Marine Battery Service, Sales & Installation
From AGM starting batteries to complete lithium house bank conversions, Accumar Marine Services provides expert marine battery solutions for boats of all sizes in Fort Myers, Cape Coral, Naples, and Southwest Florida.
ABYC Certified
Marine Electrical
25+ Years
Marine Experience
Mobile Service
Fort Myers to Naples
Free Load Testing
All Battery Types
Filter Batteries
Complete Battery Solutions
Marine Battery Types We Service & Install
Every boat has different power requirements. We help you choose the right battery technology for your vessel, usage pattern, and budget. View full comparison →
AGM (Absorbed Glass Mat)
Lifespan: 4-6 years
The workhorse of marine batteries. AGM batteries use fiberglass mats saturated with electrolyte, making them spill-proof, vibration-resistant, and maintenance-free. Ideal for both starting and deep-cycle applications.
Advantages
- + Maintenance-free — no watering required
- + Spill-proof and vibration-resistant
- + Excellent cranking power for engine starting
- + Good deep-cycle capability (50% DOD recommended)
- + Wide availability and moderate cost
- + Safe for enclosed battery compartments
Considerations
- − Heavier than lithium alternatives
- − Only 50% usable capacity to preserve lifespan
- − 300-500 cycle lifespan at 50% DOD
- − Slower charging than lithium
Best for: Engine starting, general-purpose house banks, budget-conscious upgrades
Brands: East Penn (Deka), Odyssey, Lifeline, Trojan, Fullriver
Lithium Iron Phosphate (LiFePO4)
Lifespan: 8-12 years
The gold standard for modern marine battery systems. LiFePO4 batteries offer unmatched energy density, cycle life, and efficiency. They are the preferred choice for serious cruisers, liveaboards, and performance-oriented vessels.
Advantages
- + 100% usable capacity (vs. 50% for AGM)
- + 3,000-5,000+ cycle lifespan
- + 60% lighter than equivalent AGM
- + 5x faster charging speed
- + Flat voltage curve — consistent power output
- + Built-in BMS (Battery Management System)
- + Lowest total cost of ownership over 10 years
Considerations
- − Higher upfront cost
- − Requires compatible charging equipment
- − Cannot be charged below 32°F (0°C) without heating
- − Requires BMS for safe operation
Best for: House banks, liveaboards, cruisers, high-load systems, weight-sensitive vessels
Brands: Victron Energy, Battle Born, RELiON, Lithionics, Epoch
Gel Cell
Lifespan: 5-7 years
Gel batteries use silica-thickened electrolyte that won't spill or leak. They excel in deep-cycle applications and handle high temperatures better than AGM, making them well-suited for Southwest Florida's climate.
Advantages
- + Excellent deep-cycle performance
- + Superior heat tolerance vs. AGM
- + Very low self-discharge rate
- + Spill-proof and vibration-resistant
- + Longer lifespan than AGM in hot climates
- + No maintenance required
Considerations
- − More expensive than AGM
- − Sensitive to overcharging — requires precise voltage regulation
- − Lower cranking power than AGM
- − Slower charge acceptance
Best for: Deep-cycle house banks in hot climates, sailboat house banks, trolling motors
Brands: East Penn (Deka), Trojan, Sonnenschein
Flooded Lead-Acid (Wet Cell)
Lifespan: 2-4 years
Traditional flooded lead-acid batteries remain a cost-effective option for basic marine applications. They require regular maintenance (checking water levels) but offer reliable performance at the lowest upfront cost.
Advantages
- + Lowest upfront cost
- + Proven technology — widely available
- + Easy to recycle
- + Tolerant of overcharging
- + Good for high-current starting applications
Considerations
- − Requires regular maintenance (watering)
- − Must be kept upright — can spill acid
- − Produces hydrogen gas during charging
- − Heaviest option per amp-hour
- − Shortest lifespan (2-4 years)
Best for: Budget applications, engine starting, boats used infrequently
Brands: Trojan, Interstate, East Penn (Deka), US Battery
Lithium Polymer (LiPO)
Lifespan: 5-8 years
High-performance lithium polymer batteries are used in specialized marine applications where maximum power density and lightweight construction are critical. Common in racing sailboats and high-performance powerboats.
Advantages
- + Highest energy density of any battery type
- + Extremely lightweight
- + Can deliver very high discharge rates
- + Flexible form factors
Considerations
- − Most expensive option
- − Requires careful charge management
- − Less tolerant of abuse than LiFePO4
- − Shorter lifespan than LiFePO4 in marine use
Best for: Racing sailboats, high-performance powerboats, weight-critical applications
Brands: Mastervolt, Torqeedo, Super B
Authorized Dealer & Installer
Marine Battery Brands We Carry
We source from Marysville Marine, West Marine, and directly from manufacturers to get you the best price and availability.
