Inexpensive Charging Equipment: Comparing JuiceBox, OpenEVSE and EVSEUpgrade

By · August 01, 2013

Most plug-in car owners buy a home charging station. Manufacturers often partner with charging equipment makers, bundling the hardware with installation and other assistance. But some buyers don't like the price—or prefer a DIY approach (that can result in a lower cost plus enhanced features and greater portability). Low-cost alternatives are available in the electric vehicle service equipment (EVSE) market, including a couple of open source DIY models.

Upgraded Nissan line-cord EVSE; notice the NEMA L6-30 plug on the cord

One option is to upgrade the line-cord EVSE that's bundled, for free, with all electric cars. Out of the box, these units plug into 120-volt outlets and provide a 1-kilowatt charging rate that can take a full day to juice up a car. While slow, they are useful in a pinch. Some EV owners find they can survive by just using the 120 volt line-cord EVSE, and completely skipping an expensive EVSE. What's less well known is that those line-cord EVSE's can be upgraded to run at 240 volts, and up to 5 kilowatts charge rate.

EVSE Upgrade is a popular service that performs line-cord EVSE upgrades, for less than $300. You send your existing line-cord EVSE to them. They convert the charger to have a beefier plug and cord, and make internal changes to allow use at 240 volts and to support a 3.3 kilowatt or even 4.8 kilowatt charge rate depending on the EVSE. That's similar to the charge rate of a regular EVSE, meaning you'll end up with a portable EVSE. You'll still need access to a 240-volt power outlet. It's straightforward to hire an electrician to install one at a very low cost, and sometimes 240-volt outlets can be found in public, such as at RV parks.

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Enel X's JuiceBox

Recently, Enel X announced the JuiceBox, an open source kit for building EVSE's, that's also available pre-assembled for a higher price. "Open source" means all the instructions and software source are available so you can build your own, if you wish. Enel X is making the kit and pre-assembled versions available for an excellent price, well below the price of EVSEs from the major manufacturers. The JuiceBox, by supporting charge rates as high as 15 kilowatts, is more powerful than most EVSEs on the market.

Just because the JuiceBox supports a 15 kilowatt charge rate doesn't mean your car will automagically begin charging at that rate. EVSEs are, in a way, glorified on-off switches, and it's the on-board charger mounted in the car which controls how fast it charges. The 15 kilowatt rating of the JuiceBox is maximum power it can channel. Connect it to a car with a 6.6 kilowatt on-board charger, and the charge rate remains 6.6 kilowatts.

The Enel X JuiceBox uses the open source Arduino UNO computer board to control it. The creators designed the JuiceBox to use Arduino-compatible expansion boards, for example to add WiFi support to the JuiceBox. Because you have access to the source code, you can change the JuiceBox behavior by rewriting the software and even sharing your changes with others. Enel X expects a community of hackers to start working on customizations.

OpenEVSE bare circuit board

The OpenEVSE is another DIY open source EVSE, like Enel X's JuiceBox. It's a proper open source project with designs, information and discussion hosted on Google Code, but no single company directly backing it. You could take the information there, print your own circuit boards, whip out a soldering iron, and build the whole thing by yourself. Pre-printed circuit boards and enclosures are available from a few online stores. These save you the effort of printing the circuit board, but you still have to solder components to it. Because you assemble it from parts you can customize it in many ways and it can be configured for high charge rates as well. Like the JuiceBox, you can hack on the source code to make it perform any function you desire.

Both the JuiceBox and OpenEVSE plug into regular 240 volt power outlets, so you'll have to hire an electrician to install one.

We are talking about electrical equipment that's running a fairly high power level, and there are safety considerations. Building code inspectors like to see UL labels or other certifications on this kind of equipment. Be warned: None of the solutions discussed here come with any certification. They might be built using UL certified parts, but that doesn't mean the resulting widget is UL certified. For the JuiceBox and OpenEVSE, the result will be built only as well you personally can manage, because you are the one doing the assembly. An important safety step is to make sure you have ground fault circuit interrupter (GFCI) protected outlets. The JuiceBox includes GFCI protection in the box.

Which of these options is for you depends on your needs and preferences. They all hit the mark for low cost. For the right person one of the completely DIY projects can be fun and rewarding. However, most EV owners will appreciate being able to just buy an EVSE from a store and start charging. For those, either the EVSE Upgrade or pre-assembled JuiceBox are worth a look.

New to EVs? Start here

  1. Seven Things To Know About Buying a Plug-In Car
    A few simple tips before you visit the dealership.
  2. Incentives for Plug-in Hybrids and Electric Cars
    Take advantage of credits and rebates to reduce EV costs.
  3. Buying Your First Home EV Charger
    You'll want a home charger. Here's how to buy the right one.