Make Your Backup Power Last Longer

Factors That Influence Your Backup Power

Welcome to the next part of our Power Backup Tips Series! Last time, we discussed how you would choose the right size inverter.

In this edition, we cover the key factors that affect how long and how well your backup system works. Not all backup power systems perform the same.

🔋Battery Capacity

The size or capacity of your battery is measured in Watt Hours (Wh) or more commonly Kilowatt Hours (kWh). This number can be used to calculate how long you can run your devices on a given size battery. See our blog on how to calculate this (Essential knowledge on Back-up Power). Larger batteries mean longer run times, but also cost more. Aim for a battery that supports your essential loads for at least 4 - 8 hours.

⚙️Inverter Efficiency

Not all inverters are equally efficient or work the same. A high-quality inverter converts more of the stored battery energy into usable electricity, reducing waste and extending run time.

Choosing a high-quality inverter is key to maximising your backup power system's performance and longevity. While a cheaper inverter might seem appealing upfront, it can cost you more in the long run due to lower efficiency.

Why Efficiency Matters

Inverters that combine multiple charging sources, like solar and grid power, optimise energy use by keeping your batteries charged while powering your home or small business. This ensures you get the most out of your backup power system.

Pure Sine Wave vs. Simulated Sine Wave

• Pure Sine Wave Inverters: Ideal for appliances with motors (e.g., fridges, pumps) or heating elements (e.g., microwaves, kettles). They deliver a smooth waveform, matching the grid’s power, for optimal efficiency and appliance safety.

  
  

• Simulated Sine Wave Inverters: Suitable for low-power electronics like computers or phone chargers. However, using them for motors or heating appliances can reduce efficiency and risk equipment damage.

Make the Right Choice

Invest in an inverter that matches your needs to save energy and protect your appliances. Ensure you understand the limits and efficiency of the inverter you are planning on investing in. We are here to advise you on this based on your requirements.

🔌Power Consumption

Running multiple appliances can quickly drain your backup power system’s battery. To maximise your backup time, it’s crucial to understand your average power usage in watts and prioritise essential appliances.

Smart Ways to Save Power

• Turn Off Non-Essential Appliances: Switching off items like extra lights or non-critical devices can significantly extend your battery life during outages.

  
  

• Automated Load Management: Some inverters can be configured to automatically disconnect non-essential loads when solar power isn’t available, preserving battery capacity.

  
  

• Smart Automation: Set up intelligent systems to switch off non-essential appliances under specific conditions, ensuring optimal power use even when you’re not home.

🌡️Environmental Conditions

Temperature plays a critical role in your backup power system’s performance. Extreme heat can accelerate battery degradation, while cold temperatures may reduce their immediate capacity. To ensure optimal efficiency and longevity, install your system in a well-ventilated, protected space.

Why Environment Matters

The installation location and local climate are key factors when designing a power backup solution. Proper placement of batteries, inverters, and solar panels helps maximise their performance and lifespan.

A Lesson from the Field

During a recent site visit, we saw an installation where an air conditioner was used to cool the room housing the inverters and batteries. While this might seem like a smart way to manage heat, it raises a question: how much extra power do the batteries, inverters, and solar panels need to run the air conditioner? This setup may reduce efficiency, especially during outages when solar power is unavailable.

⚡Depth of Discharge (DoD)

The Depth of Discharge (DoD) of your battery determines how much of its capacity you can use and directly impacts its lifespan. Different battery types, like lithium-ion and lead-acid, have varying DoD limits, affecting both performance and longevity.

Battery Types and DoD

Lead-Acid Batteries:

• More affordable but require frequent replacement.

• Slower to charge and less efficient.

• Recommended DoD: <50% for optimal lifespan, meaning only half the rated capacity is usable.

Lithium-Ion Batteries:

• Higher upfront cost but significantly longer lifespan.

• Faster charging, maximizing your solar charging window.

• Recommended DoD: <30%, allowing access to 70% of the rated capacity.

Why DoD Matters

DoD not only affects battery lifespan but also determines usable capacity. For example, a 100 kWh battery system provides only 50 kWh of usable energy with lead-acid (due to 50% DoD) but 70 kWh with lithium-ion (30% DoD). Choosing the right battery and inverter setup is critical to avoid over-discharging, which can damage batteries and reduce efficiency.

🔄 Battery Age & Health

As batteries age or experience frequent over-discharging, their ability to hold a charge diminishes. Regular maintenance and timely replacement are essential to ensure your backup power system keeps your home or small business powered reliably.

Batteries: Like Vehicles, Not Fine Wine

• Heavy Use Shortens Lifespan: Just like driving a vehicle hard wears it out faster, overworking your batteries reduces their longevity.

  
  

• Age Reduces Efficiency: Older batteries deliver less power and become less efficient, much like an aging vehicle.

  
  

• Maintenance Prevents Breakdowns: Neglecting regular battery maintenance is like skipping vehicle servicing - a recipe for failure

🌞Charging Source & Speed

Solar input? Eskom recharge? Generator? Your recharge time depends on your charging source and its power. The slower the charge, the longer it takes to get ready for the next outage.

As already mentioned, your battery type and age also impact this time factor.

The time of the year, weather conditions, and temperature all need to be factored in when designing an effective power backup system, ensuring you have sufficient power available when you need it.

⚖️System Design & Balance

A well-matched inverter, battery, and solar setup will always perform better than a mismatched system. That’s why it’s important to consult professionals (like us!) for system design.

Why Compatibility Matters

Think of your battery and inverter like a good marriage - they need to communicate effectively. The inverter must work seamlessly with the battery’s Battery Management System (BMS) to optimise charging and discharging. Incompatible components can lead to poor performance or breakdowns, much like an ill-suited partnership.

Building a Balanced System

A robust system design incorporates all the factors we’ve discussed - battery type, depth of discharge, environmental conditions, and charging sources - to create a stable, efficient, and long-lasting solution. Professional design ensures your backup power system is an investment, not a liability.

At Koltronics, we specialise in crafting tailored, high-performance backup power solutions.

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