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What does S and P stand for? What is Xs, Yp or XsYp with X and Y being numeric digits?
What does S and P stand for? What is Xs, Yp or XsYp with X and Y being numeric digits?

This is the notation for the configuration of the battery. S means Series, P means Parallel. XsYp means X cells in series (to get the desired voltage) and Y cells in parallel (to get the desired capacity). If Xs or Yp is missing then it is either to be read as 1s or 1p respectively or it isn't important for what is meant to be said. Note, these are not case sensitive and are usually written in lower case.

This is 4 cells in series, or a 4s, or 4s1p

This is 4 cells in parallel, or a 4p, 1s4p

• Car batteries are usually 6S lead acid batteries for a total voltage of 12V. A lead acid cell has a nominal voltage of 2V, 6 * 2V is 12V. There are no cells in parallel, so it is just 6S.
• Lithium batteries for small/medium RC vehicles are usually 3S or 4S, again no cells in parallel.
Technically these batteries can be called 3S1P, 4S1P and 6S1P. But that is not very common since the 1P part has no meaning in this case. Also, lead acid batteries are the reference when talking about 12V/24V/48V systems. They define these systems. That is why they are usually called 12V, 24V and 48V batteries instead of 6S, 12S or 18S.

• If someone says "Use a 7S battery" then there is no yP since this is not relevant in this case. It means you should use a battery with seven cells in series (of that given chemistry that is talked about, in this case lithium ion cells) and the number of cells in parallel is yet to be decided on available space, current draw and so on.

• Similar thing, "Use 90P packs" means you should take packs of 90 cells in parallel and add as many of them in series until you have the desired voltage.

• 7S90P, is a complete electrical specification of a battery. It uses 90 cells in parallel and 7 in series, so a total of 7 * 90 = 630 cells are needed. You know the voltage, it is 7 times the nominal voltage of an individual cell, and the capacity, it is 90 times the average capacity of the individual cell (or the sum of all individual cells capacities). Total energy is voltage * capacity, and its maximum discharge current is 90 * average discharge current of the cells in parallel.

Order makes a difference. A 4S3P is not the same as a 3P4S.
.   - A 4S3P is 3 cells in parallel, and then connected in series to make 4S.
.   - A 3P4S is 4 cells connected in series, then 3 of these connected in parallel at the ends of the series strings.

.   - Please note, in this example, the output is the same (4 * cell voltage = pack voltage; 3 * cell capacity = pack capacity).
The biggest difference would be that if you had a large pack and connected all the cells together in series first, you would need to have every cell alternating which end is pointing up; in other words, Pos up, Neg up, Pos up, Neg up, etc, etc. In this configuration, you would not be able to run a common bus bar on each side of the pack, but instead run smaller wires from cell to cell alternating which is connected. Even though the connection count is the same (2 * cell count = number of solder/weld joints), the tediousness and error chance goes way up.

Quote:DISCLAIMER: I am by no means an expert on any one or all of these fields/questions/topics. The results of this FAQ is a collaboration of multiple different members to come up with a common list of questions that would be asked and we have tried to answer. I was the member who was chosen to post the FAQ. If you have question that goes beyond the FAQ, please post your questions in the relevant section pertaining to your inquiry. Thank you and have a nice day
chamele0n, rodagaster, mickduc And 5 others like this post
The designation of the orientation of the naming convention can be confusing to some. Let's think of it in a slightly different manner.

If we have 5 trays of ice cubes, and each tray has 10 cubes and then laid them end to end, then we'd have 5s10p. This is similar to the way the strings/packs are assigned.
Whereas if we took those trays and laid them side by side, it'd be likened to having 1s50p, simulating several packs in parallel.

So if we have 7 packs of 40 cells, then that would be 7s40p.
chamele0n, hbpowerwall, Headrc like this post
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