So I have this 10s2p pack in my budget build. But I just destroyed it by over-discharging to a useless voltage level. So without spending too much, should I buy some lipo and enjoy that high discharge rate or just try to find some 18650 pack or make one myself? Is lipo really cheaper? I want something that can fit in this Ownboard enclosure.
Turnigy graphene lipo packs are the highest known form of lipos at the moment. There are accounts of people discharging them as low as 1.6v/c with full recovery!! Sure, they’re expensive for lipos, but they are unparalleled in performance and durability. As far as fitment, I can’t answer the question, but they are good for 1000+ charge cycles. That is also unparalleled.
7 Likes
Also, liion are far more expensive, especially if you factor in the cost of nickel strips, fish paper, all the other shit you gotta buy to make them “safe”, and a spot welder. Lol, wanna know how I really feel about it? Best bang for the buck/cm3/power to weight/etc. =lipo. Especially the HK graphene packs.
Edit: no idea, but seriously. Hk graphene
3 Likes
So what’s below graphene? Can you name a few in decreasing order, from the best/most expensive to worst/cheapest?
Zippy flightmax 2s 8ah is a nice size n states 30c.
Surprised more people don’t do lipo
10 Likes
I looked into buying HobbyKing Turnigy Heavy Duty packs for a while until my current Graphenes went on sale for 50% and I couldn’t pass them up. Heavy Duty ones have good discharge rating, around 60C advertised on the soft packs. I don’t have any experience with them, they just looked like a good alternative to Graphenes. Also check out @Namasaki thread on 10S LiPo with BMS. Tons of good info on there.
2 Likes
Yup picked up HK graphenes for $27 a pop. I’m using a 10s setup right now with no issues at all. they are rated for 90c discharge, I don’t know how true that is I’m waiting on the metr update to get data. But tons of power.
2 Likes
HK Graphenes are the closest to their stated C-rate out of all lipos. Here’s the proof: https://www.rcgroups.com/forums/showthread.php?1767093-Battery-Load-Test-Comparisons
To answer your question @mtuan293 , ALL lipos are below graphenes!!
Edit: I do realize that a 3c multistar is closer to its “10c” label, than a true55c HKG is to “75c”, but you’re missing the point if that’s what you’re concerned with
4 Likes
In a case that small, I’d probably go lipo just for the extra discharge capability. In my opinion, the advantages of li-ion really shine in either (A) large packs, where longevity is a must and extreme power density is not needed, or (B) in small to medium packs where you want the most energy density, but don’t mind taking a hit to power density.
For small packs where you want ALL the power, lipo is king. It won’t last as many cycles or hold as much energy per kg, but it’s cheaper and higher discharge.
For a high power build (anything bigger than a single 6355 or thereabouts) you really need either lipos, or at least 3-4p of li-ion to handle the required current.
3 Likes
I guess it’s because of that “safety”. People tend to afraid lipo pouch can be easily damaged causing fire and all the stuff compared to metal housing of liion 18650 cells. But I feel like using cylindrical cells there’s lots of space wasted compared to squared shaped of lipos
2 Likes
Hmm I’m inclined to bump up my settings now 
True, there is a lot of space wasted. But going by the rated capacity and dimensions of a 2.2ah 4s turnigy graphene, it has a volumetric energy density of just a hair over 200wh/l. A single flat layer of 18650-30Q cells (Including the air space!) has a volumetric energy density of 514 wh/l. Bare cells are 633 wh/l.
1 Like
I thought cylindrical lion cells are less space efficient than squared lipo cells. i.e., you can fit more chemistry into the corners of the square which would have been lost due to the circular shape of lion cells. Looking at your 18650 pack there’s always gap between cells, now imagine you make a battery pack with square corners it would utilize all the gap and give you some extra capacity/discharge.
1 Like
See above. It’s true that there is less room for battery chemicals. But, the battery chemistry is SO much better, that it still way outperforms RC pouch cells in terms of energy/l or energy/kg.
lipos still win in terms of watts/l and watts/kg though.
3 Likes
If you dont switch, @least try lipos.
1 Like
Then why don’t we have squared lion cells instead of the stupid cylindrical cells then!!!
Lipo have a nice discharge curve too staying high before finally out of juice. That’s worth something. And probably can charge them much faster without damaging.
Because the construction of the layers inside is a jelly-roll. Try and make a square cinnamon roll, and you’ll see why.
Another reason is that the layers tend to try and puff up, expanding away from each other during high discharge, etc. The cylindrical shell applies even pressure from all sides and has no tendency to buckle in one direction or another. This is why large packs of prismatic li-ion cells always have some sort of structure to keep the cells compressed. Cylindrical cells have that built in already.
If you made square cans, the flat sides would bulge out due to the forces applied to them simply from the assembly process, much less from the layers trying to puff over time.
6 Likes
You can compress lipo. Think it’s good for them.
I think lipo are safer given the track record here. So many cells and possible points of failure with ion vs plugs and fewer cells. Just scratching off the insulation on ion can be disaster
3 Likes