## How do you think solid state batteries will change how we use hardware?

JackFlorey   100 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 07 2021 2:28pm
JackFlorey wrote:
Nov 07 2021 2:21pm
ebike4healthandfitness wrote:
Nov 07 2021 2:19pm
Ok. So if the battery connected to 72v 20 amp controller is also big enough to supply 40 amps as 36v.....then it is also big enough to supply 40 amps if the cells are internally 20s1xP rather than.10s2xP. Got it.
Nope. You still don't get it.

The number of cells is the same for either configuration thus the current flow per cell would be the same if connected to a 36v 40 amp controller or 72v 40 amp controller.
IF the power going to the motor is the same in both cases - yes.

However, the same battery, designed to provide 40 amps at 36 volts (10s2p), will have to supply twice the current per cell if it is reconfigured to provide 40 amps at 72 volts (20s1p.)

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 07 2021 2:38pm
ebike4healthandfitness wrote:
Nov 07 2021 2:28pm
JackFlorey wrote:
Nov 07 2021 2:21pm
ebike4healthandfitness wrote:
Nov 07 2021 2:19pm
Ok. So if the battery connected to 72v 20 amp controller is also big enough to supply 40 amps as 36v.....then it is also big enough to supply 40 amps if the cells are internally 20s1xP rather than.10s2xP. Got it.
Nope. You still don't get it.

The number of cells is the same for either configuration thus the current flow per cell would be the same if connected to a 36v 40 amp controller or 72v 40 amp controller.
IF the power going to the motor is the same in both cases - yes.

However, the same battery, designed to provide 40 amps at 36 volts (10s2p), will have to supply twice the current per cell if it is reconfigured to provide 40 amps at 72 volts (20s1p.)
The bolded part is what I was originally thinking.

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 07 2021 2:38pm
ebike4healthandfitness wrote:
Nov 07 2021 2:28pm
JackFlorey wrote:
Nov 07 2021 2:21pm
ebike4healthandfitness wrote:
Nov 07 2021 2:19pm
Ok. So if the battery connected to 72v 20 amp controller is also big enough to supply 40 amps as 36v.....then it is also big enough to supply 40 amps if the cells are internally 20s1xP rather than.10s2xP. Got it.
Nope. You still don't get it.

The number of cells is the same for either configuration thus the current flow per cell would be the same if connected to a 36v 40 amp controller or 72v 40 amp controller.
IF the power going to the motor is the same in both cases - yes.

However, the same battery, designed to provide 40 amps at 36 volts (10s2p), will have to supply twice the current per cell if it is reconfigured to provide 40 amps at 72 volts (20s1p.)
Not true.

ZeroEm   10 MW

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Location: San Antonio, TX

### Re: How do you think solid state batteries will change how we use hardware?

We are talking about EV's now not bike's 40a per cell right? Voltage has no effect on Amps per cell. Does make a difference in watts delivered.
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

JackFlorey   100 kW

Posts: 1306
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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 07 2021 5:06pm
JackFlorey wrote:
Nov 07 2021 2:38pm
However, the same battery, designed to provide 40 amps at 36 volts (10s2p), will have to supply twice the current per cell if it is reconfigured to provide 40 amps at 72 volts (20s1p.)
Not true.
True due to Kirchoff's Law.

At the top of a 20s1p stack, there is a single cell connected to the output lead (might be a BMS in line as well, but that doesn't affect current sharing.) All the current - 40 amps - will come from that 1 cell.

At the top of a 10s2p stack, there are two cells connected to the output lead. Kirchoff says that the sum of currents into each node must be zero. So 40 amps is leaving the stack; that means each 10s stack is supplying half the current - or 20 amps per cell. (Assuming matched cells and same charge level in each string of course.)

BalorNG   1 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 07 2021 5:51pm
ebike4healthandfitness wrote:
Nov 07 2021 5:06pm
JackFlorey wrote:
Nov 07 2021 2:38pm
However, the same battery, designed to provide 40 amps at 36 volts (10s2p), will have to supply twice the current per cell if it is reconfigured to provide 40 amps at 72 volts (20s1p.)
Not true.
True due to Kirchoff's Law.

At the top of a 20s1p stack, there is a single cell connected to the output lead (might be a BMS in line as well, but that doesn't affect current sharing.) All the current - 40 amps - will come from that 1 cell.

