How Many Batteries for a 3000 watt Inverter?

You are here because you want to run a 3000-watt inverter from one or more batteries.

No problem.

Let me tell you how you should do it. Read the whole article because most blog articles which are answering this question get it wrong.

We need to satisfy two criteria before we can tell you what battery you need. These are:

  • C-rate (in this case, discharge)
  • Current


The C-rate of a battery is the rate at which the battery can deliver the promised capacity of a battery. For example, the C-rate of a 100Ah lead-acid battery is 0.2C. That means that we can discharge the battery with a 20 Amp load (100Ah x 0.2= 20A). You can discharge the battery with a higher load, let’s say 40Amps, but then the capacity of the battery will be reduced because of internal heat generation.

The C-rate of lithium batteries (LiFePO4) is 1. That means that a 100Ah battery can be discharged with a 100 Amp load and it will deliver 100Ah.

We want to respect the C-rate of the battery because that will give us the longest battery life. If we abuse the battery by discharging at a higher current than it’s made for, then the battery will get damaged and its lifespan will decrease.


The second point is the current draw from the battery to the inverter. We do not want to draw lots of current from the battery to the inverter. If we do, we need big and heavy cables. Big and heavy copper cable means a lot of money.

Another point here is that if you crimp the wires yourself, you want to limit the current. Your crimping tools might not be suited for a high current application. Therefore we need to be safe and reduce the current. I recommend not going over 100Amps if you create the system yourself.

Now how do we reduce the current in the wires?


Increase the voltage.

These are my recommendations for system voltages respectively to their inverters:

  • 12V battery system -> inverter below 1000W
  • 24V battery system -> inverter from 1000-2000W
  • 48V battery system -> inverter from 2000W to 4000W
  • More inverter power -> have multiple inverters in parallel

If you want to run a 3,000W inverter, you should have a 48Volt system. This will reduce the current to a safe level in a DIY system. If we calculate the current, it will be: 3000W/48V=62.5A, now imagine having a 3,000W inverter on 12V: 3000W/12V= 250A!

Read my article about my recommended inverters for off-grid solar here.

Putting it all together

We know that we need to have a battery that has enough capacity to satisfy the c-rate and we need to have a high voltage battery.


If we build this system with 12V 100Ah lead-acid batteries we can calculate the following:

We know that we need a 48V system. That’s 4 batteries in series.

If we put 4 batteries in series we have one 48V 100Ah battery.

The c-rate of lead-acid is 0.2C. We can draw 100Ah x 0.2C = 20Amps. That’s not enough to power the 3,000W inverter.

We saw previously that we need 62,5A if we have a 48V system. That means we need three parallel strings of 4 batteries in series for a total 12 batteries.

12 lead-acid batteries in hybrid connection 4 batteries in series and then 3 in parallel for a total of 12 batteries
12 lead-acid batteries in hybrid connection

That is how you efficiently run a 3,000 inverter on lead-acid batteries.


If we do the same calculations for a 12V 100Ah lithium battery, we become the following:

We still need a 48V system. So the 4 batteries in series stay the same.

We now have a 48V 100Ah lithium battery.

The c-rate of lithium is 1. We can draw 100Ah x 1C = 100Amps. That is enough to power a 3,000 watt inverter without damaging the battery.

You need to have 4 lithium batteries in series to power a 3,000 watt inverter.

4 lithium batteries in series
4 lithium batteries in series

How many 100Ah batteries do I need for a 3000 watt inverter?

You need 4 Lithium batteries in series to run a 3,000W inverter. If you use lead-acid batteries, you need 12 batteries with 4 in series and 3 strings in parallel.

Can I run a 3000 watt inverter on one battery?

You can but it’s not recommended because you will reduce the battery lifespan, or the BMS will stop the discharge. The battery size I recommend for a 3000W inverter is a 48V 100Ah server rack battery. Make sure the discharge rate is higher than 0.5C.


Figuring out what kind of battery you need to run a 3000-watt inverter is not as straightforward as you think. Hopefully, you know now how to put your system together. Remember that lithium is cheaper in the long term.

If you rather use a 2000W inverter, read my post here.

Off-Grid Solar Power Simplified
Seeing there was a high demand for a simplified guide to off-grid solar power, I decided to write a book about it.

I guarantee this guide will save you $100s on buying the right components by having a good design and sizing.

