HELP: Need some help choosing the wright new batteries

EFOIL.builders Electronics (ESC, remote, batteries)
1

Okay. I’m about to start building a new jet board (not foiling!), and hope that some people here can point me in the wright direction with new batteries.

At this moment I am using six 6S 4500 mAh Zippy compact LiPo’s (3 in parallel for jet motor one and 3 in parallel for jet motor two). The Zippy’s are rated 40C

The LiPo alarm triggers after about 15 minutes of having fun, and the LiPo’s do feel warm (not hot!)

Not really relevant, but the motors do 13890 rpm (according to my RPM meter).
This is pretty close to what I’ve calculated: 6S (22.4 volt) 13440 RPM (22.4*600=13440)

Today I had a Watt meter between one of the LiPo’s and I got the following max data from it:

  • 3.736 Ah (Amp Hours)
  • 78.1 Wh (Watt Hours)
  • 36.03 Ap (Peak Amps)
  • 20.80 Vm (Voltage Minimum)
  • 842.6 Wp (Peak Watts)

I’m going to build a new board, and I’m going to use the same jet box (motors and jets).
The plan is to build the new board around the battery box… So basically I have more than enough space for batteries.

Now… What should I go for? Will 18650 cells be an option as the continuous discharge rate (C rating) is 40 for the LiPo’s I’m using now. Can 18650 cells handel this?
Or… Just stay with the heavier and more dangerous LiPo’s, and buy some more…

Looking forward to what you guys think.

Kian

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Im new to efoiling or jet boards but I have build many li-ion batterys for high power e bikes and longboards.
If im understanding you right you would need a 6S battery that can provide at least 220A.
That is easily possible with li-ion you just need the right cells and enough of them.
I have build a 20S8P 16,8Ah battery pack that can provide 240A with Sony Konion US18650 VTC4 cells for a 15kw E-Bike. And the cells won’t even reach 35°C (Im monitoring them with a Bms).
But I never use full power for longer than 5s because its way to much power for me and you would reach over 100 km/h which is just to much for my bicycle front tyre and it gets instable.
So I would recommend you use eaven more parallel cells so they won’t get too hot because you are probably using full power for longer amounts of time.
And you said that the range isn’t good for you thats another reason for you to use more parallel cells.
I would recommend to you to have at least 1000wh thats around double the capacity of your current Lipos.
You could build a pack out of Murata / Sony Konion VTC6 cells these ones can provide 30A (if temprature monitored 15A if not) and have a capacity of 3Ah.
A 6S16P Vtc6 pack would have 1036wh and every single cell had only 14A to provide if you would drow 220A so you dont even have to monitor their temperature.
Of curse you could even add more parallel cells if you want to drive even longer.

If you dont want more drive time then your previous board you could use the VTC4 cells they only have 2,1Ah but can provide 30A without temprature monitoring and are cheaper.
A 6S10P Vtc4 pack would be enough and would drow 22A per cell on full throttle but only has a capacity of 450wh so it is the same sice as your previous Lipo pack.

sorry for my bad english im from Germany.

Noah

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Vielen Dank Noah,
Ich komme aus den Niederlanden… That’s about all my German :slight_smile:

Wow. 6S16P… (96 cells) And I need this 2 times … (2 motors)

I’m going to make a 1:1 mockup of this and see how big this actually will be… And if this is doable at all in a board.

Once again thank you Noah.
And… Do not worry about your English!.. It’s great!

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You wont need them 2 times I already calculated for all 6 Lipos. You would connect this battery to both motor controllers in parallel.

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But if you want to do 2 batterypacks you could make 2 6S8P Packs.

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Yes… I just relished… I only need one.
Pfffff… It was an ID - 10 - T error from me (read IDIOT) :slight_smile:

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Just to make sure I’m understanding things correct.
a Sony Konion VTC6 is 3120 Mah and 3.7 volt.

So a 6S1P (6 cells in serie) would give 3.7 x 6 = 22.2 volts and 3120 Mah (3.12 Amp)
The Watt of this 6S1P will be Amp * Volts. So. 3.12 x 22.2 = 69.264 Watt

Put 16 6S1P 's in parallel and it will end up with 22.2 volts and 16 x 3.12 Amp = 49.92 Amp
(Watt = 49.92 x 22.2): 1108.224 Watt.

The Zippy LiPo that I am using:
Volt: 22.2 V
Amp: 4.5 A
Watt: 4.5 x 22.2 = 99 Watt.

I have 6 of them, but use 3 in parallel per motor.
Volt: 22.2 V
Total Amp (3): 4.5 x 3 = 13.5 Amp
Watt: 13.5 x 22.2 = 299.7 Watt

When I add both LiPo packs, I end up with:
Volt: 22.2 V
Total Amp: 4.5 x 6 = 27 Amp
Watt: 27 x 22.2 = 599.4 Watt.

So yes. The 6S16P Sony cells will almost double the Watt’s and Amps of what I am using now.

