Samsung cell options: 40T, 50E, 50S, etc

[dimos15]

11 hours ago, Rawnei said:

I don't think so, think about it that would mean that most wheels are drawing much more current than what the cells they are using are rated for and we would see many problems.

You're worried that a high discharge cell won't be enough for our use-case meanwhile most wheels today use high capacity cells...

I am talking about the lynx and all the new wheels that come with 50s batteries.

This is what baffles me, most scooters,esk8s,e-bikes use high discharge cells.  Eucs and pedelec ebikes use high capacity

I think we belong to the first group. Especially now that euc racing is a thing .

12 hours ago, goatman said:

the p42 isnt chinese and the euc makers cant get a guaranteed supply of molicels so they quit using molicel

This is sad.  Most chinese esk8s have molicels https://www.meepoboard.com/products/meepo-hurricane-bamboo

https://tyneeboard.com/products/best-flexible-all-terrain-electric-skateboard-tynee-explorer

 

11 hours ago, Rawnei said:

It is not relevant because the wheel don't draw that much current from a single cell, so a cell torture test doesn't really tell us anything about our use case.

Another tidbit from that torture test the cells are discharged to 2.8V our wheels don't allow that low either.

If we want real tangible data the test have to be closer to our use case.

It is the same pattern at lower amps. Check the temp at 15amps compared to molicells

https://endless-sphere.com/sphere/threads/cycle-life-tests-of-high-power-density-cylindrical-cells.114473/

12 hours ago, goatman said:

you see the self healing every 50 cycles is more pronounced than the 50S

But all these cells are high capacity. Can you post the link for this diagram?

Edited November 27, 2023 by dimos15

[dimos15]

10 hours ago, Rawnei said:

How are these tests coming along? What conclusions did you draw?

Can we add p42 and 40t to the mix? @Jason McNeil

Edited November 27, 2023 by dimos15

[Panzer04]

16 hours ago, goatman said:

the P42 is a better cold weather cell than the 40T

the 40T likes regen and 10 amps, its a performance cell you can continuously discharge/charge/discharge without suffering cycle life while doing that more than you could in a day.

the p42 likes it hold or cold but not 10 amps, it cant get up to temperature for cycle life, it would rather see 12 amps right away to get its temperature up

the p42 isnt chinese and the euc makers cant get a guaranteed supply of molicels so they quit using molicel

you should want the P45 

if you ride when it isnt always sunny and 75 or warmer you shouldnt get a 40T

you should only want these cells for 4p packs if you ride hard, theyre high performance cells that perform/degrade like crap if theyre not being used  the way theyre designed to be used.

you see the self healing every 50 cycles is more pronounced than the 50S, it would be interesting to see someone do a continuous 10amp discharge/5amp charge/10amp discharge 10x in a row to see if it suffers any cycle life loss

This is not self healing. That specific test does a full 4.2-2.8V cycle every 50 cycles. The high energy cell chemsitry has a weird artifact from that which persists.

That test is not really ideal because ES insists on derating cells for cycle life (even though almost noone is putting 1k real cycles on a battery - and if they are life well lived IMO), but it's one of the only sources of data for the 50S cycle life in a low-drain application (and not 5C/25A).

21 hours ago, dimos15 said:

Sure but we got a step in the right direction by using molicells and 40t on some gotway wheels. Why are we going backwards now?

I don't want p45, i want p42 like every other performance electric vehicle.

I want to be able to charge fast and brake harder without overheating lol https://youtu.be/j3BjHuH3QNY?feature=shared&t=2909

The 50S runs hotter than the 50e

P45B is a strictly better P42A - it's the newer cell, lol.

50S runs cooler than 50E. It's lower IR, so lower heat dissipation. I don't get the weird obsession with 50E. It's a cheaper, shitter cell than the 50S that EUC makers use because they're cheap bastards and no one was really calling them out on it.

[dimos15]

20 minutes ago, Panzer04 said:

P45B is a strictly better P42A - it's the newer cell, lol.

p45b is double the price of p42, lol

 

20 minutes ago, Panzer04 said:

50S runs cooler than 50E. It's lower IR, so lower heat dissipation.

Jason posted a test which shows the contrary https://forum.electricunicycle.org/topic/33940-experience-with-50e-vs-40t/?do=findComment&comment=490354

 

 

Edited November 27, 2023 by dimos15

[Panzer04]

4 minutes ago, dimos15 said:

p45b is double the price of p42, lol

 

Jason posted a test which shows the contrary https://forum.electricunicycle.org/topic/33940-experience-with-50e-vs-40t/?do=findComment&comment=490354

 

 

Fair enough on price - all else being equal though.

