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280Ah batterybank and 3000W inverter

J

jmsol

New Member
Joined
Mar 27, 2022
Messages
42
Hi!

I'm planning for my 24V LFP 8x280Ah (290Ah) batterybank and wondering if it will be enough for a 3000W LF inverter. 3000W is the absolute max I will use continuously and only for a shorter time, the general draw will be much lower depending on what is used at any given time.

I see the recommendation below and wonder if 3000W inverter will still work?
  • 12V battery system -> inverter below 1000W
  • 24V battery system -> inverter from 1000-2000W
  • 48V battery system -> inverter from 2000W to 4000W
 
Last edited:
Technically possible. That load will draw approx 125A at 24v, so you will need suitably sized BMS. And obviously would only last about 2h.

Any reason for not going 48v?
 
SeaGal said:
Technically possible. That load will draw approx 125A at 24v, so you will need suitably sized BMS. And obviously would only last about 2h.

Any reason for not going 48v?
Click to expand...
Thanks for quick answer.

Ok. So will a 3000W inverter also work for 2000W or lower contionuously?

The reason I'm asking is I want the option for 3000W draw.

150A BMS enough?

Not necessarily, I just think it will suit my needs best.
 
jmsol said:
Thanks for quick answer.

Ok. So will a 3000W inverter also work for 2000W contionuously?
Click to expand...
Should be fine - they are rated to run at max power. Obviously some makes might be more robust that others - bit like cars!

jmsol said:
The reason I'm asking is I want the option for 3000W draw.

150A BMS enough?
Click to expand...
Yes. 3000W at 24v is 125A

jmsol said:
Not necessary, I just think it will suit my needs best.
Click to expand...
 
SeaGal said:
Should be fine - they are rated to run at max power. Obviously some makes might be more robust that others - bit like cars!


Yes. 3000W at 24v is 125A
Click to expand...
Great.

Sorry if this sound stupid, but why is minimum 300Ah battery recommended for a 3000W inverter. Is it all about the max contionous draw, and not about powering the inverter?
 
jmsol said:
Great.

Sorry if this sound stupid, but why is minimum 300Ah battery recommended for a 3000W inverter. Is it all about the max contionous draw, and not about powering the inverter?
Click to expand...

I don't know what the source of your original recommendation was, but I would not disagree that they are sensible. Not sure where the reference to 300Ah came from though - your original question was about voltages.

Increasing voltage is more efficient for handling higher currents - that's why the electricity grid runs at 1000's of volts and not 230V. V=IR, power = volts x amps, so losses increase with the square of current for a given wire resistance.

Yes, you _can_ draw 125A off a 24v system, but I would _recommend_ 48v would be a better choice. But everyone's situation / limitations on size / money etc. is different hence YMMV..
 
jmsol said:
Hi!

I'm planning for my 24V LFP 8x280Ah (290Ah) batterybank
Click to expand...
Why 280 but 290 in brackets?
jmsol said:
and wondering if it will be enough for a 3000W LF inverter.
Click to expand...
Which one?
Some LF inverters are rated in volt amps instead of watts.
jmsol said:
3000W is the absolute max I will use continuously and only for a shorter time, the general draw will be much lower depending on what is used at any given time.

I see the recommendation below and wonder if 3000W inverter will still work?
  • 12V battery system -> inverter below 1000W
  • 24V battery system -> inverter from 1000-2000W
  • 48V battery system -> inverter from 2000W to 4000W
Click to expand...
3000 ac watts / .85 conversion factor / 24 volts low cutoff = 147.058823529 inverter dc amps
147.058823529 inverter dc amps / .8 fuse headroom = 183.823529412 fuse amps

That means 150 amp BMS minimum 200 amps continuous is better.
300 amp hours of LFP battery to keep the draw down to ~.5c
That also means pure copper 1/0 awg with a 250 amp class t fuse.

Two good reasons to go with 24 volts instead of 48 is its very hard to source breakers and switching gear suitable for a 48 volt LFP system.
 
SeaGal said:
Not sure where the reference to 300Ah came from though - your original question was about voltages.
Click to expand...
Sorry if I was a bit unclear. I was reading a recommendation on how to size battery to inverter and 300Ah was said to be the minimum for 3000W. Because I only have 280Ah (3.2V 8S) I'm curious if it's still doable with said inverter. Normally I would go with 2000W but since I need the option for higher draw around 3000W I'm researching this option.
Increasing voltage is more efficient for handling higher currents - that's why the electricity grid runs at 1000's of volts and not 230V. V=IR, power = volts x amps, so losses increase with the square of current for a given wire resistance. Yes, you _can_ draw 125A off a 24v system, but I would _recommend_ 48v would be a better choice. But everyone's situation / limitations on size / money etc. is different hence YMMV..
Click to expand...
I see. It's more about efficiency than it will work or not.

