Where This Guide Comes From

Every step in this article comes from one source video — EXPLORIST life’s complete motorhome RV solar and lithium upgrade, a start-to-finish DIY installation watched tens of thousands of times. The channel is one of the most trusted names in mobile off-grid electrical work, and in this build they take a used motorhome from a single factory battery to a 540Ah Battle Born bank, a Lynx distributor, a MultiPlus inverter-charger, 1200W of roof solar and an Orion DC-to-DC charger — all while leaving the factory wiring in place.

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Why This Motorhome Needed a Full Electrical Upgrade

The rig in the video started life with the factory setup many coaches still have: a single small lead-acid battery under the entry step, a 30-amp shore power cord, a generator big enough to run the whole camper, and a factory converter turning 110V into 12V for the lights and fans. On paper that works — but only while you are parked with the cord plugged in or the generator burning fuel. The moment the owner wanted to camp off-grid, the little battery could not power the camper for any meaningful time. That is the situation most RV owners hit: the coach has plenty of factory electrics, it just has no energy storage behind them.

The interesting part is that the fix does not require rewiring the coach. As the build demonstrates, you can keep every factory branch circuit and simply feed the OEM battery location from a much larger lithium bank. The factory breaker box, the transfer switch and the converter all stay where they are; only the source of energy changes. That distinction is what makes this upgrade a realistic weekend project rather than a full coach rewire.

The Upgrade Plan: 540Ah of Lithium, 1200W of Solar

The plan breaks down into five connected jobs. First, two Battle Born GC3 lithium batteries are wired in parallel to make a 540Ah bank — and because these are the heated versions, they also get a switch enabling or disabling the thermostat-controlled internal heaters. Second, a Victron Lynx distributor becomes the central power hub: it gives the bank a safe way to distribute power to loads and accept power from chargers, and it hosts the master disconnect switch, the 400A ANL main fuse and the shunt for a BMV 712 battery monitor. Third, a Victron MultiPlus inverter-charger is spliced into the factory 120V system so the coach can run its outlets from the battery and recharge from shore power. Fourth, 1200W of solar lands on the roof with a SmartSolar MPPT charge controller. Fifth, an Orion DC-to-DC charger handles alternator charging safely.

The system was deliberately staged: after the battery and distributor are in, the coach can already run its 12V loads. The inverter-charger step adds 120V power. Solar and DC-to-DC charging make it truly off-grid. You can stop at any stage and still have a working rig.

Building the Battery Bank: Battle Born GC3s in Parallel

The battery work starts with wire fabrication. For the jumper between the two batteries, the team measures, cuts, strips, crimps and heat-shrinks both cables from the kit. Two details stand out: the lugs are sanded to remove burrs, and every electrical surface is wiped with alcohol before assembly. That extra minute of prep separates a connection that stays cool from one that heats up under load years later, and the video shows it repeated for every cable in the build.

The batteries are secured to the floor and each cable lands with a bolt through the back of the terminal, a washer, the lug, then a washer and nut on top. One bolt is deliberately left snug but not fully tight because it will connect to the Lynx distributor next. For the heated GC3s, a jumper wire runs between the two batteries, a power wire feeds the heater circuit, and a switch controls it — so cold-climate owners can warm the cells before charging while warm-weather owners leave the heaters off. In parallel the two packs total 540 amp-hours at 12.8V — about 6.9kWh.

Power Distribution: The Lynx Distributor and BMV 712

The Lynx distributor is the heart of the new system. A positive bus bar and a negative bus bar give every load and every charger a single, clean place to land, and the accessory slots hold the fuses that protect each downstream wire. The build attaches the Lynx adapter to both bus bars, puts the master disconnect switch on the positive side, and runs the main positive path through a 400A ANL fuse — the fuse protecting the cable from the batteries to the distributor itself. On the negative side, the shunt for the BMV 712 battery monitor sits in the path so every amp flowing in or out of the bank is measured.

The BMV 712 is programmed through the Victron Connect app: battery bank capacity is set to 540 for this build, auxiliary input to none, and the specific voltage settings come from the battery manufacturer’s cheat sheet for these cells. That last point matters — if you use a different brand or a different capacity, you get the settings from your own manufacturer rather than copying someone else’s numbers. The monitor then lives in a cabinet where it can be seen, showing state of charge and live current draw as loads switch on and off. A chassis ground wire with a 5/16-inch lug on each end ties the negative bus bar to the motorhome frame, the grounding path every mobile system needs.