They are doing something wrong in the test. The temperatures don't make any sense. Under the same conditions it's not physically possible the equivalently-functional 50E to be cooler than the 50S - the IR spec on the 50S is half that of 50E. I just noticed it's a pack-level test, so idk how they are measuring the temperature - it would depend a lot on where you put the probe. If it were cell-level it'd be hard to get wrong.

[Jason McNeil]

25 minutes ago, dimos15 said:

Jason posted a test which shows the contrary https://forum.electricunicycle.org/topic/33940-experience-with-50e-vs-40t/?do=findComment&comment=490354

Don't invest too much in that 3rd party lab result for the temps, those lab hands were stupid, attaching the probes in different positions, one on the outside of the foam; you wouldn't believe how much work it took to get that far & this is supposedly an accredited UL lab in Shenzhen  

This other one is from SS's 50S cell presentation is accurate. Their specs have a maximum operating temp of 80°C, but in their own presentation, they're testing the 50S to 93°C & that's not the oven test 

We might all be overthinking cell selection—difference between the latest Molicel & 50S is so marginal under synethetic loads—the main criteria is cell safety, e.g. does not spontaneously catch on fire a couple years down the road because of operating outside parameters, having that extra power on tap is icing on the cake.   

Edited November 27, 2023 by Jason McNeil

[dimos15]

19 hours ago, Jason McNeil said:

Don't invest too much in that 3rd party lab result for the temps, those lab hands were stupid, attaching the probes in different positions, one on the outside of the foam; you wouldn't believe how much work it took to get that far & this is supposedly an accredited UL lab in Shenzhen  

Damn this is crazy..  This test is very nice though because it is done with an euc battery pack. All these single cell tests are more ''inaccurate'' because the cells have different characteristics when you stack them on top of each other in a battery pack.

It would be nice if you can do a similar test under better conditions with high capacity and high discharge cells. I think it will benefit this community a lot and remove a lot of misconceptions. 

 

19 hours ago, Panzer04 said:

Fair enough on price - all else being equal though.

They are doing something wrong in the test. The temperatures don't make any sense. Under the same conditions it's not physically possible the equivalently-functional 50E to be cooler than the 50S - the IR spec on the 50S is half that of 50E. I just noticed it's a pack-level test, so idk how they are measuring the temperature - it would depend a lot on where you put the probe. If it were cell-level it'd be hard to get wrong.

iR changes with the state of charge and cell temperature depends on a lot of things. The 50s has less resistance(DC IR) than the p42 but it runs hotter https://forum.electricunicycle.org/topic/32663-inmotion-adventure-a-new-trail-wheel-from-inmotion/page/48/#comment-489438

 

Edited November 28, 2023 by dimos15

[alcatraz]

If you plot both cells together in a discharge test you should be able to see the difference in IR. The cell that voltage sags more is exhibiting a greater IR at that moment.

So while one cell might start off with less sag maybe it can't sustain it as well as another.

More sag should lead eventually to more heat building up.

I'm not an expert but it sounds plausible to me.

[alcatraz]

(The theory applies when comparing cells of equal measured capacity. Obviously a lower capacity cell will drop its voltage faster even if it has lower IR.)

[dimos15]

On 11/28/2023 at 3:04 AM, alcatraz said:

If you plot both cells together in a discharge test you should be able to see the difference in IR. The cell that voltage sags more is exhibiting a greater IR at that moment.

So while one cell might start off with less sag maybe it can't sustain it as well as another.

More sag should lead eventually to more heat building up.

I'm not an expert but it sounds plausible to me.

Yes i think that this is how you measure dc resistance..

The molicell p42 has 14.4 mOhms DC resistance while the 50s has 12.6 mOhms according to battery mooch

But at 35A pulse the 50s has higher voltage sag.

