Review: REDARC Battery Charger, AC to DC 10A SmartCharge

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REDARC Electronics have recently released a range of AC to DC battery chargers. By teaming up with Norwegian company DEFA, REDARC have brought a versatile and premium quality charger into the market.

Holding our new REDARC battery charger.
Our shiny new battery charger.

You can choose from 4, 6, 8 and 10A chargers. REDARC sent us a 10A charger to test. This is best suited to our larger truck batteries and can charge any battery up to 200Ah.

So how does it perform?







Borrowing A Battery

We were located in a sleepy village on the NSW North Coast, in a quiet caravan park. With a shiny new charger, all we needed was a flat battery.

We could have run down the 100Ah AGM battery in the second battery system on our truck, or we could have done the same with the lithium battery in our Wedgetail Camper. But I decided to ask around first.

It turns out fellow campers Brett and Claudia had an old lead acid battery. It had come out of a diesel Hyundai, after failing Hyundai’s standard test procedure. But was still working, so Brett and Claudia use it to power their spare portable fridge.

The trial setup we used to test our new REDARC battery charger.
This old battery was perfect for trying out the new charger.

This battery had been run low quite often, not ideal for a lead acid battery… a perfect test battery. Thanks Brett and Claudia!







Setting Up The Test

The REDARC battery charger is extremely easy to use. Connect the alligator clips to the terminals, plug it into 240 volts and press the On button. The charger takes care of the rest.

Go here for the full range of SmartCharge battery chargers.


It checks the terminals for correct polarity and then tests the battery for collapsed cells. If either of these are an issue, an orange warning triangle lights up.

Assuming all is well, the charger then runs through a thorough charging cycle. Once the cycle has ended, the charger then optimises the battery for charge.

We found our test battery needed a couple of hours of optimising before the charger was satisfied it was in the best possible condition.

And that’s it.


You can also leave this charger connected indefinitely. It cannot overcharge your battery. Once the initial charge is complete, it goes to sleep for a week. After a week it wakes up and checks battery condition. If the battery needs a top up, the charger optimises the charge before going back to sleep for a week.

While in Sleep mode, the charger continues to monitor the battery voltage. If it drops below 12.6V, the charger will resume charging.

The REDARC battery charger uses a set of horizontal bars to indicate charge level.
The horizontal bars indicate level of charge. This is showing the battery to be about 25% charged.


A Troubleshooting Tool

The thing that excited me most about the REDARC battery charger was an additional feature, hidden away in the user manual. You see, it can be used as a power supply. Press and hold the On button for 5 seconds and the charger supplies a constant 13.6 volts.

Learn how easy it is to use the SmartCharge as a 12V power supply.

I know this feature isn’t exclusive to the REDARC SmartCharge units, however it is a valuable troubleshooting tool. For example in our setup, we have a dual battery system in the truck. From this we run a 350W inverter.

Since the charger only pulls a maximum of 175W, we can use it in the middle of nowhere if we run into trouble.

Say the fridge stops working. Unplug the fridge and power it from the battery charger. You’ll then know whether the problem is downstream in the fridge or upstream in the wiring.

Or maybe a light isn’t working. Same thing… use your battery charger to troubleshoot.

And if you’re camped up where there’s power available, use it to power a second fridge, lighting and so on… up to a maximum of 10A of course.

This is a fantastic feature and yet another reason why we loved using this charger.







Packing It Away

In typical Scandinavian fashion, the SmartCharge battery charger packs away neatly. The power cord wraps around the body, with the plug disappearing into a custom moulding in the back of the unit.

Likewise, the cable for the alligator clips wraps around the body. Each clip clamps onto a post on either side of the body and there’s even a small lug to hold the cable firmly in place.

The new REDARC battery charger is a neat, compact unit.
It wraps tightly into a neat package.

So you don’t end up with a drawer full of messy cables. More importantly, the cables are far less likely to be damaged. Very clever!


In Summary

REDARC have finally released a battery charger and it’s typical of what you’d expect from them… premium quality, easy to use and highly functional.

This will be one unit that we’ll be carrying with us wherever we go. And I expect it will last a long time.


My Generator stock the full range of REDARC SmartCharge Battery Chargers. Go here for details.


FAQs – Common Questions About Car Battery Chargers


How does a car battery charger work?

In its simplest form, a car battery charger draws 240 volts AC and converts it into a DC voltage, around 13 – 14 volts. It passes electric current through a battery, to transfer energy into the battery. The battery stores this energy and over time, becomes fully charged.

Regular under-charging will shorten battery life. Overcharging can severely damage a battery. Why? Because the battery converts the extra energy to heat and there’s a real chance your battery will explode.

Smart battery chargers continually monitor the condition of the battery. They vary the charge going into the battery by varying voltage and current accordingly.

