A safe camper battery setup comes down to three parts working together: a box that holds the battery still, a disconnect switch that cuts everything off, and a shunt monitor that tells you how full the battery really is. Blue Sea Systems rates its m-Series 6006 battery switch at 300A continuous, Victron’s SmartShunt measures current to ±0.01A resolution, and NOCO’s Snap-Top BG24 box holds a Group 24-size battery, according to each maker’s published specs. This guide shows how those pieces fit together in a small camper, van or trailer.
As an Amazon Associate I earn from qualifying purchases, at no cost to you.
This is general information, not electrical advice. Follow each manufacturer’s manual and have a qualified technician check your work. Specs come from Blue Sea Systems, Victron Energy, NOCO and LiTime; the sizing math is labeled as estimates.
The video above shows the LiTime 12V 50Ah LiFePO4 battery I use for small 12V projects, charged from 2.7V back to 100%.
The parts list
| Part | Example | Key maker spec | Job |
|---|---|---|---|
| Battery | LiTime 12V 50Ah LiFePO4 | 640Wh, 50A BMS, about 7.68 × 6.54 × 6.77 in | Stores energy |
| Battery box | NOCO Snap-Top BG24 | Inside about 10.5 × 6.9 × 9.7 in; tray and 48-in strap included | Holds and protects |
| Main fuse | Sized to your cable | See fuse section | Protects the wire |
| Disconnect switch | Blue Sea m-Series 6006 | 300A continuous, 48V DC max, 3/8-in studs | Cuts all power |
| Battery monitor | Victron SmartShunt 500A | 6.5–70V supply, Bluetooth, VE.Direct | Tracks state of charge |
Step 1: Pick and mount the battery box
A box keeps the battery from sliding, shields terminals from shorts and contains a mess if something goes wrong. NOCO says the BG24 fits one 12V Group 24 automotive, marine, RV, deep-cycle, AGM or lithium battery and can be screwed down through internal pilot holes or held with the included tray and 48-inch strap. It has front and side cable entry ports and optional vent holes, and NOCO says it meets USCG 183.420 and ABYC E-10.7 specifications.
Fit check (from published dimensions): the LiTime 50Ah’s roughly 7.68 × 6.54 × 6.77 in body fits inside the BG24’s 10.5 × 6.9 × 9.7 in interior, leaving room along the length for cable lugs. Measure your own battery including terminals before buying; group sizes 27 and 31 need larger boxes, which NOCO also makes.
- Mount it on a flat, solid surface, such as a trailer tongue rack, a cabinet floor or a bench base.
- Use both the screws and the strap on rough roads.
- Keep it close to the inverter or fuse block to shorten heavy cables.
Step 2: Put a fuse right at the battery
The first thing on the positive cable should be the main fuse, as close to the battery terminal as practical. A fuse protects the cable, not the appliance, so it has to be at or below the wire’s ampacity and above your normal load. My fuse sizing guide walks through the method and my fuses vs breakers article covers when a breaker makes more sense.
Worked example (estimate)
The LiTime 50Ah has a 50A BMS, so the battery itself limits continuous current to about 50A. 50A × 1.25 ≈ 63A, so a fuse in the 60–70A range is a starting point, with cable rated above the fuse. If your largest load is a 300W inverter at 12V, it draws roughly 300 ÷ 12 ÷ 0.9 ≈ 28A, comfortably under that limit. Always check the inverter manual’s fuse and cable table first.
Step 3: Add the disconnect switch
A disconnect lets you kill everything for storage or service with a twist. Blue Sea’s 6006 is a single-circuit ON-OFF switch for one battery and one load group. Its published ratings:
| Blue Sea 6006 spec | Rating |
|---|---|
| Continuous | 300A |
| Intermittent | 500A (5 min) |
| Starting (30 sec) | 900A |
| Max voltage | 48V DC |
| Studs | 3/8-in tinned copper, 120 in-lb torque |
| Weight | 0.65 lb |
| Mounting | Surface, front panel or rear panel |
| Extras | Ignition protected; removable knob |
Wire it in the positive line after the main fuse. Torque the studs to Blue Sea’s 120 in-lb and use the removable knob as a simple lockout when the camper is parked for months. That stops small standby loads (propane detectors, USB ports, the shunt’s own Bluetooth) from slowly draining the battery.
Step 4: Install the shunt on the negative side
Voltage alone is a poor guide to a LiFePO4 battery’s charge, because the voltage curve is very flat. A shunt counts amps in and out instead. The Victron SmartShunt goes on the negative cable:
- Battery negative → the shunt’s battery-minus side.
- Every load and charger negative → the shunt’s system-minus side. Anything wired straight to the battery negative bypasses the shunt and makes the reading wrong.
- Small fused red lead from the shunt → battery positive to power it.
- Open VictronConnect, enter your capacity (50Ah here), and for LiFePO4 Victron’s manual suggests a Peukert exponent of 1.05 and 99% charge efficiency.
Victron sells SmartShunts in 300A, 500A, 1000A and 2000A versions; the 500A model covers most small campers. My SmartShunt wiring guide and shunt sizing article go deeper, and the SmartShunt vs budget shunts comparison covers cheaper options.
Order of parts, positive and negative
| Positive path | Negative path |
|---|---|
| Battery + terminal | Battery − terminal |
| Main fuse (within inches of the terminal) | Shunt, battery side |
| Disconnect switch | Shunt, system side |
| Fuse block / bus bar / inverter | Negative bus bar |
| Individual fused circuits | Load and charger negatives |
Wire size quick reference
Cable size depends on current and length. Size it for both ampacity (at or above the fuse) and voltage drop over the full round-trip length; my wire gauge chart has the numbers, and my voltage drop guide shows the math. Keep cables short, use proper crimped lugs, and add heat-shrink.
Charging the battery
A camper battery can be charged from shore power, solar or the vehicle. For the LiTime 50Ah, I used the LiTime 12V 20A charger, which delivers 14.6V at up to 20A. Chargers and solar controllers connect on the system side of the disconnect and shunt so the monitor counts their current.
FAQ
Where should a battery disconnect switch go?
In the positive line after the main fuse, so turning it off isolates every load and charger from the battery.
Does the shunt go on positive or negative?
The Victron SmartShunt goes on the negative side, between the battery negative and all system negatives.
Do I need a battery box for lithium?
It’s good practice. NOCO lists its BG24 for lithium batteries as well as lead-acid, and a box holds the battery in place and protects the terminals.
What size SmartShunt do I need?
Choose a rating above your maximum current. The 500A model covers most small camper systems.
Will the disconnect stop parasitic drain?
Yes. When the switch is off, everything downstream is disconnected from the battery.
Bottom line
Box it, fuse it, switch it and monitor it. A Group 24 box, a 300A Blue Sea switch and a 500A SmartShunt give a small camper a tidy, serviceable battery setup with accurate state-of-charge readings on your phone.