Accumar Marine Services
ACCUMARMarine Services
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Marine Battery Service Fort Myers, FL

Dead batteries leave you stranded. We test, replace, and upgrade marine battery systems — lithium and AGM, all brands.

ABYC certified technicians. 25+ years of marine electrical experience. Mobile service to your dock in Fort Myers, Cape Coral, Naples, and all of Southwest Florida.

90-Day Labor WarrantySame-Day Service Available5-Star Rated

Why Boat Owners Choose Us for Batteries

Lithium & AGM Specialists

Relion, Epoch, LiTime, Lifeline, Optima & more

Full System Diagnostics

Load testing, internal resistance, parasitic draw analysis

Complete Upgrades & Conversions

AGM-to-lithium conversions with charger reprogramming

Mobile Service to Your Dock

Fort Myers to Sarasota — we come to you

Not sure if lithium is right for your boat?

Use our free battery calculator to compare lithium vs AGM for your specific setup.

Diagnostics & Repair

Common Marine Battery Problems We Fix

Every battery issue has a root cause. We test first, then recommend — no unnecessary replacements.

Battery Won't Hold Charge

Sulfation, dead cells, or parasitic draw draining your bank overnight. The #1 battery complaint we hear.

Slow Engine Cranking

Weak starting battery, corroded terminals, or undersized cable. Dangerous if you can't restart offshore.

Battery Overheating

Overcharging, failed voltage regulator, or inadequate ventilation. Florida heat makes this worse.

Voltage Drop Under Load

Undersized bank, aged batteries, or high-resistance connections causing brownouts at anchor.

Charger Not Charging

Failed shore charger, alternator diode failure, or incorrect charge profile for your battery type.

Corroded Terminals & Cables

Salt air corrosion on terminals, lugs, and bus bars. Causes voltage drop and intermittent connections.

Not sure what's wrong? Call us for a free phone consultation.

Our Battery Services

Complete Marine Battery Service

From diagnostics to full bank upgrades — we handle every aspect of marine battery systems.

Battery Testing & Diagnostics

Comprehensive battery bank analysis. We measure every battery individually — voltage, internal resistance, capacity under load, and charging system output.

  • Individual battery voltage & resistance testing
  • Load testing under real-world conditions
  • Charging system verification (alternator, shore, solar)
  • Parasitic draw measurement
  • Cable & connection inspection
  • Written report with specific recommendations

Starting at $200 minimum service (includes full diagnostics)

Battery Replacement & Installation

We carry top marine battery brands and install them properly — correct torque specs, anti-corrosion treatment, and charging system verification after every install.

  • Lithium LiFePO4 & AGM battery installation
  • Starting, house, and thruster battery banks
  • Battery switch & combiner installation
  • Cable upgrades & terminal replacement
  • Battery box & tie-down installation
  • Charging system configuration & testing

Lithium Battery Conversion

Upgrade from AGM to lithium LiFePO4. We handle the complete conversion — battery sizing, charger reprogramming, BMS integration, and monitoring setup.

  • AGM-to-lithium bank conversion
  • Charger & alternator reprogramming
  • BMS integration & monitoring
  • Victron Energy system integration
  • Bank sizing based on actual load analysis
  • Full commissioning & performance verification

Electrical System Service

Batteries are only as good as the system around them. We service the complete charging and distribution system to maximize battery life and performance.

  • Shore charger repair & replacement
  • Alternator testing & high-output upgrades
  • Solar panel installation & MPPT controllers
  • Battery monitor installation (Victron, etc.)
  • Inverter installation & service
  • Complete DC electrical system audit

Marine Battery Brands We Install

Lithium LiFePO4

Relion
Watt Cycle
Epoch
LiTime

3,000–5,000 cycle life · 60% lighter · Built-in BMS

AGM (Absorbed Glass Mat)

Lifeline
Optima
Odyssey
Interstate

500–800 cycle life · Cost-effective · No BMS needed

Plus Victron Energy monitors, chargers, and inverters for complete system integration.

What Our Customers Say

4.6(61 Google reviews)
Mark Cox

Mark Cox

"I can't say enough good things about dealing with Twin Screws Marine. I first met Christina and Jimmy 4 years ago when I purchased my Grady White from them. Up front, knowledgable, honest, prompt, and accomodating all describe my experience with Twin Screws. I was so impressed with them that I came back this year to have my fishing boat repowered by them. Competitive pricing and qualtity workmanship sum up the best reasons for using Twin Screws Marine. They made smart recommendations on my project, didn't try to upcharge me for things I didn't need, and delivered my boat on time. I highly recommend calling Christina for any marine issues or projects you are contemplating. Quality people make for a great experience!"

Chip Spillane

Chip Spillane

"I can’t say enough about this operation! I spoke with Christina and Bill on the phone and they were so helpful and accommodating even though they had full load of work they recognized the jam we were in with a bad impeller. We brought the boat over on a trailer and Mike Barry and Joe all delayed their lunch so they could get the impeller in and we could get on our way. These guys really went above and beyond for us and I would highly recommend their service to anyone! They also have a very knowledgeable mechanic named Jimmy, whom they call the bearded wonder and he gave us a wealth of information that we can use in the future. Thank you again to all of you for saving our vacation. We will keep in touch! Chip"

Jeremiah Das

Jeremiah Das

"Thank you so much Jimmy and Christina at Twin screws marine.my new Suzuki 300 re power showed up and was put on in no time. matter of less then 2 weeks. They both worked super hard and kept great communication during the service making sure I was happy ,and worked through the holiday to make sure I could get back on the water fishing. They impressed me so much with the work done that I going back with them for more work to get dash panel refurbished. Thank you for the great service for sure use them going forward"

View all 61 reviews on Google →

Service Area

Marine Battery Service Across Southwest Florida

Mobile service to your dock, marina, or boatyard. We bring batteries and tools to you. No travel surcharge within Lee and Collier County.

