2 x 100Ah LiFePO4 - using 2400w = a possible 55 minutes?

[Peter Clark]

2 x 100Ah LiFePO4 - using 2400w = a possible 55 minutes?

Using an online calculator I arrived at this figure.

Would anyone with real world expertise say this number is in the right ballpark?

PS: Victron batteries via Victron 3000w inverter.

 

[funflair]

Theoretically yes the maths is about right, would I do it ? no chance

 

[Peter Clark]

Theoretically yes the maths is about right, would I do it ? no chance

Would not do it…… because?

 

[eddie]

Probably, but then you’d be sat in a van with flat batteries

 

[eddie]

Would not do it…… because?

You’d have flat batteries, risk the BMS shutting down and ‘could’ have issues re charging them

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[MisterB]

i assume you dont have the batteries yet? the reason i ask is that because the bms on my battery actually provides that information whenever i am drawing current - it tells me how long i can draw current for at the rate i am using it at. i assume it will turn itself off when it reaches a certain point, but what i dont know is whether that time is the time shown on the bms or whether it will shut off before that time as a safety function.

 

[SpeedyDux]

2 x 100Ah LiFePO4 - using 2400w = a possible 55 minutes?

Using an online calculator I arrived at this figure.

Would anyone with real world expertise say this number is in the right ballpark?

PS: Victron batteries via Victron 3000w inverter.

By my calculation allowing for inverter losses the theoretical maximum run time is 51 minutes. Before that point is reached the batteries may well shut down. Don't try this at home.

 

[jongood]

Why would you want to run 2400w for 55 minutes? Usually the highest draws are things like hair driers, 5 minutes?

 

[Peter Clark]

i assume you dont have the batteries yet? the reason i ask is that because the bms on my battery actually provides that information whenever i am drawing current - it tells me how long i can draw current for at the rate i am using it at. i assume it will turn itself off when it reaches a certain point, but what i dont know is whether that time is the time shown on the bms or whether it will shut off before that time as a safety function.

No, don’t have the batteries yet - that BMS info sounds very useful

 

[Peter Clark]

Why would you want to run 2400w for 55 minutes? Usually the highest draws are things like hair driers, 5 minutes?

Hi Jon - I wouldn’t need to run anything that long - prob 15 to 20 minutes max most of the time. The maximum possible run time that could be needed is 30 minutes, but that’s unlikely ever to happen.

Situation is - friend has bought a Ninja Foodi 8 mini oven and it’s an excellent device - but draws 2400w against the 1700w for the air fryer I’ve been considering.

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[jongood]

Hi Jon - I wouldn’t need to run anything that long - prob 15 to 20 minutes max most of the time. The maximum possible run time that could be needed is 30 minutes, but that’s unlikely ever to happen.

Situation is - friend has bought a Ninja Foodi 8 mini oven and it’s an excellent device - but draws 2400w against the 1700w for the air fryer I’ve been considering.

Might you be better off considering something with lower draw like a remoska or microwave?

I think one of you re earlier threads mentioned solar, this could change all of your calculations, we ve been in the situation where our solar was almost keeping up with the small remoska although not in UK.

 

[Jo662]

Hi Jon - I wouldn’t need to run anything that long - prob 15 to 20 minutes max most of the time. The maximum possible run time that could be needed is 30 minutes, but that’s unlikely ever to happen.

Situation is - friend has bought a Ninja Foodi 8 mini oven and it’s an excellent device - but draws 2400w against the 1700w for the air fryer I’ve been considering.

I would stick with your first choice,1700w. I have a Corsori with that power,and it’s perfect for the motorhome run on my Lithiums.

 

[Hoovie]

Hi Jon - I wouldn’t need to run anything that long - prob 15 to 20 minutes max most of the time. The maximum possible run time that could be needed is 30 minutes, but that’s unlikely ever to happen.

Situation is - friend has bought a Ninja Foodi 8 mini oven and it’s an excellent device - but draws 2400w against the 1700w for the air fryer I’ve been considering.

at 2400W, note that you will be running the Victron "3000W" Inverter at 100% power output, which is maybe not a good idea?

(Victron don't use the watts output in the product naming, but the VA output. the "3000W" Inverter has a nominal output of 2400W - and this reduces as it heats up)

 

[Peter Clark]

Might you be better off considering something with lower draw like a remoska or microwave?

I think one of you re earlier threads mentioned solar, this could change all of your calculations, we ve been in the situation where our solar was almost keeping up with the small remoska although not in UK.

I’ve ordered a Remoska and been considering a 1700w Ninja air fryer.

I oven cook a lot at home, so the Remoska should cover that - thinking the air fryer would be good for smaller and quick cook items.

But suffered a case of “oven envy” when I checked out my friends Ninja Foodi 8

 

[Jimbohorlicks]

Once you have used the air fryer for 30 mins ,that's your batteries down to 50% approx.
Have you got the ability to recharge that loss back, solar wise or b2b.?

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[Carpmart]

You could fit a sunshine type controller which only opens the relay to whatever you are powering when a certain battery voltage is detected and then shuts down when the lower voltage value you enter is reached. Effectively with the correct pre set values, you would only be using it when you have a ‘surplus’ of power available through some charging route.

However, items for the home, drawing that kind of load should be left at home.

 

[MisterB]

increasing the size of your intended battery bank might be an option.

