Why you’ll love it
3.8 kWh of dependable power
300 Ah at 12.8 V delivers long runtimes for fridges, inverters, and lights—perfect for vans, RVs, boats, and cabins.
Bluetooth 5.0 app monitoring
Check SOC, voltage, current, and status from your phone—no shunt required.
Optimized for solar systems
Works seamlessly with MPPT charge controllers, DC-DC chargers, and off-grid solar arrays—efficiently storing every watt of sunshine.
Smart BMS built-in
Over/under-voltage, over-current, short-circuit, and temperature protection for safety and longevity.
High power, lower weight
Much lighter than comparable lead-acid banks—easier to install and friendlier to your payload.
Flexible system design
Build the bank you need—compatible with common 12 V systems and solar charging setups.
Low self-discharge
Holds a charge during storage and off-season—ready when you are.
Efficient & maintenance-free
No sulfation, no watering—just clean, reliable energy for modern off-grid living.
Reliable, High-Capacity Power for Off-Grid Living
Bring serious energy storage to your setup with Sapphire’s 12 V 300 Ah LiFePO₄ battery (3.8 kWh at 12.8 V). Purpose-built for vans, RVs, boats, cabins, and backup systems, it delivers stable voltage and high usable capacity so you can run fridges, lights, pumps, and inverters all day— without stressing about deep discharges.
Real-world muscle: Power inverters up to 2 kW (150 A BMS output) or keep a fridge running for several days — even through stretches of cloudy weather.
Bluetooth 5.0 Monitoring — Real-Time Insight
Built-in Bluetooth 5.0 connects directly to your phone or tablet. View state of charge, voltage, current, cycle history and BMS status in the Sapphire Battery app—no external shunt required. It’s perfect for clean installs where the battery is tucked away but you still want full visibility.
Solar-Ready and Easy to Integrate
Designed to pair seamlessly with MPPT solar charge controllers, DC-DC chargers, and inverter/charger combos. LiFePO₄’s flat discharge curve and wide acceptance window help you capture and store every watt of sunshine, then deliver it efficiently to your loads.
- Ideal for rooftop or portable arrays on vans/RVs, marine, and off-grid cabins.
- Works great with common 12 V systems and modern solar components.
- Straightforward upgrade path from AGM/gel banks.
Expand your solar potential: Batteries can be wired in series for 24 V or higher. Doubling voltage unlocks extra wattage capacity from most MPPT controllers, letting you harvest far more energy from your array without buying bigger controllers!
Smart BMS Protection
The integrated Battery Management System protects against over-charge, over-discharge, over-current, short-circuit, and extreme temperatures. Automatic cell balancing maintains pack health and performance for the long haul.
Lightweight, Maintenance-Free Convenience
At a fraction of comparable lead-acid weight, this 300 Ah model is easier to install and kinder to your payload. There’s no watering, no equalizing, and no sulfation—just reliable energy season after season with minimal upkeep.
Built to Last
Premium Grade-A LiFePO₄ cells deliver thousands of deep cycles with minimal capacity fade—even under daily use. The result is a lower cost per cycle and years of dependable service for off-grid living or emergency backup.
Built for daily use: With a life rating of 5,000+ full cycles, this battery is designed to handle everyday charging and discharging for 10 years or more. Fewer replacements mean lower long-term costs — and dependable power you can count on season after season after season.
Van & RV, Overland, Tiny Homes
Build a reliable off-grid house battery that runs daily essentials without babysitting your power. The 12 V 300 Ah (3.8 kWh) pack is a sweet spot for modern van/RV layouts and small homes on wheels.
- Inverters up to ~2 kW for induction, coffee, tools, and entertainment.
- Multi-day fridge runtime even through cloudy stretches.
- Solar-ready with MPPT controllers; charge from alternators via DC-DC for travel-day top-ups.
- DC-DC Engine Charging supported for easy on the go power fill ups.
- Bluetooth 5.0 app visibility for SOC, volts/amps, and BMS status—no shunt needed.
- Flexibible installation allows you to mount the battery on it's side, giving you more options to squeeze in more power.
- Expandable: add a second unit in parallel for longer stays, or go 24 V series for higher system efficiency.
Cabins, Marine & Home Backup
Dependable storage for weekend cabins, moorings, and emergency kits. Stable LiFePO₄ voltage keeps electronics happy while the BMS safeguards your investment year-round.