East Penn (Deka Marine)
America's largest single-site battery manufacturer. Deka Marine batteries are built in Lyons, PA with military-grade quality control. Their AGM and Gel lines are trusted by the US Navy and Coast Guard.
Source: West Marine, Direct
Reliable OEM-quality starting and deep-cycle batteries
Trojan Battery
Industry leader in deep-cycle battery technology since 1925. Trojan's T-105 and T-125 flooded batteries are the gold standard for marine house banks. Their Reliant AGM line offers maintenance-free deep cycling.
Source: Marysville Marine, West Marine
Heavy-duty deep-cycle house banks and trolling motors
Fullriver Deep Cycle
Premium AGM batteries with true deep-cycle design. Fullriver's DC series delivers 500+ cycles at 80% depth of discharge — significantly more than most AGM competitors. Military-spec construction with heavy plates.
Source: Marysville Marine, Direct
Maximum AGM deep-cycle performance for demanding applications
Lifeline AGM
Handcrafted in San Marcos, CA — the only AGM battery made in the USA using Concorde's aerospace technology. Lifeline batteries are the choice of serious offshore cruisers and the US military. 1,000+ cycles at 50% DOD.
Source: West Marine, Direct
Premium offshore cruising and liveaboard house banks
Odyssey (EnerSys)
High-performance AGM batteries with pure lead plates that deliver 400 cycles at 80% DOD and massive cranking power. Odyssey batteries handle extreme vibration and temperature — ideal for high-performance boats.
Source: West Marine, Marysville Marine
High-performance starting batteries and dual-purpose applications
Victron Energy
View Products →The world leader in marine power systems. Victron's Smart LiFePO4 batteries integrate with their complete ecosystem of inverter/chargers, MPPT controllers, and monitoring via Bluetooth and VRM portal.
Source: Authorized Dealer — Direct
Complete integrated lithium power systems
Battle Born
Made in Reno, NV — Battle Born's 100Ah LiFePO4 is the best-selling drop-in lithium replacement battery. 3,000-5,000 cycle life, built-in BMS, and a 10-year warranty make them a top choice for marine upgrades.
Source: Direct
Drop-in lithium upgrades for existing 12V/24V systems
Quick Battery Comparison
Side-by-side comparison to help you choose. See full detailed comparison →
| Feature | AGM | Gel | Wet Cell | LiFePO4 | LiPO |
|---|---|---|---|---|---|
| Usable Capacity | 50% | 50% | 50% | 100% | 90% |
| Cycle Life | 300-500 | 500-800 | 200-400 | 3,000-5,000 | 1,000-2,000 |
| Weight (100Ah) | ~65 lbs | ~68 lbs | ~70 lbs | ~25 lbs | ~20 lbs |
| Charge Time | 6-8 hrs | 8-10 hrs | 8-12 hrs | 1-2 hrs | 1-2 hrs |
| Maintenance | None | None | Regular | None | None |
| Lifespan | 4-6 yrs | 5-7 yrs | 2-4 yrs | 8-12 yrs | 5-8 yrs |
| Cost (100Ah) | $200-400 | $300-500 | $100-200 | $800-1,500 | $1,000-2,000 |
| 10-Year Cost | $$$$ | $$$ | $$$$$ | $$ | $$$ |
| Heat Tolerance | Good | Excellent | Good | Good | Fair |
| Self-Discharge | 3%/mo | 2%/mo | 5-15%/mo | 2%/mo | 5%/mo |
* LiFePO4 batteries cannot be charged below 32°F without a heating system. Most marine-grade LiFePO4 batteries include built-in heaters.
System Design
12V, 24V & 48V Marine Battery Systems
We design and install battery systems at every voltage level. The right voltage depends on your vessel size, electrical loads, and equipment requirements.
12-Volt Systems
Standard on most recreational boats under 50 feet. Powers all basic marine electronics, lighting, pumps, and starting systems.
Common Applications:
- Engine starting
- Navigation lights & cabin lighting
- Bilge pumps & freshwater pumps
- VHF radio & basic electronics
- Small refrigerators & fans
Wiring: Larger gauge wire required for long runs
Typical vessels: Runabouts, center consoles, small cruisers, trailerable sailboats
24-Volt Systems
Common on larger sailboats and motor yachts. Reduces current draw by half compared to 12V, allowing smaller wire gauges and more efficient operation of high-draw equipment.
