Why does a 48V100Ah LFP battery have a capacity of 5,120Wh instead of 4,800Wh?

[gotbeans]

Thanks for the explanation.
Is there an acceptable voltage range for 48V systems?

no, it depends on inverters
it's gonna be like 45-60volts or something for most stuff
data sheets will tell you
There are some older inverters, for example, that pre-date the lifepo4 batteries and thus won't say they are compatible with them... not sure if they are or aren't as far as voltage goes

View attachment 217479
Enjoybot's 5,120Wh battery has a nominal votage of 48V without mentioning 51.2V.
That's confusing.

yep I saw that, that's likely non technical person writing that or they did it on purpose for confusion reasons I said previously

 

[sunshine_eggo]

16S LFP better matches the operating range of 48V lead acid, which is what almost all of this equipment was designed for (lead acid).

15S LFP (48V nominal): 37.5V - 54.75V
16S LFP (51.2V nominal): 40V - 58.4V
24S lead acid (48V nominal): 42V - 59.2V

Operating range of 48V systems depends on the battery chemistry and equipment. My Victron inverter states a 38-66V operating range. My 14S NMC Lithium battery has an operating range of 42-58.8V.

 

[Banjohn]

48 = 12 x 4

But there is no exact 12V with 3.2V LFP cells. 4 of them gives you 12.8V for your "12V" battery.

Then you put 4 of them together for your "48V" battery, but 4 x 12.8V gets you 51.2V.

So there ya go.

That explains a lot.
Thank you for the help.
Seems like it's an old habit people don't want to update.
Just like Apple's lighting cable and the Imperial system.

 

[Banjohn]

16S LFP better matches the operating range of 48V lead acid, which is what almost all of this equipment was designed for (lead acid).

15S LFP (48V nominal): 37.5V - 54.75V
16S LFP (51.2V nominal): 40V - 58.4V
24S lead acid (48V nominal): 42V - 59.2V

Operating range of 48V systems depends on the battery chemistry and equipment. My Victron inverter states a 38-66V operating range. My 14S NMC Lithium battery has an operating range of 42-58.8V.

Trying to understand Enjoybot's spec.
What's the difference between charge voltage and operating range?

 

[sunshine_eggo]

View attachment 217507
Trying to understand Enjoybot's spec.
What's the difference between charge voltage and operating range?

Charge voltage is the voltage you charge to.

Battery voltage changes between full and empty.

The operating range includes the peak charge voltage AND DIScharging the battery to its minimum safe voltage.

 

[rhino]

Being a nitpick but I don't think people are using the term "nominally" correctly here. Nominally would be the general name which in our case would be 48V. So it is 48V nominally. It doesn't change based in the chemistry since we are all dealing with 12V, 24V, or 48V nominal systems irregardless of chemistry used. All the balance of system components are based on those nominal voltages.

 

[sunshine_eggo]

Being a nitpick but I don't think people are using the term "nominally" correctly here. Nominally would be the general name which in our case would be 48V. So it is 48V nominally. It doesn't change based in the chemistry since we are all dealing with 12V, 24V, or 48V nominal systems irregardless of chemistry used. All the balance of system components are based on those nominal voltages.

Uh-oh... you're about to get out-nitpicked...

I'll partially disagree with this. Take my inverter for example. 38-66V operating range for a "48V" system. What makes this system 48V nominal? Do other inverters adhere to this same range? No.

Per NEC article 100: Voltage, Nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). (CMP-1)

It's a term of convenience, but when considering specific components, nominal voltage becomes more than a convenience. It becomes very important. The capacity of a 51.2V nominal LFP battery is higher than a 48V nominal LFP (or lead acid) battery of the same Ah capacity. The capacity of a 51.8V nominal 14S NMC battery of the same Ah is even higher. If I used "48V" for the purposes of computing capacity of 16S LFP or 14S NMC, I'd get the wrong answer.

If I'm buying a battery, I want to know the nominal voltage. In helping others diagnose their issues, sometimes, this is the only clue that we're dealing with 15S instead of 16S.

IMHO, being fast and loose with incorrect application of "nominal voltage" is why the OP was confused to start with.

 

[Banjohn]

Uh-oh... you're about to get out-nitpicked...

I'll partially disagree with this. Take my inverter for example. 38-66V operating range for a "48V" system. What makes this system 48V nominal? Do other inverters adhere to this same range? No.

Per NEC article 100: Voltage, Nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). (CMP-1)

It's a term of convenience, but when considering specific components, nominal voltage becomes more than a convenience. It becomes very important. The capacity of a 51.2V nominal LFP battery is higher than a 48V nominal LFP (or lead acid) battery of the same Ah capacity. The capacity of a 51.8V nominal 14S NMC battery of the same Ah is even higher. If I used "48V" for the purposes of computing capacity of 16S LFP or 14S NMC, I'd get the wrong answer.

If I'm buying a battery, I want to know the nominal voltage. In helping others diagnose their issues, sometimes, this is the only clue that we're dealing with 15S instead of 16S.

IMHO, being fast and loose with incorrect application of "nominal voltage" is why the OP was confused to start with.

It's indeed very confusing.
Portable power stations are much easier to understand.

 

[Mattb4]

It's indeed very confusing.
Portable power stations are much easier to understand.

Yeah, you can pretty much guarantee that anything a portable power station claims is misleading. All designed to hook the unwary.

 

[wpns]

Portable power stations are much easier to understand.

Why? Have you measured the output with a DVM?

 

[Banjohn]

Why? Have you measured the output with a DVM?

Sorry, I don't what a DVM is.
Portable power stations are why I want to know more about DIY systems.
If I visit this forum without the knowledge of the portable, I would have turned away.
There is a learning curve for someone like me.
Portable Power Stations -> DIY 48V Systems -> Residential ESS

 

[wpns]

DVM

Sorry, Digital Volt Meter.

 

[exmarkretired]

Why? Have you measured the output with a DVM?

That gets people also. Old (er) people use the term VOM. Having dinner with an Electrical engineer, elctrician and an old tv technician that can fix anything including the old tube stuff... It was suggested you can almost tell a persons age by how they refer to 110 VAC rms if they use 110 115 or 120....

 

[upnorthandpersonal]

That gets people also. Old (er) people use the term VOM

We tend to use the term multi-meter in Europe more.

 

[B-ManFX4]

It's indeed very confusing.
Portable power stations are much easier to understand.

Portable power stations all have the same confusing battery components inside them too...

 

[ricardocello]

It was suggested you can almost tell a persons age by how they refer to 110 VAC rms if they use 110 115 or 120....

If they are really old, they say 50 cycle or 60 cycle instead of Hz.

 

[Banjohn]

Portable power stations all have the same confusing battery components inside them too...

Yes, it's more suitable for entry-level DIYers like me.

 

[IGBT]

If they are really old, they say 50 cycle or 60 cycle instead of Hz.

And really really old, they say piles instead of battery (unless they really have the piles).