Turnigy multistar vs. Samsung 25R

Batteries, Chargers, and Battery Management Systems.
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Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 3:18am

So, it happened. A high discharge 18650 finally competes with the turnigy multistar packs.
I did some math in another thread and would like to show the difference.

Note: the INR18650-25R cell sheet is attached to this post.

Samsuing rates the 0.2C capacity at 9.38whrs and an average voltage of 3.66v.
Samsung rates the 8C capacity at 7.84whrs and an average voltage of 3.18v.
Therefore, 8C actually blows 17% of your battery energy as heat. Yeah, you don't want to run it at 8C. You don't want to run a turnigy multistar at 10C either because it will do basically the same thing. We're not going to talk about 8C or 10C usage here because thermal problems develop in both packs and life is shortened dramatically.
At 8C, it looks like the battery cycle life degrades pretty damn fast too. After 200 cycles, you've got a 2.0AH cell. A multistar would probably fare worse with this abuse, providing 100 cycles to 80% instead of 300 cycles to what.. 80%?

Let's do some math on the whrs/kg, eh? given that each cell is 44 grams..
0.2C energy delivered = 9.38whrs / 0.044kg = 213whrs/kg - nice!
4C energy delivered = 8.79whrs/kg / 0.044kg = 199whrs/kg - okay, that's still decent!
8C energy delivered = 7.84whrs / 0.044kg = 178whrs/kg - kinda lackluster.

Compare this to a turnigy multistar:

Christofer Parham ( icecube57 ) found out that there was extra amp hours hanging out in his. His 16AH packs came out at about 16.7AH on average. This is actually typical for RC Lipo. I have personally seen 5.2-5.3AH come out of a 5AH pack before - right before the first cell hits 3.0v at a meager 1C discharge.
http://www.endless-sphere.com/forums/vi ... &start=200
I just did 4C testing on the multistars 16AH... This is 64A. So 4C puts this pack right at it max discharge capacity. Starting to see diminishing results. The pack was able to stay above 3.5v a cell for 15.7AH. It still delivered a full 16.7AH down to 3.0v.
Nominal voltage is 3.8v as shown by discharge various graphs of RC Lipo cells at low C rates such as 1C and the turnigy multistar has the same discharge curve as all the other lipos. Hobbyking rates their capacity at much higher than 1C. Hobbyking says the cell is 3.7v nominal, but that is probably accounting for the fact that people run it closer to the max C rate. I'm going to use 3.75v nominal to do this calculation.

16.7 x 3.75v x 6 cells = 375.75 whrs.
4C energy delivered - 375.75 whrs / 1.920kg = 195.7whrs/kg.
It would be safe to assume that this pack probably delivers 200whrs/kg at 1C.

The Samsung 25R is slightly lighter than the multistar pack in weight, but the Samsung 25R is going to take up more volume and does not have as strong of a power output, especially as you increase the C rate. Once you hit 4C on the 25R, you are neck and neck to the turnigy multistar. To build a 1kw-hr pack with the Samsungs, you have to weld 111 cells together as well. You can can build a 1123whrs multistar pack by simply building a 3 connection series harness because 95% of the wiring and welding is already done. So the multistars have a huge advantage here.

If you do not require high discharge and are happy to be in 2C-3C land, the Samsung is prolly the better choice for lowest weight, but you're still going to take a tiny hit in the amount of battery you can cram in a given space. Pouch cells just use space better.

Safety advantage goes to the Samsung of course. Samsung says that the cell will smoke if damaged/abused/etc. RC Lipo packs like the turnigy multistars will most often produce fire as a failure mode.

Price? the multistars are 378whrs / $119 ( USA hobbyking price ), which would be $314 per kw-hr. That is very low for consumer-pricing.
If a Samsung 25R is 9.38whrs / $6, then the cost is $639 per kw-hr.

It is my opinion that multistars are still the king of the hill right now for overall value if you are building a large battery pack that needs to produce up to 100 amps. But 18650's have basically caught up to multistars power/energy density, and building a long range, high power bike is now finally an option with them.
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131101_Introduction of INR18650-25R.pdf
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Re: Turnigy multistar vs. Samsung 25R

Post by zener » Jul 13 2015 3:42am

neptronix wrote:If a Samsung 25R is 9.38whrs / $6, then the cost is $639 per kw-hr.
Since the LG HG2 3000mh 20A (nom. 230 wh/kg) cells are on sale the price of the 25R dropped to $2.85 if buy 200 or more cells in wholesale....
Better get a freaking DIY spotwelder and buy 18650 with PTC and CID protection if you not want a ebike fireball....