You can get the book for a reasonable price on amazon

Read more:

How many batteries for a 1000W inverter

How many batteries for a 2000W inverter

29 thoughts on “How Many Batteries for a 3000 watt Inverter?”

    • Hi Nick,
      I agree with SEJANAMANE, this is great info and I love the way you present and organize the details. I also picked up the book!

    • Good day SEJANAMANE

      I am about to go off grid.

      I have a 200/250w solar panel
      a 30a control charger
      A db box with 4-6 breakers at 32a fuses one is 10a for the lights… And a 200ah lead solar battery.

      I had a 1500w inverter it burnt out.

      But i now want to get a 3000watt inverter

      How do i go about my system now what will i need?

      Another battery?
      Another control charger
      Bigger fuses
      Bigger solar panel

      Please help!

      Kind regards.
      Kaylin Lance Dawson.

      • The maximum current you should draw is 40A (200Ah*0.2C-rate). A 12V, 3000W inverter will draw 250A max. You need to increase your battery capacity to 400Ah and get a 1000W inverter instead. That will give you a max current draw of 83A. That is a properly sized system.

        • Super. Thank you so much.. I did forget to mention that the load i want to put on the inverter is over 1500watts daily use(appliances) {no heated appliances}.

          How many batteries should i have for a 3000watt inverter and should my charge controller (30a) be bigger as well as the fuses in the db box (32a)

          • For the current: 3000W/48V=62A or 3000W/24V=125A. Up to you to choose 24 or 48V. I recommend using server rack lithium batteries.
            Lithium: 125Ah*0.5C=50A => 48V,125Ah (6kw) or 24V,250Ah

        • Ok so i figured that
          1000w-2000w inverter will be safe on 2x 12v batteries of 200ah correct?

          So if my load is say 1400w (all appliances)
          Is it safe to say i can run a 1500w inverter on 1x 12v 200ah battery as not all the appliances that = 1400w will be operating at the same time and those that will be will = to 780w(appliances) used throughout the day, on and off (on from 8am-12pm and off from 12pm-4pm and on again from 4pm-10pm.

  1. quick question I have eight 12v 20Ah how many to power my home? I have 12 100 watt panels could you please give me some info on what I should do please and thank you, I too am getting your book..

    • Hello Roy, first, you need to find out how many kWh you need in a day. The worst-case scenario would be winter. From there you can fill in my off-grid load calculator. This is located in the top menu. From there you can go and put your system together.

  2. if I want to start with about 1000W need but plan to grow, which is best, to purchase the larger inverter & 12V battery up front and grow battery capacity as needed or purchase a smaller inverter and battery and upgrade batteries and inverter as needed.

    • If you know your loads will increase, you should get the bigger inverter. However, you need to size the wires and fuses based on the bigger inverter. That’s going to cost you more. Alternatively, you can add more inverters in parallel to increase the output later. Then you need a more expensive inverter that can do this. Keep in mind the idle current of a bigger inverter is bigger.

  3. Hi, looking to confirm my RV solar system is safe:

    -Solar-2 x 400 w Piemar panels/parallel to 150/50 Viltron MPPT controller (Open circuit voltage 50.39V, Current @ PMAX 9.69A
    -Solar-1 x 400w Piemar panel to 100/30 Victron MPPT controller

    -Battery bank is 3 x 200AH SOK lithium batteries in parallel (see cabling for connection details)

    -Inverter is Victron Multiplus II – 12/3000w / 120-50A 2x120V
    – Output of Victron inverter connected to onboard breaker distribution panel which powers all RV appliances and outlets etc. as per factory build (6/3 cable). I have disconnected the factory RV converter from the panel.

    -Connected to Victron power distribution bar with 6 gauge cabling (powers 12 volt items i.e. slides/aux. lights etc.)

    -Onboard ONAN 5500w gas generator connected through transfer switch with 50A shore power then onto input of Victron inverter

    – Cabling consists of 1/0 from Victron power distribution bar to DC on inverter (3 feet), 1/0 from battery bank to Victron distribution bar (each battery cabled to distribution bar separately with separate 600A isolation switches – rationale was if any one battery or BMS failed I could isolate and have independent redundancy). Cabling from MPPT controllers to Victron distribution bar is 6 gauge, cable from rooftop solar panels to MPPT controllers is 10 gauge.

