Recreational Vans
An AGM battery is a valve regulated lead acid design where fiberglass mats hold the electrolyte against the plates. The immobilized acid limits stratification and allows the case to be sealed with pressure relief valves. Because the cells are sealed, routine watering is not required and the risk of spills is minimal even when mounted on their sides. Internal resistance is lower than many flooded batteries, which supports better charge acceptance and dependable cranking current.
For mobile power, AGM variants are built as deep cycle, starting, or dual purpose. Deep cycle AGM units use thicker plates and are intended for repeated discharge and recharge. They are popular as house batteries in camper vans and overland builds due to vibration resistance, moderate cost, and predictable performance in a wide range of temperatures. Compared with gel batteries, AGM tolerates higher charge rates and is less sensitive to charging errors. Compared with flooded batteries, AGM typically offers lower self discharge and better shock resistance.
Cold temperature behavior is another plus. Capacity declines as temperatures drop, but AGM retains more usable power in winter than many alternatives except certain lithium chemistries with active heating. Storage life is strong when kept fully charged and cool. Self discharge is usually in the low single digit percent per month, so a maintenance charger or periodic top up prevents sulfation during storage.
The absorbed glass mat holds electrolyte between positive and negative plates, improving contact and reducing gas production during normal operation. Oxygen recombination at the negative plate helps limit water loss, which is why AGM batteries remain sealed. Heavier plate construction in deep cycle models spreads the active material over a large area to handle deeper depth of discharge without excessive shedding. Grid alloys and paste formulation differ by brand, but the goal is the same: maximize cycle life while controlling resistance and corrosion.
Case design matters. Robust intercell welds, dense mat compression, and reinforcement around terminals help the battery survive constant road vibration. Many AGM batteries are approved for non upright mounting, but always check the manufacturer’s orientation guidelines and keep the vent caps accessible. A quality hold down is essential to keep the mass from moving on washboard roads.
AGM batteries prefer a multi stage charging profile: bulk, absorption, then float. Absorption voltage commonly ranges from about 14.4 to 14.7 volts at 25 degrees Celsius, followed by a float voltage around 13.2 to 13.6 volts. Time at absorption should be limited to the manufacturer’s recommendation and adjusted with temperature compensation. Overvoltage or prolonged absorption accelerates grid corrosion and dries out the mats, while undervoltage leads to chronic undercharging and sulfation.
On discharge, cycle life improves when you avoid deep depletion. Many builders plan around about 50 percent depth of discharge for routine use, which preserves capacity over the long term. Peukert’s effect means usable capacity decreases as discharge rate increases, so high draw appliances like induction cooktops can shorten runtime compared with the nameplate amp hour rating measured at slower rates.
AGM batteries deliver reliable deep cycle performance with low maintenance, strong vibration resistance, and safe sealed construction. They handle cold starts better than many chemistries and can serve both as a house bank and an emergency starting reserve in some dual purpose models. For builds that see dust, washboard, and variable climates, these traits add real resilience.
Limitations include weight per watt hour and lower cycle life compared with lithium iron phosphate under the same depth of discharge. Energy density is modest, so capacity increases quickly add mass and take space. Voltage sag under heavy loads is more pronounced than in lithium packs, and full capacity is only realized with proper charging. Repeated deep discharge below about half capacity will reduce lifespan.
Common use cases include weekend travel rigs, seasonal cabins on wheels, and applications where cold weather reliability and conventional charging equipment are valued. AGM banks pair well with alternator charging using a DC to DC charger and sensible solar arrays. They are also frequently used in mixed starting and house roles in classic four by four platforms where redundancy matters.
For stationary storage between trips, AGM is forgiving if kept charged and cool. A smart charger with temperature sensing prevents both undercharge and overcharge. When charging from shore power, an inverter charger with an AGM preset and user adjustable absorption and float voltages simplifies setup and reduces the risk of sulfation or dry out.
Choose AGM when you want proven chemistry, simple maintenance, and solid performance in cold climates. If your daily energy use is modest, space is limited, and budget matters, AGM can meet your needs without complex battery management. It also suits builds that sit for stretches between adventures, as long as the battery is kept at full charge.
Consider lithium iron phosphate when weight savings, high usable capacity, and long cycle life outweigh higher upfront cost. Lithium maintains voltage under load, supports deeper routine discharge, and recharges faster when the charging source can deliver. In very cold conditions, a heated lithium solution or a hybrid approach may be required, which adds system design complexity.
Start with an energy audit. List each device, its draw in amps, and expected daily hours of use. Multiply and sum to determine daily amp hours, then divide by the percentage of capacity you plan to use. If you want to use about half the bank each day, double the daily amp hours to find a target capacity. Add a margin for growth, and consider high surge appliances that may require larger cabling and fusing even if average use is low.
Charging paths should include a DC to DC charger for alternator power to protect the starting system and deliver the correct profile to the house bank. Solar charge controllers should be configured for AGM absorption and float voltages and include temperature sensing placed on the battery case. Shore power chargers and inverter chargers should be set to the same profile to keep all sources aligned.
Use appropriately sized cabling, short runs, and quality lugs. Fuse the positive leads close to the battery, and isolate banks with proper switches. Secure batteries in a ventilated compartment even though AGM is sealed, and keep terminals clean and torqued. Heat is the enemy of lifespan, so avoid mounting near engine compartments or enclosed spaces without airflow.
Storage practices make a difference. Before parking for weeks, fully charge the bank and connect a maintenance charger with an AGM mode, or plan a periodic top up. Resting voltage is a decent indicator of state of charge when the battery has been at rest, with a healthy full charge near the high twelves. Do not equalize unless the manufacturer specifically approves a gentle conditioning cycle for AGM, which is uncommon.
If you want a house bank that just works, professional system design eliminates guesswork. We plan loads, select the right AGM or lithium path, set charge profiles, and integrate DC to DC charging, solar, and shore power into a coherent system. Clean routing, correct fuse coordination, and thoughtful service access mean you spend time traveling rather than troubleshooting. When it is time to upgrade capacity or transition to a different chemistry, a modular layout keeps the path forward simple.
Power your build with confidence. OZK Customs designs and installs complete electrical systems inside custom vans and overland rigs, including AGM battery banks, solar, alternator charging, and shore power. Explore our platforms, see how we build, and start a conversation about your goals.
We build complete custom vans and partial upfits with integrated power systems, suspension tuning, racks, lighting, and interior fabrication. No rentals, no DIY assistance. From concept to handoff, our team delivers a quiet, efficient electrical system that fits your travel style and future upgrades. Fill out the form to start your build plan today.
Ready for dependable off grid power without guesswork? Tell us how you travel and we will design and install a quiet, efficient AGM or lithium system built around your real loads. Get a fast quote and a clear timeline from OZK Customs today.
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