Blue Sea Systems
12/24 V dual-sensing automatic charging relay, 120 A continuous. Connects two battery banks during charging; it is not a charger or an emergency-starting path. GND requires a 1 A fused connection. Simulate selects combined or isolated contacts manually; voltage thresholds, delays, optional SI and remote LED wiring are not modeled.
This part has no feed of its own to size, so its cables are sized from the complete system topology once you draw what it connects to.
Wiring diagram
The drawing shows where the feed, the return and the fuse land on this part. The starter uses the same reference circuit and sizing assumptions. Read the installation notes for manufacturer requirements before adapting the runs.
Starter bank +
positive connection
50 mm² (1 AWG) · 175 A fuse
1 m one way · 120 A design
To SI-ACR 7610 A
House bank +
positive connection
50 mm² (1 AWG) · 175 A fuse
1 m one way · 120 A design
To SI-ACR 7610 B
Starter bank −
negative connection
50 mm² (1 AWG) · unfused return
1 m one way · 0 A design
To Common negative −
House bank −
negative connection
50 mm² (1 AWG) · unfused return
1 m one way · 0 A design
To Common negative 1
SI-ACR 7610 GND (1A fused)
negative connection
1.5 mm² (16 AWG) · 1 A fuse
50 cm one way · 1 A design
To Common negative 2
Example allowances · ABYC E-11 sizing · verify actual protection
Two 12 V AGM placeholder banks share a negative bus. Each positive reaches a separate ACR stud through its own 175 A fuse and 50 mm² cable. These conservative example choices use the manual's up-to-120 A table, not a prediction of bank-to-bank current. GND has the required 1 A inline fuse. Replace placeholder bank limits and verify fuse type, location and charging source. In Simulate, select Combined or Isolated manually; automatic timing and equalization current are not predicted. Manufacturer installation manual
Open starter in CrimpBuild it out
Open the canvas with 7610 already placed, then add your batteries, charging, distribution and loads around it.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
The catalog facts for this part, which terminal takes what, and the hardware you'll want around it. Check the nameplate on your own unit before you order.
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
A and B are interchangeable battery-positive studs. GND is the small control return, not a load-return bus. Optional start-isolation (SI) and remote LED leads are omitted; follow the manufacturer diagram for them. The relay must not carry engine-starting current. A 120 A contact rating does not mean the relay limits charging current to 120 A.
A
a
positive · bidi
B
b
positive · bidi
GND (1A fused)
gnd
negative · input
Field notes
What we've read and heard about installing this exact part. These are notes, kept apart from the numbers Crimp works out.
The Blue Sea 7610 SI-ACR is a 12/24 V automatic charging relay rated for 120 A continuous current. It senses both banks and connects or isolates them as charging conditions change. It does not regulate battery charging current. The ML-ACR 7622 is a separate product.
The manufacturer diagram places one battery-positive connection on A, the other on B, with protection at each battery. The two studs are interchangeable. GND needs its own 1 A fused connection to the common DC negative.
The example contains two 12 V AGM placeholder banks, the relay and a common negative bus. Each ACR power lead is 1 m, with a 50 mm² conductor and 175 A fuse. This choice meets both manual tables at up to 120 A; it is not a prediction of equalization or charging current. The separate control-ground lead carries a 1 A fuse.
Replace the banks and their assumed current limits, then add your actual charging source and loads. Review fuse location, interruption capacity and disconnects. A relay contact rating is not a current limiter.
In Simulate, select Combined or Isolated to inspect those two circuit states. Crimp does not choose the state from battery voltage, simulate the relay's delays, or predict battery-equalization transients. The hardware performs that automatic control; the diagram records an assumed state.
The optional start-isolation and remote LED connections are omitted. Follow the manufacturer diagram for them. The 7610 must not carry engine-starting current; an emergency-start arrangement needs its own suitable switching path.
Each battery side needs appropriate protection, and the banks need a common negative connection. For a system requiring controlled battery-to-battery charging, compare the Orion XS example. Whether a relay or charger fits depends on the actual batteries, alternator and charging requirements.
Verified against the manufacturer's documentation (rev. 990170140 Rev.011), checked 2026-09-16. Manufacturer documentation →
Method & provenance
The manufacturer publishes some of these numbers and Crimp works out the rest. It's worth knowing which is which.
From the maker
Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.
ABYC E-11
Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.
Next step
It lands on the canvas already placed. Add what it connects to, and every run gets its wire and fuse as you draw.