How Many Watts Does A Battery Charger Use? Understanding Battery Charger Power Demands

Have you ever tried to charge a new device and noticed that it charges longer than expected? While different battery chargers can power the same gadget, their capacity, size, and functions are usually different. 

Before buying a new battery charger, you must consider the amount of power such a battery uses. Watts are the units of measurement for electrical power.

This article discusses the types of battery chargers, the effects of a trickle battery charger, how you can charge without a battery charger, and other comprehensive details. 

But most importantly, let’s address the main issue.

How Many Watts Does A Battery Charger Use?

A typical 10A battery charger uses less than 200 Watts, while a larger 25A charger uses less than 500 Watts. Watts, often known as wattage, is a measurement of how much power passes through your charger. 

As a result, a higher wattage battery charger will charge your gadget faster. You can easily determine Watt by looking at the voltages and amps inscription on the battery charger. The formula is; Watts = volts x amps.

Always choose the device with the maximum wattage for the fastest charge. Additionally, you can increase the voltage or the amps to generate extra watts.

What Are The Common Types Of Battery Chargers?

There are situations where you need to replace your alkaline batteries with rechargeable batteries. In this case, you’ll be left to make the right choice of investing wisely in the right battery charger.

Timer Controlled chargers and Smart chargers are two different battery chargers on the market today. The two chargers have different budgets. The timer-controlled chargers are less expensive than the smart chargers. 

More importantly, these chargers have two different technologies. 

Timer-controlled battery chargers include an automatic, built-in shut-off timer preset at the factory. This setting implies that all the batteries you place in it to charge will charge simultaneously.

 Also, once the preset period has passed, the machine will shut down, and it’ll no longer supply any further charge. This battery is a simple device that can’t tell how much energy each battery has left. Therefore, all batteries get charged for the same amount of time.

It’s a cheap way to charge batteries, but it can’t identify how much charge each requires. However, this charger overcharges some and undercharges others. 

Overcharged batteries become worn out over time. Therefore, before choosing a timer-controlled charger, consider the money you’ll spend on replacing batteries damaged due to overcharging.

Smart chargers are also known as intelligent chargers or Negative Delta Voltage Chargers. These chargers can detect missing voltage by evaluating the peak voltage left in each battery they are connected to. 

As a result, each battery is “custom-charged” as needed. The technology of this charger is quite costly. However, it provides two significant benefits: it does not damage batteries because it doesn’t undercharge or overcharge them,

In addition, smart chargers make the user worry less about the charge status of any of their batteries because the charger extends its lifespan.

For example, when the battery is 80 percent charged, intelligent chargers detect this and switch to trickle charge to maintain the battery’s charged position. 

What’s A Trickle Battery Charger?

A battery charger that uses a very low voltage to charge the battery is called a Trickle battery charger. Trickling indicates that the battery will charge gradually over time.

The key feature distinguishing a trickle charger from others is that it either has a low amperage choice or only produces a low charging amperage. The majority of trickle chargers supply power between 1 and 3 amps. 

There are two aspects to consider when using a trickle charger. One is that the alternator can only produce a certain amount of amperage, so if you only drive to work or run errands, the battery is likely to be low on charge. 

In addition, you can never use trickle chargers to charge entirely dead batteries. 

Can A Trickle Charger Ruin A Battery?

If left unchecked, a trickle charger continuously emits a little current regardless of the battery’s ability to receive it, resulting in overcharging. In addition, although the amp level is low, keeping your battery on a trickle charge for long will cause an undesirable chemical reaction.

This reaction will cause the battery to boil the electrolyte. The result would be a dead battery, fire, or explosion in the worst-case scenario. These unfortunate incidents make it dangerous to connect a trickle battery charger for days or months on end, or even overnight. 

How Fast Will A Generator Charge My Battery?

Please note that you have to use a generator’s AC output to supply power to a 240-volt or 120-volt battery charger if you want fast charging. The high voltage will charge up the battery faster. 

The uncontrolled 13.6-volts are considered too low for full and fast battery charging. So instead, it can charge a flat 100 amp-hour battery to half capacity in six hours. After that, the charging rate gradually decreases. 

It can take another 24 hours to charge it to 70%. However, the battery can take up to 2 hours to fully charge when the generator is hooked into an AC outlet.

How Can I Charge Without A Battery Charger?

A low or dead battery cell in an emergency circumstance could be disappointing. However, two main tricks are to charge a battery without a battery charger. 

Firstly, you can use a battery to charge your dead battery. Secondly, you can use the rubbing trick.

Using A Battery To Charge A Battery

Step 1: Remove the battery

You’ll need to take out the battery so that you can access the battery’s connection points. Keep in mind that it’s quite difficult to remove the batteries of some devices, especially Apple products.

Step 2: Look for a double-A battery (AA)

You can also use triple-A (AAA) or 9-volt batteries. Unlike the alternating current electricity from a wall socket, you can also use the power in these conventional household batteries.

Instead of attempting to hotwire your electrical gadget, you should use alternative batteries. However, using the wrong amount of amperage or voltage might harm your devices. 

Step 3: Identify each battery’s positive and negative connectors

These connectors will have inscriptions of AA on home batteries. The positive connector on most batteries will be the one closest to the edge, while the negative connector will be the one farther away.

Although there may be three or four connectors, the middle or two are used for temperature regulation and other functions.

Step 4: Match the voltages

At this stage, you should connect the voltage of the battery you’re charging with the voltage of the other batteries (AA, AAA or others with enough power to provide). Remember that a standard AA or AAA battery in regular use provides 1.5 volts. So to get more than 3.7V needed for a standard battery to charge, connect three AA or AAA batteries in series.

Step 5: Join two pieces of metal wire

Except for the exposed ends, these should be covered in plastic insulation.

Step 6: Tape or fasten the wires

Attach the wires to the battery that’ll supply a charge or the battery needing a charge. These wires may become quite hot, and transferring the charge will take a lengthy time. Therefore, you don’t want to keep them in your arms the entire time.

If you’re using AA and AAA batteries, you should connect them “in series” before connecting them to the battery that needs charging. 

After some hours, the dead battery cell will become charged (without a charger). Although this battery may not reach a full charge, it’ll power your device for a while. 

Using The Rubbing Trick

Step 1:

Take out the battery. Hold it in your hands and rub vigorously with both hands. Hard rubbing will cause the battery to generate adequate friction and heat. Repeat this process for 30 seconds to several minutes.

Stroking the battery gives it an extra charge due to static energy buildup. However, it’s important to note that this process does not fully recharge your battery.

Step 2: Re-insert the battery into the device

Make the most of your battery life, as it may just be for a few moments.

How Do I Store Battery Chargers?

Always keep your battery chargers dry and away from direct sunlight. In addition, it’s preferable to keep them at room temperature of 15-21 degrees Celsius. 

Always disconnect your battery chargers when not in use. In addition, remember to untangle the power cord and make sure the charger is free of any extra weight. 

Note that pulling on the power cable can destroy the connections in the plug. Therefore, use the plug to remove the battery charger carefully from the socket.


Wattage is the entire measurement of power that travels through your charger. For example, it would take less than 200 Watts to charge a 10A battery. A larger 25A charger would most likely consume less than 500 watts. 

There are times when the only information you have about your new battery charger are the Volts and Amps. You can determine the wattage by using watts = volts x amps.

A battery charger with a greater wattage means that your device will charge faster. Therefore, choose the battery charger with the highest Watt if you desire a faster charge.

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