The reality is that its an expensive solution to being able to use something you want to use! i often fall into that trap and buying your way out of it is sometimes simpler than identifying actual NEEDS as opposed to WANTS/WOULD LIKES ! i have swayed far too often into the WANTS/WOULD LIKES aspects of motorhoming and convince myself that i NEED something!


perhaps you should also consider how to replenish the power taken from your battery as quickly as possible, so that it becomes less of an issue?

 

[Hoovie]

2 x 100Ah LiFePO4 - using 2400w = a possible 55 minutes?

Using an online calculator I arrived at this figure.

Would anyone with real world expertise say this number is in the right ballpark?

PS: Victron batteries via Victron 3000w inverter.

One other point .... have you got the Battery Specs? very often a 100Ah battery will have a maximum current output of 100A. So a pair will be 200A (if perfectly balanced).
If you ran a load of 2400W (output. so load in will be more like 2700W at least) plus other DC battery loads, you will exceed 200A and cause the batteries to shut down.

 

[Peter Clark]

Once you have used the air fryer for 30 mins ,that's your batteries down to 50% approx.
Have you got the ability to recharge that loss back, solar wise or b2b.?

My 6m Burstner Travel Van only has room for 3 x 100w solar panels, but my long trips are going to be be mostly Southern Europe, North Africa, Turkey - so hoping they will be adequate.
B2B also being fitted, so could do an emergency top up in evening if necessary?

 

[MisterB]

My 6m Burstner Travel Van only has room for 3 x 100w solar panels, but my long trips are going to be be mostly Southern Europe, North Africa, Turkey - so hoping they will be adequate.
B2B also being fitted, so could do an emergency top up in evening if necessary?

could you add a folding solar panel to your 'armoury'? though i think increasing your battery capacity is key to it all if youve gone as far as you can with putting the power back into the batteries ?

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[SMB]

We've used a Remoska for a number of years and it might not have all the functions of the others but it cooks almost anything you would cook in a conventional oven whilst only using 400w (580w for the 4 litre version).

 

[Tombola]

More battery and a foldable panel really
and dont use the ninja for lunch and dinner or you'd be fooked.

or best answer as said, find a lower wattage one

 

[eddie]

I’ve ordered a Remoska and been considering a 1700w Ninja air fryer.

I oven cook a lot at home, so the Remoska should cover that - thinking the air fryer would be good for smaller and quick cook items.

But suffered a case of “oven envy” when I checked out my friends Ninja Foodi 8

Buy a generator or go on sites, or get a different van, or, have a bigger inverter and twice as many lithium batteries

Loads of choices to do what you want to do, but not with the set up you described

 

[Just smiffy]

Buy a generator or go on sites, or get a different van, or, have a bigger inverter and twice as many lithium batteries

Loads of choices to do what you want to do, but not with the set up you described

I’d just go and have a takeaway or a nice restaurant….

 

[Reevsie]

Yes you could get about 55 minutes to drain them using 2400W.
Now work out if you use your solar, charger or B2B how long will it take you to charge them back up.

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[DuxDeluxe]

Buy a generator or go on sites, or get a different van, or, have a bigger inverter and twice as many lithium batteries

Loads of choices to do what you want to do, but not with the set up you described

Good advice Eddie. My next van is likely to be all electric leisure side but heating will be diesel and the available power needs to be used smartly. It is no substitute for mains supply if a ninja or similar is going to be used

 

[Pausim]

You should not ignore the Peukerts Exponent. Even LiFePO4 with a very low level Peukert number of 1.05 to 1.1 will be adversely affected by your proposed draw of 200A. At that rate I reckon you will get a maximum of 46 minutes before the batteries are knackered. Here is a link to a Peukert calculator.

Calculate Battery Capacity, Discharge Time using Peukert's Law

Online calculator which helps to calculate the actual battery capacity and full discharge time using Peukert's Law.

www.easycalculation.com

I am no expert on Peukert but as I understand it the higher the Amps you pull from the battery the lower the Ah capacity becomes. The nominal 200Ah will be based on a much lower draw than 200A. Basically at 200A some of the battery energy will be lost to heat rather than running your devices.

 

[PatapscoPaul]

2 x 100Ah LiFePO4 - using 2400w = a possible 55 minutes?

Using an online calculator I arrived at this figure.

Would anyone with real world expertise say this number is in the right ballpark?

PS: Victron batteries via Victron 3000w inverter.

Output from the batteries reduce considerably as they get towards empty, so I don't think you'll sustain that current draw.

 

[Gromett]

You should not ignore the Peukerts Exponent.

For LiFePO4 cells you can safely ignore Peukert as it is in the weeds and other variables completely swamp this.

I seem to recall for most LiFePO4 cells I look at it was stupidly low at around 1.02 or so. Not sure where you got 1.1 at the high end from?

Victron for example from what I have seen recommend 1.05 to be on the safe side. I have not seen anyone suggest a higher value than this though.

 

[Pausim]

For LiFePO4 cells you can safely ignore Peukert as it is in the weeds and other variables completely swamp this.

I seem to recall for most LiFePO4 cells I look at it was stupidly low at around 1.02 or so. Not sure where you got 1.1 at the high end from?

Victron for example from what I have seen recommend 1.05 to be on the safe side. I have not seen anyone suggest a higher value than this though.

I used 1.05 but even at this value it knocks nearly 10 minutes off the calculation.