Are Turnigy Multistar multirotor lipo packs filled with weaksauce?

Just while we are here talking about C rating and multistar.

My zippy packs that I have always used are 20C.
The multistar pack I bought is 10C.

On that information alone you would assume that the zippy can output more current than the multi.

However half the equation is missing.
The zippy is 5000mAh and the multi is 10000mAh so the are actually the SAME C rating on paper.

So when do we get the side by side test results? :stuck_out_tongue_winking_eye:

When I get back from Vacation.

Ive found out why I hate(d) multistar packs so much! and it kind of makes me hate them a little less!

The solder connections keep breaking between the 2nd and 3rd cell and 5th and 6th cell. Both of my packs did this same thing. I had to take the whole damn thing in individual cells to figure out what it was.

The reason the middle connections didnt break is because i did them.

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@trbt555 Well at least you’re quite lucky that the multistar pack is in discount at the moment for half price. 3s 5200mah for only 15 euro lol
http://www.hobbyking.com/hobbyking/store/_65267__Multistar_High_Capacity_3S_5200mAh_Multi_Rotor_Lipo_Pack_EU_Warehouse.html

I rode quite a lot during the last few days an my Multistar 3s 5.2Ah packs are really starting to suck.
One cell just died, the cell voltages are all over the place in the remaining packs.
But most importantly, I’m lucky if I get 3Ah out of them lately.
(My low cutoff is set to 3.6V because under that there isn’t much happening.)

Anyone have similar experiences ?

Hey Tom after I analyze my lipo packs an configuration abit, I found something very interesting.

I found that my longboard is better running with 50c rating compared to 25c rating. So I better off with 2 series and 2 parallels instead of all 4 in series.

I have to agree that higher voltage is cooler for motor and esc, but it gives alot of stress to the batteries. You have multistar with only 10c rating, connected them all in series. That means each acceleration pulling high amp close to the limit of each batteries could provide. Thats probably one of the reason your battery are down so quickly.

The power that is used or drain by motor is still the same in watt hours. If it doesnt stress the motor and esc, it stresses the batteries. Too low voltage put stresses in motor and esc. Thats something we have to choose.

I literally have double acceleration and more agressive ride when connected them in parallel.

Yeah, I thought of that but I don’r really feel like rewiring my batteries.
AND my vesc has been giving me shit by cutting out due to overheating, so more amps won’t be an improvement.
I can always run my zippy’s.

I think if you want to keep the 12s format without parallel setup ( doesnt fit anyway on rosti mepal), you should try get those big capacitors and have them mounted. That should help reduces battery stress.

Otherwise get the graphene battery and test them. It has 45c or 65c rating which is great to reduce battery stress when only 1 pack is used.

You can load 4 3s 4000mah 65c in that box. Thats the best Ive seen by far with turnigy graphene setup inside rosti box.

I dont’t believe capacitors are of any use here.
Based on what ?

why wouldn’t Caps be of any use?
I reckon caps are a great idea.

People have had similar experiences like yours when they compare Zippys and Multistars in racing quadcopters. As other people have said, they last long and thats about it.

Its known that caps can help reduce cogging or stress during short burst discharge. This already help improve battery life during starting standstill or small acceleration.

It could also be that the low voltage cut off was too low everytime. But batteries die quick is always because of too much stress. This possibly have an impact to your vesc heating up. Strange that my esc doesnt even heatup while you’re with vesc+ heatsink have heat issue. Theres something wrong somewhere.

Please elaborate.
How exactly will a capacitor help to overcome limitations of batteries not able to cope with current draw ? I’m curious.

Yeah right. Please allow me to serously doubt that statement.
Please calculate for yourself how many amps a 2200uF cap can produce when discharged over an inducance like a brushless motor and report back.
Let’s not have newbies reading this thread get the wrong idea.
Capacitors over the battery leads are there to smooth out spikes in the voltage due to high frequency switching, not to provide amps when the battery can’t.
If someone can prove the opposite using the laws of physics, please do and I’ll adjust my opinion.

Don’t they have something for car amps that help with the sag in voltage when they crank up the music? Would something like that work?

LOL yeah @Michaelinvegas they are called capacitors.

@trbt555 its not the caps alone, but the caps in conjunction with the batteries.
caps can discharge quite a lot of amps in a short time and then charge back up just as fast, this is why they are useful.
a cap by itself will run high current for like a split second.
so no it physically cant run the motor alone, but when a battery is connected in parallel across the caps the battery can recharge the cap with as much current as the battery can provide.

it is only a short burst of current, but it does help.

do you know why a cap helps with ripple? because it can soak up high current spikes very quickly. (you know the arks when you hook them up?) they also do the opposite. you would be pretty naive to think that caps could be connected in parallel with a battery and not have some of the energy sucked out of them when the motor draws it.

I like to call them thingy-whatchamacallits

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Hi Tom you’re the physics man, theres no doubt that the caps wont help much within current draw as current is provided by the batteries anyway. But I meant int he previous comments was the surges, especially during startup. It smoothen out the power draw. I personally use 10000uF caps in addition from the VESC caps and or esc caps. Theres huge spark when connected without antispark.

Thats why I recommend to add parallel connections to the mutistar batteries. You can try and compare them if it works better or not compared to the all series connections.

I don’t want to be the wise ass here but as a scientifically educated person I feel I can sometimes help people understand how things work and why they work or don’t work. There’s no hocus-pocus involved.

Assume you have approx. 2200uF in caps in parallel over your battery leads, which is a typical setup in a lot of cases.
Now let’s consider a fully charged 12S system: when charged at 50V, these caps can store 2.75 Joules of energy, you can look up the equation if you like.
Suppose you want to accelerate uphill and your weaksauce-filled-Multistar-pack voltage sags to 40V, your caps will discharge 0.99 Joules of energy.
Let’s say the voltage sag takes only one second: 0.99 Joules expended over 1 second corresponds to 0.99W of power (Power is Energy over Time) available to your system.

At 40V that equates to a whopping 25mA additional current during that ONE second.

Call me old-fashioned but that just won’t cut it.

So: I agree that caps help smooth out voltage ripple (which is in the millisecond range) but I stand firmly by my statement that they will NOT help with a battery that can’t cope, and we shouldn’t be leading people to believe so either.

(EDIT: thanks to @DerBrecher for pointing out a small error in the energy calculation which is of course quadratically related to voltage)

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