If you're wiring a caravan, boat, camper, or small off-grid system, a battery switch is one of those inconspicuous parts that make your system safer, easier to use, and easier to service.
Below, we explain what a battery switch does, the main switch types, and how to choose the right one for your setup.
What does a battery switch do?
A battery switch is a manual safety and control device that lets you connect or disconnect a battery (or batteries) from your loads/charging instantly.
Common uses include:
- Isolate power when you're parked or storing the boat
- Service safely without live cables
- Select which battery bank runs your loads
- Combine banks in an emergency (on certain switch types)
General function and use cases are standard across marine/RV DC systems. For typical marine-grade features like tinned copper studs and isolated rear covers, see examples in Alvolta product pages and marine switch references.
Read more: Is it better to run 12 V or 24 V?
Where would I use a battery switch?
Caravan & 4WD: Isolate the auxiliary battery from loads when stored; choose or parallel banks if you carry a backup.
Marine: Isolate start vs auxiliary batteries; select 1-2-BOTH depending on engine starting or auxiliary loads.
Cabins & off-grid sheds: Kill-switch for maintenance or to prevent parasitic drain.
Multi-bank use and isolation practices are standard across marine/RV. See Dual Circuit and 1-2-BOTH selector explanations.
Read more: 12 V / 24 V battery & solar systems for 4WD & camping
Battery Switch Types
1) Single-Circuit ON/OFF
What it is
A simple master switch for one circuit (one battery to one load group).
Use it when
You have a single auxiliary battery bank and just want an isolate switch.
Get it here
- Single Circuit On-Off 350 A Battery Switch
2) Selector (1-2-BOTH-OFF)
What it is
One switch that lets you run from Battery 1, Battery 2, BOTH (paralleled), or OFF.
Use it when
You have two banks (e.g., start & auxiliary) and want manual control to select or combine.
Get it here
- 4 Position 350 A Battery Switch (1-2-BOTH-OFF)
- 3-Position 350 A Battery Switch with AFD (selector with built-in AFD - more on AFD below)
3) Dual Circuit (ON/OFF for two isolated battery banks)
What it is
A single twist switches two isolated circuits ON or OFF at once (e.g. start & auxiliary) without paralleling them.
Use it when
You want fool-proof installation and no accidental cross-connection (great for marine).
Get it here
- Dual Circuit 300 A Mini Battery Switch (compact; up to 32 V; M10 studs; tinned copper; rear isolation cover and breakout tabs).
- Dual Circuit 350 A Battery Switch (standard size).
4) Dual Circuit Plus (adds a "COMBINE"/emergency parallel)
What it is
Works like a Dual Circuit (keeps bank isolated) but includes a momentary or position to combine the banks for emergency starting.
Use it when
You want day-to-day isolation and an "oh-no" backup to start the engine or support a heavy load.
Get it here
- Dual Circuit Plus 350 A Battery Switch
What is AFD and do I need it?
AFD = Alternator Field Disconnect.
On selector-type switches used with engine alternators, AFD helps protect alternator diodes if you switch through OFF while the alternator is charging. An AFD contact opens the alternator field slightly before the main contacts open, preventing damaging voltage spikes.
If you have an engine/alternator (boats, some 4WD setups), choosing a selector with AFD is wise.
Get it here
Can I use a battery switch with multiple battery banks?
Yes - use Selector, Dual Circuit, or Dual Circuit Plus depending on how you want the banks to behave:
- Selector (1-2-BOTH-OFF): Manually pick Bank 1, Bank 2, or parallel BOTH. Offers great flexibility but does require user discipline.
- Dual Circuit: Turns both banks on/off without ever paralleling. Helps reduce user error.
- Dual Circuit Plus: As above, plus a safe Combine option for emergencies.
Are battery switches easy to install?
Mechanically, yes - usually panel/surface mount with two main cable lugs per circuit (M10 ring terminals are common).
Electrically, you must size the switch to your system voltage (12/24/48 V), continuous current rating (A), and cable size, and follow proper fusing and installation practices. Many Alvolta models specify tinned copper M10 studs and provide rear installation covers and breakout tabs to simplify wiring.
If you're not confident with high-current DC, get a licensed auto-sparky or marine electrician.
Read more: What size cable do I need? LV cable sizing guide
Read more: 5 tips to tidy your DC & wiring setup
Are they durable enough for outdoor use?
Quality marine-grade switches use tinned copper studs, robust housings, and ignition-protected designs; they're intended for harsh environments (boats/engine bays).
Alvolta and comparable marine switches are typically rated up to 48 V DC with 300 - 600 A continuous options, suited to caravans, RVs, and boats.
Always check the product page for exact ratings.
Which battery switch do I need if I only have one battery bank?
Simple single bank (caravan/camper/cabin):
- Single-Circuit ON/OFF. It's clean, cheap, and does the job.
What if I have two battery banks?
Decide how much manual control versus automation you want.
You want manual choice and the ability to run off either bank (and combine when needed):
- Selector (1-2-BOTH-OFF)
- Pick an AFD model if charging from an alternator
- Alvolta 3 Position 350 A with AFD
You want "set-and-forget" isolation (start vs auxiliary), with no accidental cross-connection:
- Dual Circuit
- Alvolta Dual Circuit 300 A Mini
- Alvolta Dual Circuit 350 A
You want isolation most of the time, plus a safe emergency parallel:
- Dual Circuit Plus
- Alvolta Dual Circuit Plus 350 A
The Dual Circuit family is popular on boats because it keeps the start and auxiliary isolated by default. Dual Circuit Plus adds the "COMBINE" safety net.
Read more: DC circuit protection guide
What if I have a more complex setup like a caravan or boat?
Typical patterns include...
4WD or caravan with a DC-DC charger
- Single house bank: Single-Circuit ON/OFF is fine for a master isolate
- Start + auxiliary banks: Dual Circuit or Selector depending on whether you prefer automatic isolation or manual selection (use AFD selectors if the engine alternator is in play).
Trailer or camper with two auxiliary banks (e.g., main + backup)
- Selector lets you run 1, 2, or BOTH and keep a reserve.
Small boats
- Start vs auxiliary is classic Dual Circuit territory.
- Dual Circuit Plus adds a momentary COMBINE for emergency cranking.
How do I know which battery switch is right for me?
Quick checklist
1. How many banks?
- 1 bank Single-Circuit ON/OFF
- 2 banks Choose among Selector, Dual Circuit, or Dual Circuit Plus
2. Do you have an alternator (engine charging)?
- Yes Prefer a selector with AFD
3. Do you want "idiot-proof" isolation between start and auxiliary?
- Yes Dual Circuit (no parallel)
- Want an emergency parallel option? Dual Circuit Plus
4. How much current?
- Match switch continuous rating to your system's maximum expected continuous current (inverters, DC loads). Alvolta offers 300 - 350 A continuous in compact sizes and higher in heavy-duty models. Check the specific page and specs.
5. Wiring convenience and size
- Look for M10 studs, tinned copper, rear isolating covers, and "breakout tab" housings for neat cable routing.
Understanding Battery Switches