- Cabins & sheds: lights, pumps, routers, tools—quiet off-grid power with solar recharge.
- Marine: efficient house bank for refrigeration, navigation, lighting, and entertainment.
- Backup: keep critical loads alive during outages with inverter/charger integration.
- Series/parallel options: 24 V unlocks additional solar capacity on many MPPTs; parallel easily adds runtime.
- Cold-temp protection prevents charging, to protect your battery, during colder winter months.
- Low self-discharge so it’s still ready to go in the spring, if you store it all winter.
Golf Carts & Utility Vehicles
Upgrade carts and small utility vehicles with reliable LiFePO₄ power. Enjoy stronger acceleration, longer runtimes, and far less weight than traditional lead-acid packs—plus Bluetooth visibility for peace of mind.
- 36 V / 48 V ready: wire batteries in series to match your cart’s system voltage (e.g., 3× for 36 V, 4× for 48 V).*
- Lighter, faster, farther: significant weight savings vs. lead-acid improves efficiency, hill climbing, and range.
- Consistent performance: flat LiFePO₄ discharge curve keeps speed and torque steadier throughout the charge.
- Quick, clean charging: pair with a compatible lithium charger for faster turnarounds and no sulfation.
- Low maintenance: no watering or equalizing—just charge, drive, repeat.
- Smart protections: BMS guards against over/under-voltage, over-current, and cold-temp charging.
- Great for fleets: also ideal for UTVs, campus vehicles, maintenance carts, and light commercial runs.
*Always match series wiring to the cart/controller specifications and use appropriate fusing and cabling.
Features
⚡ Power & Capacity
- Massive 300 Ah / 3.8 kWh storage — plenty for lights, pumps, fridges, and inverters up to 2 kW.
- Delivers consistent voltage under heavy loads for stable appliance performance.
📱 Smart Monitoring
- Integrated Bluetooth 5.0 module with free Sapphire app.
- Track state of charge, voltage, current, cycle count, and BMS status in real time.
🌞 Solar & Charging Flexibility
- Optimized for MPPT solar charge controllers, DC-DC chargers, and inverter/charger combos.
- Wide voltage acceptance for efficient harvesting from rooftop or portable arrays.
Protection & Safety
- Advanced Battery Management System (BMS) guards against over/under-voltage, over-current, short-circuit, and extreme temperatures.
- Automatic cell balancing preserves long-term performance.
- Cold-temperature protection prevents charging below safe limits, safeguarding cells in winter conditions.
🔗 Series / Parallel Connectable
- Link batteries in series for 24V, 36V or 48V systems. Unlock more wattage without upsizing cables.
- Parallel connections allow easy expansion of capacity for longer runtimes.
- Up to 4S4P supported, allowing you to assemble up to a staggering 61kWh system.
🧳 Lightweight & Easy to Install
- Weighs far less than comparable AGM or gel banks.
- Compact case fits tight spaces in vans, RVs, boats, and tiny homes.
⏳ Long Life & Low Cost per Cycle
- 5,000+ deep cycles at 80% depth of discharge = 10+ years of daily use.
- Virtually maintenance-free — no watering, sulfation, or equalizing.
Specifications
- High-performance A-grade LiFePO₄ cells
- Advanced 150 A BMS with low/high temp & over-current protection (cold-temp charge cut-off)
- Bluetooth 5.0 monitoring for live SoC, voltage, current, and alarms
- Automatic cell balancing for long-term stability
- IP65 dust & splash protection
- 5-year limited warranty • 5000+ cycle life
| Nominal Voltage | 12.8 V (LiFePO₄) |
|---|---|
| Nominal Capacity | 300 Ah |
| Energy | ≈ 3.8 kWh (3840Wh) |
| Continuous Discharge | 150 A (supports up to ≈2 kW inverter) |
| Recommended Charge Current | ≤ 100 A (0.3C) |
| Recommended Charge Voltage | 14.2 – 14.4V (14.6V Max) |
| Cell Balancing | Begins at ≈ 3.45 V per cell |
| Max Series / Parallel | Up to 4 S / 4 P (48V/51.2V max) |
| Cycle Life | 5000+ cycles (≈ 80% capacity) |
| Communications | Bluetooth 5.0 |
| Ingress Rating | IP65 |
| Dimensions (L×W×H) | 15.25″ × 7.7″ × 10.75″ 385 × 192 × 260 mm |
| Weight | ≈ 25 kg (55.1 lb) |
| Connection | M8 bolts (included) |
| Handles | Dual ropes with easy-grip handles |
| Temperature Notes |
Charge stops at ≤0 °C (auto-resume ≥+5 °C) Discharge stops at ≤−20 °C (auto-resume ≥−10 °C) |
| Warranty | 5-year limited |
Getting Started & Sizing
What size LiFePO₄ battery should I start with?
