EV Charger Selection

How to select EV charger power output and type?

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When selecting EV charging hardware for your depot, you need to make some simple decisions and some more complex ones. The EV charging era has progressed past the early adopter stage, which means there is more information available. You can learn from other case studies to get answers to common questions.

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• Which charger type works best for your type of fleet? 
• Which charger brand is reliable and affordable? 
• How many chargers do you need for your fleet? 

For instance, if you operate a last-mile site with electric vans charging overnight, you’ll probably want to install chargers with 5-20 kW power output. If you’re in Europe this means AC chargers or if you’re based in the Americas it means DC chargers.

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5 to 20 kW chargers allow you to charge the vehicles slowly overnight, potentially charging 2 or 3 vehicles per night.

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However, each site is slightly different and has its own challenges. 

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• Do you have ground staff on site who can swap the vehicles? 
• Do you have enough space to install a 1:1 ratio of charger and vehicles? 
• Do you need third-party access for contractors or similar?

To help you decide upon the best charging infrastructure to meet your needs, we typically run software simulations. For instance, below you’ll see simulations for a fleet charging overnight a) with slower AC chargers, and b) with faster DC chargers.

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If you operate larger vehicles, such as semi-trucks or transit buses, then you must install DC fast chargers (DCFC). While there is a buzz around these types of chargers in the press as they are big and offer a high power output, there are significant downsides such as high installation costs, expensive O&M, and high power demand to establish a grid connection.

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When you install DCFCs, you'll typically find the power output is in the range of 20-700 kW. In some cases you might even install ~1MW chargers. However, the most common range at the moment is 75-360 kW. 

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Deciding Between Single or Multi-Dispenser EV Chargers

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The more important question is how to set up these chargers and maintain power distribution. In general you can differentiate between single dispenser DCFCs (one plug per charger) or multi-dispenser DCFC (>2 plugs per charger). A multi-dispenser setup is where you have one large power cabinet (including the power modules) which supplies power to multiple chargers. The advantage of this setup is that you need less space in the parking lot with power modules  shared between plugs. This makes it more cost effective overall. 

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However, the downside of multi-dispensers is more complicated power management. Additionally, if one main cabinet is faulty, this could mean two or more plugs are out of operation. Single dispenser chargers don’t have this problem, but are typically more costly and need more space.

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Choosing a Right EV Charger Brand

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Selecting your charger brand is at least as important as selecting your EV brand. The decision is more theoretical and can be more complex. Your decision is not only based on purchase price. Instead, you evaluate total cost of ownership of the charger, support options, warranty, grant options, and technical feasibility.

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The most common challenges we’ve seen amongst our sites include the following.

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• EV charger manufacturer has poor support and responds to tickets slowly
• Onboard software is unreliable. Updates are slow or cause operational problems.
• Components break often and need constant maintenance

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If you’re planning to operate hundreds of EV chargers, you’re looking to partner with a charger brand for the next ten years, at least. We’ve seen very successful partnerships with European or American companies. We’ve also seen good partnerships with Asian brands that often come at a lower price point and have more experience in the larger Chinese EV market.

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The best way to simplify your selection process is to down-select or shortlist 3 or 4 brands, then  test them in a lab or with a simulation software partner like Ampcontrol. You’ll quickly identify which ones work best and highlight potential good partners. You might also want to select two charger brands instead of one. This reduces the chances of vendor lock-in and minimizes your long-term risk.

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