At the top of a 10s2p stack, there are two cells connected to the output lead. Kirchoff says that the sum of currents into each node must be zero. So 40 amps is leaving the stack; that means each 10s stack is supplying half the current - or 20 amps per cell. (Assuming matched cells and same charge level in each string of course.)
The thread has devolved into a horror genre.

Point is, when you ride at SAME speed, at same PHASE CURRENT, using SAME MOTOR, it means you are using SAME POWER.
And since power is volts times amps, and assuming that power is 1440w, than *controller* will draw, 20 amps from 72v or 40A 36 battery (and do the voltage/current conversion)!
And since our batteries in question are 20Ah and 40Ah respectively, both will have a nice 1C discharge rate per cell. *sigh*
Again, this is pretty obvious once you play with simulator.

In fact, 72v battery is slightly better, because your battery wires will stay colder AND it will allow you to achieve higher speeds BUT, of course, you'll need not 20A, but say, 40A current capacity because you'll be using much more POWER pushing air out of the way (and no amount of switches will help unless you'll add an *other* battery in series, but why not just wire it in and be happy about it?), but so far as climbing steep slopes are concerned, they will behave the same.

Of course, higher voltage controllers are more expencive, fets they use are a bit lossier usually, and chance of being electrocuted skyrocket when you move from 36v to 72v, but those are entirely different concerns.

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 07 2021 5:51pm
ebike4healthandfitness wrote:
Nov 07 2021 5:06pm
JackFlorey wrote:
Nov 07 2021 2:38pm
However, the same battery, designed to provide 40 amps at 36 volts (10s2p), will have to supply twice the current per cell if it is reconfigured to provide 40 amps at 72 volts (20s1p.)
Not true.
True due to Kirchoff's Law.

At the top of a 20s1p stack, there is a single cell connected to the output lead (might be a BMS in line as well, but that doesn't affect current sharing.) All the current - 40 amps - will come from that 1 cell.

At the top of a 10s2p stack, there are two cells connected to the output lead. Kirchoff says that the sum of currents into each node must be zero. So 40 amps is leaving the stack; that means each 10s stack is supplying half the current - or 20 amps per cell. (Assuming matched cells and same charge level in each string of course.)
Ok, so I was right the first time and Balor was wrong. (A battery that could configure to 36v from 72v does have advantages. See results of ebikes.ca motor simulator I posted around the middle of page 5 of this thread--> viewtopic.php?f=3&t=113484&start=100#p1681315. A 72v VESC could not do the same using a battery with the same number of cells without more stress per cell).

JackFlorey   100 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 07 2021 6:37pm
Ok, so I was right the first time and Balor was wrong. (A battery that could configure to 36v from 72v does have advantages. See results of ebikes.ca motor simulator I posted around the middle of page 5 of this thread--> viewtopic.php?f=3&t=113484&start=100#p1681315. A 72v VESC could not do the same using a battery with the same number of cells without more stress per cell).
Nope. There is no free lunch. No matter what configuration the battery is, you will pull the same power from every cell if you have the same number of cells and the same power to the motor. (Minus inefficiencies in the wiring/controller.)

Battery voltages are not decided based on some magical method that decreases load per cell for a given battery power. They are based on:

1) What voltage the controller can handle
2) What the motor's base speed is at battery voltage, and what speed it will be used at most often (assuming BLDC motor)
3) Conductor sizing (higher voltage = thinner conductor required for same loss.)

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 07 2021 10:54pm
ebike4healthandfitness wrote: Ok, so I was right the first time and Balor was wrong. (A battery that could configure to 36v from 72v does have advantages. See results of ebikes.ca motor simulator I posted around the middle of page 5 of this thread--> viewtopic.php?f=3&t=113484&start=100#p1681315. A 72v VESC could not do the same using a battery with the same number of cells without more stress per cell).
Nope. There is no free lunch. No matter what configuration the battery is, you will pull the same power from every cell if you have the same number of cells and the same power to the motor. (Minus inefficiencies in the wiring/controller.)
If you look at the comparison I did on the ebikes.ca motor simulator you will see the GMAC 10T motor made more power at 5 mph using 36v at 40 amps compared to using 72v at 20 amps. The only way for 72v to catch up is to pull a lot more amps per cell.

More power at 5 mph means the 36v at 40 amp will climb steep hills better than when using 72v 20 amp. With that noted I did notice that 72v at 40 amp makes the most power at 5 mph, but you would need twice as many cells to keep stress per cell the same.