Usually we suggest you start by calculating your daily energy use. Make a list of devices and total up their Wh (watts × hours/day = watt-hours). Add everything up, then divide by your system voltage (12/24/48 V) to estimate amp-hours (Ah). Add at least 20–30% headroom for busier days and future add-ons. Then take this number and multiply by the number of days you need the system to stay powered on without any outside energy input (no shore power/solar/etc). This will give you a rough number to look for.
Easy first picks by use case:
• Budget/compact: 1280Wh — 12.8V 100Ah Classic
• More runtime: 2560Wh — 12.8V 200Ah Classic
• Winter & higher output: 2560Wh — 12.8V 200Ah Self-Heating Bluetooth (High Output)
• Longer runtime: 3840Wh — 12.8V 300Ah Bluetooth
New to sizing? How much battery do I need?
Easy first picks by use case:
• Budget/compact: 1280Wh — 12.8V 100Ah Classic
• More runtime: 2560Wh — 12.8V 200Ah Classic
• Winter & higher output: 2560Wh — 12.8V 200Ah Self-Heating Bluetooth (High Output)
• Longer runtime: 3840Wh — 12.8V 300Ah Bluetooth
New to sizing? How much battery do I need?
Can I replace my lead-acid battery one-for-one?
Voltage is compatible, but LiFePO₄ gives much higher usable capacity—you typically get 80–90% usable vs ~50% for lead-acid. Many customers downsize Ah and still get equal or better runtime. A single 100Ah LiFePO₄ can feel like a 150–180Ah lead-acid in real-world use because you can safely use more of its capacity without damage. See All LiFePO₄ Batteries. Curious why? Lithium vs Lead—Your Choices.
What inverter size pairs well with my first battery?
Add up simultaneous AC loads and include surge (many appliances draw 2–3× their running watts for a split-second). A 1,000–1,500 W coffee maker + a 100 W laptop points to a 2,000 W inverter. For power tools or induction cooktops, either stay 12 V with a higher-output pack like 12V 200Ah Self-Heating Bluetooth (High Output), or step up to 24 V for lower current and better efficiency.
Why choose a single 24 V battery instead of 2×12 V in series?
A one-piece 24 V battery simplifies your life:
• No pack-to-pack balancing — one case, one BMS, one Bluetooth connection.
• Simpler wiring — fewer cables, no series jumpers.
• Easier monitoring — one app (if Bluetooth).
• Lower current for the same power — slimmer cables and cooler-running inverters.
See our 24V 200Ah Self-Heating Bluetooth (High Output).
• No pack-to-pack balancing — one case, one BMS, one Bluetooth connection.
• Simpler wiring — fewer cables, no series jumpers.
• Easier monitoring — one app (if Bluetooth).
• Lower current for the same power — slimmer cables and cooler-running inverters.
See our 24V 200Ah Self-Heating Bluetooth (High Output).
Charging: AC, Alternator & Solar
Do I need a charger made for LiFePO₄?
Yes. LiFePO₄ performs best when the charger uses a lithium profile. For a 12 V battery, target bulk/absorption ~14.2–14.6 V and either no float or a short/low float ≤ 13.6 V. Avoid equalization entirely—it’s a lead-acid maintenance step that isn’t used for LiFePO₄ and can be harmful.
AC → DC charging (shore power or generator) — a dedicated LiFePO₄ charger converts household AC into a precise DC charge curve matched to lithium chemistry. If you’re plugging in at campgrounds, marinas, or with a small generator, this is the simplest route. Browse our LiFePO₄ Battery Chargers.
