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12S battery configuration question

12s
battery

#1

1st off, can someone confirm the number of LiPo’s below are actually accurate to give me the end result I came up with?

2nd, which setup would make more sense to buy?


#2

It’s been a long day, but I believe you would need to multiply those numbers instead of add to get your desired results.


#3

In series you increase the voltage, but keep the same mAh rating - so each of your above x 4 and x3 would be 2200mAh and 3000mAh respectively.

In parallel you would keep the voltage 3/4s, but increase the mAh.

That make sense? I would go with larger mAh packs 3/4s x #needed to get 12s and still have a decent mAh for range.

HTH - GL!


#4

To point one:

Your calculations are not right.
Setup 1: You will get 8 2200mAh batteries for dollar 109,84, but it is not possible to do 12S4p. For 12s4p you need 16 of these. 4 in series are needed to get 12s, but then they only have 2200mAh. With 8 batteries you can only build 12s2p, so 12s and 4400mAh.

Setup 2: Same failure. You will need 9 batteries to get 9000mAh with 12s. Six are just for 12s2p, so 12s and 6000mAh.


#5

Good question @LucidLunacy. @sl33py and @hexakopter have it right… you can either increase the voltage (the “S”), or the capacity (the mAh), but not both when you combine packs. You can still achieve what you’re after, but you’ll need different battery packs to get there.


#6

In general i would suggest something around 5000mAh (aka 5Ah). if 3s packs x4 for 12s, or if 4s packs x3 for 12s.

I personally prefer the 3s packs for balance, and ability to run only 3 for 9s (great if you get a >200kv motor later or on another board and want to use these packs). Plus 3s packs can usually be a bit smaller - i like thinner packs for better clearance.

So a setup of 4 x 3s packs 5000mAh would be a great start, and unless you need crazy range should give you a decent run time/range.

GL!


#7

a favorite of mine for being super thin and light:

4500mAh (so a bit lower capacity), but only 21mm thick and 350g. x 4 and about your 100’ish $.

Even better for range would be the:
https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9184

23mm thick, 350g and 5000mAh. again around $100’ish.

GL!


#8

What kind of range would you get with 4x 3s packs at 5000mah? Thanks :slight_smile:


#9

Approximately 22km based on conditions and setup. General rule of thumb is 10wh = 1km. This setup nets you 222wh (44.4v * 5 amps = 222wh).


#10

Exactly why Im wanting to buy 3-4s packs.

Thanks for the links.


#11

How does that scale with 1 vs 2 motors? Thanks for the help! I thought if you put them in series, the capacity stays at 5000mah in total? Sorry still learning about batteries.


#12

You’ll probably get slightly more mileage out of a single motor, but it heavily depends on your weight, amount and incline of hills, if there’s heavy wind, etc. 1 or 2 motors shouldn’t affect it too drastically (maybe 3~ km in this example). Take a look at the boosted dual+ with 7 mile range (2 motors) vs the single with 8 miles (1 motor).

And yes, series = increasingly voltage. Parallel = increasing capacity


#13

I just have 2 more questions (hope that’s alright)

  • How much does the discharge rate matter? I see 1 pack with 20c and one with 30c.
  • The same 2 packs, 1 is 4S and 1 is 3S1P - what will this effect in terms of building?

The 2 batteries


Really appreciate the help!


#14

Get at least 20c continuous. It means that you times the mah of the pack by the discharge rate of the pack to get the continuous discharge.


#15

Depends on the current draw of the ESC to the motor. If you’re going up hills, your ESC is going to be drawing a lot of current. I think 60A is the default Max current from the VESC. The ‘C’ rate is the battery’s discharge potential, where 1C = complete discharge of the battery in 1 hour (2C would be complete discharge in .5 hours). To calculate the discharge rate in amp hours, multiply the C rate by the capacity of the battery (eg. 20C battery 2 5000mah = 100A discharge rate).


#16

@Jinra and @lox897 Thanks for the help

Is there an easy way to charge all lipo’s at once by plugging in 1 cable into a charger? Much like a consumer grade board.

And voltage meters can be used to find out battery capacity remaining?


#17

be cautious about “20c” is key statements - it’s really C * Capacity of batteries - i would shoot for 100A discharge (normal not peak) to ensure you have overhead and don’t damage your batteries.

While lipos aren’t super expensive they aren’t cheap either. You shorten the life of the battery with heavy draw/demand. So utilizing less of the discharge capability will give you longer battery life. That’s why i shoot for a minimum of 100A continuous (not peak) discharge batteries (5000mAh * 20C = 100A). More is better but spending on 65C batteries is just throwing away money… IMO.

Similarly charging is a big part of pack life. Lower charging will get you more re-charge cycles (life), and not charging all the way to 4.2v will also help increase cycles/life. That said - i want maximum range, and usually still charge to 4.2, but do try to slow charge when i can afford the time.

Charging multiple’s @outsider - get a paraboard. There are cheap knockoffs, but the original paraboard is what you are looking for solution-wise. It allows you to connect 4-6 batteries (depending on which board and total amps combined charging) at the same time and balance charging them.


http://www.buddyrc.com/power-system/paraboard-parallel-charge-board/paraboard-v3.html

Just pick the connectors you need, or bare wire to solder your own (wish they would get xt90’s!). It’s also helpful to get some balance lead extensions to make it easier to plug in 4 batteries at once.

If you get a decent charger (i like iCharger but $$ - iMax B6AC v2 is my budget recommended), it can show you mAh charged and some other battery testing (like Internal Resistance - great info to see if pack is spent/shot/deadjim).

HTH - GL!


#18

“consumer grade board” - you are asking about BMS. A single barrel plug and done like on your laptop.

A Battery Management System allows you to charge and discharge all the batteries to max and min safely. It likely (verify depending which you get) has a low voltage cuttoff, and will definitely have a balance/charge limit as well. Complexity wise i’ve avoided, but do like the idea for simplicity.

There are a TON of them out there and i don’t know enough to educate anyone, but hopefully someone will chime in or it can help you refine your search to good or suggested BMS’s.

GL!


#19

hey sl33py, slightly off topic question. How come some lipos like this one have a 3s configuration but have 4 balance leads? When I was looking up some BMS’s they showed configurations for 1 lead per positive terminal in a series (example)


#20

every battery will have one more wire than number of cells on the balance plug. 3s - 4 wires, 4s - 5 wires, etc.

(EDIT - it’s one power and the 3 grounds on a 3s)… let me go double check. I know they are in series, so you will see 4.2, 8.4, 12.6, etc.

uno momento

I had it backwards - one power wire, plus one ground x each cell.

here’s a good overview:


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