Stark mobile charger is out !

Theo

Theo

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Beagle said:
Cells like Molicel P50B have a fast charge rate of 5 C so they can be charged at 25 A and would take 12 min to fill up at this rate (obviously a bit longer in reality).
That would be 5,5 kW on standard 220 V.
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Actually, if you recharge, at 25 A, some series of P50B let's say made up of 100 cells each, it will be done at a voltage that will be roughly 360 V and that will rise during the charge, so the calculation isn't 25 A • 220 V = 5.5 kw; it's 25 A • 360 V = 9 kw and if you wanted to use a 220 V input current for the charger, it would be 25 C • 360 / 220 = 41 A. All this, of course, assuming a 100% efficiency.

Erwin P said:
How about you ride down the street twice, plug it in at full 6,6 and tell us what happens.
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Let's even say that he discharges the battery at 80 % (I don't know at which percentage a 6.6 kw charge would start to be reduced when getting close to 100%), consider that the charger is rated at 3.3 kw in the specification sheet downloadable at Stark's site, so he could even theoretically use an adapter and connect that charger to a charging station but he would't get more than that. After all, they would never allow a Shucko plug to pass more than 3.5 kw and I believe that it already gets 3.5 kw and roughly 0.2 kw are lost in inefficiency.
 
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Beagle

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Karinshi said:
yeah thats the new portable charger of 3.3, but should be another big one for "home charging" of 6.6kw, thats what the CEO said... no info yet but the APP is now showing the 6.6 option thats why im confused
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Surely that would "home charging" only if you already have your own EV charger setup at home, right?
 
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Erwin P

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Theo said:
Actually, if you recharge, at 25 A, some series of P50B let's say made up of 100 cells each, it will be done at a voltage that will be roughly 360 V and that will rise during the charge, so the calculation isn't 25 A • 220 V = 5.5 kw; it's 25 A • 360 V = 9 kw and if you wanted to use a 220 V input current for the charger, it would be 25 C • 360 / 220 = 41 A. All this, of course, assuming a 100% efficiency.


Let's even say that he discharges the battery at 80 % (I don't know at which percentage a 6.6 kw charge would start to be reduced when getting close to 100%), consider that the charger is rated at 3.3 kw in the specification sheet downloadable at Stark's site, so he could even theoretically use an adapter and connect that charger to a charging station but he would't get more than that. After all, they would never allow a Shucko plug to pass more than 3.5 kw and I believe that it already gets 3.5 kw and roughly 0.2 kw are lost in inefficiency.
Click to expand...
But he could just try to plug it in and see what happens, worst case the safety in his house ''falls''. Then you actually know it uses more power than normal.
 
Karinshi

Karinshi

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Beagle said:
Surely that would "home charging" only if you already have your own EV charger setup at home, right?
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What I mean is that Stark is supposedly going to release a charger identical to the one that comes with the bike but with 6.6kWh. I'm not an expert so I don't know if it's possible to plug a 6.6kW charger into a conventional wall socket or if an installation for that power is needed.
 
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OpaTsupa

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Houses in Europe and in the USA are not configured to output 6.6kW / ≈29A.
It can be done, but it requires investment in wiring, adapters, sockets and an electrician. Quick search for what EV cars use shows the range of 500-1000$.
Probably another 1-2000$ for the Stark turbo-charger.

@szczur333, explained it above with more expertise.

Leaving aside the need of such fast charging and long term impact on the battery ... This hypothetical charger would firmly be in the nice to have category, and I can't see how it will ever sell and to whom.

Only scenario is racing and racing teams, but how will they draw that much power in the field? [imagine an EV category of 10-20 bikes in MX]
 
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Beagle

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Indeed, a fast charger would be interesting if it's onboard a street bike so you can connect to the existing charging infrastructure, can't see what the point would be for MX/EX?
 
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Erwin P

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At home it makes no real sense.
But charging with 6.6 is really easy. Just need a 7kW generator/battery pack instead of a 4kW.

Also when there is an AC charger nearby you could just plug it in with an adapter.

They could even make it a 3 fase one. That's not to uncommen in a household with a serious garage. My house allready had it and gives you 11kW.

Also rental companies could really use this. You know the places where you can rent KTM 300's for Enduro tours? With the Stark that would be much cheaper to run (less maintenance) and you can put the power output to whatever you like. Range might be an issue but snapping the day in 2 (like they always do for lunch) and charge 6,6kW somewhere makes that a non issue.
 
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OpaTsupa

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What I would like to see first is definitive proof if fast charging is damaging the battery and to what extent.

