NOCO Genius5 review

There are many car battery charges on the market, and the colder it gets, the more pressing the thought of getting one is. Today we will look into one that we particularly like – the NOCO Genius5 car battery charger to see whether it would also suit your needs. In theory, everyone needs something a bit different depending on what cars they have, how many, if they need to charge something else as well (motorbikes, jet-skis, trucks, semis, etc.) – in reality though, majority of people have 1 or 2 “usual” vehicles for which this unit is (spoiler alert) well suited for.  

It is a successor of the G3500 series and if you need something with more “punch” or functions, have a look at our review of NOCO Genius10.

Before diving into Genius5’s specs, etc., it is worth noting that NOCO is a US brand established in 1914 in Ohio, and they still design and engineer their products there. You can read more about them here: NOCO

Now, back to our little car battery charger.


When you unpack the unit, you will be pleasantly surprised by how small that thing is.

With 4.6”/11.7cm in length, 1.93”/4.9cm in height, and 2.9”/7.4cm in width, it is not big at all and compares well to others, such as CTEK MSX5.

It is 1.59lbs/720g of lead-acid and lithium tech in a neat package – you would not carry it around, but that is not the point here – it will most likely rest tucked away on a shelf or lie on the floor waiting its time to shine.

Controls explained

Voltage, output power and charging current

It can be hooked to 120 or 240V, depending on which side of the ocean you are; respective versions have the right plug and have a max output power of 75 Watts and charge with 5A, both 12V and 6V batteries.

Low-voltage detection – a lot of chargers have a threshold higher which means that if the battery is almost completely dead, they will not start charging (because they essentially can’t “see” anything hooked up to it). The Genius5 has a really low threshold (1 volt), so it starts charging even when a battery is almost entirely dead. Thanks to this, it might also revive batteries you have long thought were dead and didn’t quite get to throw them away, and this goes for both 12V and 6V batteries. It also has a “Force mode” that you can switch on in case the battery is totally dead.

What's in the box?

  • The battery charger/maintainer
  • Battery clamps + integrated eyelets (if you want to use the eyelets, all you need to do is unscrew the clamps); it also contains an inline fuse for safety
  • Self-tapping screws
  • Mounting bracket with a strap
  • User guide
Genius5 what is in the box
Image credit: NOCO

What can the Genius5 charge?

It can be used for 6V/12V wet cell, gel, enhanced flooded, calcium or maintenance-free batteries and on top of that 12V Lithium-ion and AGM batteries that come with a Battery Management System.

Wet cellGelEnhanced floodedMaintenance-freeCalciumLithium-Ion (with AGM)AGM – advanced AGM and AGM plus

Repair capabilities

The Genius5 is able to repair sulfated, old, damaged, stratified, idle batteries, but take this with a pinch of salt – any repair will depend on the battery’s age, condition and any damage.

Battery charging times

Charging times
20Ah - 3 hours
40Ah - 6 hours
80Ah - 12 hours
100Ah - 18 hours
  • 20 Amp Motorcycle battery – around 3 hours
  • 40 Amp battery (lawn movers, for example) – around 6 hours
  • 80 Amp battery (full-size car battery) – around 12 hours
  • 100 Amp battery (diesel trucks) – around 18 hours
  • 230 Amp battery (deep cycle batteries) – around 34.5 hours

These times are obviously estimates as it always depends on the condition of the battery, how low the current charge is, how cold it is where you are charging, etc.…  

NOCO Genius5 charge levels
Image credit: NOCO

Advanced features

Ambient temperature – monitors what the ambient temperature is to prevent overheating or overcharging (if it’s hot, it will lower the output, if cold, it will increase it)

Plug and play – All season, all weather, you can leave it plugged without the risk of damaging the battery of the charger itself. It will come on and go off when necessary.

Repair mode – The GENIUS5 automatically detects sulfation/acid stratification. If any is found, the GENIUS5 will automatically repair and reverse the damage done to the battery, extending the usable life and increasing the performance.

Short-Circuit ProtectionYes/No
Open-Circuit ProtectionYes
Overheating ProtectionYes
Overcharge ProtectionYes
Spark-Proof ProtectionYes
Reverse Polarity ProtectionYes



8.5Our score
Really good

Place here Description for your reviewbox

  • Well-established manufacturer with a proven track record
  • Size/performance ratio
  • Versatility – charges just about any 6V or 12V battery
  • Features – intelligent features such as temperature monitoring, desulfation, force mode
  • Don’t expect a super-fast charge if you are in a hurry
  • Slower charging for large batteries (check out its big brother Genius10 here)


In this class of battery chargers, for us, there are 2 options – CTEK MSX5 (read the review here) or NOCO Genius5. 

NOCO is a super solid and reliable choice; whether you are charging a small 6V motorbike battery or a large deep battery, it will charge them in a safe, maintenance-free way. You can leave it plugged in and connected to a battery, and it will do its thing when needed. 

Yes, you might wait a bit, especially if you need to quickly charge a truck battery or something similar, but for a majority of people, this is a great product to go with.

Where to buy in the UK

  • Product
  • Features
  • Photos

NOCO GENIUS5UK, 5A Smart Car Charger, 6V and 12V Portable Heavy-Duty Battery...

& Free shipping
Last update was on: May 21, 2024 3:09 pm

Where to buy in the US



No, it has a natural convection cooling, so, in human words, it cools itself.

Hold the down the MODE button for 5 seconds. This will send a straight 5A charge to the battery for 5 minutes. This should charge the battery enough to have more than 1V, and then you should be able to use one of the other charging modes.

You need to hold down the MODE button for 3 seconds.

After holding the MODE button for 3 seconds, you can switch to Repair but push the MODE button once more. 12V lead-acid battery.

After connecting the battery and switching to the right mode, the charger will automatically start assessing the battery. As long as the LED indicator is blinking, the assessment is still in progress. As soon as it stops flashing, the assessment is complete (and ideally in green).  

Yes, it will return to the settings you have set

No, you would need a jumpstarter for this. This charger needs to be plugged in the socket for it to charge.

It means Genius5 is reconditioning the battery, and it is best to leave it connected until it stops blinking.

Stratified acid at the bottom of the battery’s cell focuses discharge activity to the bottom of the cell, causing the bottom part of the plate to work overtime. While the bottom part of the plate gets excessively discharged, the top part of the plate receives most of the charging activity.

You can find a great article about stratification here.

Martin Shaw
Martin Shaw

Martin is an automotive enthusiast with a deep passion for all things cars. He has spent the last decade immersing himself in the industry, reading up on the latest models, attending car shows, and tinkering with his own vehicles. Loves: family, all things cars (apart from selling them), pizza.

The Car Stuff