Core Service Area (No Travel Surcharge)

Fort Myers(Lee Co.)
Cape Coral(Lee Co.)
Naples(Collier Co.)
Marco Island(Collier Co.)
Bonita Springs(Lee Co.)

Extended Service Area

Estero(Lee Co.)
Sanibel Island(Lee Co.)
Pine Island(Lee Co.)
Punta Gorda(Charlotte Co.)
Port Charlotte(Charlotte Co.)
Sarasota(Sarasota Co.)
Englewood(Charlotte Co.)

Accumar Marine Services

Address

2779 N Airport Rd, Ste #201

Fort Myers, FL 33907

Hours

Mon–Fri: 8:00 AM – 5:00 PM

Emergency service available after hours

Credentials

ABYC Certified Technicians

Victron Energy Authorized

25+ Years Marine Experience

Prevent Battery Failures

Florida Heat Kills Marine Batteries 40% Faster

A $275 twice-yearly battery check prevents a $3,000+ emergency replacement when you're 20 miles offshore. Our Battery & Electrical Maintenance Program includes load testing, charging system verification, terminal cleaning, and written condition reports.

Maintenance program members get priority scheduling and 10% discount on battery purchases.

Frequently Asked Questions

Marine Battery Service FAQ

How much does marine battery replacement cost in Fort Myers?

Marine battery replacement in Fort Myers depends on battery type and bank size. AGM batteries (Lifeline, Optima, Odyssey) range from $250–$600 per battery installed. Lithium LiFePO4 batteries (Relion, Epoch, LiTime, Watt Cycle) range from $800–$3,500 per battery. Full bank replacements including wiring and programming typically run $1,500–$12,000. We provide a written estimate before any work begins. Call 239-323-9600 for a free consultation.

Should I switch from AGM to lithium batteries on my boat?

It depends on your usage pattern. Lithium LiFePO4 batteries last 3–5x longer than AGM (3,000–5,000 cycles vs 500–800), weigh 60% less, and provide consistent voltage until nearly depleted. They're ideal for liveaboards, cruisers, and boats with high electrical loads. AGM remains cost-effective for weekend boaters with modest power needs. We analyze your electrical load, usage pattern, and budget to recommend the right chemistry. Our battery calculator at accumarmarine.com/battery-calculator helps you compare options.

How do I know when my boat batteries need replacing?

Common signs: (1) Slow engine cranking. (2) Lights dimming at anchor. (3) Battery won't hold charge overnight. (4) Swollen or corroded cases. (5) Battery is 3+ years old (AGM) or showing capacity loss on load test. We perform comprehensive battery bank testing including voltage under load, internal resistance measurement, and capacity testing. This tells you exactly which batteries need replacement vs. which are still serviceable.

What marine battery brands do you install in Southwest Florida?

For lithium LiFePO4: Relion, Watt Cycle, Epoch, and LiTime — all marine-grade with built-in BMS and drop-in compatibility. For AGM: Lifeline (made in USA, military-grade), Optima (BlueTop marine), Odyssey (thin-plate pure lead), and Interstate (reliable, widely available). We also install Victron Energy battery monitors and smart chargers for complete system integration.

How long do marine batteries last in Florida?

Florida's heat accelerates battery degradation. AGM batteries typically last 2–4 years in SWFL (vs 4–6 in cooler climates). Lithium LiFePO4 batteries last 8–12 years regardless of climate, with built-in thermal management. Proper charging, ventilation, and regular testing extend battery life significantly. Our Battery & Electrical Maintenance Program includes twice-yearly testing and charging system verification.

Can you install a lithium battery system on my older boat?

Yes. We retrofit lithium battery systems on boats of all ages. The key considerations are: (1) Charging system compatibility — your alternator and shore charger must support lithium profiles. (2) BMS integration — we ensure the battery management system communicates with your existing electrical system. (3) Proper sizing — lithium banks are typically 50% smaller than equivalent AGM banks. We handle the complete conversion including charger reprogramming and monitoring setup.

Do you offer marine battery testing and diagnostics?

Yes. Our battery diagnostic service ($200 minimum, includes full electrical system check) covers: individual battery voltage and internal resistance testing, load testing under real-world conditions, charging system output verification (alternator, shore charger, solar), parasitic draw measurement, and cable/connection inspection. You get a written report with specific recommendations. Most diagnostics are completed same-day.

What areas do you serve for marine battery service?

We provide mobile marine battery service throughout Southwest Florida: Fort Myers, Cape Coral, Naples, Marco Island, Bonita Springs, Estero, Sanibel, Pine Island, Punta Gorda, Port Charlotte, and Sarasota. We come to your dock, marina, or boatyard with batteries and tools. Core service area is Lee and Collier County with no travel surcharge.

Related Marine Services

Marine BatteriesBattery ComparisonBattery CalculatorVictron EnergyMaintenance ProgramsMarine ElectronicsElectrical AuditsMarine AC RepairBattery Warning SignsLithium vs AGM Guide

Need Marine Battery Service in Fort Myers?

Call now for a free phone consultation. We'll help you determine the right battery solution for your vessel.

Never Get Stranded by a Dead Battery

Our maintenance programs include battery load testing and terminal inspection on every visit. We catch failing batteries before they leave you stuck.

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