Ever since mobile phones came 30+ years ago I'm hearing about formatting, protecting and correct charging of batteries all the while general public is using and misusing those batteries in every way imaginable.
Go to the Stark FB group to see some extreme practices that people get away with.
 
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Bodo

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Stark will set up the battery in terms of voltage @0% and @100% as well as the charging rate to get their desired battery life.

That said, their promise for the Varg EX in the manual is pretty low:
Screenshot_20251023_094429.png

That's five hours riding per week over two years; or a depreciation of €28 per riding hour for a basic Alpha.
 
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Bodo

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Aye, that's my point, Erwin. There's no reason to choose battery charge/discharge parameters to make it last longer than 500h, except to avoid warranty claims.

6.6kW charging is roughly 1C; P50B cell maximum is 5C -> 6.6kW is well within lifetime expectation while maintaining it safe against warranty claims. I imagine 2C could even be possible.
 
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Beagle

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OpaTsupa said:
What I would like to see first is definitive proof if fast charging is damaging the battery and to what extent.

Ever since mobile phones came 30+ years ago I'm hearing about formatting, protecting and correct charging of batteries all the while general public is using and misusing those batteries in every way imaginable.
Go to the Stark FB group to see some extreme practices that people get away with.
Click to expand...

For that we would need to know which cells are used in the 7.2 kWh battery.

Suppliers give very detailed information, for instance see https://www.molicel.com/inr-21700-p50b/

Screenshot_20251023-111653.png
Screenshot_20251023-111726.png

That's 80% capacity retention after 750 cycles at 5 C fast charge.

Screenshot_20251023-111846.png
 
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Bodo

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Let's do discharge:
  • 80 PS ≈ 58.84 kW mechanical.
  • Electric input (85–95% efficiency) ≈ 61.9 – 69.2 kW.
  • Pack current at 360 V ≈ 172 – 192 A.
  • Per-cell current (4P) ≈ 43 – 48 A → ~8.6C – 9.6C.
Though that's 80PS only for a few seconds.
Rated power (ie. continuous power over 30 mins) of the Varg is 9kW:
  • Electric input (85–95% efficiency) ≈ 9.5 – 10.6 kW.
  • Pack current at 360 V ≈ 26 – 29 A.
  • Per-cell current (4P) ≈ 6.6 – 7.4 A → ~1.3C – 1.5C.
The significant discharge spikes will degrade the cells further; additional to fast charging.
 
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Erwin P

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Bodo said:
Let's do discharge:
  • 80 PS ≈ 58.84 kW mechanical.
  • Electric input (85–95% efficiency) ≈ 61.9 – 69.2 kW.
  • Pack current at 360 V ≈ 172 – 192 A.
  • Per-cell current (4P) ≈ 43 – 48 A → ~8.6C – 9.6C.
Though that's 80PS only for a few seconds.
Rated power (ie. continuous power over 30 mins) of the Varg is 9kW:
  • Electric input (85–95% efficiency) ≈ 9.5 – 10.6 kW.
  • Pack current at 360 V ≈ 26 – 29 A.
  • Per-cell current (4P) ≈ 6.6 – 7.4 A → ~1.3C – 1.5C.
The significant discharge spikes will degrade the cells further; additional to fast charging.
Click to expand...
Damn, sounds like we shouldn't ride bikes at all...
 
Karinshi

Karinshi

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Bodo said:
Stark will set up the battery in terms of voltage @0% and @100% as well as the charging rate to get their desired battery life.

That said, their promise for the Varg EX in the manual is pretty low:
View attachment 15081

That's five hours riding per week over two years; or a depreciation of €28 per riding hour for a basic Alpha.
Click to expand...
that number concern me a lot, i already have 160 hours on just 5 months of use, and the limit is 500 hours? so the bike wont last me even a 2 year lifespan at this rate? and i dont even use It that much, some trails every other weekend and 2 days a week for work... i cant believe that
 
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Erwin P

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The bikes expected life where the bike functions as it should at the expected use is 500 hours.
Same for the MX.

That 500 hours is competition use. Jumping, bashing, racing. The stress to the frame and everything around it in MX or Enduro competition is something completely different to what you are doing.

You will see claims like this at any bike, especially MX and ENduro bikes.
 
Theo

Theo

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Julo EX said:
A friend of mine, actually charged at 6.6kW and it's working for him, it's drawing 5.9kW and he charged from 10-85 in like 45 min to an hour View attachment 15087
Click to expand...

Very interesting.
Considering 75% of 7.2 kwh, i. e. 5.4 kwh, in in 45/60 minutes, it must be indeed charging at more than 5 kw.
Pretty weird that Stark hasn't sent any email about this update.
I'd like to know whether there are signs of burns on the pins of the Schucko plug, though.
 
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