How Long Does It Take To Charge A 100Ah Lithium Battery? + Calculator

In general, 100ah lithium (LiFePO4) battery will take between 15 peak sun hours ( with 100 watt solar panel ) to 5 peak sun hours ( with 300 watt solar panel ) to get fully charged from 100% depth of discharge using an MPPT charge controller

How Long Does It Take To Charge A 100Ah Lithium Battery? ” ENTER THE BATTERY SPECS AND SOLAR PANEL SIZE INTO THE CALCULATOR to find out “

Solar Battery Charge Time Calculator

Solar Panel Size
Watts
Battery Capacity (Ah)
Ah
Battery Volts (V)
Volts
Battery Type
Battery Depth of Discharge (DoD)
%
Charge Controller Type

Note! Use this solar panel size calculator if you want to find out what size solar panel you need to charge your battery in desired peak sun hours.

Disclaimer!

1- The estimated charge time is not the total number of sunlight hours but the number of peak sun hours ( keep reading I’ll explain in a bit )

Calculator Assumptions

  1. Lead-acid, AGM, & Gel Battery charge efficiency: 85% 
  2. Lithium (LiFePO4) charge efficiency: 98%
  3. MPPT Charge Controller: 98% efficient
  4. PWM Charge Controller: 80% efficient
  5. Solar Panel Efficiency: 80% (which is the most common figure)

How To Use The Calculator?

  1. Enter the total solar panel array size: if you’re using a 100 watt solar panel ” ENTER 100 ” and so on…
  2. Enter Batter capacity in amp-hours: for this example, it’ll be 100
  3. Enter the battery voltage: is this a 12, 24, or 48v battery? ” Enter 12 for 12v battery ”
  4. Select Battery Type: Select “Lead-acid” if you’re using a flooded or sealed (AGM or gel) lead acid battery. Select “Lithium (LiFePO4)” if you’re using a lithium iron phosphate battery.
  5. Enter battery depth of discharge (DoD): DoD is the percentage of the battery that has been discharged relative to the total battery capacity. for half discharged battery you’d ENTER 50 if the battery is fully discharged ( which you can achieve on lithium battery ) “ENTER 100”. (Lead-acid batteries can be discharged 50%)
  6. Select the charge controller type: are you using a PWM or MPPT charge controller?

After entering the information, click “Calculate” button to find out how long it will take to charge a 100ah lithium battery.

if you’re a noob, i would suggest you watch this full video to get a complete understanding of electricity basics.

What Are Solar Peak Sun Hours?

Before explaining peak sun hours and why to use them, first, let’s see how solar panels are rated.

“ Solar panels are designed to produce their rated wattage output under standard test conditions – STC ”

STC includes: 

  • 1000 watts per meter square (1kw/m2) of sunlight intensity hitting the solar panels directly
  • 25oC temperature 

So to calculate the sunlight intensity we use peak sun hour as a reference. 

  • 1 peak sun hour = Average of 1kw/meter2 of sunlight intensity for one hour.

This number will depend on the location to location. To calculate how many peak sun hours your city receives use this PVwatt solar calculator.

Step 1: Enter your full address of just a city name & Click GO

Step 2: Click on results

How many peak sun hours in florida?

Now you’d be able to see the total amount of solar radiation your location receives per day (from month to month)

Note! it would have to place my solar panels all day long under sunlight to get those total solar radiations per day. 

Read the below-mentioned post to find out how much power output you can expect from your solar panels during peak sun hours. and also some tips to increase the solar panel’s output.

Must Read: Solar Panel Output Calculator – Average Solar Panel Output?

How Long To Charge 100Ah Lithium (LiFePO4) Battery?

Here are some charts about how long will it take to charge a 12v, or 24v 100ah Lithium (LiFePO4) battery with different size solar panels using a PWM or MPPT charge controller

How Long Does It Take To Charge A 12v 100Ah Lithium Battery?

