Frequently Asked Questions

An Absorbed Glass Mat (AGM) battery is a maintenance-free, non-spillable lead-acid battery that uses fiberglass mats to hold the electrolyte. VMAX AGM batteries feature heavy-duty, military-grade plates made with 100% virgin lead and proprietary plate separators, delivering superior shock and vibration resistance, ultra-low internal resistance, and exceptionally long deep-cycle lifespans.

Engineered to outclass conventional batteries, VMAX AGM technology sets the benchmark for deep-cycle reliability and power. We build them with military-grade alloys and plates for extreme durability and a longer lifespan. They are engineered for deep-cycle excellence, meaning they can be drained and recharged repeatedly without losing power.

If you need a battery that’s built tough for the harshest conditions, VMAX is the clear choice.

Choose VMAX AGM if you need rugged physical durability, zero-hassle extreme cold performance, or a heavy-duty dual-purpose battery capable of both massive engine cranking and deep cycling. Built with heavy-duty lead-tin alloy plates made from 100% virgin lead and encased in our extra-strong ABS "tank" containers, VMAX AGMs thrive in high-vibration and extreme-temperature environments.

Choose VMAX Lithium (LiFePO4) if you want up to 70% weight savings, zero voltage sag, and an extraordinary 3,000–6,000 deep discharge cycle life. Every VMAX MBH series lithium battery comes standard with true IP67 submersible waterproofing, automatic internal self-heating for sub-freezing charging, and integrated Bluetooth mobile monitoring.

For optimal battery health and maximum lifespan, VMAX 12V AGM batteries require a multi-stage smart charger with an AGM profile set to 14.4V–14.9V Bulk/Absorb and 13.2V–13.8V Float. VMAX LiFePO4 Lithium batteries perform best with a dedicated 14.4V lithium charger. Always check your battery's individual spec sheet for the recommended charging current (amperage) range.

VMAX 12V AGM Charging Parameters

• Standard AGM Settings: Bulk/Absorb at 14.4V–14.9V | Float at 13.2V–13.8V.
• XTR Series AGM Settings: Bulk/Absorb at 14.6V–14.9V (recommended) | Float at 13.5V–13.8V (recommended).
• Charger Type: Multi-stage smart charger featuring a dedicated AGM mode.
• Charging Amperage: Refer to your specific battery's technical specifications for the recommended charging current range.

VMAX LiFePO4 12V Lithium Charging Parameters

• Primary Recommendation: A dedicated LiFePO4 Lithium Charger outputting 14.4V to guarantee optimal charge curves, full BMS cell balancing, and maximum cycle life.
• AGM Charger Compatibility: VMAX AGM smart chargers operating in AGM mode can safely charge VMAX Lithium batteries, provided desulfation and high-voltage equalization modes are completely disabled.

VMAX AGM batteries last 8–10 years in float/standby service and up to 5–6 years in active cyclic service at 50% depth of discharge. VMAX LiFePO4 Lithium batteries last up to 4,000 cycles with a 10-year design life.

VMAX AGM batteries are heavy because they’re packed with thick lead alloy plates for superior capacity and durability. To achieve extreme durability, anchor-bonded plates utilize tight internal compression, immobilized components, and robust physical connections—locking every element in place against intense vibration and heavy abuse.

Shipping is FREE to any home or business within the 48 contiguous United States. We ship orders fast—most orders placed before 2 PM EST ship the same day. 98% of our customers receive their batteries within 2-5 business days. Heavy orders that ship via LTL Freight will ship the next business day. We use top-tier carriers for LTL shipments to ensure a safe and quick delivery.

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We aim for a simple, hassle-free process.

If we made a mistake (damaged in transit, wrong item), we will exchange it immediately at no cost to you.

If you changed your mind or ordered the wrong item, you can return it within 30 days. We offer a discounted return shipping program to make it as easy and affordable as possible. Just email us with your order number to get started.

We stand behind our products with a clear, straightforward warranty.

AGM Batteries & Chargers: 1-Year Full Replacement Warranty.

LiFePO4 Lithium Batteries: 7-Year Pro-Rated Warranty.

You can view the full warranty details on our Warranty page.

Our goal is to be fair and efficient. If you believe your battery is defective within the warranty guidelines, our Michigan-based support staff will first help you troubleshoot the issue. Often, the problem can be resolved with a simple adjustment. If a warranty exchange is needed, we will guide you through every step and offer discounted return shipping options to make it easy. Simply email us at [email protected] for help with a claim.

VMAX is a proud American company with a team of battery experts based in Michigan, USA. We operate facilities in the US, Vietnam, China, Taiwan, and Germany to ensure the highest quality standards, with the majority of our products manufactured in our main US and Vietnam facilities.

The right battery depends on your space, desired run time, and charging system. We make it easy to find your perfect fit:

Match the Group Number: If you're replacing existing batteries, simply match their Group Number (e.g., Group 31) to the corresponding VMAX battery on our website.

Let Us Help: If you're unsure, our Michigan-based battery experts are here to help. Contact us via email or phone, and we'll guide you to the perfect battery for your needs. We offer lifetime technical support for all our products.