(The point of switching to 36v 40amp (from 72v 20 amp) is to increase low speed power...and according to the simulator it works.)

The VESC idea that Balor proposed is interesting, but its problem lies in being married to 72v at low speed. I am assuming a VESC that could switch from 72v to 36v plus have all it's other functions fixes that. Either that or use a battery with twice as many cells so 72v can be used with high amps at low speed. Then at higher wheel speed dial back the amps so the max power stays within the boundary of a moped.

BalorNG   1 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 07 2021 11:35pm
JackFlorey wrote:
Nov 07 2021 10:54pm
ebike4healthandfitness wrote: Ok, so I was right the first time and Balor was wrong. (A battery that could configure to 36v from 72v does have advantages. See results of ebikes.ca motor simulator I posted around the middle of page 5 of this thread--> viewtopic.php?f=3&t=113484&start=100#p1681315. A 72v VESC could not do the same using a battery with the same number of cells without more stress per cell).
Nope. There is no free lunch. No matter what configuration the battery is, you will pull the same power from every cell if you have the same number of cells and the same power to the motor. (Minus inefficiencies in the wiring/controller.)
If you look at the comparison I did on the ebikes.ca motor simulator you will see the GMAC 10T motor made more power at 5 mph using 36v at 40 amps compared to using 72v at 20 amps. The only way for 72v to catch up is to pull a lot more amps per cell.

More power at 5 mph means the 36v at 40 amp will climb steep hills better than when using 72v 20 amp. With that noted I did notice that 72v at 40 amp makes the most power at 5 mph, but you would need twice as many cells to keep stress per cell the same.

(The point of switching to 36v 40amp (from 72v 20 amp) is to increase low speed power...and according to the simulator it works.)

The VESC idea that Balor proposed is interesting, but its problem lies in being married to 72v at low speed. I am assuming a VESC that could switch from 72v to 36v plus have all it's other functions fixes that. Either that or use a battery with twice as many cells so 72v can be used with high amps at low speed. Then at higher wheel speed dial back the amps so the max power stays within the boundary of a moped.
Where's that comparison you are speaking about? How about a link? I want to look at it's parameters - something is off here.

ebike4healthandfitness   10 kW

Posts: 553
Joined: May 19 2012 10:20pm

### Re: How do you think solid state batteries will change how we use hardware?

BalorNG wrote:
Nov 08 2021 6:53am
ebike4healthandfitness wrote:
Nov 07 2021 11:35pm
JackFlorey wrote:
Nov 07 2021 10:54pm
ebike4healthandfitness wrote: Ok, so I was right the first time and Balor was wrong. (A battery that could configure to 36v from 72v does have advantages. See results of ebikes.ca motor simulator I posted around the middle of page 5 of this thread--> viewtopic.php?f=3&t=113484&start=100#p1681315. A 72v VESC could not do the same using a battery with the same number of cells without more stress per cell).
Nope. There is no free lunch. No matter what configuration the battery is, you will pull the same power from every cell if you have the same number of cells and the same power to the motor. (Minus inefficiencies in the wiring/controller.)
If you look at the comparison I did on the ebikes.ca motor simulator you will see the GMAC 10T motor made more power at 5 mph using 36v at 40 amps compared to using 72v at 20 amps. The only way for 72v to catch up is to pull a lot more amps per cell.

More power at 5 mph means the 36v at 40 amp will climb steep hills better than when using 72v 20 amp. With that noted I did notice that 72v at 40 amp makes the most power at 5 mph, but you would need twice as many cells to keep stress per cell the same.

(The point of switching to 36v 40amp (from 72v 20 amp) is to increase low speed power...and according to the simulator it works.)

The VESC idea that Balor proposed is interesting, but its problem lies in being married to 72v at low speed. I am assuming a VESC that could switch from 72v to 36v plus have all it's other functions fixes that. Either that or use a battery with twice as many cells so 72v can be used with high amps at low speed. Then at higher wheel speed dial back the amps so the max power stays within the boundary of a moped.
Where's that comparison you are speaking about? How about a link? I want to look at it's parameters - something is off here.
Scroll up four posts from this one. You will find the link there.