Solar charging — pair your panels with a solar charge controller that has a LiFePO₄ profile (or custom setpoints). The controller handles MPPT/PWM regulation and applies the correct voltages to protect the battery and maximize harvest. See our Solar Charge Controllers. If your controller offers user-defined setpoints, use the same 12 V targets above (bulk/absorb ~14.2–14.6 V; minimal/disabled float; no equalize).
AC → DC charging (shore power or generator) — a dedicated LiFePO₄ charger converts household AC into a precise DC charge curve matched to lithium chemistry. If you’re plugging in at campgrounds, marinas, or with a small generator, this is the simplest route. Browse our LiFePO₄ Battery Chargers.
Solar charging — pair your panels with a solar charge controller that has a LiFePO₄ profile (or custom setpoints). The controller handles MPPT/PWM regulation and applies the correct voltages to protect the battery and maximize harvest. See our Solar Charge Controllers. If your controller offers user-defined setpoints, use the same 12 V targets above (bulk/absorb ~14.2–14.6 V; minimal/disabled float; no equalize).
Can I charge from my vehicle alternator?
Absolutely—use a DC-DC charger between starter and house battery. It protects the alternator, limits current to a safe level, and applies a lithium profile. Without DC-DC, modern smart alternators may under-charge or overheat. For visibility while driving, our BM02 Bluetooth Battery Monitor shows volts, amps, and SOC on an LCD and in the phone app in real time.
Why Would I Need Self Heating?
Lithium cells should not be charged below 0 °C (32 °F). Most LiFePO₄ BMSs include a low-temperature charge cutoff to prevent plating damage—on freezing days your battery may refuse to accept a charge until it’s warm enough. That’s normal and it protects your pack for the long term.
Our Self-Heating batteries solve this by warming the cells automatically whenever charging is requested below freezing. The pack heats to a safe internal temperature, then begins charging—no manual steps. This is ideal for northern climates, winter activities (ice fishing, ski trips), vanlife, and outdoor storage where temps fluctuate. Adding insulation around the battery compartment helps it warm faster and reduces temperature swings for more consistent performance.
Our Self-Heating batteries solve this by warming the cells automatically whenever charging is requested below freezing. The pack heats to a safe internal temperature, then begins charging—no manual steps. This is ideal for northern climates, winter activities (ice fishing, ski trips), vanlife, and outdoor storage where temps fluctuate. Adding insulation around the battery compartment helps it warm faster and reduces temperature swings for more consistent performance.
How much solar should I pair with a 12 V system?
A simple starting point is 100 W of solar when you’re just getting started or topping up on weekends. From there, scale based on your daily energy use and how many “backup days” you want.
Design rule of thumb (off-grid): 3 days of autonomy. That means sizing battery + solar so you can run for ~3 cloudy days without fully depleting the battery. If you also have alternate charging like a DC-DC alternator charger or occasional AC charger at campgrounds, you can safely reduce that autonomy target because you’re not relying on solar alone.
Step 1 — Calculate your daily watt-hours (Wh)
Make a list of devices: Watts × hours per day = Wh/day. Add them up.
Example day: LED lights (15 W × 4 h = 60 Wh), laptop (60 W × 3 h = 180 Wh), 12 V fridge (40 W avg × 24 h ≈ 960 Wh), phone charging (10 W × 2 h = 20 Wh). Total ≈ 1,220 Wh/day.
Step 2 — Size the battery bank
Battery capacity in Wh = Voltage × Ah. A 12 V 100 Ah LiFePO₄ ≈ 1,280 Wh, with ~80–90% usable = ~1,000–1,150 Wh usable. For 1,220 Wh/day and one day of autonomy, you’d look at ~12 V 200 Ah. For the full 3-day autonomy target, ~12 V 300–400 Ah (or a 24 V bank to reduce current).
Step 3 — Size the solar
Daily solar production ≈ Panel Watts × Sun-hours × system efficiency (efficiency often ~0.7 to include controller/battery losses). With 400 W of panels and 4 sun-hours: 400 × 4 × 0.7 ≈ 1,120 Wh/day—close to our 1,220 Wh example. If you drive daily with a DC-DC charger, you can rely on alternator charging to fill the gap and may choose fewer panels.
Be honest about heavy loads. High-draw devices (kettles, coffee makers, induction, space heaters) and large inverters increase both battery size and solar needed. Start small and expand as you confirm your real-world use.