Keeping the Factory Wiring: Junction Studs at the OEM Battery Location

The clever part of this upgrade is that the coach’s existing wiring is left untouched. All the factory branch circuits — the jacks, slides, 12V fans, lights and everything else fed from the original battery — simply stay where they are. Instead of chasing each wire through the walls, the team replaces the factory lead-acid battery with a pair of junction studs: one positive, one negative. Every wire that was attached to the old positive terminal goes to the positive stud, and every wire from the negative terminal goes to the negative stud. The new 2-gauge cables from the Lynx distributor then land on those same studs.

This is the trick that keeps the project a weekend job. The factory converter, fuse panel and breaker box all continue to work exactly as designed, because they are powered from the same point they always were. The only difference is that the source behind that point is now 540Ah of lithium instead of a tired lead-acid brick.

Wiring the Victron MultiPlus Inverter-Charger

To run 120V outlets from the battery, a Victron MultiPlus inverter-charger is mounted and wired with 4/0 cables. The negative lands on the negative bus bar of the Lynx distributor, the positive goes through a mega fuse on the positive bus bar, and an equipment ground ties back to the center stud on the negative bus bar. A VE.Bus Smart Dongle adds Bluetooth control, so the whole inverter can be monitored and configured from a phone.

The AC side is where the splice happens. A 10/3 cable is cut into the OEM wire feeding the breaker box, giving two ends: one that comes from the shore power inlet and one that goes to the breaker box. The MultiPlus’s AC input connects to the wire coming from the transfer switch, and its AC output connects to the wire heading to the breaker box. From that moment, the breaker box does not care whether power is coming from shore, the generator or the battery — it just distributes whatever it receives. The team also labels the splice box, a habit that saves hours later.

The Converter Trap: Why You Must Disable the OEM Converter

One step in the video is easy to miss and genuinely important: the factory converter breaker must be switched off and taped so nobody toggles it back on. Here is the loop that forms if you skip it. When you are off grid, the battery powers the MultiPlus inverter, which powers the breaker box, which powers the converter, which converts 110V back down to 12V to charge the battery — and the battery charges the inverter, and the circle goes round and round, losing power at every hop. It is a closed loop of pure energy loss that can keep a converter humming and draining the bank for no reason at all.

In most coaches the converter has its own breaker inside the breaker box. Turning it off and taping it over is the standard fix; the converter becomes inactive, and the MultiPlus handles all charging. If you ever need the converter again, un-tape and flip it back. Knowing this one trap exists will save a lot of head-scratching on the first night off-grid.

1200W of Solar: Panels, MPPT Controller and Solar-Ready Wiring

The solar side starts with the charge controller. A SmartSolar MPPT 150/85 is wired with 2-gauge battery cables to the positive and negative terminals of the bank through the Lynx distributor, with an equipment ground and a mega fuse in the path. The 10-gauge solar wires get ferrules and land in the PV terminals. From the controller, the array side runs through a solar isolator — a switch that lets you kill solar power by hand — and then to the coach’s factory solar-ready wires.

Up top, six panels are mounted with Z-brackets and self-tapping screws, with 3M VHB tape on each mounting foot for extra hold. The six panels are arranged as two series strings of three, and the two strings are then paralleled at PV branch-circuit combiners before entering the roof entry gland. Every mounting screw gets Dicor sealant, and the combiners are fused on the positive side. On a cloudy day the charge controller shows only a trickle — the crew even jokes about dodging rainstorms — but a screenshot from the next sunny morning proves the 1200W array is really producing.

Alternator Charging Done Right: The Orion DC-to-DC Charger

Most motorhomes have a factory battery isolator that lets the alternator charge the house bank, but an isolator provides no voltage or amperage regulation. Whatever the alternator puts out is what the lithium cells get, and because lithium accepts charge very fast, the alternator can be pushed to its limits and wear out early. The fix shown here is a Victron Orion DC-to-DC charger wired in parallel with the isolator. The charger regulates both voltage and current for the lithium chemistry, protecting both the batteries and the alternator.