You can read more about why this happens here https://www.patreon.com/posts/why-are-cell-2-2-68482553

Edited November 29, 2023 by dimos15

[Jono]

Hi Everyone, this post is complimentary to my video regarding 50S vs 50E cells for the Lynx here:

 

 

This post is a more detailed chat with Jordan into the 50S battery cells.
The purpose being to shed some light on the expected differences to 50E and how to make an informed decision if buying a 50S EUC.

to Jordan (Electrical Engineer - responses in italics) from Jono

TAKEAWAYS:
- 50S

• A few percentage points more range

• Safer especially at higher speeds with unexpected loads (eg. sudden uphill)

• Batteries get less hot/more efficient, could have longer life but very marginal for almost everyone

• Tolerate fast charging better, but unlikely to make a difference unless using a massive charger (most will have 1.5kW/10A or something, would need 3kW/20A > more than most circuits)

It’s not a huge difference, but given the choice 50S > 50E, basically. And most people buying Lynxes are probably “best of the best” types. 

General statements about 50S cells

50S the new dog on the block and promises these benefits: Many of these claims are based on lab test data and not real world.

1. greater range of performance over the full 100% euc battery. Faster riding, acceleration and hillclimb power demands with a lower risk of cutout. Due to:

2. less voltage sag risks at lower battery due to the higher current (amps) output of the 50S

   1. Yep. Long story short, cutout mostly relevant at high speed. 50E will give you current at low speed, you’ll just blow up a lot of power as heat in the cells is all.

3. Higher continuous peak output for eg long speed runs or hillclimbs with lower risk of cell damage.

   1. You’ll waste less power in the battery, and heat it up less. In the extreme case of overheating your battery pack, 50S will take much longer thanks to reduced waste energy

4. Predicted to be better with higher voltage EUCs. Since they have less parallel packs (thus shared amps)

   1. Doesn’t matter, only total power demand. Higher voltage EUCs are often higher power, but it could be 100V like a sherman, doesn’t make a difference.

Why aren’t all EUCs 50S if they’re so great? Cost. Also:

There is a debate about the lifecycle being HALF the 50E. However the test data is for the MAXIMUM current draw of 25A this is 2.6x that of the 50E. Meaning it’s working a lot harder and likely generating more heat thus degrading the cell faster.

Our use case in EUCS won’t be working the cells this hard continuously. Therefore it’s predicted that the life cycle improves dramatically and maybe as good as the 50E at lighter loads.

• Yep! All low cycle life rumour is based on 25A 5C discharge testing, which is extremely high load

Questions

Voltage sag is the danger of 50E?

• Mainly - 50E rated internal resistance is rated at approximately 30mOhm, 50S is 15mOhm. This means at the same current 50S has ½ the voltage drop across the batteries as 50E. For example, at 10A:
  - 50E drops 0.3V, wasting 3W per cell
  - 50S drops 0.15V, wasting 1.5W per cell

• Don’t oversell the benefit of 50S:

  • Under typical high load of 10A (5kW on a lynx), a 50S might drop 0.15 V less - across a 36S (36 cells in series) battery like the lynx, this is about 6V (ie. 50E = 12V drop, about 8%, 50S = 6V drop, about 4%)

  • Dropping voltage is most dangerous at speed, as you need more voltage just to maintain a speed - if you drop below this it doesn’t matter how strong the battery is, you can’t get torque from the motor since you can’t increase current.

  • At low speeds it just doesn’t really matter (safety-wise), although 50S will be more efficient by wasting less energy as heat.

 

What is voltage sag?

• Voltage sag is the voltage dropped across the battery itself, due the Internal Resitance of the battery (nothing has zero resistance). High energy batteries have high internal resistance and high voltage sag under load, causing them to heat up and waste energy.

• Voltage sag is just wasted energy.

 

Do higher voltage wheels have higher voltage sag?

• Not really. It depends on the POWER of the wheel. All else being equal (battery, power) it makes no difference

  • A 100V wheel with 3kWh of battery will have identical energy losses and relative voltage sag at 3kW as a 150V with 3kWh wheel at 3kW. 

    • Eg. 100V wheel sags 2V, 150V wheel sags 3V (because it has 1.5x as many batteries in series), but this is 2% of either’s normal voltage. So the effect is the same

    • 100V wheel needs more current (3kW = 30A), but it has more batteries in parallel so the current per cell is the same.

 

Voltage sag issues are exacerbated because the Lynx is only 4 parallel packs (36S4P)?

• No, the most important factor is the total battery size compared to the power level

  • 1kWh of battery on an EUC that runs up to 5kW means possibly 5C discharge (C rating = how many times you could discharge the battery at that rate in an hour)

    • Eg. 5C for a 50E/50S battery is 5*5Ah = 25A discharge

  • 2.5kWh of battery on an EUC that runs up to 5kW is only 2C, (so 10A per cell if made with 50E/S)

• So EUCs with bigger batteries have more cells to distribute the load. EUCs with smaller batteries ask more of their batteries
  
   

Why is it more dangerous at lower battery charges?

