Pairing a NOCO charger with a homemade MPPT controller requires carefully connecting the charger’s output to the MPPT controller’s input, ensuring proper voltage compatibility and communication between the devices.
This setup optimizes battery charging by combining NOCO’s reliable charging technology with the efficiency of an MPPT controller, which maximizes power extraction from your solar panels.
If you’re building a solar system on a budget or experimenting with custom electronics, understanding how to integrate these two components can save you money and improve your system’s performance. However, the process can be confusing without clear guidance because each device has unique wiring and voltage requirements.
Best Batteries for Pairing NOCO Charger with MPPT Controllers
Choosing the right battery is crucial when pairing a NOCO charger with a homemade MPPT controller to ensure efficient energy storage and longevity. Here are three top batteries ideal for this setup:
Battle Born LiFePO4 Deep Cycle Battery
Known for its exceptional lifespan and safety, this lithium iron phosphate battery provides stable power output and is perfect for solar applications. Its lightweight design and deep cycling capability make it a favorite among DIY solar builders.
Renogy Deep Cycle AGM Battery
This AGM (Absorbent Glass Mat) battery offers maintenance-free use and reliable performance in various conditions. It’s a solid choice for those who want a robust, budget-friendly battery that pairs well with MPPT controllers and NOCO chargers.
Trojan T-105 Flooded Lead Acid Battery
A classic choice for off-grid solar systems, this battery is durable and cost-effective. While requiring regular maintenance, it provides steady power and pairs well with MPPT controllers for efficient charging.
What Is an MPPT Controller and How Does It Work with a NOCO Charger?
An MPPT controller (Maximum Power Point Tracking) is a smart charge controller that adjusts its input to find the “maximum power point” of your solar panel, ensuring the highest possible efficiency when charging a battery.
When solar panels produce electricity, the voltage and current fluctuate depending on sunlight intensity and temperature. A basic controller would just send the current to the battery — but this leads to wasted energy. MPPT controllers, on the other hand, constantly monitor the panel’s output and adjust the voltage and current to find the sweet spot where the panel delivers the most power.
How It Interacts with a NOCO Charger
A NOCO charger is designed to provide smart, multi-stage charging using AC power (like a wall outlet) or sometimes DC input. It’s meant to maintain, charge, and even recover deeply discharged batteries using intelligent algorithms. These chargers don’t typically draw power from solar panels directly — this is where the MPPT controller comes in.
Here’s how they work together:
- Solar Panels → MPPT Controller:
The solar panels send raw power to the MPPT controller. The controller “tracks” the best voltage-current combination to maximize power. - MPPT Controller → Battery Bank:
The controller then adjusts the output to safely and efficiently charge your battery, typically matching the battery’s required charging profile. - NOCO Charger → Battery Bank (Secondary or Maintenance):
The NOCO charger comes in as a support tool — either for maintaining battery health when solar isn’t enough or for recovery charging if the battery becomes too low.
Key Compatibility Insight
While the NOCO charger and MPPT controller both charge batteries, they must not charge the battery at the same time unless coordinated properly. Doing so may confuse the voltage readings and damage either device. To make them work together:
- Use a battery switch or charging relay to alternate between the NOCO charger and the MPPT.
- Consider using the NOCO only when solar isn’t producing — for example, during the night or cloudy days.
This setup gives you the best of both worlds: efficient solar charging during the day and smart backup charging when needed.
Step-by-Step Guide: How to Connect a NOCO Charger to a Homemade MPPT Controller Safely
Pairing a NOCO charger with a homemade MPPT controller can boost your off-grid or backup power setup — but it must be done correctly to avoid damaging your system. Follow these detailed steps to ensure safe, effective integration.
Step 1: Understand the Charging Sources
Before you start wiring, understand that the MPPT controller and NOCO charger are two separate charging sources. You cannot feed them both into the same battery simultaneously unless you’ve accounted for current flow direction and voltage management.
- MPPT Controller: Takes solar panel input and outputs to the battery.
- NOCO Charger: Takes AC wall power or another DC source and charges the battery directly.
Step 2: Install a Dual Power Input System
To prevent conflicting voltages, set up a manual or automatic switch to choose between solar (MPPT) and AC (NOCO charger) input.
- Manual Option: A battery selector switch or simple toggle allows you to manually alternate between charging sources.
- Automatic Option: Use a voltage-sensing relay or an automatic transfer switch that gives priority to solar, and activates NOCO only when solar is inactive.
