Battery chargers and maintainers, a buyers guide

6th September 2021, 3:07am
4 min read
Battery chargers and maintainers, a buyers guide

The best battery charger to buy depends on your needs. How quickly do you need the battery to charge? What types of batteries will you be charging? Are you looking to maintain batteries held in storage or to bring an old battery back from the dead?

In this guide, we’ll outline everything you need to know about battery chargers and list the top five options you can buy today.

Our pick of the battery chargers

1. CTEK MXS 5.0 Battery Charger

CTEK MXS 5.0 Battery Charger

An automatic charging and maintenance device, the MXS 5.0 from CTEK offers excellent performance for all lead-acid battery types between 1.2 and 110Ah. It has automatic temperature compensation, so even if there’s a sharp drop in climate, the MXS 5.0 will continue to supply the right current at all times.

The MXS 5.0 has an automatic de-sulphation program that can help restore the capacity of older batteries. A special Recondition mode can bring deeply discharged batteries back to life.

Safe, easy to use, IP64 certified, and well-tested in the field, the CTEK MXS 5.0 is an all-around excellent trickle charger for lead-acid batteries.

Voltage12V
Charging current5A
Fully automatic / charging stepsFully-automatic 8-step charging
Battery compatibilityAll lead-acid battery types: WET, MF, AGM, CA, GEL

2. NOCO GENIUS 10 Battery Charger

NOCO GENIUS 10 Battery Charger

The NOCO GENIUS10UK is the most powerful charger on our list, capable of outputting a current of 10A. It’s a smart battery charger with auto-detection of sulphation and acid stratification. It can automatically repair most batteries and extend their use.

The GENIUS10UK has thermal compensation for more precise charging no matter the weather. It can avoid overcharging in cold weather to -4 degrees F and hot weather up to 104 degrees F.

This charger has eight charging modes, including 12V, 12V AGM, 12V Lithium, and 12V repair mode.

If that’s not enough, it also works as a 12V supply to power any 12V DC device. It’s a powerful battery charger and maintainer all rolled into one, making it a fantastic all-around choice.

Voltage6V & 12V
Charging current10A
Fully automatic / charging steps9 selectable modes
Battery compatibilityWet, Gel, MF, CA, EFB, AGM, LIB

3. NOCO GENIUS 5 Battery Charger

NOCO GENIUS 5 Battery Charger

If you don’t need 10A power, then you can get the GENIUS5UK from NOCO for about half of the price of the GENIUS10UK. It offers most of the features of the GENIUS10UK, too, but it doesn’t have a 12V Supply Mode like the 10A charger.

Again, this charger offers the best of both worlds, as you can quickly charge your batteries and then leave the NOCO GENIUS 5 running in maintenance mode where it will engage when needed to keep your battery fully charged and in good condition.

Voltage6V & 12V
Charging current5A
Fully automatic / charging steps7 selectable modes
Battery compatibilityWet, Gel, MF, CA, EFB, AGM, & LIB

4. TOPDON TORNADO4000 Battery Charger

TOPDON TORNADO4000 Battery Charger

Arguably the most intelligent charger on our list, the TOPDON TORNADO4000 has a 10-step charging process that can diagnose and charge your battery up to its need. It’s quite quick too - a 20Ah 12V battery will charge within 5 hours, on average.

This smart charger can perform battery recovery that detects sulphation and acid stratification automatically, fixing issues with older batteries and bringing many dead batteries back to life.

It’s easy to use, IP65 waterproof, and it works on batteries rated from 10Ah up to 80Ah. And besides the usual range of 12-volt lead-acid batteries, this battery charger also works on 6-volt and lithium-ion batteries.

Voltage6V & 12V
Charging current4A
Fully automatic / charging stepsFully automatic 10-step charging
Battery compatibilityWet, Gel, MF, CA, EFB, AGM, & LIB

5. AA AA0725 Battery Charger

AA AA0725 Battery Charger

The AA0725 Battery Charger is a fully automatic 4A intelligent battery charger from AA. It has a built-in processor that assesses the situation of your battery to provide exactly the right current and voltage.