For a deeper walkthrough, see How much battery do I need?, and explore Solar Products plus Charge Controllers.
Design rule of thumb (off-grid): 3 days of autonomy. That means sizing battery + solar so you can run for ~3 cloudy days without fully depleting the battery. If you also have alternate charging like a DC-DC alternator charger or occasional AC charger at campgrounds, you can safely reduce that autonomy target because you’re not relying on solar alone.
Step 1 — Calculate your daily watt-hours (Wh)
Make a list of devices: Watts × hours per day = Wh/day. Add them up.
Example day: LED lights (15 W × 4 h = 60 Wh), laptop (60 W × 3 h = 180 Wh), 12 V fridge (40 W avg × 24 h ≈ 960 Wh), phone charging (10 W × 2 h = 20 Wh). Total ≈ 1,220 Wh/day.
Step 2 — Size the battery bank
Battery capacity in Wh = Voltage × Ah. A 12 V 100 Ah LiFePO₄ ≈ 1,280 Wh, with ~80–90% usable = ~1,000–1,150 Wh usable. For 1,220 Wh/day and one day of autonomy, you’d look at ~12 V 200 Ah. For the full 3-day autonomy target, ~12 V 300–400 Ah (or a 24 V bank to reduce current).
Step 3 — Size the solar
Daily solar production ≈ Panel Watts × Sun-hours × system efficiency (efficiency often ~0.7 to include controller/battery losses). With 400 W of panels and 4 sun-hours: 400 × 4 × 0.7 ≈ 1,120 Wh/day—close to our 1,220 Wh example. If you drive daily with a DC-DC charger, you can rely on alternator charging to fill the gap and may choose fewer panels.
Be honest about heavy loads. High-draw devices (kettles, coffee makers, induction, space heaters) and large inverters increase both battery size and solar needed. Start small and expand as you confirm your real-world use.
For a deeper walkthrough, see How much battery do I need?, and explore Solar Products plus Charge Controllers.
Installation & Wiring
Can I connect multiple Sapphire batteries together?
Yes. In series, voltage adds (Ah stays the same): two 12 V 100 Ah in series = 24 V 100 Ah. In parallel, Ah adds (voltage stays the same): two 12 V 100 Ah in parallel = 12 V 200 Ah. Series lowers current for the same power (thinner cables, higher inverter efficiency), while parallel increases runtime at the same voltage. Many 12 V models—like the Classic 100 Ah—support 24/36/48 V series.
Best practices: fully charge each battery before linking, use equal-length interconnects so currents share evenly, and match model/age/capacity. A Bluetooth model or a shunt monitor makes verification easy.
Best practices: fully charge each battery before linking, use equal-length interconnects so currents share evenly, and match model/age/capacity. A Bluetooth model or a shunt monitor makes verification easy.
What wire size and fuse should I use?
Wire is sized for current and length. Higher current or longer runs need thicker wire to keep voltage drop low. For 12 V systems, try to keep drop under ~3%. The main fuse/breaker should be as close to the battery as possible and sized to protect the cable (ampacity) and your system’s max current. If your inverter draws 150 A continuous, use cable and a fuse rated for at least that plus a safety margin.
Need parts? See Wiring & Accessories. For manuals and inverter/charger specs, visit Downloads.
Need parts? See Wiring & Accessories. For manuals and inverter/charger specs, visit Downloads.
Can I install my battery indoors?
Yes—LiFePO₄ doesn’t produce routine off-gassing like flooded lead-acid, so indoor installs (RVs, vans, cabins, boats) are common. Secure the battery, cover terminals, use proper fusing, and ensure chargers/inverters have ventilation. If you see freezing temps, consider our Self-Heating models or insulate the compartment.
Can I mount the battery on its side? Is the case weather-resistant?
Our prismatic-cell packs can be installed in multiple orientations (just protect the terminals from stress). Models like the Classic 100 Ah are IP65 with carry handles—great for marine, RV, and mobile setups. IP65 means dust-tight and protected from low-pressure water jets; don’t submerge it.
Operation, Safety & Monitoring
Are Sapphire LiFePO₄ batteries safe?
Yes. LiFePO₄ is a stable chemistry with strong thermal safety compared to many other lithium types. Each pack includes a BMS that protects against over/under-voltage, high/low temperature, over-current, and short circuits. Combine that with proper wire sizing, fusing, and a quality charger, and you’ll have a safe, long-lasting setup.