Step 3: Wire the MPPT Controller
- Connect your solar panel’s positive and negative leads to the MPPT input terminals.
- Connect the MPPT output (typically labeled “Battery + / -“) to your battery bank, using proper fuses and cables.
- Ensure correct polarity — reversing it can damage your controller.
Step 4: Wire the NOCO Charger
- Plug the NOCO charger into a power outlet or DC source, depending on model.
- Connect the charger’s battery clamps or ring terminals to the same battery bank — again, using proper gauge wire and checking polarity.
Important: If both MPPT and NOCO are wired to the battery, ensure only one is charging at a time using the switching system from Step 2.
Step 5: Test the System Carefully
- Turn on solar input only. Monitor the MPPT controller’s screen or indicators to ensure it’s charging.
- Then switch to the NOCO charger and unplug solar. Confirm the NOCO charger starts charging the battery.
- Use a battery monitor (like the Victron BMV-712) to track real-time voltage and current.
Step 6: Add Safety Features
- Install fuses or circuit breakers between all connections to prevent overcurrent.
- Use diodes or charge controllers with backflow protection to avoid reverse current damage.
- Label all wires and switches clearly.
Common Mistakes to Avoid When Pairing NOCO Chargers and MPPT Controllers
Even experienced DIYers can run into problems when combining a NOCO charger with a homemade MPPT controller. Here are the most common mistakes — and how to avoid them.
Mistake 1: Charging from Both Sources Simultaneously
Why it’s a problem:
Simultaneous charging from a NOCO charger and an MPPT controller can cause conflicting voltage regulation, inaccurate readings, or even system damage. These devices aren’t designed to communicate with each other and can “fight” over control.
How to avoid it:
Use a battery switch or an automatic charging relay that ensures only one source charges at a time.
Mistake 2: Skipping Proper Fusing or Overcurrent Protection
Why it’s a problem:
Without fuses or breakers, any short circuit or overload could damage your wiring, charger, or battery — or worse, start a fire.
How to avoid it:
Install inline fuses near the battery terminal on all positive leads. Choose fuses based on your wire size and system voltage.
Mistake 3: Mismatched Battery Type Settings
Why it’s a problem:
Both NOCO chargers and MPPT controllers often have selectable settings for different battery types (AGM, lithium, flooded). If these settings don’t match the actual battery chemistry, you risk overcharging or undercharging.
How to avoid it:
Check your battery specifications and make sure both devices are set to the correct type (e.g., LiFePO4, AGM, etc.).
Mistake 4: Ignoring Temperature Compensation
Why it’s a problem:
Charging voltage should vary with battery temperature. Without compensation, batteries may charge too aggressively in the heat or too weakly in the cold.
How to avoid it:
Use a temperature sensor if your MPPT controller or NOCO charger supports it. This ensures accurate charging throughout temperature swings.
Mistake 5: Poor Cable Sizing or Loose Connections
Why it’s a problem:
Undersized cables can cause voltage drop, heat, and poor charging. Loose terminals can lead to arcing and eventual failure.
How to avoid it:
Always follow ampacity charts to size your cables properly. Use ring terminals, tighten connections securely, and recheck them regularly.
How to Monitor Battery Health When Using Multiple Charging Sources
When combining a NOCO charger with a homemade MPPT controller, one of the most critical tasks is to monitor your battery’s health consistently. Without proper monitoring, you could unknowingly damage your battery over time.
Why Monitoring Matters
Multiple charging sources can lead to:
- Overcharging
- Inconsistent charging cycles
- Battery sulfation or lithium imbalance
- Shortened battery lifespan
To prevent this, monitoring tools and methods are essential.
Recommended Monitoring Tools
Here are the most effective tools you can use:
Battery Monitor (e.g., Victron BMV-712 Smart)
- Tracks voltage, current, and state of charge (SOC)
- Can alert you to overcharging or deep discharges
- Bluetooth-enabled for app-based monitoring
Voltmeter and Ammeter
- Provides real-time voltage and current data
- Useful for manual system checks
- Easy to install inline with your battery wiring
Smart Shunt
- Works like a battery monitor but with fewer wires
- Offers precise current flow data and historical logs
NOCO’s Built-In Battery Indicators
- Some NOCO models include LED indicators for battery health
- Useful for quick visual checks
Monitoring Strategy: What to Look For
To keep your battery healthy, monitor the following:
- Voltage: Should stay within safe ranges (e.g., 12.6V–14.4V for lead-acid, 13.0V–14.6V for lithium).
