10 Best Onboard Battery Charger of August 2025

• An 8 amp (4 amp per bank) on-board battery charger for charging and maintaining two 12-volt batteries independently.
• Safely charge all types of lead-acid batteries from 20-120Ah, including wet, gel, AGM, and deep-cycle batteries.
• Advanced safety protection featuring spark-proof technology, plus reverse polarity, thermal, ignition, and overcharge protection.
• Rugged and waterproof construction capable of submersion down to 3-meters and rated IP68 and NEMA 6P.
• One of the most advanced battery chargers in its class, which is certified to UL1236, ISO 8846, 33 CFR 183. 410, plus backed by a 5-year .

NOCO

• 12V 10 amp 2 bank bank on-board battery charger
• Built-in safety: reverse polarity, over-current, over-voltage, over-temperature and ignition protection. In-line fuses for maximum DC wire protection.
• 100% Waterproof (IP67) and shock resistant for all fresh and saltwater applications
• Dedicated battery charging, sensing and control per bank
• For all 12 volt flooded and AGM lead acid batteries. 2 year warranty

Guest

• The 12/24/36V, 20 Amp, 3 battery bank ProSport 20 Plus waterproof battery charger delivers fast efficient charging in a lightweight design. Not compatible for 4D batteries
• Distributed on Demand Technology utilizes 100% of the available charging amps and automatically distributes charge amongst all the batteries as needed . The result is faster, more efficient charging
• Advanced technology eliminates time consuming troubleshooting by clearly indicating system and battery connections are OK or if a fault is present on a specific battery bank
• During short or long-term storage, ProSport automatically reconditions all batteries on board once a month for maximum battery life and performance
• Compact and rugged extruded aluminum design, dual in-line DC safety fuses for trolling motor and house battery banks. Built-in over-voltage, overload, over-temperature, reverse polarity and ignition protection

ProMariner

• Automatic Temperature Compensation: Chargers sense and adjust to ambient temperature fluctuations to ensure a fast, accurate charge
• Digital Control: Microprocessor-based design delivers a faster, more precise charge every time
• LED Indicator Lights: Inform of charge stage, maintenance mode status, error notifications and full charge
• Automatic Multi-Stage Charging: Controls the voltage and current your battery gets throughout the charging cycle, ensuring a fast, safe and precise charge
• Waterproof Construction: All on-board chargers are built to be waterproof, shock-resistant and vibration-resistant
• 2 banks; 5 amps per bank
• Multi-stage charging and automatic temperature compensation
• Saltwater tested and fully corrosion-resistant
• Three-year warranty
• Digitally controlled microprocessor design protects your batteries so you can stay on the water longer

Boating Accessories

• 2 Year Warranty
• Energy Saver Mode
• Storage Recondition Mode
• Built-in Quality and Safety

ProMariner

• Provides 1.5A to maintain your 6V or 12V battery
• Microprocessor-controlled, with multi-stage charging for added precision, safety, and battery life
• Auto voltage detection automatically detects 6 or 12V batteries
• Reverse hook-up protection ensures charger will not operate if clamps are reversed
• Includes double-sided adhesive and cable tie for mounting

Schumacher

• 3 banks, 5 amps per bank
• Multi-stage charging and automatic temperature compensation
• Saltwater tested and fully corrosion-resistant
• Three-year warranty
• Digitally controlled microprocessor design protects your batteries so you can stay on the water longer

