resistance (Ri): .043 ohms
Idle Current (Io): 2.10A @10V
Continuous Current: 30A
Maximum Burst Current: 38A (15 sec)
Cells: 6–10 Ni-MH/Ni-Cd or 2–3S Li-Po
Speed Control: 35A to 40A Brushless
Weight: 122g (4.3 oz)
Overall Diameter: 35mm (1.40 in)
Shaft Diameter: 5mm (.20 in)
Overall Length: 43mm (1.60 in)

Needed to Complete

35A-40A ESC

6-10 Cell NiMh/NiCd or 2-3S Li-Po

10x5 to 12x6 Electric Props

Fliprob17

I do not understand the 3 cell 4S. That just does not make sense. It should be a 3S or a 4S or a 3S2P or 4S2P.

If the E-Flite is spec'd at 7.2-12 volts, then NO it cannot handle a 4S LiPo.

The Extreme Flight will handle a 3 or 4S pack

The E-flite will handle a 2 or 3S pack

jdetray

I think the technical term for the "3 cell 4S lipo" statement is "mistake."

Just above that, it says

Suggested Prop:APC 10*7 , APC 12*6
Suggested Pack:3-4 Cell

Often, when a range of cells and a range of props is given, the smaller cell count goes with the larger prop, and the larger cell count goes with the smaller prop. So 3 cells and a APC 12*6 prop makes sense to me.

- Jeff

dac8

could any one explain this to me ?I was going to order a lipo receiver pack from a company called MaxAmp the add says it does not come with tabs what does that mean i would think that means no wire leads with a u or futaba j connector am i correct also if its a 7.4v pack doesnt it require a bec or voltage regulator to lower v to 6v also is the run time really that much more with lipo over nicd/nmh as i wish to use the batt for a gas car rx and need at least 45min run time

jdetray

dac8-

Read the description more carefully. The receiver packs do not come with TAPS. That means that you can not access the individual cells for balancing or checking their voltage. Taps are an option (for $2.99 or $3.99).

The MaxAmps packs come with wires but no connector. You can add the connector yourself or pay extra for MaxAmps to install a connector. Use the "Plug" dropdown to select a connector, or select "No Plug."

On the same page as the receiver packs, MaxAmps sells a voltage regulator, which I think you'll need.

The run time is a function of the battery capacity (mAh), no matter whether you are using a lipo, NiMH, or NiCd. More mAh = more run time.

- Jeff

dac8

thank you