Marine lithium battery sales and installation on Long Island.
We supply LiTime LiFePO4 batteries and install complete lithium house banks on boats across Nassau County and Suffolk County. Drop-in replacement for AGM. Half the weight. Three times the cycle life. Properly wired and commissioned by NMEA certified technicians.
Lithium iron phosphate is the safest lithium chemistry for marine use — stable, no thermal runaway risk, built-in battery management system protecting every cell. We handle the battery, wiring, charge controller programming, and alternator compatibility so you don't have to figure it out yourself.
Why Upgrade
Why Long Island boat owners are switching to lithium.
AGM batteries work — until they don't. They're heavy, they discharge only to 50%, and they degrade noticeably after 300–500 cycles. Lithium iron phosphate changes the math entirely.
A LiTime 100Ah 12V LiFePO4 battery weighs about 24 lbs. The AGM equivalent weighs 60 lbs. On most Long Island cruisers, replacing two to four house batteries saves 100–150 lbs — real performance gain in terms of speed, fuel, and trim.
LiTime LiFePO4 batteries are rated for 3,000–5,000 cycles at 80% discharge. A quality AGM bank runs 300–500 cycles before significant capacity loss. On a boat used 80 days a year, that's 6+ years vs 3–5 years — with lithium maintaining flat voltage across the entire discharge curve.
You can safely discharge LiFePO4 to 20% state of charge without damage. AGM should never go below 50%. A 200Ah LiFePO4 bank gives 160Ah of real usable power. A 200Ah AGM bank gives 100Ah. Same Ah label — very different real-world capacity on the water.
LiFePO4 vs AGM
LiFePO4 vs AGM — what actually changes on your boat.
| Spec | LiTime LiFePO4 | Standard AGM |
|---|---|---|
| Usable capacity | 80% (deep discharge safe) | 50% max |
| Cycle life | 3,000–5,000 cycles | 300–500 cycles |
| Weight (100Ah 12V) | ~24 lbs | ~60 lbs |
| Charge speed | Accepts full alternator output | Tapers off at 80% |
| Self-discharge | <3% per month | 5–15% per month |
| Drop-in replacement | Yes (12V / 24V / 48V) | — |
| Built-in BMS | Yes | No |
The 80% usable capacity rule is critical: a 100Ah LiFePO4 bank gives you 80Ah of real usable power. A 100Ah AGM bank gives you only 50Ah before it starts degrading. To get equivalent capacity from AGM you need twice the battery — double the weight and cost.
Bank Sizing
How much lithium does your boat actually need?
Calculate your daily amp-hour draw — what runs, how long it runs — then size the bank at 1.5× that number so you're never below 20% state of charge. Long Island averages 5 peak sun hours in summer; pair with solar to recharge without running the engine.
| Boat Profile | Daily Draw | Recommended Bank |
|---|---|---|
| Day boat — starting and accessories | 10–20Ah | 100Ah 12V (single) |
| Weekend cruiser — fridge, lights, nav | 40–70Ah | 100–200Ah 12V |
| Extended anchoring — full electronics | 80–120Ah | 200Ah 12V or 100Ah 24V |
| Offshore / liveaboard — inverter loads | 150–300Ah+ | 400Ah 12V or 200Ah 24V |
We do a full electrical audit before recommending any battery bank. Call 516-448-6221 and we'll size the right system for your Nassau County or Suffolk County boat in minutes.
The Installation
What LIME handles — supply, install, and commission.
Dropping lithium batteries into a boat wired for AGM without updating the charging system is one of the most common mistakes we see. LIME handles the full conversion — batteries, wiring, charger programming, and alternator compatibility.
We supply LiTime lithium iron phosphate batteries in 12V, 24V, and 48V configurations. Every LiTime battery includes a built-in BMS with overcharge, over-discharge, short circuit, and low-temperature protection. You don't source the batteries separately — we bring everything.
Dropping lithium into a boat wired for AGM without updating the charger is a common mistake. We configure your Victron SmartSolar MPPT, Mastervolt ChargeMaster, or Xantrex Freedom for lithium charge profiles, and check that your alternator won't overload the battery's BMS during high-current charging.
Lithium batteries deliver high current — wire sizing, fusing, and bus bar connections must match. We run tinned marine wire, install correctly rated fuses or breakers, label every circuit, and load-test the completed system. Written service report and ABYC-compliant wiring throughout.
Ready to talk? Or keep reading below.
Applications
Where lithium batteries make the biggest difference on a boat.
