Who Is the NOCO Genius 5 Amp Smart Charger For?
The NOCO Genius 5 is the perfect do it all charger for the average battery owner. I got it a few years ago to maintain my RV’s 12 volt AGM battery during the winter. Since then I’ve used it to charge 6 volt lead-acid batteries, car batteries, and even 12 volt LiFePO4 (lithium) batteries.
Being 5 amp, it’s got enough power to charge large capacity batteries, but it’s small enough use on smaller batteries and stay very portable.
It gets a little warm when charging depleted lithium batteries, but it hasn’t shown any signs of damage yet.
In this review, I’ll go over everything you need to know about this handy little charger, including my own testing on my deep cycle AGM RV battery.
NOCO Genius 5 Overview
NOCO Genius 5 Amp Smart Charger
Key Features
- Charges 12V, AGM, lithium, and repair mode batteries.
- Adjusts charge based on temperature to prevent over or undercharging.
- Has a repair mode to restore old or damaged lead-acid batteries.
- Includes safety features like spark-proof and reverse polarity protection.
- Compact, lightweight, and portable for easy storage and use.
- Maintains batteries long-term without overcharging.
- Can charge completely dead batteries with Force Mode.
- Works with car, RV, motorcycle, boat, ATV, and deep cycle batteries.
- Automatically resumes charging after a power outage.
- Features a built-in digital display for charge status and diagnostics.
Buy This If You
- Need a versatile charger for multiple battery types.
- Want a compact, portable charger for easy storage and transport.
- Live in extreme temperatures and need automatic charge adjustments.
Don’t Buy This If You
- Need a faster charger for large-capacity batteries.
- Have 6V AGM or lithium batteries, as this model is not compatible.
- Prefer a simpler charger with current voltage display screen.
NOCO Genius 5 For RV Batteries
When winterizing our RV a few years ago, we faced a battery maintenance challenge. Our VMAX 12 volt 125 ah deep cycle AGM battery (click to view on Amazon) and the standard 12-volt starter battery both needed power while the rig sat under covered storage, rendering our roof-mounted solar panel charging system useless.
Most trickle chargers just wouldn’t cut it for our setup. The deep cycle’s hefty 125Ah capacity demands more than the typical 1-amp charger can deliver without straining, and we needed something with an AGM charge mode.
After researching options, I landed on the NOCO Genius 5. Though technically rated for batteries up to 120Ah, I suspected its build quality would handle our slightly larger battery. NOCO’s reputation for overengineering their products gave me confidence in pushing this 5-amp unit just beyond its stated specs.
After running continuously during our coldest months, the Genius 5 maintained both batteries flawlessly. The AGM stayed at optimal charge without the telltale heat buildup that would signal a struggling charger. The extra 5Ah capacity hasn’t posed any issues whatsoever.
NOCO Genius 5 Deep Dive
The Genius 5 packs impressive functionality into its compact frame. Here’s my breakdown of its features
Battery Compatibility
This versatile charger handles virtually any battery you’ll encounter in recreational vehicles or automotive applications.
The only significant limitation I’ve found is its incompatibility with 6V AGM batteries, a niche case but worth noting if you maintain vintage equipment.
Compatible Battery Types
- 12 Volt
- 6 Volt
- Flooded Lead Acid
- SLA
- AGM
- Gel
- VRLA
- Lithium-ion (lifepo4)
Intelligent Charging Modes
Five charging modes cover the spectrum of common battery types:
- 12V standard mode for everyday applications.
- AGM-specific profile with optimized voltage curves.
- Lithium mode with BMS integration.
- 6V legacy battery support.
- 12V Repair function for sulfated lead-acid batteries.
Critical safety note: The repair mode should never be used with sealed batteries. The elevated voltage that effectively removes sulfation from flooded batteries can damage AGM, gel, or lithium cells.
I particularly appreciate the memory function that retains your selected mode through power interruptions, which is essential during winter storage when outages are common.
Deep Discharge Recovery
Unlike basic chargers that fail to recognize severely discharged batteries, the Genius 5’s Force Mode has rescued several “dead” batteries in my collection.
Activating it requires a deliberate 5-second button press, preventing accidental triggering while providing a 5-minute window to revive critically low cells before transitioning to standard charging.
