Lipos : test, feedback, temp,


#22

Well, 5,2Ah is like nothing (empty in 5-10mins), take at least 4 parallel. Then you get ~150A without a problem.
I got the 5,2Ah 4s Multistar for flying. ~10C/~45A hasn’t been a problem so far.


#23

I hate black friday, it makes us buy too much stuff we dont need… Buuut there is a good deal on Lipos now :slight_smile:


#24

Might not be that great offers after all :stuck_out_tongue:


#25

The 5,2 6s is even cheaper now.
I made an excel sheet, price per Wh, it is still the best.


#26

So I bought 4 pieces of 10Ah, 10C, 6S Multistar batteries. Two will be connected in series and those 2 wil go in paralel. I am putting the ESC separately in an aluminium housing. The battery box will be far forward and submerged in the board. I hope the temp will just be ok.


#27

Is 10C going to be enough? My understanding was that we needed closer to 40C discharge and running in parallel won’t change the ability of the battery to deliver the amps, only the capacity.


#28

10c means 10 times the capacity. So in this case 10 x 10amps = 100 amps per battery.
And yes, in parallel this can be accumulated, so 200 amps - on paper.

So maxmakers lipo pack can deliver around 200amps x 12 x 3.7V = 8880 watts. On paper.
Should be enough to get up on the foil.


#29

That was my thinking. I am glad you confirmed it. 200€ is not that bad. I wouldn’t mind doubling it if everything works out and riding it is fun.


#30

I think I can see where the confusion lies, related to the nomenclature.

The C rating DOES NOT change when run in parallel, consistent with what I initially believed. However, because it’s expressed as a cumulative sum of storage capacity (which I neglected to consider), which has doubled, in this case because it’s still 10C, it’s expressed at the 20ah, rather then the 10.

My concern was everything I’ve read says you need more 100At o get going. Based on this, you should be right. Hope this helps someone else.

(where’s the wiki??!)


#31

You do not need more than 100A. We max out on about 70A.

And ride on 30-40A with ease. (Big foil)

40-50A on small foil.

Cheers.


#32

But then you could run higher pitch or larger prop.


#33

Sorry for digging up an old thread but is this the battery from test 4?

If not would 2 of these work? I’m just starting to sort our batteries and I feel a little lost.


#34

this is what i will do to choose lipo (based of what i have read and done myself):

  • first you need to known what power you need:

i would say, depending on set up, board size, weight, front wing (and you can correct the numbers)

take off: 1800-3000W
planning 20km/h: 800-1800W
planning 30km/h: 2000-3000W
(propably less but i don’t think more)

i am running on 8S but i will use 12S next time , it pull to much amp

  • lipo, you will not use all the power, it is best to use 70% after, to much heat and voltage sag

  • C rating

the way i would use the number: i will use the max C rate for the energy left at 30% of the lipo

exemple:

you want to use mutistar , at the end (30%) you will have 22.60V x 2 =45,2v

if you need 2000W for take of: 2000/45.2=44A

max amp for multistar is 10C: 44/10= 4,4A and this at 30%
so for at 100% this will be 4.4/0,3= 15A

so for me NO the 10A won’t work for a long time and will probably burst

but you can use 2X 16A or 2x20A: this works and as be done

if you want to use 10A, i will need higher C , this happen to me:

on a 8S 32A pack, so not a small one…


#35

This is the right way to calculate battery bank!
I don’t think 10A 12s would do.
I have 2 banks, 2x6s 20A Multistar and 4x6s 16A, the first is ok for my setup (max 80A and half of that when foiling) but after the first minutes performances go down when squeezing the throttle. With the 32A bank you can feel the motor a little more alive


#36

Thanks! That helped clear things up a bit.


#37

Ok I know I’m dragging this thread up again but I want to get advice on batteries my local shop recommend.

I should be good running two of these in series right? Also is it possible to run off a single battery for testing?


#38

You can run of only a single 6S battery for testing. As the number of cells in series determines the voltage your motor can not reach full rpm. The max rpm will be about half as much as with 12S. (That’s because a turning brushless motor is also always a generator and creates a bigger voltage when it’s turning faster. This means simplyfied, to get power into the motor you need to apply a higher voltage that that.) With 12 series cells you get about 45V nominal and with 6S only ~22V.
I don’t have experience with the specific cell you want to buy.


#39

yes, they should be able to provide enough power with 2 in series. But, there is only 6.5AH capacity, so ride time will be low. Most people here use at least 16AH, you could have 6 of them so 3 sets of the 2 in series in parallel with each other, this would make 19.5AH 12S.

I would imagine that they sell that battery for a very high price, Hobbykings batteries are very cheap and work well.