A smart battery charger will never undercharge or overcharge a battery because it “knows” when the battery is fully charged.


What is a smart charger for car battery? 

A smart charger has an in-built microprocessor that monitors the battery as it’s being charged. This means the battery:

  • Cannot be overcharged, and
  • Will be fully charged to its optimal condition.

Good quality smart chargers will mostly have the following features:

  • Automatically detect if the charge cables are incorrectly connected (reverse polarity),
  • Spark protection,
  • Short circuit protection,
  • Over-current protection
  • Over-voltage protection,
  • Low voltage protection, and
  • Over-temperature protection.


What’s the best portable car battery charger?

Without mentioning brands (that’s an endless argument for which there’s no correct answer!), the best portable battery charger is a smart charger.

A smart charger will never undercharge or overcharge your battery.

Three other features to look for:

  • If a battery is connected to the charger long-term, does the charger continually monitor battery state of charge and top it up as needed? This keeps the battery in optimum condition and will extend its life.
  • Does the battery charger double as a 12v power supply? This is an invaluable troubleshooting tool.
  • Can the battery charger charge LiFePO4 lithium batteries? These are quite common and becoming more so as the price continues to drop.
  • Does the charger indicate when the battery is faulty? It should give you a warning.


How long does it take to fully charge a car battery charger with a battery charger?

It depends on the current rating of the battery charger.

Say you have a 100Ah battery, 50% discharged. A 2A battery charger will take (50Ah/2A =) 25 hours to fully charge the battery.

A 10A charger will take (50Ah/10A =) 5 hours to fully charge the battery.

That’s a rough indication. Other factors affect charge time:

  • Ambient temperature. A smart charger will decrease charging current as ambient temperature increases. This protects the battery from overheating.
  • Condition of the battery. A smart battery charger will make every attempt to optimise the battery’s charge level. So it might take longer to finish off the charge, as it attempts to restore the battery to its optimal state.


What is the best battery charger for a car?

Look for these features:

  • Lightweight and easy to carry.
  • Solidly made and durable.
  • Gives you a fast charging time. Look for a high current rating, like 8 or 10A for a car battery.
  • Easy to use. Just an on/off button and the charger does the rest.
  • Automatically detects if the charge cables are incorrectly connected (reverse polarity), has spark protection, short circuit protection, over-current & over-voltage protection, low voltage protection and over-temperature protection.

Quality smart chargers will have all of these features at a minimum.


Can I start my car while the battery charger is attached?

The answer is maybe, but don’t risk it. It depends on your battery charger and on the state of charge of the battery.

The safest option? Disconnect the battery charger before attempting to start your car. This way you’ll avoid any potential damage to the battery charger.


How do you use a car battery charger?

  1. Make sure the battery charger and the battery are compatible. Check the car owners manual for battery details.
  2. Connect the red clamp to the positive terminal.
  3. Connect the black clamp to the negative terminal.
  4. Plug battery charger into 240 volt wall socket and turn on.
  5. Turn battery charger on.
  6. Check it is charging okay and not showing any warning lights or alarms.
  7. When charging is complete, turn battery charger off.
  8. Unplug 240 volt power cord from wall socket.
  9. Disconnect black clamp from negative terminal.
  10. 10.Disconnect red clamp from positive terminal.

It’s okay to charge your car’s battery while it’s still in the car and connected.


Can I charge a dead car battery?

It depends on what you mean by “dead”. If the battery is flat because you left the headlights or stereo on, or you haven’t driven the car for ages… then yes you can.

However, if the battery fails internally it cannot be recharged. If you have a smart battery charger, it should let you know if the battery is faulty. For example, the REDARC SmartCharge battery charger has a flashing warning triangle to indicate battery failure.


Is it safe to leave a car battery charger on overnight?

Yes, if you use a smart battery charger. It constantly monitors the battery’s charge level and adjusts itself accordingly. Once the battery is fully charged, a smart charger will not overcharge the battery.


Can I leave trickle charger on overnight?

Trickle chargers slowly charge your battery. Some trickle chargers are designed  to be used for short periods, like overnight. Others are designed to keep your battery charged for long periods, like when you have a car in storage for example.

Many smart chargers have a trickle charge function. They can be left connected to the battery indefinitely and are smart enough to monitor the battery and decide when it needs topping up.


What happens if you leave a car battery charger on too long?

It depends on the type of battery charger. Simple battery chargers will continue to charge the battery, even when it’s fully charged. This causes the battery to overheat and can lead to it swelling or even exploding.

A smart charger will constantly monitor the battery and adjust the charger accordingly. Most smart chargers can be left connected to a battery indefinitely without damaging the battery.


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Any errors or omissions are mine alone.


NOTE: The REDARC battery charger was supplied to us free, in return for a review. (That said, our reviews are always honest and authentic – we tell it how it is).


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