- Charge Cycles: Avoid full discharges or continuous 100% charging.
- Temperature: Hot batteries degrade faster — use a temp sensor if available.
- Charging Source Priority: Know when solar (MPPT) is active and when NOCO takes over.
Add Alarms & Cut-Offs for Safety
Install voltage alarms or automatic low-voltage cutoffs to protect your battery from:
- Deep discharges
- Overvoltage scenarios
- Unattended damage when off-grid
Maintaining your battery health isn’t just about extending its life — it’s about ensuring your entire charging system works efficiently and safely.
Is It Worth Combining a NOCO Charger with a DIY MPPT Setup?
Yes, combining a NOCO charger with a homemade MPPT controller can be extremely worthwhile — if done correctly. This hybrid approach gives you flexible, reliable battery charging whether you’re on the road, off-grid, or facing inconsistent solar input. But it’s not for everyone.
Why People Consider This Setup
Here’s what makes this pairing attractive:
- Redundancy – When the sun isn’t shining, your NOCO charger (AC-powered) ensures your battery is still topped up.
- Efficiency – MPPT controllers maximize solar input, providing the most charge from limited sunlight.
- DIY Cost Savings – Building your own MPPT controller can be far more affordable than buying a high-end off-the-shelf unit.
- Customization – DIY systems allow fine-tuning for specific battery chemistries, use cases, and power needs.
Weighing the Pros and Cons
| Pros | Cons |
| Dual-source reliability | Requires technical knowledge |
| Solar optimization | Risk of poor integration if not properly isolated |
| Flexible for RVs, boats, off-grid use | No manufacturer support for DIY components |
| Lower long-term charging costs | Misconfiguration can shorten battery lifespan |
Who Should Use This Setup?
- DIY Enthusiasts & Tinkerers – If you’re comfortable with basic electronics and troubleshooting, this is a great hands-on project.
- Off-Grid Users – Especially useful for cabins, vans, and RVs where solar isn’t always available.
- Backup Power Users – Having both AC and solar charging ensures you’re never left with a dead battery.
Who Should Avoid It?
- Total beginners to solar or battery systems
- Anyone looking for a plug-and-play, maintenance-free solution
- Users without time to monitor or troubleshoot issues
Conclusion
Pairing a NOCO charger with a homemade MPPT controller is a smart, flexible solution for anyone managing off-grid or backup power systems — but it must be done with care. From understanding the fundamentals of MPPT charging to ensuring you avoid common mistakes like charging source conflicts or incorrect battery settings, each step matters.
By following a proper setup, monitoring battery health consistently, and using tools like shunts or battery monitors, you can safely harness the best of both solar and AC-powered charging. This hybrid setup not only ensures consistent battery performance, but it also protects your investment over the long term.
Whether you’re a DIY enthusiast, an off-grid adventurer, or simply looking to make your energy system more resilient, this pairing can be both practical and cost-effective — provided it’s implemented correctly.
Frequently Asked Questions About Pairing a NOCO Charger with a Homemade MPPT Controller
Can I connect a NOCO charger and MPPT controller to the same battery at the same time?
Yes, but only if both are properly isolated using diodes or charge controllers with backfeed protection. Running them simultaneously without precautions can cause feedback loops or overcharge the battery.
Do NOCO chargers have built-in smart charging features?
Yes. Most NOCO Genius models come with multi-phase smart charging, temperature compensation, and automatic shutoff. This ensures safe, efficient charging without overloading the battery.
Is a homemade MPPT controller safe to use?
It can be safe, but only if built using proper components and with accurate voltage/current calibration. DIY controllers should be tested thoroughly and include protections like overvoltage cutoff and reverse polarity prevention.
How can I switch between solar and NOCO charging manually?
You can use a manual switch or an automatic transfer relay that prioritizes solar (MPPT) during daylight and defaults to NOCO (AC) when the sun is unavailable.
What type of battery works best with this dual setup?
AGM and LiFePO4 batteries are excellent options due to their stability, charge acceptance, and compatibility with both MPPT and NOCO systems. Ensure both sources are configured for your battery chemistry.
Can this setup damage my battery over time?
Not if it’s installed correctly. Using battery monitors, fuses, and isolators will protect against overcharging, backfeeding, and uneven charge distribution.
Should I disconnect one charger when the other is active?
Not necessarily. If your system includes isolation circuitry, both can remain connected. Without it, disconnect one when using the other to prevent electrical conflict.