Can You Charge a Battery While Using an Inverter?

Batteries and inverters work hand in hand, but at some point the battery charge will go down. But what if you need to power a load and the battery is at 10%? Can you keep the inverter running or does everything have to stop?

It is safe to charge a battery while using an inverter, and it benefits both because this reduces heat and the amps drawn. If you are using solar panels to charge the battery there is no problem, but a battery charger might overheat if left connected for too long.

Why You Can Charge Batteries While the Inverter Runs

To better understand why you can recharge a battery even when the inverter is connected, we have to take a look at how these components work.

In a solar panel system , the battery serves as a repository for solar energy. The PV modules convert the sun’s energy into direct current (DC) and it is placed in the battery. Without a battery, any energy converted by the solar panel is lost, unless you are on a grid tied system. In a grid tied system, the energy is stored in the grid.

The inverter is connected to the battery and turns DC into AC. If you only run DC powered devices, you don’t need an inverter. But almost all appliances use AC, so an inverter is required. Once solar power is in the battery, the inverter transforms it into AC, which is what home appliances use.

So how does this explain why it is safe to charge batteries while the inverter is connected?

If you are charging the battery with a solar panel, it is perfectly safe because PV modules are designed to do this. You don’t have to worry about overheating because the power going into the battery is managed by a charge controller.

The inverter is safe too because it only draws the necessary power required from the battery bank. As long as the inverter is the right size there will be no issues here.

But what if you use a battery charger instead of a solar panel? is it safe? As we will show it is safe for the battery and inverter, though not so good for the charger itself.

The Inverter

Suppose you have a 500 watt inverter and a 105ah battery. If the battery is almost drained, the inverter has to deal pull in about 45 amps an hour to generate 500 watts.

But if you have a 10A battery charger like the Schumacher SC1303 and connect it, the battery volt goes up to 13.8 at 36A. Instead of 45A, it is 36A, which is great for your inverter because it means less heat. Jut like other electronics, the less load the better overall for the system.

Heat is not good for inverters, so the less amps drawn the better. But it is not just the inverter, but the battery too. As you can see, charging is good for the inverter and the battery.

The Battery

The inverter pulls power from the battery to keep your appliances going. The more amps drawn the faster the battery power goes down. But if you charge it, the amps pulled from the battery will be augmented by the charger.

Doing this will conserve the battery duty cycle, and this is the most important element in prolonging battery life. Whether it is lead acid or lithium, charging while the inverter operates is great for both components.

Without the charge all the amps taken by the inverter are from the battery. With the charger, the battery is being constantly replenished.

The Charger

The only drawback is it will overheat the charger. It won’t cause serious damage overnight, but if done on a regular basis the device may not last long. Here’s why.

When you connect a charger to a battery, it continuously supplies power to the system until it is full. Or when you pull the plug, because solar batteries are better off topped at 85% or so.

The time it takes to fully charge a battery depends on the type and how depleted it is. But if the inverter continues to run, the battery will never be fully charged.

Depending on the inverter load, for every amp the charger puts in the battery, more amps are pulled out because of the inverter. The longer the charger runs, the hotter it will get. And electronic devices should never be allowed to overheat for prolonged periods.

Should You Even Do This?

It is all right to do this if the battery is being charged by a solar panel or array. However you should be more careful with a battery charger.

If you decide to do this with a battery charger, here are some things to keep in mind. First, you will never be able to top the battery off as long as the inverter has a load. The charge can only provide so many amps, but if the inverter has a huge load it will not be enough.

If the inverter load is greater than the amps being supplied by the charger, the inverter will eventually come to a halt because there is not enough power. But if the incoming and outgoing amps are just about even, the battery power will remain roughly in the same state.

If you want to fully charge the battery, better reduce the inverter load if not drop everything off for a while. When the battery is filled, you can reload everything. If you have to load something, keep the number down as low as possible.

Again this will only be a problem if you use a battery charger. As long as your solar panels are working correctly you can recharge the battery while the inverter runs. Is there a risk to this?

The only risk is if the solar panel is unable to supply power. This can occur if the panels are damaged or there is no sun. During the summer you will probably not run into these issues. But if it is winter or there are overcast skies, you have to make adjustments to your power loads. For instance, you may have to recharge early or add another battery to the system.

Inverter and Battery Frequently Asked Questions

Can You Charge an Inverter with Its Output?

It is not possible because AC power, which the inverter produces, is greater than DC power, which comes from the battery. Also, majority of inverters are not designed to accept this type of output.

Can an Inverter Draw Too Much Power From a Battery?

No, inverters will pull the amps that its load require. If the load needs 10 amps an hour, that is what the inverter will take from the battery. As long as the battery has sufficient power, the load will run. If battery power is low, the inverter will not be able to run the appliance.

What are the Different Types of Solar Inverters?

There are three types, grid tied inverters, off grid inverters and hybrid inverters. A grid tied inverter is designed for solar powered homes that are connected to the grid. An off grid inverter is for solar power configurations that are independent from the grid. A hybrid inverter works for both setups.

What Type of Inverter Works Best with Batteries?

You can use any solar inverter and there will be no problems with charging. However, some like the GELOO 300W Inverter are more effective in using power for appliances. This eliminates energy loss and allows the system to use more of the battery power without letting it go to waste.

What is the Best Inverter Type?

Pure sine wave inverters are the best because they are the most efficient. If you want to get the most out of your batteries, then get a pure sine, not modified wave inverter.

Do I Need a Solar Panel to Charge a Battery?

No, you can charge a battery via electric power if you are on the grid. A small battery can be powered up by a charger as well. The advantage of a solar panel is you can charge the battery without overheating, provided you have a working charge controller.

Should I Use Lithium/AGM/Lead Acid Battery with an Inverter?

You can use any type of solar battery, but keep in mind that lead acid batteries have a lower depth of discharge level. With lead acid, AGM and gel it is 50%, but with lithium it is 75% to 100%. You have to decide if the extra cost of lithium is worth the extra power.

Can a Solar Panel Overcharge a Battery?

This can only happen if the system does not have a charge controller, or the controller is faulty. In that case, yes overcharging can occur. More information here about overcharging batteries with solar panels.

Conclusion

Knowing how to manage your battery bank and inverter is essential for any solar power system. By knowing that you can use an inverter and keep charging the battery, you can maximize solar power production.