Knowledge Base

How Many Watts Does a Trickle Charger Use? (Power Consumption Test)

By:Michael Johns

trickle charger power header

On this page, you will find out how many watts a trickle charger uses.

Not using your vehicle for an extended period of time? Then it’s best to invest in a trickle charger. It keeps your battery topped up so it’s not flat next time you need to use it. Plus, it avoids the damaging effects of leaving a deep cycle battery to run flat.

If you’re leaving your equipment plugged in for weeks (or months) you’re probably concerned about the power consumption. Or you might need to know what power output your charge provides.

Below we will discuss and test trickle charger wattage, explain how to work it out for yourself, and calculate the total electricity required.

How Many Watts is a Trickle Charger?

The average trickle charger uses between 5 and 15 watts.

The exact number depends on the amperage and voltage of your trickle charger. For example, a 0.5 amp charger delivers upto 6 watts. While more powerful 1 amp devices reach 12 watts.

Tickle charges are designed to charge a car or deep cycle battery very slowly. They are often referred to as ‘maintainers’ as it keeps a battery topped up rather than delivering a full charge. You use a trickle charge when leaving a vehicle unused for long periods of time.

Most commonly, they are used to keep RV batteries fully charged during the winter. As they only need to provide a tiny amount of electricity the current/amps is low. This leads to the small wattage we see above.

How to Find Out Your Trickle Charger Wattage

There’s 3 ways you can work out the wattage of a trickle charger.

  1. Check Product Specification

The quickest way is to look at the trickle charger’s specification. The watts (W) is usually written on a sticker on the base of the appliance. If not, you can check the user manual or the manufacturer’s website for technical details.

trickle charge power spec
  1. Wattage Formula or Calculator

If you know the amperage and voltage of your trickle charger you can use this to find the maximum watt rating. Simply use the formula Amps x Volts = Watts. Or you can head over to the ‘Watt Calculator’ to work this out.

  1. Use a Wattmeter

A wattmeter is brilliant for getting a live wattage reading and tracking total energy usage of any appliance. You can plug it into your trickle charger to get instant information. 

Trickle Charger Wattage Examples

Let’s take a look at specific examples of how many watts a trickle charger draws. Below is a collection of modern trickle chargers with their listed power ratings.

Trickle Charger ModelMax Power (Watts)
Battery Tender Junior9
Foval Automatic Trickle Battery Charger12
MOTOPOWER MP00205A 12V 800mA Automatic Battery Charger9.6
Nexpeak Car Battery Charger9
Mroinge Trickle Charger12
ECO-WORTHY 12 Volt Solar Car Battery Charger10
Sunway Solar Car Battery Trickle Charger5
Suner Waterproof Solar Battery Charger 12
Sun Energise Solar Battery Charger10

As you can see, the power ratings vary between different trickle chargers. So you should take the time to check your own device.

How Much Electricity Does a Trickle Charger Use?

It is hard to calculate the amount of electricity a trickle charger uses. This is because it won’t always deliver a continuous power level. Their slow charging design means it only sends electricity to the battery when it drops from full charge.

If you are using a 12 watt trickle charger, it won’t always be running at 12 watts. In fact, it will probably only reach this power level when used on a battery when it has 80% or less charge. When used on a nearly full battery it doesn’t need to work so hard to ‘top up’ the energy level.

Let’s look at some rough numbers to give you an idea anyway. 

A watt (W) is a measurement of power at a single point in time. A watt-hour (Wh) is the total amount of electricity used in an hour. For example, a charger drawing 12W would use 12Wh when running for an hour.

Happily, electricity bills are recorded in kilowatt-hours (kWh). A kilowatt is simply 1000 watts. So a 12W trickle charger running at full power for 1 hour uses 0.012kWh.

Let’s say,  you use a trickle charger at full power for 10 hours a month. This means it uses about 120Wh or 0.12kWh electricity a month. That’s 1.44kWh a year. 

That’s a rough electricity cost of $0.21.

Using a Solar Trickle Charger Off-Grid

Solar trickle chargers are incredibly popular on boats, RVs, and cars to ensure you never have a flat battery. 

They provide several massive benefits. Firstly, they don’t draw any electricity from your mains supply which makes it free to use. Secondly, it charges your battery completely off-grid, all you need is sunlight. 

Even a small solar panel is enough to generate 5 or 10 watts needed to maintain a battery.

They’re reasonably priced and easy to install. Most solar trickle charges arrive with handy alligator clips so you can attach to your battery in seconds.

How Many Watts is a Trickle Charger Summary

I hope you now understand how many watts a trickle charger uses.

These are low powered devices only required to deliver a small amount of electricity over a long period of time. They generally run at 12 volts to match car and deep cycle voltage. In addition, the current is very low at 0.5 to 1 amps. These two factors lead to a small power draw when charging. Remember, amps x volts = watts. 

When running a trickle charge from your mains electricity you’ll barely notice any difference in your energy usage. To be honest, it won’t even make a dent in your bills over the course of a year.

Most people now choose solar trickle chargers. They provide enough power even with small solar panels, plus you don’t need to plug into the mains. It’s 100% the best way to trickle charge your batteries for free anywhere during the daytime. Just remember, a solar trickle charger won’t work on a vehicle parked in a garage!