Johnson Outdoors

• Meet the GENIUS2 - Similar to our G1100, just better. It's 30% smaller and delivers 140% more power. It's the all-in-one solution - battery charger, battery maintainer, trickle charger, plus battery desulfator.
• Do more with Genius - Designed for 6-volt and 12-volt lead-acid automotive, marine, and deep-cycle batteries, including flooded, gel, AGM, and maintenance-free, plus lithium-ion batteries.
• Enjoy precision charging - An integrated thermal sensor detects the ambient temperature and alters the charge to eliminate over-charging in hot climates and under-charging in cold climates.
• Charge dead batteries - Charges batteries as low as 1-volt. Or use the all-new Force Mode that allows you to take control and manually begin charging dead batteries down to zero volts.
• Restore your battery - Automatically detects battery sulfation and acid stratification to restore lost battery performance for stronger engine starts and extended battery life.
• Beyond maintenance - It's not just a trickle charger, it's an advanced battery maintainer. A fully-automatic, worry-free battery charger for everyday use - 24/7 - with zero overcharge.
• Compatible with all types of vehicles - Charge and maintain cars, motorcycles, lawnmowers, ATVs, tractors, trucks, SUVs, boats, classic cars, hot rods, and more - you name it.

NOCO

• 【UPGRADED DEFECTIVE BATTERY DETECT/FAST CHARGING CAR BATTERY BOOSTER】Updated with battery condition diagnose to detect the defective battery before charge. DC Output 13.8V/5A, AC Input 100-240V, 1.5A 60/50Hz; With 5A DC output current, BMK 12V 5A car battery charger is suitable for charging batteries with 15-100Ah. NOTE: To better tender the battery, please make sure the battery capacity is higher than 15Ah, it can also charge over 100Ah batteries, just more charging time.
• 【UPGRADED 72-HOUR SAFETY FEATURES/MULTI SAFETY PROTECTIONS - BATTERY RESCUE & RECOVER】Updated with 72 hours safety feature to commence anytime the charger is onto protect marginal batteries from over charging. Made of high quality ABS, IP65 Waterproof, multi-protects of Short Circuit/ OV/ OC/ Overload/ Polarity Reverse, featured with Constant Pulse Current Maintenance function to avoid overcharge and discharge; Full-loaded and burn-in test prove its high reliable efficiency, stable performance
• 【4-STAGE SMART CHARGING - FULLY AUTOMATIC BOAT BATTERY CHARGER】 12V battery charger operated with 4 stages automatic charging process by MCU controller, 25%/50%/75%/100% to indicate quantity of electricity and monitor the whole charging progress. Stop automatically when the battery is fully charged. LED indicator designed to display different charging status of the 12v smart charger
• 【UPGRADED WITH 10A FUSE ONTO RING CONNECTORS & MULTI-PURPOSES DEEP CYCLE BATTERY CHARGER】Pb/SLA/VRLA/GEL/AGM lead acid battery charger tender, operated with vulcanization function, BMK battery maintainer charger is a great choice for lawn mower, boat, car, motorcycle, electric vehicle, electric tools and emergency battery charging, lightweight(15.87oz) allows you take it to anywhere, used as Trickle Battery Charger as well
• 【QUALIRY ENSURANCE & IN TIME SERVICE】BMK is devoted to provide boat battery trickle charger with higher qulality to meet buyers' needs better and timely after-sale services, eliminate all your worries about getting this trolling motor battery charger. Just get your Automotive Car Battery Charger Maintainer with confidence, and contact us if you have any problems about the item when using

BMK BLUEMICKEY

• Primary Digital Technology: Microprocessor and software controlled pulse charging technology delivering a 40 percent lighter design than the previous generation of epoxy filled chargers, cooler charger operation and faster charging
• System OK and Battery Bank Trouble Status Indicators: Advanced technology eliminates time consuming troubleshooting by clearly indicating system and battery connections are OK or if a fault is present on a specific battery bank
• Digital Multi-Stage Performance Charging: Fully charge and extend the life of your batteries - automatically charges, conditions and safely maintains all batteries on board for maximum time on the water
• Energy Saver Mode: After fully charging and conditioning batteries, Pros port's Energy Saver Mode will monitor and Auto Maintain batteries only when needed, maintaining a full state of charge. This significantly reduces AC power consumption, lowers operating costs and maximizes reserve power performance.
• storage Recondition Mode: During short or long-term storage, Pros port automatically reconditions all batteries on board once a month for maximum battery life and performance

ProMariner