• Mostly because you need a fixed amount of voltage to overcome motor back-voltage

  • See worked example
     

How does the higher current output of the 50S help mitigate this problem?

• Reduced voltage sag gives you more leeway. Most relevant at Higher speeds where you need to have enough voltage to overcome motor back-emf to start with. 

• Also, It’s worth noting that you get some extra range “for free” because you are wasting less energy in the battery pack, along with the extra voltage drop margin. Overall you’ll just get a bit more range on 50S than 50E.
   

Charge rate of lynx dc 151.2V at  5Amp by 4 packs = 5/4 = 1.25A charge per pack? This is to compare to some graphs I have at a 6A charge rate for cycle life.

• You could comfortably charge a 4P pack at 24A based on a 6A per cell charge spec. This is obviously pretty intense and equates to fully charging the battery in ~1hr. 5A for the full pack is quite slow. You could charge regularly at 12A and probably suffer fairly low degradation. 

 

Worked example

Max listed power 8000W for the Lynx

This gives a current draw per pack of 8000w / 151.2V = 52.9A / 4packs = 13.2A

You see it already exceeds the 50E cell limit of 9.8A however the 50E can peak higher at 15amps subject to thermal throttling (source david).
 

BUT the Lynx will ALSO likely peak higher than 8000W if previous wheels are anything to go by. EG i’ve seen 11000W on my Sherman S = 18.2A per pack. Now you can see why you will want the higher current of the 50S cells.

Note i’ve hit acceleration beeps on the Sherman S at 50% battery thus really making me rethink things. The Sherman S has more parallel packs thus shares the load better than the 4P of the Lynx.

 

It depends on back-emf margins in the motor. In theory, with free-spin of 125kph at 150V means the motor has a spin speed of 0.8kph/V. At 70 kph this is 84V of back-emf. This means the controller has 65V to push current through the motor at full charge. This is probably enough that you would be limited by the controller current capability and not the motor.

 

Now if the pack is 130V, you only have 45V of margin, or 30% less. In your Sherman example, 18A will cause about 0.5V of voltage sag on 50E cells. This would actually be higher on the Lynx because the battery is smaller! Assuming 0.5V of sag, you would lose *18V* under load, or in the example at 70kph, 45V - 18 = 27V left to drive the motor. Now much less current can be driven, reducing motor torque when it’s already heavily loaded by wind resistance etc. 0.5V at 11kW means ~1.5kW of power is being blown up in the battery as heat, doing nothing.

 

Basically, 50S would have half the sag here (9V), leaving you with 36V, or possibly 30% more torque in this situation. This is most important near the max motor speed for a battery voltage.

 

Eg. For lynx, half charge = 130V = 104kph instead. This is why beeps happen at lower speeds as the pack drains - the battery could tolerate giving more current but the motor can’t spin faster at that voltage.

Into some data

Lithium ion individual cell operating range:

3.2V to 4.2V

Power in watts = Volts (V) x Amps (A) short form P = VI

Watt Hours is the measure of battery capacity and is what gives you riding range.

Watt Hours = Volts (V) x Amp Hours (Ah) 

 

50E, this is what we’ve been using and it’s tried and true.
They’re rated at 9.6A. Where as the 50S 2.6x greater at 25A

The 50S reduces voltage sag because power = VI thus if we have more available amps to generate the same power, a greater voltage sag differential isn’t required.

 

Easiest way to frame this is V = IR - lower battery resistance, more voltage across the motor and less across the batteries. You want as much voltage available to the controller/motor as possible

[cegli]

On 11/26/2023 at 4:14 PM, dimos15 said:

You are right, i thought after all these years that they changed it but no.. Still call it current..

I still think that they can draw 90-100 battery amps , around 25A per battery .

How is it not relevant? Even from the spec sheets you can see that the samsung 40t completes the same test with 10A higher discharge!

It is obvious that the 40t will have higher cycle life than the 50s at the same amps..

Rawnei already covered a lot of this, but just to add some additional comments:

25A per battery in a 2700WHr pack (36s4p) would be 36*4*3.7*25 = ~13,320 Watts.  There isn't any wheel that's going to continuously output 13,320 watts.  In an 144 cell pack 40Ts are a definite step backwards.  This can be seen clearly in the discharge curves at 20W/30Ws per cell, which is a much more realistic "stress-test" for a wheel with a decent sized pack.

