Why You’ll Love This
- High Current Output: Up to 25 A at 36 V or 18.5 A at 48 V charges banks quickly and keeps gear powered.
- Power Supply Mode: Provides its full rated amps to run DC loads while holding batteries at Float voltage.
- Multi-Chemistry Charging: Four profiles (Lead-acid, AGM, Gel, LiFePO₄) keep batteries healthy and ready.
- Selectable Voltage: Simple switch lets you choose 36 V or 48 V — one charger for multiple systems.
- Generator Friendly: Accepts weak or “dirty” AC power and automatically adjusts so charging continues.
- Three-Stage Smart Control: Bulk, Absorb, and Float stages optimize performance and extend battery life.
- Adjustable Output: Turn the knob down to protect smaller banks or match limited shore power.
- Quiet & Efficient: >80 % conversion with a fan that only runs when needed.
- Comprehensive Safety: Reverse polarity, over/over-voltage, over-temperature, and short-circuit protection.
- Certified & Supported: UL/CSA listed and backed by a 2-year manufacturer’s warranty.
AIMS 25A AC Converter/Battery Charger — 36V/48V
A robust, higher-voltage shore/generator charger for 36V and 48V battery systems. This UL & CSA Listed converter/charger accepts a wide 70–145VAC input and lets you select 36V or 48V output via a DIP switch—perfect for cabins, boats, vans/RVs with 48V banks, trailers, and mobile work rigs running higher-voltage inverters.
Up to 25A Output (≈18.5A @ 48V)
36V / 48V Selector Switch
70–145VAC Input
UL 458 & CSA 22.2
Flooded, AGM, Gel, LiFePO₄
Why It’s Great
- High current output: Up to 25A at 36V (≈18.5A at 48V) charges banks quickly and powers loads.
- Power-supply mode: Provides full rated amps to DC loads while holding batteries at Float voltage.
- Simple setup: Pick 36V or 48V with the selector switch, then plug into shore or generator power.
- Wide AC window: Works great with shore power or portable generators thanks to the 70–145VAC input range.
- 3-stage smart charging: Automatic Bulk, Absorption, and Float maximize battery capacity and life.
- Four easy algorithms: Presets for flooded, AGM, gel, and LiFePO₄—no guesswork.
- Dial-back current: Adjustable output lets you safely charge smaller banks.
- Quiet & efficient: Thermal/load-based fan runs only when needed; >80% efficiency keeps heat low.
- Protection built-in: Reverse polarity, over/under-voltage, over-temp, short-circuit, and over-current safeguards.
- Ready to wire: Heavy-duty 4 ft hard-wired AC input cord included.
- Certified & warranted: Listed to UL 458 & CSA 22.2, backed by a 2-year manufacturer’s warranty.
Applications
- Off-Grid Cabins (48V Inverter/Charger Systems)
- Boats & Marine (Shore Power Charging)
- Vans/RVs with 48V Banks (High-efficiency builds)
- Mobile Work Rigs & Trailers
- 36V or 48V Battery Bank Systems
Tip: Select the correct battery type & voltage with the DIP switches before powering on. Use appropriately sized AC/DC wiring, fusing, and ventilation for continuous charging.