JackFlorey   100 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 07 2021 11:35pm
If you look at the comparison I did on the ebikes.ca motor simulator you will see the GMAC 10T motor made more power at 5 mph using 36v at 40 amps compared to using 72v at 20 amps.
Right. And the 72 volt system pulls more than twice the power than the 36 volt system at 20mph.

And that has nothing to do with battery layout or how much each cell contributes. It has to do with matching the battery and controller to the motor.

You are confusing system design and basic electrical design here. Basic electrical design says that if you have a nS2P battery vs a nS1P battery, the 1P battery will see 2x the current draw from each cell for a given current. Likewise, if you have an nS2P battery vs a 2nS1P battery, and you are drawing the same POWER from both batteries, then each cell will contribute the same amount of power to the output - because there are the same number of cells in each battery, and a properly designed battery drains all the cells at the same rate. (Again, assuming matched cells at the same state of charge.)

Note that one of those batteries will have twice the voltage as the other, which is where system design comes into play.

You can certainly choose a SYSTEM design where a 36 volt design draws more power than a 72 volt one; that's trivial. But it's also not that meaningful.

ZeroEm   10 MW

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Location: San Antonio, TX

### Re: How do you think solid state batteries will change how we use hardware?

Getting lost in the details. Build for your needs. The best battery is the one that is most useful for you. Have more volts than needed is a waste of money and efficiency. Limited myself to 40a mostly over wiring, to lazy to upgrade. Adjusted the motor and battery to hit my targets.
2019 Performer E-Trike
2013 Nissan Leaf S 7 bars 331.5w/KM

ebike4healthandfitness   10 kW

Posts: 553
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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 08 2021 12:27pm
ebike4healthandfitness wrote:
Nov 07 2021 11:35pm
If you look at the comparison I did on the ebikes.ca motor simulator you will see the GMAC 10T motor made more power at 5 mph using 36v at 40 amps compared to using 72v at 20 amps.
Right. And the 72 volt system pulls more than twice the power than the 36 volt system at 20mph.
Yes, the 36v 40 amp is better at low speed and the 72v 20 amp is better at high speed.

So a system that could switch between the two on the fly would be an improvement compared to current ebikes and e-mopeds. (I noticed several of the electric power tool companies have batteries that can switch voltages and amps, so I know this is possible at the battery level at least.)

JackFlorey   100 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 08 2021 12:49pm
Yes, the 36v 40 amp is better at low speed and the 72v 20 amp is better at high speed.
If you have a 36V battery with a given motor and you want to go faster, then yes, going to 72V would allow you to go faster.

However, a better design choice would be to choose a voltage, a controller and a motor that gives you the speed/torque ranges you want.

Again, nothing to do with battery design, and nothing to do with solid state batteries.
So why not make a system that can switch between the two on the fly? (DeWalt had a battery that could switch voltages and amps, so I know this is possible at the battery level at least.)
1) You then need two sets of regen limit voltages and LVC voltages
2) You need to design for the 36V current draws, which means the cabling will be thicker, heavier and more expensive
3) You need that one very big switch (cost/performance.)

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 08 2021 1:20pm
ebike4healthandfitness wrote:
Nov 08 2021 12:49pm
Yes, the 36v 40 amp is better at low speed and the 72v 20 amp is better at high speed.
If you have a 36V battery with a given motor and you want to go faster, then yes, going to 72V would allow you to go faster.

However, a better design choice would be to choose a voltage, a controller and a motor that gives you the speed/torque ranges you want.
I think single voltages make more sense for any application where there are an abundance of cells present for battery capacity reasons.

But for something like an ebike or e-moped they don't have a lot of capacity per combined vehicle/rider weight or capacity per vehicle power. So for ebike or e-moped switchable voltage and amps makes more sense than single voltage.

BalorNG   1 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Oct 11 2021 9:16pm
Here is a comparison I ran of a 72v GMAC 10T with 20 amp controller vs. 36v GMAC 10T with a 40 amp controller.
DAFUQ, excuse my french?
You were talking about 20ah vs 40ah batteries, and how we are suddenly talking about 20amp vs 40amp *controllers*?
How's that for a bait and switch...

BalorNG   1 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 08 2021 1:45pm
JackFlorey wrote:
Nov 08 2021 1:20pm
ebike4healthandfitness wrote:
Nov 08 2021 12:49pm
Yes, the 36v 40 amp is better at low speed and the 72v 20 amp is better at high speed.
If you have a 36V battery with a given motor and you want to go faster, then yes, going to 72V would allow you to go faster.