The best marine battery for a trolling motor depends on your setup and priorities. For many boaters, a deep cycle battery is the right choice because trolling motors require repeated discharge and recharge cycles. VMAX offers both AGM deep cycle marine batteries and lithium deep cycle marine batteries for trolling motor applications, including 12V, 24V, and 36V options.

VMAX batteries are maintenance-free in the sense that you never have to add water or worry about acid spills like with old wet cell batteries. However, like any premium equipment, basic care ensures the best performance and longest life. We recommend periodically checking that all terminal connections are clean and tight.

While other AGM batteries may look similar on the outside, the real difference is inside. VMAX AGM batteries are overbuilt from the ground up to deliver superior performance, a longer lifespan, and unmatched reliability in the most demanding conditions.

Here’s what sets a VMAX AGM battery apart:

Extreme Durability and Toughness: The heart of every VMAX battery is the unique physical and chemical structure of its heavy-duty, plates. A special manufacturing process gives them strength and performance that far exceeds competitors. We pack these plates tightly with a specially designed Absorbed Glass Matt (AGM) that maximizes the battery's resistance to shock and vibration. The entire package is protected by an extra-strong ABS container that reduces bulging and warping, ensuring high performance for years to come.

Reliability When It Matters Most: VMAX batteries are known for their ability to recover after repeated deep discharges. Our heavy-duty grids provide an extra margin of performance even after being over-discharged. This means you get one of the highest numbers of discharge/recharge cycles in the industry, making VMAX the favorite choice for any application where failure is not an option.

Truly Maintenance-Free & Safe: Our sealed, leak-proof construction guarantees operation in any position. Because the electrolyte is fully absorbed, there is no need to ever add water or check specific gravity. The design controls and recombines over 99% of gases, and a built-in safety valve prevents any excessive pressure, making it incredibly safe. VMAX batteries are classified as non-spillable and non-hazardous, meaning they are not restricted for air, sea, or surface transport.

Longer Life & Better Value: VMAX AGM batteries have an expected float service life of 8 to 10 years. They also hold their charge much longer when not in use, with a self-discharge rate of just 1-2% per month compared to 15-20% for many standard lead-acid batteries. This means your battery is ready to go when you are, even after sitting in storage.

Anyone is welcome to order. If you are a dealer or distributor, please click here to apply for a dealer account.

The lifespan of a battery is measured in cycles. With proper care and charging, VMAX batteries provide exceptional longevity.

VMAX AGM: Designed for an 8-12 year lifespan in float service (like a backup system). In active use, an AGM battery discharged to 50% every other day can last 5-6 years. Daily deep discharges of 90-100% will shorten the life to around 300 cycles.

VMAX Lithium: Our LiFePO4 batteries are rated for an incredible 4,000 life cycles and have a 10-year design life.

The heart of a VMAX battery is the unique physical and chemical structure of its plates. Through specialized plate treatment and manufacturing processes, VMAX batteries achieve a level of reliability, structural strength, and high performance that far exceeds standard Pb-Ca (lead-calcium) plates used in similar-looking alternatives.

By combining these advanced plates with custom-engineered Absorbed Glass Mat (AGM) separators, VMAX delivers distinct physical and electrical advantages over traditional wet lead-acid batteries—maximizing resistance to extreme shock, impact, and heavy vibration. Because 100% of the electrolyte is suspended within the AGM separators, every VMAX battery is classified as non-spillable and non-hazardous.

Enclosed in a tough "Tank" casing, these tightly packed plates deliver a 100% maintenance-free power package. While VMAXTANKS™ are best known for their exceptional lifespan, their ability to consistently recover after repeated deep discharges is what makes them the preferred choice for demanding applications.

Core Technical Advantages of VMAXTANKS™
Sealed, Leak-Proof Construction: Advanced construction and sealing techniques guarantee leak-proof operation in any position without compromising capacity or service life. VMAX batteries are officially classified as non-spillable, non-hazardous dry batteries, making them unrestricted for Surface, Maritime, and Air Transport.

Pure Electrolyte Suspension System: High-porosity AGM separators totally absorb and contain the electrolyte. VMAX uses zero silica gels or external contaminants in the suspension system.

Recombinant Gas Design: Built-in internal design controls gas generation and induces recombination of over 99% of gases generated during float service.

100% Maintenance-Free Operation: No specific gravity checks or water replenishment are ever required during float service life (in fact, there is no provision for this type of maintenance).

Low-Pressure Safety Valve System: Every VMAX battery features self-resealing safety release valves engineered to operate between 0.98–196.1 kPa, preventing dangerous gas accumulation inside the battery case.

Heavy-Duty Virgin Lead Grids & Anchor Bonding: Built with heavy-duty lead-tin alloy grids made from 100% virgin lead, VMAX plates feature anchor-bonded construction to achieve extreme physical durability. Tight internal compression, immobilized components, and robust physical connections protect the grid structure, delivering an extra margin of performance and service life in float or cyclic applications—even after repeated over-discharges.