What I do not understand is the continuous discharge rate (C rate).
The LiPo is rated 40 C The Sony 12 C.
Will this be a big problem for me?

8

C rating continious ( probably a few minutes)
A 18650 cell of 3000mah so 3A rated at 10C can give up 30A but it will heat up and waste energy and at the end you will get probably like 2,5A of it

Better use 1/2 of C rating for calculation
4,2v full - 3,2v for almost empty average take 3,6v

So for 6s1p you will have on average 21,6v and you can pull at least : 21,6x 3x 5 ( 1/2 C rating) = 324W to 648w

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Read data specification I believe Sony cells don’t have pressure valve , so I suggest to get Samsung 30q ( safer)

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Are you talking about the Samsung 30Q with or without the buttontop?
One of the reasons for the Sony was that it does have a little bit more mah’s, and the Sony does have a bigger max current! (Price wise they are about the same.)

VTC6 = 3210 Mah and 30 Amps max
30Q = 3000 Mah and 15 Amps max.

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Without bottomtop
I shortcut 30Q without problem , need to test on vct6 , just didn’t time to do it but what I have read they don’t degaz easly
It s always safer the lipo … but some are even safer if the worst happen

Didn’t find the same for vtc6

Nothing about short safety test : probably fire
Just no solder in the middle of the bottom of the cell

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“Just to make sure I’m understanding things correct.
a Sony Konion VTC6 is 3120 Mah and 3.7 volt.”

No the nominal voltage of a Li-ion is 3,6 V

6S1P would give 3,66=21,6 V nominal
thats 4,26=25,2V fully charged
thats 3*6=18V empty
it would have 3120 mah nominal (thats 3,12Ah not 3,12Amp, Ah is capacity and Amp would be current)
it is rated at 30Amp with 80°C tempcut and 15Amp without

There is a difference between 166S1P in parallel and 6S16P (All parallel cells of one series are parallely conected so they stay at the same level all the time).
It will end up with 21,6V nominal and 163,12Ah=49,92Ah nominal (not Amp) but the rated capacity is only 3Ah so only 48Ah
and if you drowing over 10A out of a single cell only 2,94Ah so 16P is 47Ah
so you have a capasity between 49,92Ah and 47Ah.
Thats between 1078Wh and 1015Wh (Its Wh not W).

A Lipo has 3,7V nominal so thats correct.
But your reading from the wattmeter only showed 3,7Ah
so 22,2V*3,7A+6P=492Wh

C like Alexandre said is continues discarge rate
To get the current you have to multiply the C with your Ah rating
the Lipo = 40C4,5Ah=180Amp
but you have 6 in parallel so your battery can provide 1080Amp
the VTC6 dosent have such a clear C rating but the datasheet says a single cell can provide
30A with temp monitorand 15 A without
so the whole 16P can provide 30A16P=480A with temp monitoring
and 15A*16P=240A without temprature monitoring:

No because you are only drowing:
your wattmeter says 36A per Battery so 216A for the whole pack
thats even less than the Current of without Temprature monitoring.
So you dont even have to moniture the cells.

I dont think thats nessasary because he isent even using half the current the Battery pack can savely provide and if he dosent short or overcharge or have huge disbalance nothing will happen.
and with an BMS with overcharge, Balancing and Short circut protection even then doing something terebbly wrong you should be fine.

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Thank you @Alexandre and @EbikeGuy,

You guys are my guru’s … I am a gambler, and like to do different than other.
So I’m going to order 96 VTC6 cells as the shop around the corner has them in stock :slight_smile:
128 V2.1 Vruzend’s are already ordered and on it’s way.

Once again thank you both for helping…
And Noah. I understand the calculation now!

You both stay safe!

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are you buying at NKON?
I love this shop.
I also order there every time

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Yes I am buying from NKON.

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Don’t know one big 6s16p or two 6s8p … peak amp is 220A that is a lot for the terminal and the wires …
better off I think you 2 battery set in // , you double the wires like this

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there is no reason for not just using 2 sets of 8 awg in a single battery even though a single 8 awg should do the trick. But if he is using 2 Escs anyway he could just use double xt90s.

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I’m going to double the plus and minus and use 2 XT90’s

I’m also going to use V2.1 Vruzend to put the box together as I have more than enough room to play with. Using Vruzend will also enable me to change the build from 6S to whatever I want…

Once again thank you all for the info.

I will keep you guys updated!

19

I have shorted a few of these vtc6 cells and they go up in flames. Even if they are only charged to 3,5V (from factory). I have 2 14s11p packs, but my next packs will be the samsung 30q. Almost the same internal resistance. Sony is 11,8mOhm samsung 12,1mOmh if I remember correct. Also capacity is the same VTC6 is 3000mah not 3100mah.

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Thank you for the info.
I have no clue where I got the bigger capacity of the VTC6 cells from, but I am sure that I’ve read this somewhere…
I guess I was wrong.