Common Applications:
- Windlass & anchor systems
- Bow & stern thrusters
- Inverter/charger systems
- Watermakers
- Large refrigeration systems
- Electric winches
Wiring: Half the current of 12V — smaller, lighter wiring
Typical vessels: Sailboats 40'+, motor yachts, trawlers, catamarans
48-Volt Systems
Used on large yachts, commercial vessels, and modern electric/hybrid propulsion systems. Maximum efficiency for heavy electrical loads and long cable runs.
Common Applications:
- Electric & hybrid propulsion
- Large inverter banks
- High-capacity shore power systems
- Industrial marine equipment
- Stabilizer systems
Wiring: Minimum current draw — maximum efficiency
Typical vessels: Superyachts, commercial vessels, electric boats, hybrid propulsion
Our Marine Battery Services
From a single battery replacement to a complete lithium conversion, we handle every aspect of your boat's electrical power system.
Battery Replacement
Quick, professional battery replacement for all types — AGM, lithium, flooded. We carry common sizes in stock for same-day service.
Lithium Conversion
Complete AGM-to-lithium upgrade including batteries, BMS, compatible chargers, and battery monitors. Reduce weight and increase capacity.
Battery Load Testing
Free battery load testing to determine remaining capacity and health. We test individual batteries and complete bank performance.
Charging System Service
Shore charger installation, alternator upgrades, solar panel systems, and MPPT controller setup. Ensure your batteries charge properly.
Battery Bank Design
Custom battery bank design for your specific vessel and usage. We calculate loads, size batteries, and design wiring for optimal performance.
Battery Monitoring
Install Victron, Mastervolt, or other battery monitors so you always know your state of charge, current draw, and remaining runtime.
Customer Testimonials
What Our Customers Say About Our Battery Work
Victron lithium conversion was a game-changer
Roland and the Accumar team converted my entire house bank from 8 AGM batteries to 4 Victron 200Ah lithium batteries. Lost 400 lbs of weight, gained more usable capacity, and the Victron monitoring system is incredible. Best investment I've made on this boat.
Captain Mike D.
42' Hatteras Sportfish
January 2026
Verified
Perfect AGM setup for our cruising sailboat
We needed a reliable house bank for our Great Loop trip. Accumar installed 4 Lifeline GPL-4CT AGM batteries with a Victron BMV-712 monitor. The system has been flawless through 6 months of cruising. They really know marine electrical systems.
Dave & Linda S.
38' Island Packet
December 2025
Verified
Odyssey starting battery solved my cranking issues
My boat was struggling to start in the Florida heat. Accumar recommended the Odyssey 31M-PC2150 — massive cranking power and it handles the heat much better than my old battery. Quick install, fair price, and they load-tested my old battery for free.
Tom R.
28' Grady-White Canyon
November 2025
Verified
Complete Victron system — batteries, inverter, solar
Accumar designed and installed a complete Victron system: 2x 200Ah Smart LiFePO4 batteries, MultiPlus-II 3000 inverter/charger, SmartSolar MPPT, and Cerbo GX monitoring. I can monitor everything from my phone. These guys are the real deal.
Sarah K.
34' Catalina Sailboat
October 2025
Verified
Trojan T-105s for the house bank — solid choice
Went with Trojan T-105 flooded batteries for my house bank — 8 batteries in a 24V configuration. Not as fancy as lithium but at half the cost. Accumar set up the bank properly with good ventilation and a quality charger. Very happy with the value.
Jim P.
46' Grand Banks Trawler
September 2025
Verified
48V Victron Quattro system for our sportfish
Accumar installed a Victron Quattro 48/5000 with a full Lynx Distribution system and 48V lithium bank. The power quality is incredible — clean sine wave for all our electronics. Roland personally designed the system layout. First-class work.
Robert M.
50' Viking Convertible
August 2025
Verified
5 Signs Your Boat Batteries Need Replacing
Don't get stranded on the water. Watch for these warning signs.
Slow Engine Cranking
If your engine turns over sluggishly or requires multiple attempts to start, your starting battery is likely failing. This is especially dangerous in Southwest Florida's summer heat, which accelerates battery degradation.
Lights Dim at Anchor
If your cabin lights dim noticeably after a few hours at anchor, your house bank can no longer hold adequate charge. AGM batteries lose capacity gradually — by the time you notice dimming, they may be at 60-70% of original capacity.
