Turnigy Multistar 10C 10AH versus Allcell pack comparison

[TheBeastie]

Your math is wrong. The RC lipos are rated 22.2V 6 cell makes 3.7V per cell. so the Multistar have 186,7whrs/kg.
..

My assumption is that the rated voltage is so chosen that the Wh can be calculated.
So i think the IR rises with the state of discharge and that's what shifts the rating to the lower than expected.

Yep full 300 cycles worst case. If you use them carefully than there should be 900-1100 cycles be possible.
..
For full 4.2V to 2.5V. There is no way someone will use them like that in a EV.
Tesla gives 8 years warranty on there 18650 li-ion system.

No way you would use HK LiPo in an EV either !....but we are talking about practical Ebike sized packs..10Ahr, 36 V and such like where you do want to get most of the capacity used.......or you would choose a smaller lighter pack.
And with those cells you have to dip down to under 3 volts to use that capacity.
Oh, and those Tesla packs only ever see 3C max , and have a very complex cooling system to help cell life.

And on that other point of yours about assembly....

economics calculation don't includes cycle life, shipping cost and bits&peaces to connect the lipos into a real battery.

Started reading this whole thread again because it was bumped and I can't help but agree with Vampa on the whole nominal debate for the sake of comparing total Wh of a battery pack. The "nominal voltage" by its self is harmless enough but when using it compare its total ability to give out amps over a time line to work out total watt hours it becomes very important.

If a HK pack only give out power till say v3.4 and a modern 18650 can give out amps to 2.5volts (
according to manufactures PDFs ) then you are essentially denying the 18650 its total power output based on a dubious voltage number.
4.2 - 3.4 = 0.8 (lipo finished)
3.4 - 2.5 = 0.9 (oh we got almost another whole 1 volt to go through on the 18650). If this 'nominal' voltage is god worthy then we are denying almost half 50% of the usable voltage level the 18650 when it could be giving out more amps/energy, its technically insane to otherwise to give other cell a higher multiplier for the total energy it can release based on this fact.
The lipo is going to be able to give out its power quicker but the 18650 will still get there over a longer period of time, the 18650 can't be denied of all its Ah.

Yes I know that HK packs have less sag but thats worth like 0.2v to 0.3v at most, what about the whole 0.7v left in the 18650? I think it should be included.

The official "nominal" voltage for Alkaline batteries Alkaline batteries is 1.5v which is at its very top, (just ctrl+f for nominal), for metal hydride ( NiMH ) its 1.2v which is also at its very top. In fact all the battery chemistries have their "nominal" voltage at the very peak of its charge except for lithium.
According to Batteryuniversity the convention of 3.6v for lithium is based on the fact that it represents three nickel-based (NiMH or Nicad) batteries connected in series (3 x 1.20V = 3.60V).

http://batteryuniversity.com/learn/article/confusion_with_voltages
I like hobbyking, but I don't think they are industry standard setting worthy to be able to choose the nominal voltage, they are just a another company operating out of China (sure I know they got local warehouses etc)
Considering all other chemistries alone have "nominal" voltage as the PEAK voltage the lithium nominal voltage of 3.x is proof that its completely arbitrary alone.
The other torpedo I have to fire on total Wh calculation via 3.7 is the fact that Batteryuniversity claim its done for marketing purposes.. "Some cell manufacturers mark their Li-ion as 3.70V/cell or higher. This offers a marketing advantage because the higher voltage boosts the watt-hours on paper"

Also we all know that 18650s have more total cycles then HK cells do, (example say 300HK-cycles vs 500-18650-cycles), so if you add this 3rd dimension to it on a super long enough time line your going to get more Wh out of the 18650 pack on its total cycles time line, sure thats worth an extra .1volt in the total Wh calculation and comparison?

