Lipo price vs. quality

[SchrodingersCar]

Hi guys, apologies if this topic has been done to death, just looking for some piece of mind.

I'm trying to stock up on batteries for my new heavy lifter, and I'm puzzled by the differences here: http://www.getfpv.com/batteries.html?battery_voltage=332

I've been shopping a lot of places but that link is the most stark example.

I know tattu batts are supposed to be some of the best, but the luminier branded lipos are lighter weight, sometimes higher c rated, and ~$100 cheaper! So why do we think this is? Are the luminier stats stretching the truth? Or are tattu lipos just overpriced? I'm looking at a lot of lipos in the 10-16A range so this is a huge investment for me... I'd prefer to make the right choice the first time if at all possible. Price is a huge consideration of course, but so is weight, as I'll be flying with 3 at once. Thoughts?

 

[SleepyC]

Higher C rating is not always great for heavy lift. Higher C rating helps 3D helicopters that tend to get pushed hard in 3D type maneuvers.

From my experience, price doesn't matter as much as reputation.

Usually what you are paying for with higher priced batteries is much tighter QC.

I used to buy a lot of HobbyKing Lipos. The Turnigy Zippy. And I'd say 1 out of 10 were not usable. But the other 9 were fine. SO I included that one bad one into the cost.

But search around, from personal experience, Max Amps, Pulse, Thunder Power, Turnigy Nano tech, RC Rotors and Aerial Media, Optipower all make great packs.

I'm sure there are more, but these are packs that I trust right now.

I have heard great things about Tattu, and how they are using the lower C rating to give a better stability and solid pack.. but have not tried them yet.

 

[SchrodingersCar]

To tack on a question related to that: I know in most cases C rating is less important, but is it important to have a certain amount of "headroom" in your C rating? I've been looking at the low price multistar 10c packs. But and an example, if the average flight is drawing close to that 10c for the entire duration, would that cause more potential wear and tear on the lipo, as opposed to, say a 20c pack?

 

[SleepyC]

Bart did a great job of explaining this:
http://www.multirotorforums.com/threads/understanding-lithium-polymer-batteries.12072/

 

[SchrodingersCar]

Yes I've read that guide, it's very helpful, but unless I missed it, it doesn't seem to answer my specific question? Which, more specifically, is this: According to ecalc, at max payload, my setup will draw up to 300 amps at hover, up to 600 amps at full throttle. I could conclude that that means I could use 3x10000mAh lipos (parallel) with 10c discharge, 20c burst rating equal to 3 x 100 amps discharge, 3 x 200 amps burst, correct? Is this a fine setup or is it not a good idea to be riding that close to the potential "ceiling" of the lipo's performance? Should I search out something like a 20c/40c, even though I'd never use the full discharge rating?

 

[fltundra]

To tack on a question related to that: I know in most cases C rating is less important, but is it important to have a certain amount of "headroom" in your C rating? I've been looking at the low price multistar 10c packs. But and an example, if the average flight is drawing close to that 10c for the entire duration, would that cause more potential wear and tear on the lipo, as opposed to, say a 20c pack?

Yes, and they will run warmer. Also C rating will drop as IR rises over time. Need to take that into account. Take a look at readymaderc's lipos,
using 3 of their 8000mah 4s lipos and have been amazed how well they have held up. Granted, I'm only drawing 17 amps at hover, but IR for me hasn't changed in over 100 cycles on my oldest pack, not ever charging above 1C.

 

[SchrodingersCar]

Yes, and they will run warmer. Also C rating will drop as IR rises over time. Need to take that into account. Take a look at readymaderc's lipos,
using 3 of their 8000mah 4s lipos and have been amazed how well they have held up. Granted, I'm only drawing 17 amps at hover, but IR for me hasn't changed in over 100 cycles on my oldest pack, not ever charging above 1C.

Thanks, that's what I figured. I'll shoot for a little more lipo headroom. It's a shame that so many of the high capacity lipos are out of stock everywhere!

 

[Vojec]

I wouldn't relies so much on ecalc. Make your own amp test. Full load your bird and measure amp in hover and max throttle. Upon then you will be able decide what battery you need. Cosider also different prosp if you need in higher altitude...

I started with zippy but when I step into havy lifters I switch to Gens (tatuu). Difference is in the last thirds of flights. Gens just have constant power during whole flight and this is the important key especially if you in bussiness...

 

[binlagin]

I'm loving my cheapo turnigy packs for my medium lifter (Align M480L + G3 gimbal + LX100)... SleepyC is 100% correct though.

1 out of every 10 cheapo pack will not be usable upon arrival. I break these apart for their good cells and build packs for other things like RC cars or arduino projects.

Those Tunrigy 20-30c... so cheap, I've owned well over 50 of those 5,000mah 6s packs over the past 3 years now. Once they have gone past initial inspection and charging, I have never had a pack fail unexpectedly

Here are some cheapo packs powering my 100km/h e-bike...

 

[dazzab]

600Amps???? That sounds incredibly high to me. Is this a new 24 motor beast or something?

 

[SchrodingersCar]

It's probably much closer to 500 amps at full load and throttle. Was just rounding up. It's a 12 motor beast