Batteries Won't Hold Charge Overnight
A healthy battery bank should maintain your essential loads (anchor light, bilge pump, refrigerator) through the night. If you're waking up to dead batteries, it's time for replacement or a system upgrade.
Swollen or Corroded Battery Cases
Physical damage to battery cases — swelling, cracking, or heavy corrosion on terminals — indicates internal failure. Swollen batteries can be dangerous and should be replaced immediately.
Batteries Are Past Their Rated Lifespan
Even if they seem to work, batteries past their rated lifespan (2-4 years for flooded, 4-6 for AGM) are operating on borrowed time. Florida's heat shortens battery life — proactive replacement prevents unexpected failures.
Marine Battery FAQ
Common questions about marine batteries answered by our certified technicians.
What type of marine battery is best for my boat?
The best marine battery depends on your usage. For starting engines, AGM batteries offer reliable cranking power with low maintenance. For house banks powering electronics, refrigeration, and AC, lithium (LiFePO4) batteries provide the deepest discharge cycles and longest lifespan — up to 10 years. For budget-conscious boaters, quality AGM deep-cycle batteries are an excellent middle ground. Call Accumar Marine at 239-323-9600 for a free battery system consultation.
How much does it cost to replace marine batteries in Fort Myers?
Marine battery replacement costs vary by type and system voltage. A single AGM starting battery typically runs $200-$400 installed. A 4-battery AGM house bank costs $800-$1,600. Lithium (LiFePO4) batteries are a higher upfront investment — $800-$2,500 per battery — but last 3-5x longer than AGM and provide more usable capacity. We provide free estimates and can design a complete battery system upgrade. Call 239-323-9600.
Should I upgrade my boat to lithium batteries?
Lithium (LiFePO4) batteries are the best long-term investment for most boats. They weigh 60% less than AGM, provide 100% usable capacity (vs. 50% for AGM), charge 5x faster, and last 3,000-5,000 cycles vs. 300-500 for AGM. The upfront cost is higher, but the total cost of ownership over 10 years is lower. Lithium is especially beneficial for liveaboards, cruisers, and boats with high electrical loads. Accumar Marine installs complete lithium conversion systems.
Can I mix AGM and lithium batteries on my boat?
We do not recommend mixing AGM and lithium batteries in the same bank because they have different charging profiles and voltage curves. However, you can use AGM for engine starting and lithium for your house bank — this is actually a popular and cost-effective hybrid setup. Your charging system (alternator, shore charger, solar) needs to be compatible with lithium. Accumar Marine can design a hybrid system that works safely and efficiently.
What is the difference between 12V, 24V, and 48V marine battery systems?
12V systems are standard on most recreational boats under 50 feet. 24V systems are common on larger vessels and sailboats — they reduce wire gauge requirements and improve efficiency for high-draw equipment like windlasses, thrusters, and inverters. 48V systems are used on large yachts and commercial vessels for maximum efficiency with heavy electrical loads. Accumar Marine designs and installs all voltage configurations and can upgrade your system.
How often should marine batteries be replaced?
Replacement intervals depend on battery type and usage: Flooded lead-acid batteries last 2-4 years. AGM batteries typically last 4-6 years with proper maintenance. Gel batteries last 5-7 years. Lithium (LiFePO4) batteries last 8-12 years or 3,000-5,000 charge cycles. In Southwest Florida's heat, batteries degrade faster — regular testing and maintenance extends life significantly. Accumar Marine offers free battery load testing.
Do you install solar panels and battery charging systems?
Yes, Accumar Marine installs complete solar charging systems including panels, MPPT charge controllers, battery monitors, and inverters. Solar is especially popular with cruisers and liveaboards. We also install and service shore power chargers, alternator upgrades, and wind generators. We design systems that properly charge both AGM and lithium battery banks.
What brands of marine batteries do you carry and install?
We install and service all major marine battery brands including Victron Energy, East Penn (Deka Marine), Trojan, Fullriver Deep Cycle, Lifeline AGM, Odyssey, Battle Born, RELiON, Lithionics, and more. We source batteries from Marysville Marine, West Marine, and direct from manufacturers. As an authorized Victron Energy dealer, we carry their complete line of LiFePO4 batteries, inverter/chargers, and monitoring systems. Call 239-323-9600 for pricing.
Ready to Upgrade Your Boat's Battery System?
Call Accumar Marine for a free battery consultation. We'll test your current batteries, assess your power needs, and recommend the best solution for your vessel and budget.
Serving Fort Myers, Cape Coral, Naples, Sanibel, Marco Island, Punta Gorda & all of Southwest Florida