How Long To Charge 100Ah Battery (Lead-acid, Lithium)

Calculating the charging time for a 100ah battery can be challenging, given the many factors that can affect it.

However, there's an easier way! Our 100ah battery charge time calculator can help you estimate the charge time, whether you're using a solar panel or a battery charger.

Click on a charging method to jump to the calculator:

These calculators will help you estimate how long it will take to charge your 100ah battery, taking into account the charging efficiency for different types of batteries. In addition, I've included some tips to increase your 100ah solar battery charge efficiency.

How long to charge 100ah battery?

Use the below calculators to find out the charging time for your 100ah battery with solar panels or battery charger.

With solar panels

Enter the battery specs, solar panel size, and select the charge controller type into our solar battery charge time calculator to find out how long does it take to charge 100ah battery with solar panels.

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

Note: The estimated charge time of your battery will be given in peak sun hours. For more information on what peak sun hours are and how to calculate them, please refer to our in-depth guide.

What is battery depth of discharge (DoD)? It indicates the percentage of the battery that has been discharged relative to the overall capacity of the battery.

Limitations of this calculator --- It does not take into account the battery absorption stage, which takes 2-3 hours to fully charge the lead acid battery from 80% to 100% regardless of the size of the solar panel and 20-30 minutes for lithium battery type.

The calculator assumes the following efficiencies: 

1. Battery charge efficiency - Lead-acid --- 85%, lithium --- 95%
2. Charge controller efficiency - PWM --- 80%, MPPT --- 95%
3. Solar panel output efficiency - 80%

with battery charger

Enter the battery specs and charging amps to find out how long to charge 100 amp hour battery with a battery charger using our calculator.

Battery Capacity (Ah)
Ah
Battery Type
Depth Of Discharge (DoD)
%
Charge Current
Amps (A)
Note: 

1. It also does not take into account the absorption stage of battery charging.
2. The calculator assumes the battery charge efficiencies: Lead-acid --- 85%, lithium --- 95%. 

How Fast Should You Charge Your 100ah Battery?

Deep cycle batteries are designed to charge and discharge at a specific rate. It’s important to note the recommended charge time for different types of batteries:

  • Lithium (LiFePO4) ≈ 2 hours
  • Lead acid ≈ 20 hours
  • AGM ≈ 5 hours

100ah battery recommended charge rate: That means you can safely charge your 100ah lithium battery with 50 amps or 600 watts for a 12v battery, and 1200 watts for a 24 battery. For a lead acid battery, usually, it's recommended to be charged with 5 amps or 60 watts for a 12v battery.

Effect of charging a battery at a higher rate: Charging your battery at a higher rate than what’s recommended can increase the battery’s internal cell temperature, which will ultimately decrease the battery’s overall health and charging efficiency.

Battery's recommended charging or discharging rate will be mentioned as C-ratings, or max. charge, or max. discharge rate.

Note: Refer to your battery's data sheet to find its c-rating or maximum charge rate.

Related post: Battery Charge And Discharge Rate Calculator: C-Rating To Amps

Tips To Increase Solar Battery Charge Efficiency

Follow these tips to decrease the charging time of your 100ah battery.

  1. Use an MPPT charge controller: MPPT charge controllers are 20-30% more efficient than PWM charge controllers.
  2. Ensure Proper Panel Orientation: Proper orientation of solar panels is crucial to maximizing solar battery charge efficiency. Ideally, panels should face south or north if you live in the southern hemisphere. Panels should also be angled to match your latitude. By doing this, the panels will receive maximum sunlight and increase the amount of energy generated. (source)
  3. Keep solar panels clean: Dirt, dust, and debris can accumulate on the surface of solar panels and reduce their efficiency. (source)
  4. Use High-Quality Components: Such as cables, connectors, and charge controllers can help to increase the efficiency of solar battery charging.
  5. Keep your batteries under a recommended temperature range: Batteries usually perform best at about 25oC temperature. Check your battery specs sheet for more accurate numbers.

How Long To Charge 100ah Battery With 200 Watt Solar Panel?

Here's a chart showing how long a 200w solar panel will take to charge a 12v 100ah battery.

Solar Panel Size12v 100ah Battery TypeCharge Controller TypeEst. Charge Time
200 wattlead-acidPWM5.5 peak sun hours
200 wattLithium (LiFePO4)PWM10 peak sun hours
200 wattlead-acidMPPT4.5 peak sun hours
200 wattLithium (LiFePO4)MPPT8 peak sun hours

Summary

  • 200 watt solar panel will take about 5 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge.
  • 200 watt solar panel will take about 8 peak sun hours to fully charge a 12v 100ah lithium (LiFePO4) battery from 100% depth of discharge.

How Long To Charge 100ah Battery With 100 Watt Solar Panel?

Here's a chart showing how long a 100w solar panel will take to charge a 12v 100ah battery.