Thanks for explaining.
 
John Frum said:
Why 280 but 290 in brackets?
Click to expand...
According to manufacturer 290 actual vs 280 rated.

Which one?
Some LF inverters are rated in volt amps instead of watts.
Click to expand...
EPEVER NP3000-22
3000 ac watts / .85 conversion factor / 24 volts low cutoff = 147.058823529 inverter dc amps
147.058823529 inverter dc amps / .8 fuse headroom = 183.823529412 fuse amps

That means 150 amp BMS minimum 200 amps continuous is better.
300 amp hours of LFP battery to keep the draw down to ~.5c
That also means pure copper 1/0 awg with a 250 amp class t fuse.
Click to expand...
Ok. Unfortunately I already have a 150A BMS. Will that risk causing problems even though drawing 3000W occacionally 30-60 minutes?
 
jmsol said:
According to manufacturer 290 actual vs 280 rated.
Click to expand...
That makes me worried that you are going to get mystery meat cells.
Did you perhaps get these from AliX or similar?
jmsol said:
EPEVER NP3000-22
Click to expand...
This one?
Are you in a country that uses 230VAC@50Hz mains power?

That makes the numbers even higher as it a low frequency inverter that seems to not have a configurable low voltage disconnect.
3000 ac watts / .85 conversion factor / 20 volts low cutoff = 176.470588235 inverter dc amps
176.470588235 inverter dc amps / .8 fuse headroom = 220.588235294 fuse amps

That means 200 amp BMS minimum 250 amps continuous is better.
300 amp hours of LFP battery to keep the draw down to ~.5c
That also means pure copper 1/0 awg with a 250 amp class t fuse.

jmsol said:
Ok. Unfortunately I already have a 150A BMS. Will that risk causing problems even though drawing 3000W occacionally 30-60 minutes?
Click to expand...
If its a FET based BMS you run the risk of killing the FETs with heat.
FETs have a habit of failing closed so you may not know anything is wrong until your BMS fails to protect your battery.
If its a contactor based BMS you risk the contactor not being able to open the circuit under load.
 
Looks like you can add a configurable low voltage disconnect via one of these.
www.victronenergy.com

Smart BatteryProtect - Victron Energy

Disconnect the battery from non essential loads before it is completely discharged with Victron Energy's Smart BatteryProtect. Find a dealer near you.
www.victronenergy.com www.victronenergy.com
 
John Frum said:
That makes me worried that you are going to get mystery meat cells.
Did you perhaps get these from AliX or similar?

This one?
Are you in a country that uses 230VAC@50Hz mains power?

That makes the numbers even higher as it a low frequency inverter that seems to not have a configurable low voltage disconnect.
3000 ac watts / .85 conversion factor / 20 volts low cutoff = 176.470588235 inverter dc amps
176.470588235 inverter dc amps / .8 fuse headroom = 220.588235294 fuse amps

That means 200 amp BMS minimum 250 amps continuous is better.
300 amp hours of LFP battery to keep the draw down to ~.5c
That also means pure copper 1/0 awg with a 250 amp class t fuse.


If its a FET based BMS you run the risk of killing the FETs with heat.
FETs have a habit of failing closed so you may not know anything is wrong until your BMS fails to protect your battery.
If its a contactor based BMS you risk the contactor not being able to open the circuit under load.
Click to expand...
Alibaba. I guess it's no way of knowing until I set the system up?

Yes.

Is class-t a must? They are expensive!

JDB BMS
 
John Frum said:
Seems to be shenzen docan
Might be ok.

Link seems to be to a 4s bms

I can't find this product on epever's website so I can't verify its functionality.
Click to expand...
Ok.

Not sure why that is. It's the link from my order and I have 8S. But it should be that typ of BMS anyway.

Strange. I will have to look into this more closely.I have not bought that one yet, but If it doesn't work I will go with the Victron suggestion.
 
John Frum said:
That makes the numbers even higher as it a low frequency inverter that seems to not have a configurable low voltage disconnect.
3000 ac watts / .85 conversion factor / 20 volts low cutoff = 176.470588235 inverter dc amps
176.470588235 inverter dc amps / .8 fuse headroom = 220.588235294 fuse amps

That means 200 amp BMS minimum 250 amps continuous is better.
300 amp hours of LFP battery to keep the draw down to ~.5c
That also means pure copper 1/0 awg with a 250 amp class t fuse.
Click to expand...
This is found in the NP manual.

epeverlfi.png

EPEVER support comfirms the BLE adapter supports communication by app and data ecryption to inverter.

Will I still need 200-250A BMS or would it still be possible to use the 150A I already have configured by inverter?

Class t or alternative with 10000 amps breaking capacity at 30 plus volts dc.
Click to expand...
Sorry, but why 1000A and not recommended 250A?
 
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