Replacing a battery selector switch starts with identifying its exact model, not just matching the number of knob positions. Blue Sea 11001-BSS is an e-Series selector, while 11003-BSS is a heavier-duty HD-Series design. Both have three switch settings and alternator field disconnect (AFD) contacts, but their main cable studs and specified ratings are different. Use the illustrations and product images below to distinguish the two before choosing a part.
Understand the selector's three positions
These are battery selection switches, not battery combiners. The common positive output can be switched to the first battery bank, to the second bank or disconnected in the OFF position. There is no BOTH setting on either 11001 or 11003.
OFF — no selected bank
Neither bank is joined to the selector's common output.
1 — bank one
The first battery input supplies the shared load connection; input 2 stays isolated.
2 — bank two
The second battery input supplies the shared load connection; input 1 stays isolated.
What do the smaller AFD terminals do?
The F1/F2 auxiliary contacts are separate from the battery power terminals. An appropriately wired alternator field-disconnect circuit can help protect an alternator if the battery switch is opened during engine operation. This feature must be installed to match the alternator and Blue Sea instructions; it is not a substitute for shutting down equipment safely.
Check the details that affect replacement
| Identification point | 11001-BSS | 11003-BSS |
|---|---|---|
| Blue Sea product family | e-Series | HD-Series |
| Switch positions | OFF / 1 / 2 | OFF / 1 / 2 |
| Battery inputs | Two | Two |
| Maximum voltage | 32V DC | 32V DC |
| Main terminal stud | 3/8 in–16 (M10) | 1/2 in (M12) |
| AFD auxiliary contacts | Yes | Yes |
| Bank-combining position | No | No |
| Installation options | Surface or rear-panel mount | Surface or rear-panel mount |
A different stud diameter can mean the existing cable lugs will not fit, even when the selector positions look right. Match the mounting opening, cable clearances, ratings and original equipment requirements, not merely the knob shape.
Product photos for identification
These are the matching 11001-BSS and 11003-BSS listings on UsedRVParts. Use the photos to compare your existing switch, then check the individual listing for current availability and ordering details. In-person viewing and pickup, where offered, are by appointment in Kelowna.
Find the original terminal and mounting drawings
For safe identification of rear stud locations, opening sizes and connection hardware, use the Blue Sea 11001 e-Series manufacturer page and 11003 HD-Series manufacturer page. Each provides a model-specific instruction sheet. Check the actual component and have battery-distribution work performed by a qualified installer.