Allcell 48v 20AH = 962whrs ( 3.7v nominal ), 5.830kg / 12.85lbs. or 165whrs/kg
Turnigy multistar 12S 20AH = 912whrs (3.8v nominal ), 4.756kg / 10.5lbs or 191whrs/kg

OK fine lets use your Whrs comparison but add the total expected cycles for the life time of the pack with HK 300 cycles vs 500 cycles, the Allcel pack is 8P, thats a lot of cells working together to share the work load, a lot of cycles should be expected.
Allcell 48v 20AH = 962whrs x 500 = 481,000 wHrs
Turnigy multistar 12S 20AH = 912whrs x 300 = 273,600 whrs

481,000 wHrs? Oh my god, the Allcell pack is now almost double the HK pack? Choosing any number other then this would technically mean you bought a whole battery pack for a single bike ride instead of a long term investment in a battery pack.
I guess the single watt hour comparison might be good if these battery packs aren't rechargeable but the fact is they are.
OK I admit it this post is a bit of a crazy man rant but you got to admit I have a bit of a point over the total whrs over total cycles comparison.

When I was doing capacitor math I discovered its harder to calculate Wh out of a compactor because it never pretends to have a constant voltage like a battery does but we are trying to pretend a battery does have a constant voltage when we know it doesn't, trying to take an average voltage doesn't cut it for me and this is why I believe battery cell/pack makers don't specify Wh on their products, its just too approximate and not accurate enough.
Wh should ideally only be used in mains power where the voltage is constant and not supplied via a chemical reaction.

I think I had a few other arguments as well but I forget them now..
Considering half of this thread of hi-jacked by arguments about lithium nominal voltage and my arguments above can't we just for the sake of next time do a comparison with the 18650 pack the extra 0.1v (3.7v) for the total Wh comparison in the future?
I just can't help but feel it will always come up again and hijack the thread and also leave me with a nagging feeling about it all my self.

Who knows maybe its starting a aneurysm or tumor in my brain and in 30 years time they will be able to pin point it via a super tech CAT-scan back to this argument about nominal voltage. I have a right to disagree and I will until I can be convinced otherwise.

 

[neptronix]

The nominal voltage is actually closer to 3.8.
icecube57 confirmed that it is within +/- 0.01v of 3.8.

The nominal voltage is not what hobbyking advertises. The give figures based on RC usage, where you're draining your battery in 5-30 minutes.. so they quote you a lower nominal voltage, yet in reality for our uses, nominal voltage is much higher if you are conservative with your C draw.

 

[neptronix]

Typical RC Lipo curve. Multistars match this curve. I drew a line for 3.7v. At low load ( same way that nominal voltages are calculated for 18650's ), does this look closer to 3.7 or 3.8v nominal to you? you can do the averaging math if you want.. but it does not look like 3.7 to me. Look at how short a period of time it spends underneath 3.7.

 

[zackclark70]

Your math is wrong. The RC lipos are rated 22.2V 6 cell makes 3.7V per cell. so the Multistar have 186,7whrs/kg.
..

My assumption is that the rated voltage is so chosen that the Wh can be calculated.
So i think the IR rises with the state of discharge and that's what shifts the rating to the lower than expected.

Yep full 300 cycles worst case. If you use them carefully than there should be 900-1100 cycles be possible.
..
For full 4.2V to 2.5V. There is no way someone will use them like that in a EV.
Tesla gives 8 years warranty on there 18650 li-ion system.

No way you would use HK LiPo in an EV either !....but we are talking about practical Ebike sized packs..10Ahr, 36 V and such like where you do want to get most of the capacity used.......or you would choose a smaller lighter pack.
And with those cells you have to dip down to under 3 volts to use that capacity.
Oh, and those Tesla packs only ever see 3C max , and have a very complex cooling system to help cell life.

And on that other point of yours about assembly....

economics calculation don't includes cycle life, shipping cost and bits&peaces to connect the lipos into a real battery.

Started reading this whole thread again because it was bumped and I can't help but agree with Vampa on the whole nominal debate for the sake of comparing total Wh of a battery pack. The "nominal voltage" by its self is harmless enough but when using it compare its total ability to give out amps over a time line to work out total watt hours it becomes very important.

If a HK pack only give out power till say v3.4 and a modern 18650 can give out amps to 2.5volts (
according to manufactures PDFs ) then you are essentially denying the 18650 its total power output based on a dubious voltage number.
4.2 - 3.4 = 0.8 (lipo finished)
3.4 - 2.5 = 0.9 (oh we got almost another whole 1 volt to go through on the 18650). If this 'nominal' voltage is god worthy then we are denying almost half 50% of the usable voltage level the 18650 when it could be giving out more amps/energy, its technically insane to otherwise to give other cell a higher multiplier for the total energy it can release based on this fact.
The lipo is going to be able to give out its power quicker but the 18650 will still get there over a longer period of time, the 18650 can't be denied of all its Ah.