It’s IP64 water and dust resistant and has a clear LCD. It’s easy enough for anyone to use, and it has both ring connectors and clamps for maximum versatility.

This battery charger has a 4A DC, an 8-step smart charging process, and a dead battery recovery feature. We recommend it for car owners who want a simple car battery charger with trickle charge capabilities.

Voltage6V & 12V (Lead), 12.8V (Lithium)
Charging current4A
Fully automatic / charging stepsFully automatic 8-step charging
Battery compatibilityWet, Gel, VRLA, AGM, & LIB

Types of Battery Chargers

  • A regular battery charger is designed to charge a battery as quickly as possible. But charging a battery too quickly shortens its lifespan and can be unsafe.
  • Trickle chargers instead deliver a very low voltage over a period of time. They are used for keeping a battery at full charge while the battery is in storage.
  • Maintenance chargers are similar and can be used to set a specific charge range. The maintenance charger will automatically switch on and off to maintain this level of charge.

When should you use a battery maintainer?

If you plan on occasionally charging a battery for quick use, then a regular charger is the best option. Trickle and maintenance chargers are best if you regularly store batteries unused for 30 days or more.

If you know your batteries will go long periods without use, such as if you have vehicles in storage, a trickle charger or battery maintenance unit will keep your batteries in their best condition.

Luckily, the best battery chargers offer a combination of features, so you can use them as a fast charger or trickle charger as you see fit.

What to look for when buying a trickle charger or battery maintainer

Voltage

A battery charger must have the same voltage as the battery it is charging. For example, if you’re looking to charge a 12V car battery, you need a battery charger capable of outputting 12V. If you’re charging 24V batteries found in larger trucks, buses, and boats, you need a 24V battery charger.

Charging current

Charging a battery safely requires sufficient charge current, measured in amps. The more amps, the faster the battery will charge. Basic chargers charge at around 2A, meaning they’ll take 24 hours to completely recharge a 48-amp hour battery. A 4A charger will take around 12 hours for the same battery, while an 8A charger would take just 6 hours.

As advised above, charging a battery too quickly can shorten the battery’s lifespan or even be unsafe. Good battery chargers offer multiple charging speeds and automatically adjust the rate when required.

Fully automatic

A fully automatic charger will stop charging and switch to a maintenance mode when the battery is fully charged. This prevents overcharging and essentially allows a smart battery charger to work as both a fast battery charger and a maintenance charger.

Charging steps

Smart battery chargers and trickle chargers use a multistep process when charging a battery. This is designed to maintain the best life of the battery while delivering the fastest performance. A smart charging process includes steps similar to these:

  1. Pulse voltage to de-sulphate the lead plates
  2. Test if the battery will accept a charge
  3. Charge at maximum current until the battery reached 80% capacity
  4. Charge to 100% with declining steps of current
  5. Analyse whether the battery is retaining a charge
  6. Perform reconditioning on batteries that were deeply discharged
  7. Maintain the battery at maximum charge by providing a constant voltage
  8. Maintain the battery at a charge between 95-100% by pulsing voltage

Battery compatibility

Batteries come in various types. As a brief summary, we have:

  • Lithium-ion batteries (LIB) are more expensive but have a long life and charge faster
  • WET cells, basic lead-acid batteries with electrolyte and water. Can be serviceable or maintenance-free
  • GEL cells use silica. They’re more expensive than WET cells but store well, degrade slower, and are safer
  • AGM (Absorbed Glass Mat) batteries offer higher performance and have longer life cycles
  • Calcium batteries include calcium for a longer shelf and perform better at cold temperatures

There are other types of battery too with more niche applications. The most important thing to remember is your battery charger must support the type of batteries you plan to charge.

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Written by Raymond Burrett

Raymond is the quintessential car enthusiast. Motorsports and sports-cars have played a prominent role since a young age. He can now be found tinkering with his Japanese sports cars, at local car meets or out on a track-day.