Selection of EV Charger

Charging technologies are converging in electric vehicles (EV), and it is beginning to offer a clearer picture from the initial confusion.

The key issue related to EV charging is range anxieties. EV newbies are always anxious of running out of juice and would love to have the quickest EV charger everywhere. But do we really need the fastest EV charger at our home, retail malls, or highways? And it is good for the EV batteries? ?

A typical EV today has a range of approximately 400+ km, some as high as 600-700 km, some lower. This is similar to a conventional petrol engine car, where we top-up the petrol after driving around 400-500 km. But do we top-up petrol in our car every day? No, for most of us, it is only once or twice a week driving around town. Typically, we clock around 60-120 km per day for our daily commute. It is only when we are going on a long-distance trip that we need to pump petrol more frequently.

As a rule of thumb, a single-phase 7 kW charger will give approximately 50 km in an hour; a 3-phase 11 kW is 80 km in 1 hour of charge; and a 3-phase 22 kW is 160 km in 1 hour of charge. If the battery is large enough, charging at 7 kW for 10 hours (10pm to 8am) will get us >500 km range.? Most EV will be fully charged overnight from 0 to 100% with a single-phase 7 kW charger.

However, it is not a good practice to run a battery down to zero and to fully charge it up to 100% every time. Latest studies shows that batteries lifespan is extended when we keep it between ~20% to ~80%. The concept of charging a battery to full is like red-lining a petrol engine when we are driving it aggressively.? Red-lining the engine occasionally is OK, but doing this all the time, the engine will breakdown.

Based on typical charging of 20% to 80% for an EV with 400 km range, a 7 kW ac charger can do this in ~5 hours. There are articles published that one 7 kW ac home charger can be used for 2 EVs, charging each one on alternate nights. Alternate night is necessary to allow the battery to be driven down to ~20% before recharging. Charging up to 80%, will still get a range of ~300 km. This is a lot for 2 to 3 days of city driving. As comparison ~300 km will get us from KL to Butterworth (Penang).

Previous plug-in hybrids typically have 30 to 60 km range, requiring us to charge it full every day to max out the driving on electricity. On the other hand, a full EV only need to be charged 2-3 times a week. It is possible to top up the battery to 80% daily, but it is not healthy for the battery to be charged frequently before it is down to ~20%.

A major factor on a battery lifespan is its heating-cooling cycle.? Each time we charge it, it heats up. This is why all EV has a highly sophisticated battery cooling system. The better the heat is managed, the longer the range and lifespan we get out of the battery.? Constantly charging a battery with high kW will cause the heating-cooling cycle to be wider and it will shorten the lifespan of it.

Therefore, DC (direct-current) super-fast charging up to 350 kW is only meant for occasional charging in 20 minutes or less, for long trips. DC is not meant for daily use. Use it daily, the battery will have a shorter lifespan or in the words of WHO - premature death.

For those who are not into EV charging, you should realize by now that EV can be charged with both AC or DC. Each EV has its own limit of AC and DC charging capability. For example, BYD Atto, has a limit of 7 kW for AC and 80 kW for DC. Smart #1 from Mercedes/Geely, has a limit of 22 kW for AC and 150 kW for DC. Tesla has a limit of 11 kW for AC and up to 250 kW for DC. ?

In Malaysia, we are lucky to get 3-phase electricity in many developments. This allows a 3-phase, 22 kW ac charger to be installed easily and at a much lower cost than a DC charger. A 22 kW ac will have a charging time from 20% to 80% in ~1.5 hours.? Unfortunately, it is rare for an EV today to benefit from a 22 kW ac charger.

Most Chinese and Japanese EVs are only capable of 7 kW ac, because in these countries, they only get single phase electricity to their homes. While there are many new EVs with 11 kW ac charging, only a few rare ones have 22 kW ac charging. We can always plug-in a 22 kW ac charger, but the EV will only draw at 11 kW or 7 kW, depending on its capability.

It does make a lot of sense for restaurants, coffee houses, malls, and retailers to provide a few 22 kW ac to attract EV to park there for added business opportunities, especially if it is along a road for long distance travel. A 22 kW ac will need 1 to 2 hours for a full charge for most EV, and it is perfect for a meal, drink, or light shopping. Most importantly, it is not that expensive to install a 22 kW ac charger if the premise is already provided with 3-phase electricity. A super-fast DC is more expensive because it requires additional infrastructure to support it. ?

For a hotel operator, it may be more interesting to install many 7 kW ac chargers, to ‘nudge’ the EV guest to stay overnight for a full charge with them.

On highways and trunk roads for long-distance travel, DC super-fast charging is the way to go, as we want to get out of the place fast. Unfortunately, 15 to 30 minutes of charge is still much slower than pumping petrol. However, this 15 to 30-minute break is perfect to recharge the driver after driving 2.5~3 hours nonstop (~ 300 km) on a highway. Drowsiness is a major cause of accidents.

To charge at home? One 7 kW ac charger is easily adequate for 2 EVs. It is not necessary to go for higher kW because we have the entire night to charge it. And if we are in a hurry, it is better to look for a super-fast DC charger nearby. Many car showrooms have installed such super-fast DC charger that is open to public. And with apps like JomCharge and ChargeEV, it is easy to find the nearest locations for fast charging. At 150 kW charging, 15 minutes can get up to 270 km range or more (depending on the efficiency of the EV). 15 minutes is just a long toilet break for some.

In this transition to electricity, we recommend providing a single-phase 7 kW ready charging point to all residential home car parks, as we have the entire night to charge it. Moreover, a 7 kW ac charger is better for the EV battery because it maximizes its lifespan. ?It is not necessary for 3-phase electricity to be provided for homes. In our humble opinion, 3-phase is more meant for retailers to attract customers to spend time at their premises, and DC super-fast chargers are meant for long road trips.

Finally, I would like to give a shout out to a good friend of mine, Lee Yuen How , a highly entrepreneurial greenies, who started JomCharge more than 8 years ago. He installed personal charging points at our existing condo >5 years ago and is now a leading EV charging station installer/supplier in Malaysia and Singapore. He is my go-to ‘sifu’ for all my charging station needs.