    -parallel solar panel array input cable wired to 12 volt-30A breaker box then to Victron power distribution bar (60a mega fuse on bar)
    -single panel input cable wired to 12 volt-30A breaker box then to Victron power distribution bar (60a mega fuse on bar)
    -12 volt distribution panel protected 60a fuse on power distribution bar
    -each + battery cable protected – 200A fuse on power distribution bar
    -inverter+ DC input protected – 450A mega fuse between the inverter and power distribution bar.
    -each solar array cable from the breaker box protected with 60a mega fuse on the power distribution bar
    – + cable from power distribution bar to levelling jacks protected with 100a mega fuse as per manufacturer

    I was concerned about installing a 12 volt system vs. 24 or 48 but in the end opted for 12 volt with what I thought was appropriate gauge welding cable. I would appreciate your comments.

    • Hello Cam,
      I cannot go into every detail of your system. Please refer to my fuse and cable sizing guide on the website.
      I do not recommend sticking with 12V because you will draw 250Amps. For a 3000W inverter I recommend a 48V system, 24V is doable but don’t recommend it.
      I recommend reading my book so you will not waste your money on the wrong components.

      • appreciate your response, why is 12 volt not acceptable with appropriate cabling? my 3 x 200 AH lithium batteries are connected individually to a Victron Distribution bar (rated at 1,000 A) with appropriate fusing. I am not questioning your advice just looking for additional explanation. All my cables are professionally crimped so I am not concerned with 250A shorts (etc.). thank you

        • Hello Cameron,
          Good question. I have these guidelines that are shared with many other experts. The main reason is that a DIY crimp is not as good as a professional crimp. Additionally, the cost of the wire will be very high if you have a 12V battery and a 3000W inverter. I’m not saying you cannot do it, but I do not recommend it. Another reason is voltage drop if your cables are long. You have professionally crimped cables and you already have your components, so you don’t need to change that.

  4. My load need is arround 500w. Is it still ok to get 48v 3000w inverter as i am planning to increase my load in the future?

  5. hey Nick, this was really helpful.
    one thing I want to clarify, if I need a 3000watt inverter for my needs, instead of 4x 12v 100Ah lithium batteries, can I use 2x12v 200Ah?

    The 12v vs 48v has me confused, as all batteries available are 12v, does the 48v system refer to once all batteries are connected? or does it mean it has to have 4 X 12v batteries in the series not inclusive of amp hours?

    I hope my question makes sense.

    The other question I have is for solar panels – we have 4 X 270 watt panels – is this sufficient to recharge the system?
    Thanks so much for your help and time .

    • Good questions.
      1. The highest voltage with 2x12v 200Ah will be 24V (two in series). The current will be: 3000W/24V=125A. The C-rate of lithium is 0.5 or 1C, depending on the BMS inside. Since the battery is 200Ah, a battery with 1C will be ok (200Ah*1C=200A). A battery rated at 0.5C will not be sufficient(200Ah*0.5C=100A).
      2. The 48V refers to the total battery voltage. These can be 8x6V batteries, 4x12V batteries or even 16×3.2V cells.
      3. 4x270W=1080W*3hours a day = 3240Wh. you need to recharge the battery in one day. Your battery capacity is 4800Wh. You need at least 6 of these panels to recharge the battery. I recommend using my calculator here

  6. Hi. I am a little confused on the powering of an inverter. I have a Magnum 4000 watt inverter with e-panel. It is a 24 volt system. I have 4 L16 x 6 volt Rolls Surrettes batteries (450 amp hr). Cables to inverter are 2 gauge and are factory crimped (about 4 feet long). I have 500 watts of solar and 500 watts of micro hydro (approx). I have been running a 16 cu. ft refrigerator, 7. 5 cu. ft. freezer, 2 tv’s, led lights, computer for almost 10 years on these flooded batteries with no major issues. I recognize my batteries are at end of life and am looking to replace them with lithium. it would seem to me using your recommendations that I do not have enough battery power at 24 volts to run my inverter properly. Am I correct?

    • If I read correctly, your battery is 24V @450Ah. You should only be drawing: 450Ah*0.2C=90A, but with a 4000W inverter you draw 166A.
      While you can draw more than double the C-rate, I do not advise it because you will degrade your batteries faster.
      Because you said you would change to lithium, you need a 24V battery with at least 332Ah to have a 0.5C.


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