[alcatraz]

* At room temperature. 

At 0 or below you have maybe 1/3 of the amperage. At 35C you have reduced the thermal headroom with 15C so current needs to be pulled back.

[alcatraz]

Does any wheel set its tiltback depending on pack temp? And I'm not referring to max temp, but simply reduce power output depending on ambient temp.

[goatman]

more sag could be the resistance of the internal tag at high discharge rates that makes it hotter

25amp from a battery is useless in euc's but when i was looking for a real 10 amp cell for cycle life your typical 10amp cell was really only a 1c cell 3-5 amps

and also looking for a cell that could discharge then automatically switch to receiving a charge from solar then go back to discharging without suffering losses (like regen) and that was the 30Q and 40T but theyre both prone to self discharging and cant handle cold weather

it makes sense that what i saw as self healing was actually a discharge to 2.8v

if you fully cycle a 40t/30q or nissan leaf battery from 4.2v to 2.5v 2x youll straighten out the discharge carve and rejuvenate the cell

when i was doing those tests and uploading the results nobody knew what to call it.

the molicels i like because they can handle freezing temperatures if your wheel has to stay outside for 8 hours in the winter

ive pulled 8.5kw peak on my Master according to euc world and 5.5kw is normal which i really dont believe unless thats phase amps

whats euc world, phase amps or battery amps? i dont use euc apps unless i want to see something i find them annoying

[dimos15]

44 minutes ago, alcatraz said:

Does any wheel set its tiltback depending on pack temp? And I'm not referring to max temp, but simply reduce power output depending on ambient temp.

The s22 does that but this wheel has 125v mosfets so avoid like the plague

37 minutes ago, goatman said:

ive pulled 8.5kw peak on my Master according to euc world and 5.5kw is normal which i really dont believe unless thats phase amps

whats euc world, phase amps or battery amps? i dont use euc apps unless i want to see something i find them annoying

Euc wolrd reports phase amps and the peak power numbers are inaccurate

50 minutes ago, goatman said:

if you fully cycle a 40t/30q or nissan leaf battery from 4.2v to 2.5v 2x youll straighten out the discharge carve and rejuvenate the cell

Interesting. Do you have a link?

[Rawnei]

1 hour ago, dimos15 said:

The s22 does that but this wheel has 125v mosfets so avoid like the plague

S22 limits top speed when any of the battery sensors go 5C or below, not current though, also the mosfets in S22 is 150V mosfets.

[Rawnei]

@Jason McNeil question regarding a statement here: https://www.ewheels.com/product/veteran-lynx-2700wh-battery-3200w-motor-8kw-peak/

Quote

the 50S commands a slight lead over the the 50E for longevity, with >82% capacity retention over 600 cycles.

I might have missed it but where is the data/tests that supports this? I'm guessing this graph was based on some test data?

[alcatraz]

That's interesting. Let's see what the first wheel owners report. Most of the degradation happens in the first 100 cycles.

[dimos15]

7 hours ago, Rawnei said:

S22 limits top speed when any of the battery sensors go 5C or below, not current though, also the mosfets in S22 is 150V mosfets.

 

[Rawnei]

13 minutes ago, dimos15 said:

 

I'll be damned, but what this is saying is that there are 2 variants out there.

[dimos15]

21 minutes ago, Rawnei said:

I'll be damned, but what this is saying is that there are 2 variants out there.

What do you mean? You can't buy a s22 anymore. The pro is basically s22 batch 2

 

5 hours ago, Rawnei said:

@Jason McNeil question regarding a statement here: https://www.ewheels.com/product/veteran-lynx-2700wh-battery-3200w-motor-8kw-peak/

I might have missed it but where is the data/tests that supports this? I'm guessing this graph was based on some test data?

Ewheels/Veteran have a lot more data directly from samsung.

Edited November 29, 2023 by dimos15

[Rawnei]

10 minutes ago, dimos15 said:

What do you mean? You can't buy a s22 anymore. The pro is basically s22 batch 2

We weren't talking about what you get when you buy one today, we were talking about wheel throttling during low temperatures, I have an S22, it's early batch, most likely 150V controller, it throttles speed during low temperature as I already said.

[Tomallo]

Great info, very cool to see the differences clearly laid out. Especially the worked example. Clears up how it all works, with enough depth to be understood by a hobbyist. Thanks!

[dimos15]

2 years warranty on the battery!

Is Kebye reading this thread?

Edited December 3, 2023 by dimos15