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 3:55am

Really? i haven't seriously priced any out. I googled and saw Samsung 25R for about $6 a cell.

I've been using RC Lipos for 5 years safely. Not worried about a fireball. But if you don't know how to treat 'em right, they are a fireball in the hands of an inexperienced user; that much is correct.

$2.85 a cell does make them a better value. But add the cost of a spot welder, nickel tabs, insulation, wires, and labor. If you aren't seeing that price shipped from the USA, then the shipping cost is gonna make getting the cells delivered to your door in the USA higher overall. You're also comparing wholesale prices to retail tho.

The cost to do a multistar pack is easily 1/10th the labor time and the materials to build a wire harness are gonna cost ya, maybe 10 bucks.. as long as you already have a soldering iron.

Personally i am pretty conflicted on which way to go.. for now, i am going to continue to amortize my 5 and 3 year old turnigy packs. The next generation of 18650's from the big companies will probably blow away the multistars. That's when i'd be willing to make the switch.

P.S. i cannot find a cell spec sheet or discharge graph for the LG H2. Can you link me to one?
zener wrote:
neptronix wrote:If a Samsung 25R is 9.38whrs / $6, then the cost is $639 per kw-hr.
Since the LG HG2 3000mh 20A (nom. 230 wh/kg) cells are on sale the price of the 25R dropped to $2.85 if buy 200 or more cells in wholesale....
Better get a freaking DIY spotwelder and buy 18650 with PTC and CID protection if you not want a ebike fireball....
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by zener » Jul 13 2015 4:47am

If someone is on a budget or have two "left-hands" than yeah get these lipo's plugged together. Its still far better than riding a ICE bike.
I also can't find spec. sheet from LG HG2. But my next battery is maybe made of the Sanyo GA 3500mah 10a cells since my bike would only peak 8A for a few seconds and continuous is about 3A i calculated.

So we can conclude:

multistar-rc-lipo :
Slightly cheaper
Easier and faster to assemble
More wires if in 2p configuration (more prone for errors)
Silicone wires prone to get cut and sharp edges.
No protection if overcharged or shorted.

Modern 18650 NCA:
Better QC from manufacturer
Can be build to any shape with an minimum of wires.
Due to build in PTC and CID protection almost fail safe.
More cycle life can be governed with end-charge voltage e.g. 4V = 1500 cycles

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Re: Turnigy multistar vs. Samsung 25R

Post by TheBeastie » Jul 13 2015 9:38am

neptronix wrote: The Samsung 25R is slightly lighter than the multistar pack in weight, but the Samsung 25R is going to take up more volume and does not have as strong of a power output, especially as you increase the C rate.

Price? the multistars are 378whrs / $119 ( USA hobbyking price ), which would be $314 per kw-hr. That is very low for consumer-pricing.
If a Samsung 25R is 9.38whrs / $6, then the cost is $639 per kw-hr.
.
I am glad you noted that the 25R's are light, last time I saw a comparison the poster was just assuming they would weigh more all up then lipo which didn't work with the sums I was getting in my google spread sheet.

I am a bit dubious on your cost maths there, because I can just google up fasttech and see I can 25Rs them for $4.65 each if I buy a pack of 4 and thats not including if I choose the bulk purchase option below on the fasttech page, where it says 5+ = $17.44 (which works out to $4.36)
https://www.fasttech.com/products/1420/10002357/2204402

Also did you include shipping on the HK lipo or is it assumed to be free delivery like what fasttech.com etc do?

If you price compare for the largest group of consumers in the world (Europe) then nkon.nl they are buying the cells for €3.50
http://eu.nkon.nl/rechargeable/18650-si ... 0-25r.html

"Buy 100 times for €3.50" which works out to $3.86 US Dollars each.
Thats pretty far from $6 dollars each..