Here’s a chart about what size solar panel you need to charge a 12v 100ah lithium (LiFePO4) battery in different peak sun hours using an MPPT or PWM charge controller

Solar Panel SizeCharge Controller TypeEstimated Charge time
20 wattPWM91 peak sun hours
50 wattPWM36 peak sun hours
70 wattPWM26 peak sun hours
100 wattPWM18 peak sun hours
120 wattPWM15 peak sun hours
150 wattPWM12 peak sun hours
170 wattPWM10 peak sun hours
200 wattPWM9 peak sun hours
250 wattPWM7 peak sun hours
300 wattPWM6 peak sun hours
400 wattPWM4.5 peak sun hours
500 wattPWM3.6 peak sun hours
600 wattPWM3 peak sun hours
20 wattMPPT75 peak sun hours
50 wattMPPT30 peak sun hours
70 wattMPPT21 peak sun hours
100 wattMPPT15 peak sun hours
120 wattMPPT12.5 peak sun hours
150 wattMPPT10 peak sun hours
170 wattMPPT9 peak sun hours
200 wattMPPT7.5 peak sun hours
250 wattMPPT6 peak sun hours
300 wattMPPT5 peak sun hours
400 wattMPPT3.7 peak sun hours
500 wattMPPT3 peak sun hours
600 wattMPPT2.5 peak sun hours

Summary

  • 12v 100ah lithium (LiFPO4) battery will take about 15 peak sun hours to get fully charged from 100% depth of discharge with 100 watt solar panel using an MPPT charge controller
  • 12v 100ah lithium (LiFPO4) battery will take about 7.5 peak sun hours to get fully charged from 100% depth of discharge with 200 watt solar panel using an MPPT charge controller
  • 12v 100ah lithium (LiFPO4) battery will take about 5 peak sun hours to get fully charged from 100% depth of discharge with 300 watt solar panel using an MPPT charge controller

How Long Does It Take To Charge A 24v 100Ah Lithium Battery?

Here’s a chart about what size solar panel you need to charge a 24v 100ah lithium (LiFePO4) battery in different peak sun hours using an MPPT or PWM charge controller

Solar Panel SizeCharge Controller TypeEstimated Charge time
20 wattPWM184 peak sun hours
50 wattPWM73 peak sun hours
70 wattPWM52 peak sun hours
100 wattPWM36 peak sun hours
120 wattPWM30 peak sun hours
150 wattPWM24 peak sun hours
170 wattPWM20 peak sun hours
200 wattPWM18 peak sun hours
250 wattPWM14 peak sun hours
300 wattPWM12 peak sun hours
400 wattPWM9 peak sun hours
500 wattPWM7 peak sun hours
600 wattPWM6 peak sun hours
20 wattMPPT150 peak sun hours
50 wattMPPT60 peak sun hours
70 wattMPPT42 peak sun hours
100 wattMPPT30 peak sun hours
120 wattMPPT25 peak sun hours
150 wattMPPT20 peak sun hours
170 wattMPPT18 peak sun hours
200 wattMPPT15 peak sun hours
250 wattMPPT12 peak sun hours
300 wattMPPT10 peak sun hours
400 wattMPPT7 peak sun hours
500 wattMPPT6 peak sun hours
600 wattMPPT5 peak sun hours

Summary

  • 24v 100ah lithium (LiFPO4) battery will take about 30 peak sun hours to get fully charged from 100% depth of discharge with 100 watt solar panel using an MPPT charge controller
  • 12v 100ah lithium (LiFPO4) battery will take about 15 peak sun hours to get fully charged from 100% depth of discharge with 200 watt solar panel using an MPPT charge controller
  • 12v 100ah lithium (LiFPO4) battery will take about 7 peak sun hours to get fully charged from 100% depth of discharge with 400 watt solar panel using an MPPT charge controller

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I'm an experienced Sales Consultant with a demonstrated history of working in the renewables and environment industry. Skilled in Photography, Customer Service, and Sales.