"Add-A-Battery" Dual Circuit System
Complete Your Purchase
Adding a second battery to support your new electronics or trolling motor? Charge it and use it as an emergency backup with an Add-A-Battery system.
Managing two battery banks doesn't have to be complicated. The Blue Sea Systems Add-A-Battery Kit 120A is as simple to operate as an ON-OFF switch: turn it on when you arrive and off when you leave, and the system handles the rest automatically. Designed for boats with an alternator output of 120A or less, the kit packages the e-Series Dual Circuit Plus Battery Switch (5511e) and the SI-ACR Automatic Charging Relay (7610) into a complete two-battery-bank management solution for inboard- and outboard-powered boats. Whether you're adding a second battery to support a trolling motor, fishfinder, or upgraded stereo system, this kit protects both banks, maximizes charging efficiency, and keeps a reserve ready when you need it most.
The SI-ACR Automatic Charging Relay is the brain of the system. It automatically combines both battery banks when charging voltage is detected, allowing a single source, such as your engine alternator, to charge both batteries simultaneously without requiring an external regulator, additional wiring, or a voltage-dropping isolator. When discharging, the ACR isolates the banks, protecting sensitive electronics from voltage sags and spikes during engine cranking. The e-Series Dual Circuit Plus Battery Switch keeps the house and start circuits separate during normal operation, eliminating the risk of a drained start battery from running accessories for too long. When you need it, the combine feature draws from both banks simultaneously for emergency starting or a critical radio call. The make-before-break contact design ensures no power interruption occurs when switching between banks. Both components are ignition-protected and rated for installation inside engine compartments of gasoline-powered boats.
Built to Blue Sea Systems' exacting standards, the battery switch carries a 350A continuous rating with tin-plated copper studs for maximum conductivity and corrosion resistance, accepts up to 4/0 AWG cable, and fits 3/8" (M10) ring terminals. The switch is rated IP66; the ACR is rated IP67. The ACR's integrated LED provides at-a-glance status indication across both banks. CE Marked and ISO 8846 certified; meets UL 1500, SAE J1171, and UL 1107 requirements. Available in surface- or rear-panel mounting configurations.
Key Features
- Complete two-battery bank management solution rated up to 120A continuous
- e-Series Dual Circuit Plus Battery Switch simultaneously switches two isolated battery banks or combines them for all loads
- Make-before-break contact design allows switching between battery banks without power interruption
- Isolates Start and House circuits; combines both battery banks for emergency starting
- SI-ACR Automatic Charging Relay automatically combines battery banks when charging voltage is detected and isolates them when discharging
- Charges two batteries from a single source with no external regulators, isolators, or rewiring required
- Start isolation protects sensitive electronics from voltage sags and spikes during engine cranking
- Shares charge between two batteries more efficiently than a battery isolator, with no voltage drop
- Senses charge on two battery banks; integrated LED indicates ACR status
- 350A continuous rating for inboard gasoline or diesel engines
- Tin-plated copper studs for maximum conductivity and corrosion resistance
- Accepts up to 4/0 AWG battery cables; terminal studs accept 3/8" (M10) ring terminals
- Ignition-protected ACR and switch; both rated for installation in engine rooms of gasoline-powered boats
- Surface or rear panel mounting options
- Switch rated IP66; ACR rated IP67
- CE Marked and ISO 8846 certified; meets UL 1500, SAE J1171, and UL 1107 requirements
Specifications
SI-ACR Automatic Charging Relay (7610)
- Nominal Voltage: 12V, 24V
- Continuous Rating: 120A
- Intermittent Rating: 210A for 2 min.
- Cable Size to Meet Rating: 1/0 AWG
- Terminal Stud Size: 3/8"
- Closing Voltage: 13/26V (2 min.) or 13.6/27.2V (30 sec.)
- Opening Voltage: 12.75/25.5V (30 sec.)
- Engages: 12.7/25.4V DC
- Disengages: 13.5/27V DC
- Over Voltage Lockout: 16V @ 12V, 32V @ 24V
- Under Voltage Lockout: 5V @ 12V, 19V @ 24V
- Amperage Operating Current: 175mA (combined), 15mA (open)
- Start Isolation: Yes
- Weight: 25 lbs.
e-Series Dual Circuit Plus Battery Switch (5511e)
- Switch Type: Dual Battery Switch Plus
- Switch Positions: 3
- Battery Combine: Yes
- Maximum Voltage: 32V
- Continuous Rating: 350A
- Intermittent Rating: 525A (5 min.)
- Cranking Rating (30 sec.): 700A
- Battery Inputs: 2
- Cable Size to Meet Rating: 4/0 AWG
- Terminal Stud Size: 3/8"
- Mounting Holes: 4-1/4"
- Dimensions: 3-5/8" x 3-5/8", 3-5/8" diameter face
- Alternator Field Disconnect: No
Manufacturer's Documents