Diagnostic Capabilities
The built-in troubleshooting system stops common issues like:
- Overvoltage conditions requiring attention.
- Failed batteries needing replacement.
- Reversed connections requiring correction.
Each diagnostic is displayed via intuitive icons on the face panel.
Power Output & Adaptability
Though rated for batteries up to 120Ah, I’ve successfully maintained our 125Ah deep cycle AGM without any overheating or performance issues.
The thermal compensation system automatically adjusts charging parameters based on ambient conditions. Which is particularly valuable in climates with extreme temperatures.
Charge Voltages
- 12V – 14.5 volts
- 12V AGM – 14.8 volts
- 12V Lithium – 14.6 volts
- 6V – 7.25 volts
- 12V Repair – 16.5 volts
- Standby Mode – 0 volts
Design
Measuring just 4.5 × 3 × 2 inches, the Genius 5 uses minimal space while delivering substantial performance.
The power and battery cables provide adequate reach (6ft and 4.5ft), while the fused clamps offer additional protection against short circuits.
The IP65 waterproof rating has proven itself reliable during unexpected exposure to weather, and the included mounting bracket allows permanent installation in workshop environments.
AGM RV Battery Test Results
The Genius 5 handled the engine battery without issue (as expected), the real test was whether it could properly maintain our oversized AGM house battery, which slightly exceeds the charger’s rated capacity.
The VMAX AGM deep cycle battery requires precise charging voltage between 14.4-14.9 volts and a float voltage between 13.5-13.8 volts.
Testing began with the AGM battery at approximately 65% capacity following several weeks without solar input. Upon connecting the Genius 5 in AGM mode, voltage measurements showed 14.56V. Which is perfectly within VMAX’s recommended charge voltage.
After multi-day charging cycle the resting voltage (measured after 30-minute disconnection) was 13.7 volts.
These readings confirm the charger delivered both the correct bulk charging voltage and properly transitioned to float maintenance once charging completed.
NOCO Genius 5 Review
What separates this charger from budget alternatives is its intelligent charging profiles. When connected to my partially discharged lithium battery, it followed a calibrated charging curve that avoided the common voltage spikes that can trigger BMS protection circuits.
The 5-amp output offers a practical balance. It’s slow but it’s enough to charge high capacity deep cycle batteries without overheating.
I like the automatic thermal compensation. During a recent cold snap where temperatures dropped below freezing, the charger adjusted its output appropriately, preventing the undercharging.
The spark-proof connections are a nice touch, especially for tight battery compartments, and the reverse polarity detection saved me from an expensive mistake when I hurriedly connected clamps incorrectly in poor lighting.
For power outage situations, I’ve tested the memory function multiple times, the NOCO Genius5 consistently resumed its previously selected charging mode rather than defaulting to standard settings. Which is crucial when maintaining specialized battery types.
The Force Mode has successfully revived two batteries that other chargers failed to recognize due to deep discharge. This feature alone has justified the purchase price by extending the service life of otherwise “dead” batteries.
If you’re juggling multiple battery types across various vehicles, the NOCO Genius 5 offers exceptional versatility without the complexity of more technical chargers.
good review man appreciate it. looking to purchase a noco genius 10 or a 2×4
Do you think it would be safe to repeat the Repair Cycle in order to optimize performance on an ageing 12v 45 amp/hr flooded car battery? Is there a danger of the electrolyte evaporating?
Have completed one repair mode cycle but on a later charge the green light pulsed indefinitely, suggesting the charger cannot complete.
Hi James,
Open the cell caps and check the water levels inside your batteries, they may need a refill with distilled or deionized water.
Once you’ve refilled the cells, it’s ok to run the repair cycle again.
Make sure you refill the cells after each repair cycle.
Hi, this review was great and nearly exactly what I needed. I have the NOCO Genius 5 as well, I just bought. I borrowed a friend’s one and used it to charge my old 100 AH battery a couple of times and a new 138 AH battery, but only once, and it was new when I did it. I was just checking it was fully charged. Is 138 AH too much for the NOCO 5? Should I get the 10? It is nearly twice the price. But I don’t want to damage either the battery or the charger.
Hi Matt,
If you’re not concerned with fast charging the NOCO 5 should be fine for a 138 AH battery.