Reliable off-grid power is essential for overlanding, camping, RVing, or working from your vehicle. Whether you’re running lights, a fridge, tools, or even luxuries like a coffee machine or TV, you’ll need an auxiliary battery to support your setup.
But how do you choose the right one? From budget and weight to performance and lifespan, this guide covers the most common battery types — plus REDARC’s lithium solution, the Alpha150 that redefines auxiliary power.
WHY AN AUXLIARY BATTERY?
Your starter battery is designed to crank the engine, not to power appliances for long periods. Drawing from it to run a fridge or charge your devices risks leaving you stranded.
An auxiliary battery provides a separate power source for your accessories. With a DC to DC charger, both your starter and auxiliary batteries stay charged and healthy.
Want to learn more about Auxiliary Batteries? Read the article What is an Auxiliary Battery.
UNDERSTANDING YOUR OPTIONS
There’s no one-size-fits-all auxiliary battery. Your choice depends on cost, available space, weight, and how much power you need.
STANDARD LEAD ACID
Best for: Budget-conscious beginners
- Lowest upfront cost
- Can be mounted under the hood
- Heavy (around 60 lbs for 100Ah)
- Requires maintenance
- Limited depth of discharge (50% max)
- Shorter lifespan
CALCIUM
Best for: Budget setups needing maintenance-free performance
- Similar price and weight to lead acid
- Sealed and maintenance-free
- Can be mounted under the hood
- Still heavy with limited depth of discharge
GEL/AGM
Best for: Mid-tier setups with deeper cycling
- More expensive than lead acid
- Cannot be mounted under the hood (heat sensitive)
- Handles deeper discharges better
- Heavy (~60 lbs for 100Ah)
- Needs a precise charging profile
LEAD CRYSTAL
Best for: Heavy-duty use with deep discharge recovery
- Higher cost but very robust
- Handles deep discharges and high charge currents
- Heat resistant, under-hood capable
- Very heavy (~70 lbs for 100Ah)
LITHIUM (LIFEPO4)
Best for: High-performance, lightweight setups
- Lightest option (~25 lbs for 100Ah)
- Can discharge up to 80% safely
- Maintains higher voltage during use
- Fast charging, long lifespan
- Requires lithium-compatible charger
- Higher upfront cost
REDARC'S LITHIUM OPTION
ALPHA150 LITHIUM BATTERY
Best for: Fixed installs needing maximum output
- 150Ah LiFePO₄ battery
- Compact, lightweight design
- Consistent voltage under heavy loads
- High charge/discharge rates
- Compatible with REDARC chargers and BMS systems
- Perfect for serious overlanders, RVs, and marine users
CHOOSING THE RIGHT BATTERY SIZE
Battery size is about balance.
- Too small: you’ll run out of power quickly.
- Too big: you’ll need extra space and a larger charging system.
Example: A 12V fridge typically draws ~48Ah in 24 hours.
- A 100Ah lead acid battery powers it for about a day.
- A 100Ah lithium battery powers it for two days or more without recharging.
WHY CHARGE CAPABILITY MATTERS
No matter which battery type you choose, pairing it with the right charger is essential. REDARC’s In-Vehicle Battery Chargers are designed for all battery types, including AGM, Gel, and Lithium, ensuring long life and consistent performance.
WHICH ONE SHOULD YOU CHOOSE?
- Budget, basic needs, fixed install: Standard Lead Acid or Calcium
- Mid-range, deeper cycling: Gel/AGM
- Rugged, heat-resistant use: Lead Crystal
- Lightweight, high-performance power: Lithium (REDARC Alpha150)
- Portable, plug-and-play convenience: REDARC GoBlock
The right auxiliary battery depends on your budget, power needs, and how you use your vehicle. From entry-level lead acid to REDARC’s advanced Alpha150 and GoBlock lithium systems, there’s a solution for every rig and every adventure.
Explore the REDARC lithium range, or speak with an authorized REDARC dealer to design the perfect power setup.
