chadman.net · ATC PLA 450 · 12V camper system

PLA 450 Battery Upgrade

Swap the two Battle Born 100Ah batteries for one VATRER 600Ah self-heating battery, then add a Victron charger on its own outlet. The converter, solar, inverter and Firefly stay as they are. An automatic pause for the A/C and microwave is optional, for later, if current turns out to be a problem.

New plan · battery swap + second charger Second-charger parts ordered Front compartment Updated Nov 10, 2026

Scroll sideways to see the whole diagram.

120V AC 12V DC Shore power 30A pedestal Honda EU3000is 2,800W running Transfer switch existing AC out OPTIONAL: current switch black wire only · trips ~15A Camper AC panel existing A/C or microwave existing Converter PD9360 60A · existing 10/3 Romex tap red wire capped NILIGHT outlet box 20A breaker + GFCI · NEW plug Victron Phoenix IP43 12/50 charger · NEW 12V relay OPTIONAL · later later: 18 AWG to the Phoenix remote terminals 2A fuse · coil + camper 12V + existing bus up to 50A 60A MIDI · NEW Solar MPPT 100|30 existing VATRER 600Ah 12V LiFePO4 · NEW self-heating · 300A BMS replaces 2× Battle Born + Class T 200A · NEW disconnect · existing main cable · 2/0 or larger Inverter 200A breaker · existing Firefly + 12V loads existing Shunt · existing · set it to 600Ah data to the Firefly: % and amps charger − Camper negative · the camper side of the shunt The converter, solar, inverter and 12V loads land here too · existing
120V AC 12V positive 12V negative Data wire Optional, for later New part Already in the camper
The VATRER takes the Battle Borns' place, with a 200A Class T fuse at its positive post. The Phoenix plugs into the new outlet box and lands where the converter does: positive through a 60A fuse, negative on the camper side of the shunt so the Firefly counts its charge. The dashed current switch and relay are optional, for later: if current becomes a problem, the switch would watch the wire to the camper panel and, above about 15A, its relay would open the Phoenix's remote terminals and pause the charger until the load drops.

How it runs

Shore power · 30A

Two chargers

The converter and the Phoenix charge together, about 110A, so 600Ah goes from empty to full in about 6 hours instead of 10. The A/C or the microwave fits alongside both chargers on 30A; both of them at once plus both chargers is more than 30A, so switch the Phoenix off first.

Generator day · Honda

Same, inside 2,800W

Both chargers together draw about 1,750W. Before turning on the A/C or microwave, switch the Phoenix off at the outlet box's 20A breaker, which keeps the Honda under its limit. Don't run the A/C and microwave together on the Honda, with or without the chargers.

No hookups

Three times the battery

600Ah against the Battle Borns' 200Ah, with the solar topping it up during the day. The Firefly shows its charge once the shunt is set to 600Ah.

Power on the Honda

The EU3000is gives about 2,800W continuously. Figures marked ~ are estimates until the A/C label is read.

LoadWatts
A/C running, typical rooftop unit (the soft start covers its start)~1,300–1,700
Microwave ("1,000W" is cooking power, not the draw)~1,500
Converter PD9360 at its full 60A~950
Phoenix 12/50 at full rate (label)780
Converter + Phoenix~1,730Fits
A/C + converter + Phoenix, so the Phoenix goes off first~3,030–3,430Over
A/C + converter, Phoenix off~2,250–2,650Fits
Microwave + converter, Phoenix off~2,450Fits
A/C + microwave, even with no chargers~2,800–3,200Over

Parts

Battery swap

PartModelPriceStatus
BatteryVATRER 12V 600Ah LiFePO4, self-heating, 300A BMS, Bluetooth app. 25 × 9.6 × 8.7 in, 108 lb, non-returnable$1,299.98Chosen
Fuse holderBlue Sea 5007100 Class T holder (110–200A)$89.51Chosen
Main fuseMersen A3T200, 200A Class T. The same fuse Blue Sea sells as its 5116 for this holder. Zoro~$30.47To buy
MountingNo box fits a 25 in battery: a floor frame or blocks, hold-down straps, and boots on both terminals—To buy

Second charger

PartModelPriceStatus
ChargerVictron Phoenix Smart IP43 12/50 (1+1), 120–240VAC, Bluetooth$335.00Ordered
Breaker + outletNILIGHT 20/30A RV outlet box: 20A breaker, 20A GFCI outlet. The 30A breaker and RV outlet go unused$68.38Ordered
DC fuse holderBlue Sea 7720 MIDI safety fuse holder$40.95Ordered
DC fuseBlue Sea 5253 MIDI 60A, on the Phoenix positive where it lands$12.03Ordered
Charger cableShirbly 6 AWG, 10 ft red and 10 ft black$32.39Ordered
Ordered totalBefore tax$488.75
AC feed10/3 Romex: black hot, white neutral, bare ground, red capped at both ends—On hand
Lugs and shrinkCrimp lugs with holes matched to each stud; adhesive-lined heat shrink—On hand
Charger cordThe US charger ships without one. A cord of your own works if it locks in the charger's cord clip and is rated 10A or more; otherwise the Victron cord, about $20 shipped—Check
Cable clampsNM cable clamps listed for 10/3, sized to the box knockouts. If the transfer switch output won't take a second wire, a connector rated for three 10 AWG wires and a short 10 AWG jumper—To buy
BusbarsOnly if the converter's positive point or the shunt's camper-side stud is already crowded—Maybe

Auto-pause · optional, for later

Not part of this build. Add it only if the Phoenix plus the A/C or microwave starts tripping the Honda or a breaker.