However, a better design choice would be to choose a voltage, a controller and a motor that gives you the speed/torque ranges you want.
I think single voltages make more sense for any application where there are an abundance of cells present for battery capacity reasons.

But for something like an ebike or e-moped they don't have a lot of capacity per combined vehicle/rider weight or capacity per vehicle power. So for ebike or e-moped switchable voltage and amps makes more sense than single voltage.
No, it does not... maybe for legal reasons only, but than a switch that would simply change a few software settings in an existing controller will do the same jobs and better in fact, in fact you do not even need a visible 'switch' at all, just say a hall sensor and magnet you that you place and remote to 'throttle' the system to legal values if you'll get examined by authorities if you are after than (but if you want to blast uphill with two riders onboard I doubt that will fool anyone).

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

BalorNG wrote:
Nov 08 2021 2:16pm
ebike4healthandfitness wrote:
Oct 11 2021 9:16pm
Here is a comparison I ran of a 72v GMAC 10T with 20 amp controller vs. 36v GMAC 10T with a 40 amp controller.
DAFUQ, excuse my french?
You were talking about 20ah vs 40ah batteries, and how we are suddenly talking about 20amp vs 40amp *controllers*?
How's that for a bait and switch...
Are you feeling OK?

The conversation was always about 36v @ 40 amps and 72v @ 20 amps, not 20ah vs 40ah batteries.

JackFlorey   100 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 08 2021 1:45pm
But for something like an ebike or e-moped they don't have a lot of capacity per combined vehicle/rider weight or capacity per vehicle power. So for ebike or e-moped switchable voltage and amps makes more sense than single voltage.
IMO you are still better off choosing the right voltage/battery/controller for your needs. There's no significant advantage to switching between voltages. You're pulling the same power from each cell in either case (assuming same power to the motor.)

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

JackFlorey wrote:
Nov 08 2021 2:35pm
ebike4healthandfitness wrote:
Nov 08 2021 1:45pm
But for something like an ebike or e-moped they don't have a lot of capacity per combined vehicle/rider weight or capacity per vehicle power. So for ebike or e-moped switchable voltage and amps makes more sense than single voltage.
IMO you are still better off choosing the right voltage/battery/controller for your needs. There's no significant advantage to switching between voltages. You're pulling the same power from each cell in either case (assuming same power to the motor.)
Your suggestion works well enough as long as a relatively large battery pack accompanies it.

For people that want battery packs smaller than
that the dual voltage and amps works better

Chalo   100 GW

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### Re: How do you think solid state batteries will change how we use hardware?

How about instead of speculating on these things, you actually build up some different systems and develop a body of informed experience? You sure like to hand out a lot of prescriptions to folks who've done much more of this stuff than you have.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

BalorNG   1 kW

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### Re: How do you think solid state batteries will change how we use hardware?

Chalo wrote:
Nov 08 2021 4:00pm
How about instead of speculating on these things, you actually build up some different systems and develop a body of informed experience? You sure like to hand out a lot of prescriptions to folks who've done much more of this stuff than you have.
Yea, I think the guy is an elaborate troll. I'm out of here...

ebike4healthandfitness   10 kW

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### Re: How do you think solid state batteries will change how we use hardware?

BalorNG wrote:
Nov 08 2021 4:07pm
Chalo wrote:
Nov 08 2021 4:00pm
How about instead of speculating on these things, you actually build up some different systems and develop a body of informed experience? You sure like to hand out a lot of prescriptions to folks who've done much more of this stuff than you have.
Yea, I think the guy is an elaborate troll. I'm out of here...
You weren't even reading the thread.....claiming I was talking about 36v 40ah vs. 72v 20ah batteries. What the \$#@ ?!?!

Yeah go....please. You weren't contributing anything useful.

JackFlorey   100 kW

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### Re: How do you think solid state batteries will change how we use hardware?

ebike4healthandfitness wrote:
Nov 08 2021 3:08pm
Your suggestion works well enough as long as a relatively large battery pack accompanies it.
Nope. Same-same. You don't get any magic "more power from fewer cells" by tricky combinations of S and P parameters. You just get a voltage (via the S parameter) and the current/ampacity you need (via the P parameter) and you go from there.

You are missing something very basic here, and I'm not even sure what it is.