Solar Panel Size12v 100ah Battery TypeCharge Controller TypeEst. Charge Time
100 wattlead acidPWM11 peak sun hours
100 wattLithium (LiFePO4)PWM20 peak sun hours
100 wattlead acidMPPT9 peak sun hours
100 wattLithium (LiFePO4)MPPT16 peak sun hours

Summary

  • 100 watt solar panel will take about 9 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge.
  • 100 watt solar panel will take about 16 peak sun hours to fully charge a 12v 100ah lithium (LiFePO4) battery from 100% depth of discharge.

How Long To Charge 100ah Battery With 400 Watt Solar Panel?

Here's a chart showing how long a 400 watt solar panel will take to charge a 12v 100ah battery.

Solar Panel Size12v 100ah Battery TypeCharge Controller TypeEst. Charge Time
400 wattlead acidPWM3 peak sun hours
400 wattLithium (LiFePO4)PWM5 peak sun hours
400 wattlead acidMPPT2.5 peak sun hours
400 wattLithium (LiFePO4)MPPT4 peak sun hours

Summary

  • 400 watt solar panel will take about 1.5 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge.
  • 400 watt solar panel will take about 4 peak sun hours to fully charge a 12v 100ah lithium (LiFePO4) battery from 100% depth of discharge.

How Long To Charge 100ah Battery With 300 Watt Solar Panel?

Here's a chart showing how long a 300 watt solar panel will take to charge a 12v 100ah battery.

Solar Panel Size12v 100ah Battery TypeCharge Controller TypeEst. Charge Time
300 wattlead-acidPWM4 peak sun hours
300 wattLithium (LiFePO4)PWM6.5 peak sun hours
300 wattlead-acidMPPT3 peak sun hours
300 wattLithium (LiFePO4)MPPT5.5 peak sun hours

Summary

  • 300 watt solar panel will take about 3 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge.
  • 300 watt solar panel will take about 5.5 peak sun hours to fully charge a 12v 100ah lithium (LiFePO4) battery from 100% depth of discharge.

How Long To Charge 100ah Battery With 10 Amp Charger?

To Calculate how long to charge a 100ah battery 10 amp charger follow these steps:

1- Multiply the battery capacity (ah) with its depth of discharge (DoD). Let's say you have a 100ah lead-acid battery with a 50% depth of discharge.

100 × 50% = 50 amp hours (Ah)

2. Multiply the battery amp-hours after the depth of discharge by 1.15 if you're using a Lead acid, AGM, or Gel battery and by 1.05 if you're using a Lithium, LiFePO4, or Lipo battery type to take into account the battery charge efficiency.

50 × 1.15 = 57.5 amp-hours

3. Divide the battery's required charging amp-hours by the charger amps.

50 ÷ 10 = 5 hours.

Turns out, a 10 amp charger will take 5 hours to fully charge the 100ah lead acid battery from 50% depth of discharge and 10 hours to fully charge the 100ah Lithium (LiFePO4) battery from 100% depth of discharge.

How Long To Charge 100ah Battery With Solar Panel?

Here's a chart showing the 100ah lead acid and lithium battery charging time using different size solar panels.

Solar Panel Size100ah Battery TypeEst. Charge Time
50 wattLead-acid18 peak sun hours
100 wattLead-acid9 peak sun hours
150 wattLead-acid6 peak sun hours
200 wattLead-acid4.5 peak sun hours
300 wattLead-acid3 peak sun hours
400 wattLead-acid2.5 peak sun hours
500 wattLead-acid2 peak sun hours
50 wattLithium (LiFePO4)33 peak sun hours
100 wattLithium (LiFePO4)16 peak sun hours
150 wattLithium (LiFePO4)11 peak sun hours
200 wattLithium (LiFePO4)8 peak sun hours
300 wattLithium (LiFePO4)6 peak sun hours
400 wattLithium (LiFePO4)4 peak sun hours
500 wattLithium (LiFePO4)3.5 peak sun hours

Summary

  • 12v 100ah lead acid battery will take between 3 to 10 peak sun hours to get fully charged from 50% depth of discharge with solar panel.
  • 12v 100ah lithium (LiFePO4) battery will take about 4 to 16 peak sun hours to get fully charged from 100% depth of discharge with solar panel

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

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Chris Tsitouris is a renewable energy professional with 10+ years of experience as Director of Engineering at Solar Spectrum, previously working as Project Manager at SunPower and Energy Analyst at the National Renewable Energy Laboratory. As a thought leader, Chris has authored numerous articles and research papers.

2 thoughts on “How Long To Charge 100Ah Battery (Lead-acid, Lithium)”

  1. Thank you so the information. Can you recommend a specific type of solar charge controller that is compatible with 200 watt solar panel and a 100ah AGM battery to ensure efficient and safe charging?

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