The most common upgrade we do on Long Island boats — replacing two to four AGM house batteries with a single LiTime 200Ah or 100Ah LiFePO4 unit. Half the weight, twice the usable power, and a flat voltage curve that keeps electronics running properly down to the last amp.
LiFePO4 is the ideal match for solar charging. The chemistry accepts full charge controller output, holds charge for weeks between uses, and pairs natively with Victron and Mastervolt MPPT controllers. See our marine solar installation page for complete system options.
Thrusters and windlasses draw 80–200A in bursts — exactly the high-current discharge that AGM handles poorly and lithium handles easily. A dedicated LiTime 100Ah battery at the bow provides clean, consistent voltage for every maneuver in Nassau County and Suffolk County marinas.
Customer Reviews
Five-star reviews from Long Island boat owners.
LIME replaced four group 31 AGMs with two LiTime 200Ah lithium banks. Saved about 180 lbs and now have more usable capacity than before. They programmed the Victron MPPT for lithium charge profile same day. Everything works perfectly.
Best upgrade I've made to the boat. LIME handled the full conversion — batteries, wiring, and getting the alternator and solar charging sorted for lithium. Been on a two-week cruise with no shore power and the bank never dropped below 50%.
Had LIME add a dedicated LiTime battery for the bow thruster. Rock solid — no voltage drop during docking, no hesitation. They handled everything in one visit. Called the owner directly, got straight answers, fair price.
Our Work
Marine lithium battery installations on Long Island boats.
Government vessels, cruisers, and center consoles — we install lithium battery systems across Nassau County and Suffolk County.
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Common Questions
Frequently asked questions
Is LiFePO4 safe on a boat?
LiFePO4 (lithium iron phosphate) is the safest lithium chemistry available. Unlike lithium cobalt oxide used in consumer electronics, LiFePO4 is chemically stable — no thermal runaway, no combustion risk under normal marine conditions. Every LiTime battery includes a built-in Battery Management System that monitors cell voltage, temperature, and current, and disconnects the battery before any unsafe condition occurs.
Is lithium a true drop-in replacement for AGM?
LiTime batteries are sized to match common AGM group sizes (Group 24, Group 31, 8D) and use the same terminal connections. They are drop-in replacements physically — but the charging system must be configured for lithium chemistry. AGM and lithium have different charge voltage profiles. LIME always checks and updates your charger, MPPT controller, and alternator output as part of every lithium installation.
Will my alternator work with lithium batteries?
Most standard alternators work fine with LiFePO4 batteries. The concern is that lithium accepts charge faster than AGM — a stock alternator can overheat running at high output continuously into a deeply discharged lithium bank. We check your alternator during the site assessment. If needed, we recommend a Battery-to-Battery charger or an external voltage regulator to protect the alternator while keeping your lithium bank charging efficiently.
Do lithium batteries work with marine solar?
Yes — LiFePO4 is the best match for solar charging on a boat. Victron and Mastervolt MPPT charge controllers have built-in lithium charge profiles. Set the controller to "LiFePO4" mode and solar charges the bank correctly with no overcharge risk. The combination of a lithium bank and solar panels is what allows most cruising boats to stay off shore power and away from the marina for days at a time. See our marine solar installation page.
How much does a lithium battery installation cost?
The battery cost depends on bank size — a single LiTime 100Ah 12V runs around $300–400. Installation time depends on how much wiring needs to be updated: a straight swap on a simple system can take 2–3 hours; a full conversion with alternator check, new bus bars, and charge controller programming typically runs 4–6 hours. LIME charges $140/hr portal-to-portal with a 4-hour minimum. We provide a written estimate before any work starts.
Can I connect multiple LiTime batteries together?
Yes. LiTime batteries can be connected in parallel to increase amp-hour capacity (two 100Ah banks become 200Ah at 12V), or in series to increase voltage (two 12V banks become 24V). Parallel connections must use identical batteries with matched cable lengths. LIME handles all multi-battery configurations correctly — improper parallel wiring is a common issue we see on boats that owners have wired themselves.
Do you service all of Long Island?
Yes — LIME serves Nassau County and Suffolk County, including marinas from Manhasset Bay and Oyster Bay to Fire Island, the South Shore, and the East End. Portal-to-portal billing means travel time is included in the hourly rate. Call 516-448-6221 to discuss your boat's location and get an estimate.
Get Started
Ready to upgrade to lithium on your Long Island boat?
NMEA certified. ABYC electrical standards. Serving Nassau County and Suffolk County marinas. When you call LIME, you're calling the person doing the work.
Portal-to-portal billing · $140/hr · 4-hour minimum · Written estimate before we start