Explanation of Lipo battery configurations

[jasonyng]

I am new to this and am trying to get my head around battery configurations.

I can't find a write up on how they can be configured, can someone point me in the direction of an explanation of the different configurations and their meanings; 6s, 10s, 12s? And how each would be wired? Series or parallel? How each configuration affects amps or mah?

Thanks!

 

[LEVer]

Here's a good info about lithium polymers (li-pos) including their ratings and specs: http://www.rchelicopterfun.com/rc-lipo-batteries.html

 

[torqueboards]

Series increases the voltage of a pack. 1S is 1 cell, 2S is 2 cells in a series connection, 3S 3 cells, 6S 6 cells in series etc.

Parallel adds capacity for the pack.

Better way to measurement is to use the total watt hours of a pack. 12S3P can be the same as a 6S6P. The difference between the two is 12S is double the voltage than 6S.

12S3P = 12 cells in series and 3P means 12 series are in 3P.

Best place to learn would be here -> http://batteryuniversity.com/learn/

By increasing in series - you increase total voltage. The voltage adds up for each cell.
By increasing in parallel - you increase capacity + maximum amps for each cell.

Typically, 12S is the highest voltage we use for electric skateboards since most esc/motors don't run above 12S.

6S is typically used for up to 20mph.
Many people use 12S for added power/range and efficiency over 6S.
Although, there's nothing wrong with 6S except after a while you get use to 6S top speed.

Typical, 10Wh is .62 miles and/or .98 km.

Calculate your total watt hours which is total nominal voltage * ah(Mah/1000) rating.

Ex. 6S * 3.7v = 22.2v * 5 ah (5000mah) = 111Wh pack.
111Wh / 10Wh = 11.1 * .62 miles = 6.882 mile range.
11.1 * .98 km = 10.878 km range.

Although, this is a rough estimate and you could get a bit more mileage out of the pack.

 

[spinningmagnets]

The nominal ratings of each cell can be confusing. S is for series, and when cells are configured in series, the voltage is added, but the Amp-hours (Ah) which is a rough indication of range, is not changed. When you add cells together in parallel, the voltage of the pack stays the same, but the Ah are added together.

LiPo means Lithium Polymer, but there is a lot more information that is not in the name. The "nominal" voltage is the average voltage across the entire useage cycle. If you charge a pack to 4.10V per cell (in series), then a 6S pack would be 6 X 4.10 = 24.6V. If you set the Low Voltage Cutoff (LVC) at 3.3V, then the battery will cut out after running the E-bike for a while, and the 6S voltage is down to 6 X 3.30V = 19.3V

Some builders will charge their pack to 4.15V or 4.20V per cell in order to get a hair more range, but I have been convinced that 4.10V per cell is the best compromise. The LVC can be set lower, maybe 3.0V per cell.

The nominal voltage of LiPo is generally listed at 3.7V per cell, so a 6S pack would be 22.2V, 10S is 37.0V, 12S would be 44.4V, 13S is 48.1V

_________________

The parallel strings determine the amount of amps the pack puts out, and also how much range the pack has. If you make the parallel strings out of 5 cells (5P), and the cell is rated for a peak of 10 amps (10A), then that pack would put out a peak of 50A. If you use a cell that has 3000-mAh (one thousand milli amp hours is equal to one Amp hour), then a pack made from 5P strings of 3000-mAh cells would have 15000-mAh (or 15-Ah).

A pack might be called a 12S / 5P pack. The nominal voltage would be 44.4V, but the peak voltage when fully charged is 12 X 4.10V, so 49.2V

 

[jasonyng]

Ok I did some reading and lets see if i get this.

If I take 4 of these packs:
http://www.hobbyking.com/hobbyking/store/__24310__Turnigy_nano_tech_A_SPEC_4500mah_3S_65_130C_Lipo_Boat_Pack_Mono1_.html

Wire them in series I get a 12s1p pack with 4500mAh,
and using torqueboards equation would go ~12.3 miles.

Correct?

Same goes for these if i took 4 of them:
http://www.hobbyking.com/hobbyking/store/__45145__Turnigy_nano_tech_A_SPEC_G2_5000mah_6S_65_130C_Lipo_Pack.html

Wire each pair in parallel and the the 2 of those in series I end up with a 12s2p, correct?
And 10000mah for ~27 miles?

Let me know if my thought process here is correct.

Thanks!!

 

[torqueboards]

Well first off, you don't want to put batteries which aren't the same in series or parallel together. It's better to keep them the same brand/style to prevent any differences between the build batch and for them to be equal when discharging. You also IMO don't need 65C and are more than fine with a 20C or even 10C/15C isn't a noticeable difference. These packs don't have any battery protection over undervoltage/overvoltage or even balanced voltage. You have to proactively do that to each pack yourself. These RC Lipo packs are simply batteries only.

The last thing you want is buying/spending X amount and accidentally ruining the pack and your out $100-200 bucks.. so IMO I prefer 20C packs since they are cheaper... way cheaper.. 3S 5ah is about $20-22 bucks and a 6S 5ah 20C is about $40 bucks. These packs which you get at hobby king are 6S1P or similar.. they usually mention it.

Personally, I would hate running 4x packs 3S 5ah since there's much more to go wrong and to disconnect if you are charging packs. Personally, I'd take the 1.75-2" height of a 6S5ah pack and only have to take out two packs versus 4 packs. You have to be careful not to accidentally short these packs since if left short'ed too long it can ruin the pack and create a fire which you don't want.

What I've seen/heard is some people take the 6S5ah pack and lay them flat and then re-wrap them. I would use something like GAFF tape which you can easily get from eBay. That's my take on it. Go with Turnigy or Zippy Flightmax 3S 5ah $22/each for short deck and/or 6S 5ah for $40/each.

I wouldn't waste my time or money trying to make these packs any thinner or smaller besides taking the 6S and making it thinner. IMO, if you want.. Go with the SPACE cell and/or Chaka's deck and 18650 batteries. And/or Run (2) 6S 5ah packs.

 

[LEVer]

Ok I did some reading and lets see if i get this.

If I take 4 of these packs:
http://www.hobbyking.com/hobbyking/store/__24310__Turnigy_nano_tech_A_SPEC_4500mah_3S_65_130C_Lipo_Boat_Pack_Mono1_.html

Wire them in series I get a 12s1p pack with 4500mAh,
and using torqueboards equation would go ~12.3 miles.

Correct?

Same goes for these if i took 4 of them:
http://www.hobbyking.com/hobbyking/store/__45145__Turnigy_nano_tech_A_SPEC_G2_5000mah_6S_65_130C_Lipo_Pack.html

Wire each pair in parallel and the the 2 of those in series I end up with a 12s2p, correct?
And 10000mah for ~27 miles?

Let me know if my thought process here is correct.

Thanks!!

Yes you are correct. Although your miles range estimate is very optimistic.

I would get 8 pieces of the thin 3s 4500mah and lay them flat under the deck. Parallel connect 2 packs to make 4 pairs of 3s 9000mah, and then series-connect those 4 pairs. That will give you 12s2p 9000mah and a very sleek deck.

In my experience, lipos with higher C ratings gives you more range. I guess it's because they are better able to handle the higher amps output than the lower C rated packs.