RoamEnergy has introduced a third-party Vehicle-to-Load (V2L) option for Tesla electric cars in the US, enabling power export of up to 3.5 kW at 120 volts. In the latest State Of Charge video, Tom Moloughney reviews the RoamEnergy Tesla EV Discharger.
According to the manufacturer, more than 20,000 units have already been sold in China, Japan, South Korea, Australia, and a few European countries so far. It will be interesting to see whether the North American version will also gain popularity. Tesla itself does not offer a V2L for its EVs, aside from the Tesla Cybertruck and the recently launched Tesla Model Y Performance.
Specs
The RoamEnergy Tesla EV Discharger is an external inverter that converts DC electricity into AC electricity. On the input side, it has a six-foot charging cable with a NACS connector. On the output side, there are two 120-volt AC outlets, which can supply a total of 3,500 watts (3.5 kW) with a current limit of 32 amps.
RoamEnergy says the device is compatible with certain 2021 or newer Tesla EVs — the Model 3, Model S, Model X, and Model Y — that support the CCS charging protocol (older Teslas do not). To check compatibility, one can enter Vehicle settings / Software and then select “Additional Vehicle Information” to see whether there is “CCS and 3rd-party NACS DC charging Enabled” like Tom shows at 22:52.
The device enables power export from Tesla’s charging port, provided the vehicle’s state of charge (SOC) is 20% or higher. This allows powering external devices within the power limit (with overheat, short-circuit, and over-current protection).
The RoamEnergy Tesla EV Discharger is UL-certified. Its operating temperature is 14-104°F (-10°C to 40°C). It’s important to note that it’s not water-resistant.
RoamEnergy Tesla EV Discharger — 120V, up to 3,500W (Model 3/Y/S/X). (Source: RoamEnergy)
The Tesla EV Discharger has its own battery. If it runs out, it must be recharged, and RoamEnergy provides a 12-volt cigarette lighter plug for that. Tom mentioned that this isn’t convenient, and it would be good to have another option, like an external 12-volt power supply to connect to a regular 120-volt outlet.
In case of any troubles, the device is equipped with a microSD card reader and a card. If the device experiences problems during charging, it records the error info on the microSD card. The file can then be sent to the manufacturer.
The device has an Ethernet port in the back for software updates. According to RoamEnergy, an update might be necessary if Tesla’s software updates affect the power export.
How It Works
Tesla does not offer V2L for its electric cars, aside from the few examples mentioned earlier (the Cybertruck and the latest Tesla Model Y Performance). It seems that Tesla users aren’t intended to export power, which makes us wonder how it works.
RoamEnergy has figured out a special case to offer such a capability, even in older Teslas. When connected, the device communicates with the car using the CCS charging protocol. As far as we understand, it tricks the vehicle into thinking it will charge to access the battery pack. The car thinks that it will get a DC fast charge, which triggers its battery thermal management system (TMS). It makes some noise and probably wastes some energy on preparing the battery’s optimal temperature for fast charging. At that point, the device is ready to draw power from the battery. The user can connect loads to its 120-volt outlets.
Tests
Tom Moloughney conducted multiple tests of the RoamEnergy Tesla EV Discharger, starting by charging another EV (a Rivian R1S). At 120 volts, the mobile connector delivers 1.3 kW as designed. At such low power, it would be difficult to quickly rescue stranded EVs (maybe to provide a few miles), but the possibility of charging another vehicle has been confirmed.
A more typical use case for the V2L is powering external devices. Tom tested the RoamEnergy with a pizza oven (1,200 watts), a coffee maker (1,470 watts), and a heater (1,500 watts). It worked fine with each of them individually and in combination (pizza oven and coffee maker together at 2,670 watts).
The manufacturer notes that for extended use, Camping Mode should be selected on the vehicle to prevent automatic shutdown after one hour.
A separate test with all three devices powered simultaneously (4,170 watts) confirmed the overcurrent protection, as the RoamEnergy Tesla EV Discharger shut down after a short while when power exceeded its 3.5-kW limit. Tom unplugged one of the loads to reduce the power demand and successfully restarted power export.
The review revealed that the NACS connector on the RoamEnergy Tesla EV Discharger does not open the Tesla charging flap. It has a button for that, but apparently it works only with some Tesla EVs.
Price
The RoamEnergy Tesla EV Discharger is currently priced at $1,299 (down from the regular $1,499, according to the manufacturer’s website). However, with State Of Charge’s coupon code “TOM300” one can save $300 and bring the price to $999.
A thousand dollars is still a noticeable cost for a V2L adapter (which is actually an inverter), but it also opens a unique power export option for Tesla EVs. At least if Tesla does not decide to close the option one way or another.
Next Generation
RoamEnergy plans to launch a new V2L adapter at some point in 2026. The new version is expected to offer twice the power (about 7 kW) at a voltage of 240 V.
This would significantly increase the number of potential applications, although we don’t know the pricing (it might be even higher than the current one).
Video timestamps:
02:02 Unboxing
05:42 The RoamEnergy Tesla discharge device key features
07:51 Charging another EV with the RoamEnergy Tesla discharge device
10:39 Using the unit to charge other electrical appliances
15:24 Overloading the device to see what happens
18:34 How does it work
22:52 How to find out if it’s compatible with your Tesla
23:52 Thoughts after using the Tesla EV discharge for a while
29:48 How to save $300 on the RoamEnergy Discharge Device
Very cool! I wonder if this would be possible with other EVs. Thanks for the review Tom