Charging 200Ah Lithium Battery Complete Guide

This is going to be a complete guide on charging a 200ah lithium (LiFePO4) battery with solar panels.

in this post you’ll learn:

Solar Panel Size Calculator To Charge a 200Ah Lithium Battery

Battery Capacity (Amp-hours)
Ah
Battery Voltage
V
Battery Type
Battery Depth of Discharge (DoD)
%
Charge Controller Type
Desired Charge Time (Peak sun hours)
hours

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.

Calculator Assumptions: 

  • Lead-acid Battery Charge efficiency rate: 85%
  • AGM Battery Charge efficiency rate: 85%
  • Lithium (LiFePO4) Charge efficiency rate: 99%
  • PWM charge controller: 80% efficient
  • MPPT charge controller: 98% efficient
  • Solar Panels Efficiency during peak sun hours: 80% (meaning a 100 watt solar panel will produce 80 watts during peak sun hours)
  • Charge controller is the only load connected with the battery

How To Use The Calculator?

Enter the following info into the calculator ( located at the top of this page )

  • Battery Capacity: Enter your battery capacity in amp-hours (Ah). in this case it’ll be 200
  • Battery Volts: is this a 12v, 24v, or 48v battery?
  • Battery Type: Select the battery type, in this case, select lithium-ion (LiFePO4) battery
  • Battery Depth of discharge 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)
  • Charge Controller Type: Are you using a PWM or MPPT charge controller to charge the battery? 
  • Desired Charge time (in peak sun hours): How fast would you like to charge your battery or how many peak sun hours your location receives? (keep reading i’ll explain how you can calculate the number of peak sun hours)  

After entering the information, click “Calculate” button to find the required size for a 200ah 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?

What Size Solar Panel To Charge 200Ah Lithium Battery?

here are some charts about what size of solar panel you need to charge a 12v, & 24v 200ah lithium battery in different peak sun hours using a PWM or an MPPT charge controller.

What Size Solar Panel To Charge 12v 200Ah Lithium Battery

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

Charge TimeCharge Controller TypeRequired Solar Panel Size
5 peak sun hoursPWM700 watts
10 peak sun hoursPWM350 watts
15 peak sun hoursPWM230 watts
20 peak sun hoursPWM175 watts
25 peak sun hoursPWM140 watts
5 peak sun hoursMPPT580 watts
10 peak sun hoursMPPT290 watts
15 peak sun hoursMPPT190 watts
20 peak sun hoursMPPT150 watts
25 peak sun hoursMPPT120 watts

Summary

  • You need about 700 watts of solar panel to charge a 12v 200ah lithium (LiFePO4) battery in 5 peak sun hours from 100% depth of discharge using a PWM charge controller.
  • You need about 580 watts of solar panel to charge a 12v 200ah lithium (LiFePO4) battery in 5 peak sun hours from 100% depth of discharge using an MPPT charge controller.

Full Article: What Size Solar Panel To Charge 200Ah Battery?

What Size Solar Panel To Charge 24v 200Ah Lithium Battery

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

Charge TimeCharge Controller TypeRequired Solar Panel Size
5 peak sun hoursPWM1400 watts
10 peak sun hoursPWM700 watts
15 peak sun hoursPWM460 watts
20 peak sun hoursPWM350 watts
25 peak sun hoursPWM280 watts
5 peak sun hoursMPPT1160 watts
10 peak sun hoursMPPT580 watts
15 peak sun hoursMPPT390 watts
20 peak sun hoursMPPT290 watts
25 peak sun hoursMPPT230 watts

Summary

  • You need about 1400 watts of solar panel to charge a 24v 200ah lithium (LiFePO4) battery in 5 peak sun hours from 100% depth of discharge using a PWM charge controller.
  • You need about 1160 watts of solar panel to charge a 24v 200ah lithium (LiFePO4) battery in 5 peak sun hours from 100% depth of discharge using an MPPT charge controller.

Read the below post to find out how fast you can charge your battery.

Related Post: Guide: Maximum Charging Current & Voltage For 12v Battery

What Size Charge Controller Do I Need To Charge The Battery?

The job of the charge controller is to regulate the voltage coming from the solar panels to safely charge the battery and prevent the battery from being overcharged.