PartModelPriceStatus
Current switchSplit-core, normally open, self-powered, adjustable set point, such as the Veris H608. Clamps the black wire from the transfer switch to the camper panel—Optional
Relay12V SPDT automotive relay with an 87a terminal and a built-in diode, plus its socket—Optional
Coil fuseInline fuse holder with a 1–2A fuse, on the relay's 12V feed—Optional
Control wire18 AWG two-wire cable, relay to the Phoenix remote terminals—Optional
Sensor leadsWire rated 300V or more for the switch's leads, since they share the transfer switch box with 120V—Optional

Build rules

AC side

  • Tap hot and neutral from the transfer switch output, never an input. Split in a covered junction box if the terminals aren't rated for two wires.
  • 10/3 Romex, since only 30A protects that run: black hot, white neutral, bare ground. Cap the red wire at both ends.
  • Clamp the cable at both boxes, strap it about every 4 ft and within a foot of each box, and keep it in its own bundle away from the DC cables.
  • Mount the outlet box upright, since its breakers are calibrated for that, and within reach of the charger's cord. Leave its 30A breaker off. The rain hood can come off indoors; the flat front panel stays on.
  • Neutral and ground stay on separate bars in the new box. Remove any bonding screw or strap. The Honda's N–G plug is the only bond on generator power.
  • The tap must only ever see shore or generator power, never an inverter's output.
  • The box's 20A breaker is the Phoenix's off switch. On the Honda, switch it off before turning on the A/C or microwave.
  • If the auto-pause is added later: the current switch clamps only the black wire from the transfer switch to the camper panel, not the outlet box feed, so the Phoenix's own draw never trips it. Set it to about 15A.
  • Turn off shore power and the generator before opening the transfer switch.

DC side

  • Class T 200A as close to the VATRER's positive post as it fits. Nothing lands on the battery post ahead of it.
  • Battery cable 2/0 or larger, for the inverter's 200A circuit.
  • Phoenix positive on the same positive point as the converter, after the Class T, with the 60A MIDI fuse at that end.
  • Phoenix negative on the camper side of the shunt, where the converter's negative lands, so the Firefly counts its charge.
  • Move the thin sense wires from the Battle Borns to the VATRER, and change the shunt's battery capacity from 200Ah to 600Ah.
  • Phoenix in Li-ion mode: 14.2V absorption, 13.5V storage, inside the VATRER's 14.2–14.6V range.
  • Leave the factory jumper on the Phoenix's remote terminals. If the auto-pause is added later: remove it and wire the relay's 87a (normally closed) contact across the two terminals, with the relay coil fed from camper 12V through a 2A fuse.
  • Match each lug's hole to its stud and measure the Class T holder's studs first; listings disagree on 1/4" or 5/16". Tug-test every crimp, then seal it with adhesive-lined heat shrink.
  • Strap the battery to its frame and boot both terminals.
  • Charging LiFePO4 below freezing damages it. The VATRER warms itself before it takes a charge and has its own cold cutoff.

Still to confirm

Shelved Nov 10, 2026

Earlier plan: separate reserve battery

Kept for reference. The VATRER was going to be a second battery, filled by the Phoenix and feeding the Battle Borns through an Orion DC-to-DC charger. The swap above does the same job with fewer parts and connections.

Scroll sideways to see the whole diagram.

120V AC 12V DC Shore power 30A pedestal Honda EU3000is 2,800W · N–G bonding plug Transfer switch auto · existing AC out Camper AC panel 30A main · existing A/C or microwave one at a time Converter existing 10/2 NM-B tap from switch output NILIGHT outlet box 20A breaker + GFCI · NEW plug Victron Phoenix IP43 12/50 charger · NEW LATER: current sensor pauses charger for A/C 60A fuse up to 50A VATRER 600Ah 12V LiFePO4 · NEW self-heating · 300A BMS + Class T 110A shutoff 70A fuse Victron Orion XS 12/12-50A · NEW 60A fuse BMV-712 monitor NEW · on 40%, off 80% 18 AWG · remote camper 12V + existing bus Solar controller existing Camper 12V loads existing 2× Battle Born 100Ah each · existing charger − GND Negative busbar · Victron 6-position · NEW BMV-712 shunt · NEW to camper −, on the shunt's camper side data cable
120V AC 12V positive 12V negative Control wire Planned for later New part Already in the camper
The new tap comes off the transfer switch output, so the Victron charger works on shore power or the Honda. The charger fills the reserve battery. The Orion moves power from the reserve battery into the camper's 12V bus, the same bus the converter and solar already charge the Battle Borns on.