How can I monitor health and state of charge (SOC)?
We recommend two beginner-friendly options—use one or both:
1) Shunt-based monitor (most accurate) — installs on battery negative and measures all current in/out to compute SOC, amps, Ah used, and time remaining. Our BM02 includes the shunt, an LCD, and a phone app. Wiring: battery negative → shunt → system negative, plus a small positive lead for the display.
2) Bluetooth batteries (fast & easy) — our Bluetooth packs report voltage, current, temperatures, cell balance, and BMS status in the app. A great example is the 12V 200Ah Self-Heating Bluetooth (High Output). Manuals and apps: Downloads.
Tip: Shunt monitors excel at accurate SOC over time; Bluetooth is great for diagnostics and cell-level detail.
1) Shunt-based monitor (most accurate) — installs on battery negative and measures all current in/out to compute SOC, amps, Ah used, and time remaining. Our BM02 includes the shunt, an LCD, and a phone app. Wiring: battery negative → shunt → system negative, plus a small positive lead for the display.
2) Bluetooth batteries (fast & easy) — our Bluetooth packs report voltage, current, temperatures, cell balance, and BMS status in the app. A great example is the 12V 200Ah Self-Heating Bluetooth (High Output). Manuals and apps: Downloads.
Tip: Shunt monitors excel at accurate SOC over time; Bluetooth is great for diagnostics and cell-level detail.
What temperature range should I plan for?
Rule of thumb: discharge down to about −20 °C (with reduced power) and charge at 0 °C or above. Below freezing, the BMS will usually block charging to protect the cells. If you regularly operate in the cold, our Self-Heating models warm themselves before charging. If the pack is flat and won’t start charging, see: Under-Voltage Protection & Recovery.
Maintenance & Storage
What’s your warranty and typical lifespan?
We back our batteries with a 5-year limited warranty. Lifespan depends on depth of discharge (shallower cycles last longer), charge/discharge rates, temperature, and storage practices. Many customers see years of daily cycling. For terms, visit Warranty Policy.
How should I store the battery off-season?
Store around 50–80% SOC in a cool, dry place. Check SOC every 2–3 months and top up if it drifts toward ~50%. Disconnect small parasitic loads (trackers, meters) so the battery doesn’t slowly drain. If storing where it’s cold, avoid charging below 0 °C unless you’re using a Self-Heating model.
Do your batteries need routine maintenance?
LiFePO₄ is low-maintenance: no watering and no equalization. Periodically tighten lugs, check for corrosion or heat discoloration, secure cabling against vibration, and keep vents clear on chargers/inverters. Need parts? See Wiring & Accessories.
Troubleshooting
My battery shut off under load—what caused it?
The BMS likely protected the pack from over-current (load too large) or low-voltage (battery nearly empty). Check inverter surge rating, cable gauge, and that all connections are tight. If the pack was deeply discharged, begin charging—most BMSs reset automatically once a healthy voltage is reached. Bluetooth models show which protection triggered; see the app. If you ran flat, this guide helps: Under-Voltage Protection & Recovery.
It won’t start charging after running flat—how do I “wake” it?
Some chargers won’t begin if the BMS is in low-voltage cutoff. Use a LiFePO₄-compatible charger with a recovery/start function, or briefly parallel a known-good 12 V source under supervision to raise voltage, then swap to the normal charger. Verify the charger has a lithium profile (no equalize, short/low float). To prevent repeat events, install a shunt monitor like BM02 and set low-SOC alerts.
Policies, Shipping & Compatibility
Where do you ship from and what are the terms?
We’re a Canadian-owned supplier. We frequently run free-shipping promos across much of Canada; exact eligibility and timelines show at checkout on each product. Start here: Sapphire Energy.
Can I mix different brands or capacities?
We don’t recommend mixing. Different internal resistances and BMS behaviors can fight each other, causing imbalance. If you must combine, match model/age/capacity, fully charge and balance each first, and monitor carefully (Bluetooth plus a shunt is best). The ideal approach is to build your bank from the same series.
Where can I find manuals, spec sheets, and apps?
Everything’s in one place: Downloads — BM01/BM02 apps, the JBD (XiaoXiang) app for Bluetooth batteries, plus product manuals and spec sheets.