When I cost factored HK lipo vs fasttech about a year ago including weight and delivery costs and total whrs it all matched to about the same, the lipo pack was just few dollars cheaper. I could skip the cup of $3 coffee and be almost ahead already..
The only real difference was less space for 18650s but a huge relief from stress from not having to worry about fire or just merely stress relief not causing early age or cancer...

Also now I am beginning to see the 25R as old crap.. Already its easy to buy the LG MJ1 10amp 3500mah cells, these are more accurate to your $6 per cell cost but have a significant more capacity.
https://www.fasttech.com/products/1420/10004182/2762803
http://eu.nkon.nl/rechargeable/18650-si ... 0-mj1.html
http://www.endless-sphere.com/forums/vi ... 7&start=25

As well as the Samsung INR18650-30Q https://www.fasttech.com/products/1420/10002357/2363400

Don't have to have a spot welder nut you can build it parabellum style
http://www.endless-sphere.com/forums/vi ... 14&t=66555
Or nib style which I have been doing.. http://www.endless-sphere.com/forums/vi ... 14&t=60517
I believe only practical for lower discharge rate packs (unless you put more cells in P) but it still works..
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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 12:16pm

hobbyking Packs can easily be permanently paralleled to reduce the wiring greatly. I do this with all my packs.
Never heard of anyone cutting a silicone wire on a sharp edge. That's easily avoidable. You have more issues with an 18650 pack because you have to wrap it and then also consider how weight and vibration is distributed amongst this thing that is held together by plastic and thin nickel strips.
It's no problem to govern a charge voltage of a rc lipo. You can use the same charger for any battery.. i charge my lipos to 4.15v/average in bulk mode without a BMS and get very very long life outta em.. i've heard of people getting 500-600 cycles this way.

Just sayin.
zener wrote: multistar-rc-lipo :
Slightly cheaper
Easier and faster to assemble
More wires if in 2p configuration (more prone for errors)
Silicone wires prone to get cut and sharp edges.
No protection if overcharged or shorted.

Modern 18650 NCA:
Better QC from manufacturer
Can be build to any shape with an minimum of wires.
Due to build in PTC and CID protection almost fail safe.
More cycle life can be governed with end-charge voltage e.g. 4V = 1500 cycles
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 12:38pm

TheBeastie wrote: I am glad you noted that the 25R's are light, last time I saw a comparison the poster was just assuming they would weigh more all up then lipo which didn't work with the sums I was getting in my google spread sheet.
They are.. but once you build a 25R pack, it is no longer really lighter, is it? Add those plastic cell dividers ( if you use those ), nickel tabs, solder, discharge wire, then wrap the cell in heatshrink or whatnot, and you're prolly right on par with multistar.. since we're comparing a completed pack to bare 18650 cells.

I did give variable cost for the cells in my comparison because i didn't know the cost..
OK, so retail pricing would be $4.36 / 9.38whrs = $464 per kw-hr.
I didn't factor shipping because it's variable, but HK is pretty cheap for shipping and the product does come from the USA. I'm not sure if fasttech is located in China or what.. that does factor into things.
Europeans are lucky to have such low pricing.. it's not fun to ship from Europe to the USA though.. :lol:
There's a lot of variables at play. HK lipo may magically become more expensive in some countries.
So one can't really factor shipping into the cost calculation, unless i make the post even more tedious to read :lol:
TheBeastie wrote:Also now I am beginning to see the 25R as old crap.. Already its easy to buy the LG MJ1 10amp 3500mah cells, these are more accurate to your $6 per cell cost but have a significant more capacity.
https://www.fasttech.com/products/1420/10004182/2762803
http://eu.nkon.nl/rechargeable/18650-si ... 0-mj1.html
http://www.endless-sphere.com/forums/vi ... 7&start=25

As well as the Samsung INR18650-30Q https://www.fasttech.com/products/1420/10002357/2363400

Don't have to have a spot welder nut you can build it parabellum style
http://www.endless-sphere.com/forums/vi ... 14&t=66555
Or nib style which I have been doing.. http://www.endless-sphere.com/forums/vi ... 14&t=60517
I believe only practical for lower discharge rate packs (unless you put more cells in P) but it still works..
The 25R isn't old crap.. what you get from it is a nice combination of performance to weight. If you don't need such high performance, IE you want to build a 1-2C pack, then the higher energy cells certainly win out. If you run the higher energy cells near their maximum C rating though, you lose out because you have low efficiency, low voltage, and less watt hours per kg in the real world.