Applications
- Off-Grid Cabins (48 V inverter/charger systems)
- Boats & Marine (shore-power charging)
- Vans / RVs with 48 V Banks (high-efficiency builds)
- Mobile Work Rigs & Trailers (36 V / 48 V tools & lighting)
- Golf-Cart & Utility-Vehicle Packs (36 V / 48 V)
- Landscaping & Grounds-Keeping Rigs (36 V / 48 V mower & trimmer batteries)
- Trades / Contractor Vans & Trailers (charging higher-voltage tool packs)
- Utility & Telecom Service Trucks (aux / lift-gate banks)
- Mobile Detailing / Pressure-Wash Trailers (pumps, vacuums, lighting)
- Security / Surveillance Trailers (48 V camera/router systems)
- Material-Handling & Warehouse Carts (36 V quick top-ups)
- 36 V & 48 V Battery Bank Systems
Key Features
| Max Charging Output | Delivers up to 25 A at 36 V (≈18.5 A at 48 V) for fast, efficient charging. |
| Power-Supply Capability | Acts as a steady DC source — supplies its full rated amps to loads while maintaining Float voltage. |
| Status Indicator LEDs | Bright, easy-to-read lights show Bulk, Absorb, Float, or fault conditions at a glance. |
| 36 V / 48 V Selector | DIP switch lets you choose the proper system voltage before powering up the unit. |
| Three-Stage Smart Charger | Automatic Bulk, Absorption, and Float stages maximize battery capacity and service life. |
| Four Charging Algorithms | Pre-set profiles for flooded, AGM, gel, and LiFePO₄ batteries simplify setup. |
| Adjustable Output | Front-panel dial safely limits current when charging smaller batteries. |
| Wide AC Input Range | Operates from 70–145 VAC, ideal for shore power or portable generators. |
| High Conversion Efficiency | >80 % efficiency reduces energy loss and keeps the charger running cooler. |
| Smart Cooling Fan | Thermal & load-based fan runs only when needed, cutting noise and extending lifespan. |
| Built-In Protections | Reverse-polarity, over/under-voltage, over-temp, short-circuit, and over-current safeguards. |
| Optional Temp Sensor | Add an external battery temperature sensor for optimized charging in extreme climates. |
| Heavy-Duty AC Cord | Includes a rugged 4 ft hard-wired input cord for dependable connections. |
| Certified Safety | Listed to UL 458 & CSA 22.2 No. 107.1 standards for mobile/industrial use. |
| 2-Year Warranty | Backed by a full two-year manufacturer’s warranty for peace of mind. |
Specifications
| INPUT | |
| AC Input Voltage | 96–145 VAC (full performance); 70–96 VAC (≈50% rated output) |
| Frequency | 40–70 Hz |
| Nominal Input Current @ Rated Output | < 9 A AC |
| Voltage Measurement Accuracy | ± 8 VAC |
| Frequency Measurement Accuracy | ± 1 Hz |
| OUTPUT | |
| Nominal Voltage | 36 V & 48 V DC (selector switch) |
| Output Current | ≤ 25 A DC (36 V mode); ≤ 18.5 A DC (48 V mode) |
| Current Accuracy | ± 6% of full rated output current @ 25 °C (10%–limit range) |
| Load Regulation | 1.5% |
| Current Limit | 25 A |
| Charging Voltages |
36V Mode
48V Mode
|
| Selectable Battery Types | LiFePO₄, Open Lead-Acid, Gel, AGM |
| Parallel Outputs | Max 2 × CON120AC36/48VDC units in parallel |
| Efficiency | ≥ 80% |
| PROTECTION | |
| Input Over-Voltage | Safe up to 150 VAC RMS (≈215 V peak). Above this level, damage may occur. |
| Output Over-Voltage |
36 V mode: shut down if Vcharging > target + 1.0 V for > 2 s; restart when ≤ target for > 2 s. 48 V mode: shut down if Vcharging > target + 1.5 V for > 2 s; restart when ≤ target for > 2 s. |
| Charger Over-Temperature | ≥ 90 °C → output reduced to 50% ≥ 105 °C → charge stop ≤ 95 °C → charge restart |
| Battery Temperature Sensing (BTS) | Optional sensor: > 40 °C → reduce to Float & current −10% per +2 °C; ≥ 50 °C → shutdown. |
| Reverse Battery Polarity | Non-destructive, fused protection; unit meets specs after fuse replacement. |
| ENVIRONMENTAL | |
| Operating Temperature | −10 °C to +40 °C (ambient) |
| Relative Humidity | 5–95% non-condensing |
| Acoustic Noise | ≤ 50 dB(A) @ 1 m (fan full speed) |
| Storage Temperature | −20 °C to +80 °C |
| Cooling | Thermally controlled fan |
| Safety Certifications | UL 458; CSA 22.2 #107.1 |
| MECHANICAL | |
| Dimensions (D × W × H) | 10.25″ × 6.75″ × 3.25″ |
| Unit Weight | 2.9 kg (6.5 lbs) |
| Boxed Weight | 3.2 kg (7 lbs) |
| AC Power Cord | 4′ (hard-wired, included) |
| DC Output Connection | Bolted terminals |
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.