The build wires the Orion with 6-gauge cable, lands the output through the Lynx distributor with a mega fuse, and runs the input side down to the engine bay with zip ties and loom keeping it clear of hot parts. A green jumper pin in the Orion box enables remote on-off, and the installer adds a secondary switch in line with the isolator’s ground wire under the dash. When that switch is off, the isolator is disabled but the emergency-start feature still works — the coach battery can still jump the start battery if needed. Programmed via the Victron Connect app, solar, alternator and shore power can all stay on at once; each source regulates itself and they share the load automatically.

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What Viewers Are Asking (Top Comments on the Video)

The video’s most useful top comments, with our practical answers; where the creator replied, we quote the creator’s own words. Thanks-only comments were left out on purpose.

@Charlie-zl6pc · 4 likes
"So the DC to DC charger is optional, but the isolator needs to remain switched off unless needed for emergency starts?"
Our take: Correct on both counts. The DC-to-DC charger is an optional layer of safety on top of the factory isolator, and the switch the installer adds disables the isolator for normal driving while leaving the emergency-start jumper path intact. Without a DC-to-DC charger, you accept unregulated alternator voltage and current going into lithium cells — workable, but harder on the alternator, which is why the video installs the Orion for the owner.
@rudivandoornegat2371 · 4 likes
"The blue cable ducting with integrated isolator switch makes this install look extra neat."
Our take: That duct is a slotted wire duct, and the creator left a link for it in the video description precisely because it is a specialty item. Running the distributor wires through a covered duct keeps the compartment looking professional and protects the conductors — a small detail that elevates the whole install.
@waterwings2661 · 3 likes
"@EXPLORISTlife Nice work! I couldn’t find the link you mentioned in the video for the wire duct in your video description."
Our take: The creator pinned the wire duct link in the video description, and the pinned comment keeps an FAQ with current kit links and pricing. If the description has changed since this build, message the channel and they will point you to the exact product.
@craigobrine9643 · 3 likes
"I'm looking at getting the 26M, any regrets on your part for buying it?"
Our take: For the 26M specifically, the crew has mentioned few regrets beyond the usual coach quirks — the biggest point is that this electrical upgrade transforms the usability of any floor plan. If you are deciding on a floor plan, choose the layout you will live in; the electrical system is the easy part to upgrade, the floor plan is not.
@taadventures6312 · 2 likes
"Great video. At 28:00mins what are the two wires that you said go up under the countertop. The red and white ones. I assume the other wires are the solar panel wires correct."
Our take: Those two wires running up under the countertop are the solar-ready conductors that come down from the roof: one positive and one negative. The other pair capped off in the compartment are the wires that originally went to the OEM battery, which are not needed once the bank is fed through the Lynx distributor. Matching red to red and black to black is how the solar side is identified.
@ACampo-r1o · 2 likes
"Awesome and detailed upgrade! I have a 25R model. Jayco says the chassis alternator does not charge and has not charged the house batteries since 2021 or before. There is no connection between the chassis and house batteries unless the dash button is pushed. If this is true is that switch you put in actually needed? Do I have to worry about my alternator getting fried trying to charge the lithium house battery I plan on installing? I think Jayco tech is giving bad info. 😢"
Our take: If Jayco says your chassis alternator never charges the house batteries, then your isolator path is effectively absent and the dash-button path is the only connection. The same approach applies: run a DC-to-DC charger from the start battery to the house bank, and it will regulate charging for lithium while the isolator (if any) stays out of the circuit. The video’s switch solution is built exactly for that scenario.
@maxschmeling1527 · 2 likes
"You said in the video you would leave a link for the wire duct in the video description, but I don't see it. I can't find that big blue slotted wire duct anywhere. Is it still being sold?"
Our take: The big blue slotted duct is a wire duct product that the creator links in the video description; if it is no longer listed, a standard slotted wire duct from any electrical supplier achieves the same tidy result. The key is matching the width to your cable bundle and mounting it so the cover can still snap shut.

Source video: EXPLORIST life Mobile Marine & Off-Grid Electrical — "Motorhome RV Solar & Lithium Upgrade - Start to Finish DIY Installation" (youtube.com/watch?v=9fmL1RfmZJk). Comments are quoted verbatim; build details are transcribed from the video.