Nib style looks like it would significantly increase the weight of the pack which negates the whole reason for going to 18650s in the first place. But the higher the capacity of the cell, the better.
Parabellum style is cool because it's easy, but this increases the total volume of the pack, and i'd imagine that all that plastic adds decent amounts of weight too.

I guess my interest is in jamming as much capacity in a triangle bag as you possibly can, so turnigy multistar always wins out for a higher discharge setup. Until you get into those 3000-3500mah high energy cells and build the pack with nickel tabs. You could probably stuff 60AH 48v pack into a falconEV/em3ev type bag with those babies. If you need no more than 60A peak draw from a 60AH pack, then the 3000mah formulations are a real good match and will perform well.
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Re: Turnigy multistar vs. Samsung 25R

Post by 999zip999 » Jul 13 2015 1:01pm

Samsung 25r for ebike. Ask Elon 18650. Can't loan your multi star ebike to your brother, girlfriend or father for the weekend.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 1:15pm

999zip999 wrote:Samsung 25r for ebike. Ask Elon 18650. Can't loan your multi star ebike to your brother, girlfriend or father for the weekend.
Latter point is not true at all.
I charge my battery the exact same way you charge a commercial pack. One plug.. charger shuts off at 4.15v/cell average.. controller LVC prevents you from going too low by stopping at 3.5v average.

Yes, if you invent some pain in the ass series-parallel charging setup, then loaning the bike to someone is out of the question, but that's your fault.. not hobbyking's :)
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
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Re: Turnigy multistar vs. Samsung 25R

Post by DrKraut » Jul 13 2015 1:27pm

I just want to add a little story from me
I'm an electronics engineer and 2 years ago i started to build my first ebike. At that time i didn't had too much knowledge about batteries, but i knew i want 18650 since they seemed to be way more safe. Lifepo wasn't a choice for me since its really heavy. So as a student you don't have much money at all :lol: and i bought 120x 18650 with 2200mah from a laboratory for about ,7€ per cell. Only problem was they were only 1C cont.
I build a spot welder and started to assemble the pack. It had 72V and about 12Ah. For riding i put it in my backpack, because i live in the mountains and jumped pretty hard.
Anyway after about 50km a cell did explode, and the cooking electrolyte and other stuff punched through the insulation of the pack, then going through the backpack and my heavy winter jacked directly on my skin.
Wich caused a very deep flesh wound.Today i still have a pretty big scar.
I just wanted to tell that 18650, even with the protection functions can be pretty dangerous if you mistreat them

Today i only use 25R reinforced with EPDM sheets and a 2mm steel plate. Don't have any worries anymore :)
Just use the batteries below its spec and you can be happy ;)

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Re: Turnigy multistar vs. Samsung 25R

Post by okashira » Jul 13 2015 1:33pm

I don't even ...
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Re: Turnigy multistar vs. Samsung 25R

Post by zener » Jul 13 2015 1:42pm

Watch here http://www.ebikes.ca/product-info/cycle ... cycle-life charge these 18650 NCA to 4.05V and get double the live of RC-lipo. the LG HG2 have more capacity than multiStars so charging to 4.05V is about the same wh/kg as multistars charged to 4.15V. In the long run 18650 NCA are much cheaper. Simple calculation.... :wink:

You can also order cheaply pre spotwelded parraleled cells from china which can be easy put in serial with a solder iron and wires. Not damaging the cells with direct solder on them. No spotwelder needed.
neptronix wrote: They are.. but once you build a 25R pack, it is no longer really lighter, is it? Add those plastic cell dividers ( if you use those ), nickel tabs, solder, discharge wire, then wrap the cell in heatshrink or whatnot, and you're prolly right on par with multistar.. since we're comparing a completed pack to bare 18650 cells.
Most use hotglue some compress them just with adhesive tape. Thats all just a few 100gr for a whole pack.
But if you wan do pouch pack (rc-lipo) right without occasional puffing you must compress them between heave stiff plates!!! Calculates this please. :lol:

DrKraut wrote: So as a student you don't have much money at all :lol: and i bought 120x 18650 with 2200mah from a laboratory for about ,7€ per cell. Only problem was they were only 1C cont.
I build a spot welder and started to assemble the pack. It had 72V and about 12Ah. For riding i put it in my backpack, because i live in the mountains and jumped pretty hard.
Anyway after about 50km a cell did explode, and the cooking electrolyte and other stuff punched through the insulation of the pack, then going through the backpack and my heavy winter jacked directly on my skin.
Wich caused a very deep flesh wound.Today i still have a pretty big scar.
Maybe these 2200mah dont have the CID or even PTC protection which preven explosion trough vention on an overpressure event trough miss use.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 1:44pm

Wow :shock:
If you abused a RC Lipo and it caught on fire, the situation would be much worse.
Even a headways cell will ooze nasty liquid.

I think that a backpack battery is a problem waiting to happen. If you fall, there is a high chance that the battery pack will hit the ground and you'll be sitting there lying on it.

I think that triangle packs are the safest way to mount any battery. Your pedals, rear wheel, and front fork will prevent the battery pack from hitting the ground if you dump the bike.
I had a serious accident where my bike probably even rolled, and my RC Lipos did not take a scratch. They did not even any additional padding or protection. I still use that pack today. It's the handlebars, disc brake, fork, and rear wheel that got dinged really hard.
Efficiency is everything :bolt:

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 1:53pm

zener wrote:They are.. but once you build a 25R pack, it is no longer really lighter, is it? Add those plastic cell dividers ( if you use those ), nickel tabs, solder, discharge wire, then wrap the cell in heatshrink or whatnot, and you're prolly right on par with multistar.. since we're comparing a completed pack to bare 18650 cells.
Most use hotglue some compress them just with adhesive tape. Thats all just a few 100gr for a whole pack.
But if you wan do pouch pack (rc-lipo) right without occasional puffing you must compress them between heave stiff plates!!! Calculates this please. :lol:.[/quote]

I have never seen the need to compress a pouch pack and have used RC Lipo for 5 years without doing it and never seen a problem. I believe that compressing the pouch packs is dangerous, as you are preventing a critical safety mechanism ( puffing ) from engaging if you do that. The packs are designed to puff under stress.

My well-abused 5 year old pack shows no signs of puffing, but it has lost discharge capability as i've put the cycles on and calendar life on it. This is completely normal.

So i would not consider this a requirement in any way.
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by 999zip999 » Jul 13 2015 2:08pm

When I crashed I step off my bike and let go. I take a tumble, but learn to tumble without bike and battery. Can be hard to ditch a back pack battery. Luna Cycle now has 25r packs. No brainer

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Re: Turnigy multistar vs. Samsung 25R

Post by zener » Jul 13 2015 2:13pm

neptronix wrote: I have never seen the need to compress a pouch pack and have used RC Lipo for 5 years without doing it and never seen a problem. I believe that compressing the pouch packs is dangerous, as you are preventing a critical safety mechanism ( puffing ) from engaging if you do that. The packs are designed to puff under stress.

My well-abused 5 year old pack shows no signs of puffing, but it has lost discharge capability as i've put the cycles on and calendar life on it. This is completely normal.

So i would not consider this a requirement in any way.
Believing is not knowing. You maybe just got lucky with no puffing. I had read alot of puffed RC-lipo from other users.
Maybe liveforphysics can chime in and enlighten our believing's ?

Thanks for mentioning calendar life which NCA 18650s are also superior against RC-lipo.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 13 2015 3:05pm

zener wrote:Believing is not knowing. You maybe just got lucky with no puffing. I had read alot of puffed RC-lipo from other users.
Maybe liveforphysics can chime in and enlighten our believing's ?

Thanks for mentioning calendar life which NCA 18650s are also superior against RC-lipo.
I did not get lucky. Other folks who understand how to correctly spec and graph charge a RC Lipo pack also do not use compression and have not required compression either.
These packs swell naturally when being pushed very hard. They are designed to do that as a way of relieving internal stress. You want them to do that if you are pushing them very hard, too; otherwise they will find the weakest point of your compression and the swelling pressure will accumulate at that point, making it more likely to vent at that point because the edge of the foil pouch can no longer hold all that pressure in one place. You do NOT want to increase the possibility.

