battery consumption

roadroamer

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Just a question to all the technical people that understand electrics, I have a 1000w air fryer running through an inverter, my question is how many 12v AH does it use for 15 minutes use? I have 300AH’s of lithium batteries and a 2500w inverter (said to be 95% efficient) sensible answers please or a chart that a simple person can understand thank in advance
 
Basic maths are this ...

1. Ohms Law == P = I * V - or Power (Watts) = Current (A) x Voltage (V)
Another way to say that is I = P / V (Current = Power / Volts)
so 1000W / 12V = 84A
if you lose 5% due in inefficiencies, add 5% to the current, so the current drawn is 84A *105% = 90A (I rounded up to 90A as 95% efficient is pretty optimistic)

2. 1AH = 1A drawn for 1 hour. so 90A would be 90AH if drawn for 1 Hour.
you are drawing for 1/4 of an hour, so AHs used will be 1/4 of 90A = 22.5AH

Those are the theoretical numbers. a 12V system is not actually 12V of course.
With a Lead Acid Battery system with that load, that Voltage would probably drop down to under 12V (and the lower the voltage, the greater the current to deliver 1000W - remember P = I * V).
With a Lithium Battery system like you have, the Voltage drop does not occur and your batteries will be greater than 12V (so there will actually be a lower current draw to achieve that 1000W and a corresponding decrease in AHs consumed)
 
Basic maths are this ...

1. Ohms Law == P = I * V - or Power (Watts) = Current (A) x Voltage (V)
Another way to say that is I = P / V (Current = Power / Volts)
so 1000W / 12V = 84A
if you lose 5% due in inefficiencies, add 5% to the current, so the current drawn is 84A *105% = 90A (I rounded up to 90A as 95% efficient is pretty optimistic)

2. 1AH = 1A drawn for 1 hour. so 90A would be 90AH if drawn for 1 Hour.
you are drawing for 1/4 of an hour, so AHs used will be 1/4 of 90A = 22.5AH

Those are the theoretical numbers. a 12V system is not actually 12V of course.
With a Lead Acid Battery system with that load, that Voltage would probably drop down to under 12V (and the lower the voltage, the greater the current to deliver 1000W - remember P = I * V).
With a Lithium Battery system like you have, the Voltage drop does not occur and your batteries will be greater than 12V (so there will actually be a lower current draw to achieve that 1000W and a corresponding decrease in AHs consumed)
thank you wildebus that was explained in my language (simpleton) I now understand
 
A simple formula I have always been taught.
The ratio of 12 into 240 =20, for every 1 amp at 240v you will draw 20 at 12v, 1000w roughly 4a so 80a at 12v

Alf

Just a question to all the technical people that understand electrics, I have a 1000w air fryer running through an inverter, my question is how many 12v AH does it use for 15 minutes use? I have 300AH’s of lithium batteries and a 2500w inverter (said to be 95% efficient) sensible answers please or a chart that a simple person can understand thank in advance
 
I'd suggest a ratio of 22 rather than 20, to allow for losses in the conversion. I know that's 10% not 5% but I don't believe your inverter really is 95% efficient.
 
Have you not thought of using a Battery Computer such as a Victron BMV712 or Smart Shunt?
Once set up you can see everything going in and out of the lithium, pre-set the available AH to suit the Lithium's you've fitted and give you a percentage capacity of the battery bank. Saves all the guessing games.
 
Have you not thought of using a Battery Computer such as a Victron BMV712 or Smart Shunt?
Once set up you can see everything going in and out of the lithium, pre-set the available AH to suit the Lithium's you've fitted and give you a percentage capacity of the battery bank. Saves all the guessing games.
When Phil fitted my battery's he also fitted a smart shunt with a gauge similar to the victron BMV712 (cheep Chinese one) which is working well at the moment if that stops working it will be replaced with the Victron thanks for your thoughts
 

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