To select the right size charge controller according to your solar panel size. Follow these 2 steps

  1. Divide the solar panel rated wattage by battery volts (e.g by 12 for 12v battery and so on…)
  2. Now add an extra 25% to the result value to keep the system safe in case of any fluctuations.
  3. Now the value will be the size of charge controller you’d need with your particular solar panel size to charge the battery.

For Example

let’s suppose you have a 400-watt solar panel and a 12v battery. the calculation will look like this.

100 / 12 = 33.3A
33.3 + 25% or 33.3 * 1.25 = 41.6 A

you’d need a 40A charge controller with a 400-watt solar panel to charge a 12v battery.

PWM vs MPPT

This guy has explained soo well about the PWM vs MPPT charge controller and which one to use and when. ( if you’re a noob i suggest you watch this video! )

– PWM charge controller

will only decrease the voltage coming from the solar panels and will not increase the amps (current).

which as a result will cause power losses which makes the PWM charge controllers 20-30% less efficient.

The formula to power is… ( Watts = amps * volts )

Remember: a 12v solar panel will produce about 18 volts under direct sunlight conditions… and the amps will be lower.

Note! If you’re using an PWM charge controller the voltage of solar panel and battery should be the same. ( eg. 12v solar panel for 12v battery and 24v solar panel to charge a 24v battery ). Otherwise you’ll experience a huge power loss. If you have different voltage solar panels and battery then use an MPPT charge controller.

– MPPT charge controller

An MPPT charge controller will not only decrease the voltage coming from the solar panel to charge the battery but will also increase the amps to cover up the losses.

which makes them 98-99% more efficient than a PWM charge controller.

Pro Tip: if your solar panel system is higher then 100 watts then i would suggest using an MPPT charge controller.

Related Post: How Many Watts Can A Charge Controller Handle?

How Long To Charge 200Ah Lithium (LiFePO4) Battery?

Here are some charts about how long will it take to charge a 12v, or 24v 200ah Lithium (LiFePO4) battery with different size solar panels using a PWM or MPPT charge controller

How Long Will It Take To Charge 12v 200Ah Lithium Battery?

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

Solar Panel SizeCharge Controller TypeEstimated Charge time
100 wattPWM41 peak sun hours
200 wattPWM20 peak sun hours
300 wattPWM14 peak sun hours
400 wattPWM10 peak sun hours
500 wattPWM8 peak sun hours
100 wattMPPT35 peak sun hours
200 wattMPPT17 peak sun hours
300 wattMPPT12 peak sun hours
400 wattMPPT9 peak sun hours
500 wattMPPT7 peak sun hours

Summary

  • a 100 watt solar panel will take about 41 Peak sun hours to fully charge a 12v 200ah lithium (LiFePO4) battery from 100% depth of discharge using a PWM charge controller
  • a 100 watt solar panel will take about 35 Peak sun hours to fully charge a 12v 200ah lithium (LiFePO4) battery from 100% depth of discharge using an MPPT charge controller

How Long Will It Take To Charge 24v 200Ah Lithium Battery?

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

Solar Panel SizeCharge Controller TypeEstimated Charge time
100 wattPWM82 peak sun hours
200 wattPWM41 peak sun hours
300 wattPWM27 peak sun hours
400 wattPWM20 peak sun hours
500 wattPWM16 peak sun hours
100 wattMPPT70 peak sun hours
200 wattMPPT34 peak sun hours
300 wattMPPT24 peak sun hours
400 wattMPPT18 peak sun hours
500 wattMPPT14 peak sun hours

Summary

  • a 100 watt solar panel will take about 82 Peak sun hours to fully charge a 24v 200ah lithium (LiFePO4) battery from 100% depth of discharge using a PWM charge controller
  • a 100 watt solar panel will take about 70 Peak sun hours to fully charge a 24v 200ah lithium (LiFePO4) battery from 100% depth of discharge using an MPPT charge controller

Video – How To Built a Solar Power System To Charge a Battery

Watch this beginner-friendly video on how to build your first solar power system to change a battery and run AC appliances

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I hope this guide was helpful to you. If you have any queries Contact Us, Thank You!

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.