Victron Phoenix 24/3000 or MultiPlus 24/3000: which inverter does my RV need?

Three Victron units share the 24/3000 label and they are not interchangeable. The forum poster who asked this said he "really doesn't need shore power". That sentence is the whole decision.

What each one is

Phoenix Inverter 24/3000. An inverter and nothing else. 3000 VA of pure sine 120 V, Victron's SinusMax design for high start-up power on compressor and motor loads, a VE.Bus port for a Cerbo GX or the MK3 interface, and up to six units in parallel. It has no AC input, so no charger and no transfer switch. Our listing says it plainly: if you want a transfer switch, buy a MultiPlus, whose charger can simply be disabled. The unit measures 14.3 x 10.2 x 8.6 inches.

MultiPlus 24/3000/70-50. The same 3000 VA inverter with a 70 A battery charger and a 50 A transfer switch built in. Plug in and it passes shore power through, charges the bank, and if the pedestal cannot keep up, PowerAssist adds battery power to the output. Lose the pedestal and it is inverting in under 20 ms. This is the UL 1741 and UL 458 listed version for North American installs, and up to four can run in parallel or split phase.

MultiPlus-II 24/3000/70-50. Same ratings on the charger and transfer switch, in a lighter case with a second AC output. Victron's datasheet gives 2400 W continuous at 25 °C, 2200 W at 40 °C, a 5500 W peak, 13 W idle (9 W in AES mode), 94 percent peak efficiency and a weight of 42 lb. The second output is rated 32 A and drops when inverting, which is where the air conditioner belongs. It also comes in a 2x120V version for 50-amp coaches.

The decision rule

• Never any AC source, not even a generator: Phoenix. You save the charger you would never use.
• Shore power or a generator at any point: MultiPlus or MultiPlus-II. The transfer switch alone is worth it, because the alternative is a separate transfer switch and a separate 24 V charger.
• Already own a good 24 V charger: still the MultiPlus. Disable its charger in VictronConnect and keep the transfer switch and PowerAssist.
• Want loads that shed automatically off grid, or a physical remote switch alongside a GX device: MultiPlus-II.

Sizing the DC side at 24 V

Running 3000 VA from 24 V roughly halves the battery current compared with 12 V, which is the main reason to be at 24 V in the first place. Victron's figures for the MultiPlus-II 24/3000: a 200 to 700 Ah bank, a 300 A DC fuse, AWG 1/0 per terminal up to 5 m and two AWG 1/0 per terminal from 5 to 10 m. Confirm against the manual of the exact unit you buy.

We stock the Phoenix 12/3000 and 24/3000, the MultiPlus 24/3000 and the MultiPlus-II in 120 V and 2x120V, all shipped from Upland, California. The 24V Off-Grid Trailer Power Kit is the MultiPlus-II 24/3000 2x120V with the MPPT, DC-DC, Lynx and Cerbo parts matched around it.