Yes I know that HK packs have less sag but thats worth like 0.2v to 0.3v at most, what about the whole 0.7v left in the 18650? I think it should be included.

The official "nominal" voltage for Alkaline batteries Alkaline batteries is 1.5v which is at its very top, (just ctrl+f for nominal), for metal hydride ( NiMH ) its 1.2v which is also at its very top. In fact all the battery chemistries have their "nominal" voltage at the very peak of its charge except for lithium.
According to Batteryuniversity the convention of 3.6v for lithium is based on the fact that it represents three nickel-based (NiMH or Nicad) batteries connected in series (3 x 1.20V = 3.60V).

http://batteryuniversity.com/learn/article/confusion_with_voltages
I like hobbyking, but I don't think they are industry standard setting worthy to be able to choose the nominal voltage, they are just a another company operating out of China (sure I know they got local warehouses etc)
Considering all other chemistries alone have "nominal" voltage as the PEAK voltage the lithium nominal voltage of 3.x is proof that its completely arbitrary alone.
The other torpedo I have to fire on total Wh calculation via 3.7 is the fact that Batteryuniversity claim its done for marketing purposes.. "Some cell manufacturers mark their Li-ion as 3.70V/cell or higher. This offers a marketing advantage because the higher voltage boosts the watt-hours on paper"

Also we all know that 18650s have more total cycles then HK cells do, (example say 300HK-cycles vs 500-18650-cycles), so if you add this 3rd dimension to it on a super long enough time line your going to get more Wh out of the 18650 pack on its total cycles time line, sure thats worth an extra .1volt in the total Wh calculation and comparison?

Allcell 48v 20AH = 962whrs ( 3.7v nominal ), 5.830kg / 12.85lbs. or 165whrs/kg
Turnigy multistar 12S 20AH = 912whrs (3.8v nominal ), 4.756kg / 10.5lbs or 191whrs/kg

OK fine lets use your Whrs comparison but add the total expected cycles for the life time of the pack with HK 300 cycles vs 500 cycles, the Allcel pack is 8P, thats a lot of cells working together to share the work load, a lot of cycles should be expected.
Allcell 48v 20AH = 962whrs x 500 = 481,000 wHrs
Turnigy multistar 12S 20AH = 912whrs x 300 = 273,600 whrs

481,000 wHrs? Oh my god, the Allcell pack is now almost double the HK pack? Choosing any number other then this would technically mean you bought a whole battery pack for a single bike ride instead of a long term investment in a battery pack.
I guess the single watt hour comparison might be good if these battery packs aren't rechargeable but the fact is they are.
OK I admit it this post is a bit of a crazy man rant but you got to admit I have a bit of a point over the total whrs over total cycles comparison.

When I was doing capacitor math I discovered its harder to calculate Wh out of a compactor because it never pretends to have a constant voltage like a battery does but we are trying to pretend a battery does have a constant voltage when we know it doesn't, trying to take an average voltage doesn't cut it for me and this is why I believe battery cell/pack makers don't specify Wh on their products, its just too approximate and not accurate enough.
Wh should ideally only be used in mains power where the voltage is constant and not supplied via a chemical reaction.

I think I had a few other arguments as well but I forget them now..
Considering half of this thread of hi-jacked by arguments about lithium nominal voltage and my arguments above can't we just for the sake of next time do a comparison with the 18650 pack the extra 0.1v (3.7v) for the total Wh comparison in the future?
I just can't help but feel it will always come up again and hijack the thread and also leave me with a nagging feeling about it all my self.

Who knows maybe its starting a aneurysm or tumor in my brain and in 30 years time they will be able to pin point it via a super tech CAT-scan back to this argument about nominal voltage. I have a right to disagree and I will until I can be convinced otherwise.

my a123 amp20 16s pack has over 800 cycles mostly 14ah + charges so thats 537,000 wh minimum but probably closer to 750,000wh i have done over 20,000 miles on that pack it still has over 18ah capacity thats less than £0.02 a mile if it died right now but i think it will last much longer as they are rated to 3000 cycles