01
Loan Calculator
Works out the monthly payment, total interest and full repayment schedule for any loan from…
Inverter Battery Runtime Calculator
Calculates backup time from an inverter battery bank for a given load, plus the current drawn and the time to recharge.
Calculators
Nothing uploaded
No sign-up
Free, unlimited
Enter your figures and press Calculate.
In short
Inverter Battery Runtime Calculator is a free online tool on inputtesthub.com that calculates backup time from an inverter battery bank for a given load, plus the current drawn and the time to recharge. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.
How to use the Inverter Battery Runtime Calculator
- Enter your figures in the input fields.
- The result updates as you type, together with the full working.
- Check the breakdown table to see exactly how the number was reached.
About the Inverter Battery Runtime Calculator
The Inverter Battery Runtime Calculator calculates backup time from an inverter battery bank for a given load, plus the current drawn and the time to recharge. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.
What people use it for
- Sizing an inverter battery for load-shedding.
- Checking the cable size needed for the current drawn.
- Working out whether the battery will refill between outages.
Details
| 800 W at 12 V | Over 80 A from the battery |
|---|---|
| Lead-acid DoD | 50% |
| Charging losses | ≈ 20% |
| Recharge is slower | Than discharge |
The maths behind it
This tool uses Usable Wh = Ah × V × count × DoD × inverter efficiency. Backup = usable Wh ÷ load. Recharge ≈ Ah replaced ÷ charger current × 1.2 for charging losses. Every intermediate value is shown on screen, so the result can be checked by hand.
The current drawn from a 12 V battery is roughly a twelfth of the load in watts and then some — an 800 W load pulls over 80 A, which needs properly sized cable and a fuse. Recharging also takes far longer than discharging, so a second outage the same day finds the battery still low.
Frequently asked questions
Is there a limit on how often I can use the Inverter Battery Runtime Calculator?
It is free, with no account, no trial and no daily cap. Every calculators tool on inputtesthub.com works the same way: open the page and use it.
Can you see what I put into this utility?
No. The Inverter Battery Runtime Calculator runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
What is the equation behind the Inverter Battery Runtime Calculator?
It uses Usable Wh = Ah × V × count × DoD × inverter efficiency. Backup = usable Wh ÷ load. Recharge ≈ Ah replaced ÷ charger current × 1.2 for charging losses. The full working is printed under the result, so you can follow every step rather than trusting a black box.
Who is the Inverter Battery Runtime Calculator for?
The most common reasons people reach for it: sizing an inverter battery for load-shedding. Checking the cable size needed for the current drawn. Working out whether the battery will refill between outages. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is there a catch?
The current drawn from a 12 V battery is roughly a twelfth of the load in watts and then some — an 800 W load pulls over 80 A, which needs properly sized cable and a fuse. Recharging also takes far longer than discharging, so a second outage the same day finds the battery still low.
What figures does the Inverter Battery Runtime Calculator work from?
800 W at 12 V is Over 80 A from the battery. Lead-acid DoD is 50%. Charging losses is ≈ 20%. These are printed on the page itself, so you do not have to take them on trust.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.
Related calculators tools
All 38202
EMI Calculator
Calculates your Equated Monthly Instalment with a full principal-versus-interest breakdown and…
03
Mortgage Calculator
Estimates a full monthly housing payment including principal, interest, property tax…
04
Car Loan Calculator
Calculates a car finance payment from the price, deposit, trade-in, interest rate and term…
05
Personal Loan Calculator
Works out instalments and total cost for an unsecured personal loan, including any processing…
06
Amortization Schedule Calculator
Produces a complete month-by-month table showing how each payment splits between interest and…
07
Compound Interest Calculator
Shows how savings grow with compound interest, including regular contributions and any…
08
Simple Interest Calculator
Calculates simple interest and the final amount from principal, rate and time, without…
09
SIP Calculator
Projects the maturity value of a monthly Systematic Investment Plan, showing invested amount…
10
Lumpsum Investment Calculator
Calculates what a one-off investment grows to at a given annual return over any number of years.