🔋How to Choose the Right AGM Battery for Your Setup

When building an off-grid power system – whether for a campervan, boat, solar setup, or mobile workstation – the battery is a crucial component. One of the most popular choices is the AGM battery (Absorbent Glass Mat), known for its reliability, maintenance-free design, and excellent price-to-performance ratio.

But how do you determine the right capacity? What do you need to look out for when selecting the best battery for your application?

This blog explains it step-by-step.

What is an AGM battery?

An AGM battery is a type of sealed lead-acid battery in which the electrolyte is absorbed in fiberglass mats. This makes it leak-proof, vibration-resistant, and maintenance-free, making it ideal for mobile and off-grid installations.

AGM batteries are commonly used in:

• Campervans and RVs

• Boats and yachts

• Solar/off-grid energy systems

• Service vehicles and mobile workshops

• Emergency power supplies (UPS)

Advantages of an AGM battery

• 🔋 Maintenance-free – no refilling, no gas emissions under normal use

• 💪 Deep discharge capable – more robust than traditional lead-acid batteries

• 🌡️ Performs well in cold conditions

• 🚚 Shock and vibration resistant – perfect for mobile applications

• 🔌 Faster charging – charges quicker than gel or flooded batteries

• ✅ Safe in enclosed spaces – sealed, spill-proof design

How to calculate the right battery capacity

Battery capacity is measured in Ah (amp-hours). The higher the Ah, the more energy you can store.

1. Calculate your daily power usage

Add up the consumption of your devices. For example:

2. Convert Wh to Ah

For 12V systems:
830Wh / 12V = ~69Ah daily consumption

3. Account for depth of discharge

To extend lifespan, AGM batteries should ideally be discharged only up to 50%.
So:
69Ah / 0.5 = 138Ah required battery capacity

👉 In this example, a 150Ah AGM battery would be suitable.

Other key factors to consider

🔄 Cyclic use vs. standby

Using your battery daily (e.g., in a camper)? Choose a deep-cycle AGM battery.
Using it for backup only? A standard AGM will do.

⚡ Charger compatibility

Ensure your MPPT charge controller or battery charger supports AGM profiles (typically around 14.4V charging voltage).

🌡️ Ambient temperature

AGM performs better than gel in cold environments, but still avoid extreme heat or deep freezing.

📏 Physical space

Check size and weight – especially important in campers, boats, and enclosures.

Common mistakes to avoid

❌ Undersized battery bank
➡ Always aim for at least 2x your daily Ah consumption for better performance and lifespan.

❌ Fully discharging the battery
➡ Repeated full discharges will significantly shorten battery life.

❌ Using the wrong charger
➡ Use a charger or MPPT controller with AGM-specific settings – not a generic “auto” mode.

❌ No temperature compensation
➡ Charge voltage should be adjusted based on climate conditions for optimal charging.

EcoLine Tip: Two smaller batteries = more flexibility

Using 2 x 100Ah AGM batteries in parallel gives you the same capacity as 1 x 200Ah – but more flexibility for placement, replacement, and balance during charging/discharging.

Conclusion: The right AGM battery = power confidence

Choosing the right AGM battery is key to a reliable and durable DC power system. By carefully calculating your power needs and selecting the correct capacity, you'll avoid system failures, extend battery life, and enjoy worry-free energy – wherever you are.

👉 Need help choosing the right AGM battery? Contact us for expert advice or explore our full range of high-quality AGM batteries.