Can anyone explain why a 100ah lithium battery will only power up to a 1000watt invertor ?
1000 watts from a nominal 12V source means that the load will be drawing 83 amps. The maximum continuous discharge rate specified for most lithium cell chemistries is 1C. In this case 1C corresponds to 100A.
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In some lithium batteries the inbuilt Battery Management System severely limits both maximum charge and discharge. I have a Chinese battery allegedly of 300Ah capacity. The inbuilt BMS limits charge to 30A and discharge to 50A which is about as much good to me as a chocolate teapot. The 200Ah battery I now use has a recommend discharge rate of 200A and a recommended charge rate of 100A. Max charge and discharge rates are 400A.
So, in answer to the original question. I reckon that you are being limited by the inbuilt BMS and not the actual battery.
Can anyone explain why a 100ah lithium battery will only power up to a 1000watt invertor ?
when theres no issue with my current 150ah lead crystal battery powering my 2000watt redarc invertor !!
why are more lithium batterys required ?
Lithiums are usually controlled by their inbuilt BMS to the industry recognised maximum safe discharge/charge rate of 1C (one times their capacity)
The maths for that 1000W inverter is as follows:
1000watts divided by 230volts = 4.35 amps, times the conversion factor of 25* equals 109amps
* conversion factor :- (230volts divided by 12volts equals 19.17 times greater amps, plus 25% for inverter inefficiencies and appliances with power factors other than 1 = approx. 25 times greater amps).
If you need to run larger inverters then get two LiFePO4 batteries in parallel rather than one. ie, 2x100 rather than 1x200.
-- Edited by Hylife on Sunday 26th of June 2022 08:09:12 PM
Can anyone explain why a 100ah lithium battery will only power up to a 1000watt invertor ?
when theres no issue with my current 150ah lead crystal battery powering my 2000watt redarc invertor !!
why are more lithium batterys required ?
There is no reason why you cant connect your 2000W inverter to a 100Ah lithium battery. As others have said it is the BMS that will generally limit the current but you cant be sure unless you test it. The cell manufacturer will also nominate the maximum discharge rate and the BMS is generally matched with that.
If you did connect your inverter to a 100Ah battery you would need to be aware of the maximum current you are drawing for the appliances that you use. In case you forget then you could consider putting a breaker in.
Otherwise as Hylife said 2 x 100Ah batteries with a 1C discharge capability or a 200Ah with 1C.
-- Edited by TimTim on Sunday 26th of June 2022 10:58:16 PM
Is it ok to use a 1500 inverter with a 100 ah agm battery. I doubt anything I use will be above 500 watts. Cheers Stewart
Yes.
You may use a10,000W inverter with a 25Ah battery - the inverter, with nothing plugged into it will only draw perhaps 10W (call it 1A) from the battery. The problem arises when you plug a 240V load into the inverter and then you must ensure your battery and charging system is commensurate with that load.
A100Ah battery will typically support a load of 100 to 200W for a "while" and more than that for a much shorter "while" - NB. This is not a linear equation.
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I am looking at getting a better pure sine wave as my repco mod sine wave 600 watt, screams with the solar plugged in and charging at over 14 volts. Hi voltage error I guess. So I was thinking ahead for upgrades to come. If I unplug solar, start inverter and run appliance, then plug in solar it works ok. Cheers Stewart
As others have mentioned added external or usually internal BMS current rating is usually the limiting factor.
Our 300Ah LiFePO4 battery with no such BMS circuitry has delivered peak currents of up to 750A - near 10000W albeit briefly starting our 3.9l TD engine many hundreds if not thousands of times over the last 8 years.
I have no doubt that is could easily power a fully loaded 4 or 5kW inverter with ease but not long. Battery capacity dictates that.
