When tracing an RV's dual-battery charging system, the relay's stamped model number and stud sizes help distinguish similar-looking components. Blue Sea's 7601 m-ACR and 7610 SI-ACR both sense charging on two battery banks, but one is rated for 65A and the other for 120A. Use this reference to understand which unit you have before replacing it.
What the ACR is connected between
An ACR normally connects the positive sides of two battery banks when charging voltage is present; it opens to reduce unwanted cross-discharge. Start-isolation control, when installed, can separate the banks during cranking. The illustration is a guide to how the parts relate, not a wiring plan.
The ACR senses a qualifying voltage increase on a bank and can connect both banks for charging.
The relay separates the battery banks when disconnect conditions occur; it does not allocate charge to the emptier battery.
With proper start-isolation wiring, the relay releases during engine starting to reduce voltage dips at house electronics.
Identification table: match the current and stud sizes
| Model detail | Blue Sea 7601 | Blue Sea 7610 |
|---|---|---|
| Type | 7601 mini automatic charging relay (m-ACR) | 7610 start-isolation automatic charging relay (SI-ACR) |
| Battery systems | 12V DC / 24V DC | 12V DC / 24V DC |
| Continuous relay rating | 65A | 120A |
| 5-minute intermittent rating | 115A | 210A |
| Main battery studs | 1/4 in–20 (M6) | 3/8 in–16 (M10) |
| Main stud material | Tinned brass | Tinned copper |
| Stud tightening torque | 60 in-lb (6.78 Nm) | 140 in-lb (15.82 Nm) |
| Start isolation input | Yes, when correctly wired | Yes, when correctly wired |
| Factory kit association | 7649 mini Add-A-Battery | 7650 / 7650003 Add-A-Battery |
Check the part number printed on the original unit, then inspect the cable lugs and connections. A larger relay cannot be assumed compatible simply because it performs the same general function. The correct choice also depends on the charging system, space and existing fusing.
Compare actual catalog photos and replacement listings
The pictures below are from the matching UsedRVParts product listings. Confirm the listed item's condition and availability on its page. Viewing or pickup in Kelowna, where available, is by appointment.
Manufacturer installation diagrams and specifications
Blue Sea publishes connection, mounting and troubleshooting documents on its 7601 mini ACR page and 7610 SI-ACR page. The original side-by-side specifications show the terminal differences. Use the current installation sheet for the exact relay revision to determine protective fuse sizing, terminal locations, start-isolation control, and polarity.