My old 150whrs/kg RC Lipos have excellent calendar life within the C rate i have been using them at. They've outlasted my interest in owning them because the >190whrs/kg multistars are so much better. It's the cycle life that could use improvement. 600 cycles is enough for me because i do not commute daily and battery technology improves faster than i wear a pack out.

It all depends on your expectations, i suppose.
If an 18650 chemistry were to cost twice as much but last twice as long, i can see how the value evens out for you.
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by Punx0r » Jul 15 2015 2:35am

neptronix wrote:They are designed to do that as a way of relieving internal stress
I'm not sure this is true...

It wouldn't explain how can cells survive, nor why pouch cell manufacturers like A123 specify compression requirements for pack builds.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 15 2015 4:02am

Ever seen a RC Lipo pouch cell?
Even better, ever seen how far one can puff?
There is extra material on the edges that is folded on each of those cells, which unfold under pressure and allow expansion under stress.

Image

Here is an example of a lipo cell 'unfolding' after being abused.
This is a safety feature. It also allows an easy visual inspection of a RC Lipo cell in order to determine it's health.

I actually had a 1 week old RC Lipo pack do this to me on the blue, before i'd even gotten to cycle test it. It had shorted internally very slowly.

Image

If i would have compressed the pack, i would have never caught this in time to put it in a fireproof area and let it do it's thing ( luckily, it just emitted a little smoke ).

Image

A healthy cell expands and contracts slightly under various states of charge as well. If you compress things really heavy at the wrong SOC, you're gonna have a bad time. I say just avoid it. I don't know of any performance or longevity advantages to that practice.

I have no experience with A123 pouch cells, so i can't comment on that.
Punx0r wrote:
neptronix wrote:They are designed to do that as a way of relieving internal stress
I'm not sure this is true...

It wouldn't explain how can cells survive, nor why pouch cell manufacturers like A123 specify compression requirements for pack builds.
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
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Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by Punx0r » Jul 15 2015 4:48am

I don't see the extra material in the last photo? It just looks like a square shape gone round.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 15 2015 2:22pm

Part of the flaps that are not glued/sealed are the extra material that helps the expansion happen. Lipos can puff up to almost twice their size.

If you took a RC lipo cell that was brand new and abused it to the point where it puffed ( usually this is due to heat ), you'd be able to observe this in person.
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by riba2233 » Jul 15 2015 3:57pm

neptronix wrote: The next generation of 18650's from the big companies will probably blow away the multistars. That's when i'd be willing to make the switch.

P.S. i cannot find a cell spec sheet or discharge graph for the LG H2. Can you link me to one?

Next generation? You mean current? Like Samsung 30Q and LG HG2? Same current as 25R/HE2 but 3000 mah. So, are you going to use them now? :mrgreen: :wink:

You can't find datasheet? Did you even see/read this thread?

http://endless-sphere.com/forums/viewto ... 14&t=57291

If you didn't, you've missed out a lot :)

Also, when calculating price per kwh or any price at all, take cycle and calendar life into account. When you do, 18650 cells become much cheaper compared to lipo. Lipo is meant to be (ab)used and to to last long. And yeah, 6$ wasn't price even when thy came out, now they are below 3$ for any meaningful quantity. Any volume will be low enough, just use tight hexagonal arrangement instead of standard, square one.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 15 2015 5:08pm

That thread is about the HE2, not the newer HG2. In 27 pages of that thread, is there something about the HG2?
Sag and watt hours delivered are terrible on the higher energy type cells at higher C rates. You can easily turn a 250Whrs/kg cell into a 175whrs/kg cell, which would be inferior to the turnigy multistars. In that use case, there is no point to forking over for the 18650s extra cost and going through all the work to assemble the pack.

I have seen poor cycle life on some of these newer cells as well. There is a poster ( i forget his name ) that did a bunch of cycle life tests on the Samsung 30Q for example, and saw cycle life falling off pretty fast. He had to keep tuning down the discharge and charge rates to get the cycle life to NOT rapidly deteriorate after 100-150 cycles.