Exceptional Cyclic Service Life: Delivers industry-leading discharge/recharge endurance, offering 900–1,000 cycles at 50% Depth of Discharge (DOD) and 3,500+ cycles at 10% DOD.

Long Float Service Life: Engineered for an expected float lifespan of 8 to 10 years in stationary and backup applications (with up to 10–12 years in our flagship XTR series).

Ultra-Low Self-Discharge: Retains charge significantly longer during storage, with a self-discharge rate at room temperature of just 1–2% per month (compared to 2–3% for standard AGMs and 15–20% for flooded lead-acid batteries).

Broad Operating Temperature Range: Operates and charges natively across broad ambient temperature extremes without failure.

Ultra-Low Internal Resistance (Up to 99% Efficient): Extremely low internal resistance achieves up to 99% electrical efficiency (compared to 85–95% for flooded lead-acid and ~97% for typical GEL and standard AGM batteries).

High Power Density: Specialized cell assembly technology maximizes energy output relative to physical footprint.

Heavy-Duty ABS Tank Container: Extra-strong ABS container construction eliminates case bulging and plate warping, ensuring structural integrity and peak performance over years of hard service.

Storage:

1- Batteries must be stored clean and away from any moisture.
2- Storage room must be dry, ventilated and kept at a temperature range of 10°F (-12°C) – 104°F (40°C) degrees. Storage at room temperature is MOST recommended.
3- Fully recharge your batteries before storage.
4- Though VMAX batteries can be stored for 6-9 months without a recharge, it is highly recommended to recharge your stored batteries at least once every 3 months, or once every 2 months if stored at over 85°F (30°C).
5- If batteries are not accessible, or if they cannot be periodically charged while in storage, then leave your three stage charger connected to them until they are ready to be reused again.

Commissioning:
1- Ensure that batteries are clean. Use a damp cloth to clean battery surface. Dry surface after cleaning. The use of cleaning agents, solvents, petroleum or any other products of the sort is not recommended and may cause damage to battery surface.
2- Fully recharge your batteries. A float charge of 48-96 hours at room temperature is highly recommended (13.5-13.7V for 12V or 6.69-6.81V for 6V batteries). Or you can fast charge your batteries (14.5-14.9V for 12V or 6.9-7.05V for 6V batteries) for 12-24 hours.
3- Check battery voltage with no load. It should be above 12.9V for 12V or 6.45V for 6V batteries.
4- Connect batteries to load.
5- Check the tightening of connections.

Most of the time, this problem happens to sealed lead-acid batteries of either AGM (Absorbed Glass Mat) or GEL (gelled electrolyte) construction. These batteries are known as "recombinant", referring to the absorption of gasses generated by the chemical process of the battery. In order to absorb these gasses, the positive and negative plates must be as close together as possible and are usually held apart by the thickness of the separator. A consequence of the necessity of gas absorption, the pack of plates is inserted very tightly into the cell cavity, resulting in a lack of space for any other components. In the situation of a swollen battery, the cell plate components expanded, and the force exerted on the case will cause it to swell and in some cases split.

The expansion of the plates is a result of internal heat caused by either overcharging the battery or from a drastic shorting of its terminals. Either one of these situations will generate internal heat in the battery. And since lead has a high expansion rate when exposed to heat, the expansion pressure will cause the case to swell and cause battery damage.

Overcharging of the battery can be the result of using a charger that is delivering the wrong Voltage or Current to the battery. Regardless of the cause, the result is almost always the same; swelling and the destruction of the battery.

For your safety and to avoid this problem, it is very important to ask the following questions:

1.  Is the charger designed to be used with my battery (AGM, WET, GEL, LITH…)?
   

2.  Does the charging voltage fall within the range specified for my battery?
   

3.  Does the maximum current of the charger fall within the charging range of my battery?
   

4.  Do I have the right polarity connection between battery and charger?
   

5.  Are the battery terminals prevented from possible shorting at all times?
   

Two popular premium Group 31 AGM marine battery options from VMAX are:

XTR31-135 (AGM Dual Purpose Group 31)

MR137-120 (AGM Deep Cycle Group 31)

The XTR31-135 is ideal for boaters needing dual-purpose performance, while the MR137-120 is a strong choice for deep cycle marine applications.

Yes. VMAX offers AGM deep cycle marine batteries in multiple group sizes, including Group 24, Group 27, and Group 31.

For dual purpose marine applications, VMAX’s premium AGM options include:

XTR31-135 (Group 31 AGM Dual Purpose)

XTR27-110 (Group 27 AGM Dual Purpose)

These are designed for boaters who need a battery that can support both engine starting and exceptional deep cycle performance.

Yes. VMAX is a Michigan-based battery manufacturer, established in 1991.

12V AGM Performance Charts
12V GEL Performance Charts
6V AGM Performance Charts
LIFEPO4 Performance Charts
Number Of Cycles vs Depth Of Discharge Graph
State of Charge Chart
Float Charge Voltage vs Temperature

DC Winches Application Guide
Estimated Wire Sizing Chart
Trolling Motors Breakers and Cables Chart

AC and DC Loads
DC Motors (HP)
Sump Pumps
Trolling Motors
Water Pumps