The only newer 18650 that is of any interest to me is the Samsung 25R
My interest is in building multi thousand watt ebikes that go very long distances.

RC Lipo is designed to be abused, but it has so much C rate headroom that you can use it as a substitute for a higher quality, more expensive cell at the rating that the more expensive starts really suffering at and get good life and great performance out of it.

These big name 18650 companies rate their watt hours and cycle life at 0.2-0.5C for a reason.
I guess if you plan on using your 18650 pack at 0.2-0.5C on average, then that's no problem.
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
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Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: Turnigy multistar vs. Samsung 25R

Post by riba2233 » Jul 16 2015 2:37am

neptronix wrote:That thread is about the HE2, not the newer HG2. In 27 pages of that thread, is there something about the HG2?
Sag and watt hours delivered are terrible on the higher energy type cells at higher C rates. You can easily turn a 250Whrs/kg cell into a 175whrs/kg cell, which would be inferior to the turnigy multistars. In that use case, there is no point to forking over for the 18650s extra cost and going through all the work to assemble the pack.

I have seen poor cycle life on some of these newer cells as well. There is a poster ( i forget his name ) that did a bunch of cycle life tests on the Samsung 30Q for example, and saw cycle life falling off pretty fast. He had to keep tuning down the discharge and charge rates to get the cycle life to NOT rapidly deteriorate after 100-150 cycles.

The only newer 18650 that is of any interest to me is the Samsung 25R
My interest is in building multi thousand watt ebikes that go very long distances.

RC Lipo is designed to be abused, but it has so much C rate headroom that you can use it as a substitute for a higher quality, more expensive cell at the rating that the more expensive starts really suffering at and get good life and great performance out of it.

These big name 18650 companies rate their watt hours and cycle life at 0.2-0.5C for a reason.
I guess if you plan on using your 18650 pack at 0.2-0.5C on average, then that's no problem.
Yeah you wrote H2, I thought you asked for HE2 datasheet, not HG2. They should be the same, only different capacity. 30q and HG2 have same performance as 25R, only higher capacity. Okashira did a cycle test on 30Q, but that was with ultra fast charge, he was just testing that possibility. Quick charge is quickest killer of these cells, and 25R would perform the same. You need to learn how to interpret graphs. If you want, I will soon get one 30Q cell and I can do cycle life test in normal, real life conditions, and you'll see that the results will be much different.
Okashira also did same test on tesla s cells, and guess what, they performed the same! And tesla gives 8 year warranty on them. So, point is that the test is too harsh, not using real life conditions.

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Re: Turnigy multistar vs. Samsung 25R

Post by neptronix » Jul 16 2015 3:55am

I understand how to read graphs. I've been doing so for years.
You participated in the thread of discussion about the cell and obviously read the datasheet for that cell, and you're saying that the cells are equivalent? it may be you with the reading problem:

http://endless-sphere.com/forums/viewto ... 14&t=68556
riba2233 wrote:Now that's interesting! Datasheet looks ok. Cycle life doesn't look promising, but that's at bad conditions.
The 30Q is even more putzy than the 25R and not equivalent at all. Samsung's datasheet says that it's maximum continuous discharge is 15A. That's rather bad for a cell with another 500mah in it.
That's 5C max. The 25R is rated for 8C max.

The datasheet also says:
Cycle life
With standard charge and maximum continuous discharge.
Capacity after 250cycles,
Capacity ≥ 1,800mAh (60% of the nominal capacity at 25℃)
That's pathetic. Multistar lipo at 5C would last longer for sure. Funny how they did not cherry pick the data as cell manufacturers usually do and rate the cycle life at 0.00001C or somesuch.

But okashira's lower amp rate tests were not good either:

Image

That cell is a dead end.

Sorry if i miswrote HG2 but you cannot prove what you're saying without a datasheet.
Even lygte-info.dk has not tested it yet.
I'd guess that 20A ( 6.6C ) performance is awful just like on the samsung 25R on 8C where it's sagging down to 3.2ish volts and giving you lifepo4 cell voltages.
Attachments
INR18650-30Q Cell SPEC(Tentative)(1).pdf
(303.65 KiB) Downloaded 59 times
131101_Introduction of INR18650-25R.pdf
(792.04 KiB) Downloaded 58 times
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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