Designing Electric Vehicle Battery Charging Solutions. DIY ev charger

Designing Electric Vehicle Battery Charging Solutions

The popularity of electric vehicles (EVs) is increasing rapidly in India. According to a survey, the EV market in India is estimated to increase from 3 million units in 2019 to 29 million units by 2027 with a CAGR of 21.1%. As a result, demand for AC/DC chargers and Smart EV chargers will also increase.

In order to charge the batteries efficiently and to ensure their long life, we need Smart battery management or charging system. To realize such EV charging stations, Holtek has come up with Smart Electric Vehicle Battery Charging Solutions based on their low-cost ASSP flash microcontroller (MCU) HT45F5Q-X for charging EV batteries.

At present, three EV charger designs suitable for the Indian market with specifications of 48V/4A, 48V/12A, and 48V/15A are available for Rapid development of the product. This semiconductor-based Smart charging system can support both lithium-ion as well as lead-acid battery types.

EV Charger Block Diagram

The Block diagram of the Electric Vehicle Battery Charging Solution is shown in Fig. 1. Here, battery charger ASSP flash MCU HT45F5Q-X is the heart of the EV charger circuit with in-built operational amplifiers (OPAs) and digital-to-analog converters (DACs) that are necessary for battery charging function.

Designers can choose an appropriate MCU from the HT45F5Q-X series according to their application requirements.

Specifications of the battery charger flash MCU HT45F5Q-X series are shown in Fig. 2.

The features and working of the EV charger solution for 48V/12A specification are briefly explained below. This EV charger design utilizes HT45F5Q-2 MCU for implementing the battery charging control function.

The MCU incorporates a battery charging module, which can be utilized for closed-loop charging control with constant voltage and constant current for efficiently charging a battery. The internal block diagram of MCU HT45F5Q-2 is shown in Fig. 3.

The battery charging module in HT45F5Q-2 has built-in OPAs and DACs that are needed for the charging process. Therefore the design reduces the need for external components like shunt regulators, OPAs, and DACs, which are commonly used in conventional battery charging circuits. As a result, the peripheral circuit is compact and simple, resulting in a smaller PCB area and a low overall cost.

EV Charger Working

Input power to the EV charger is an AC voltage in the range of 170V to 300V. The EV charger uses a half-bridge LLC resonant converter design, because of its high-power and high-efficiency characteristics, to obtain DC power for charging the battery.

The design utilizes a rectifier circuit for converting input AC voltage to high-voltage DC output, and it also has an electromagnetic interference (EMI) filter to eliminate high-frequency noise from the input power source. A pulse-width modulation (PWM) controller IC, like UC3525, can be used for driving the MOSFETs of the half-bridge LLC converter.

The battery charging process is supervised by the MCU HT45F5Q-2. It monitors the battery voltage and charging current levels and gives feedback to the PWM controller IC. Based on the feedback, the PWM controller varies the duty cycle of its PWM signal and drives the MOSFET circuit to obtain variable output voltage and current for charging the battery.

For better protection, HT45F5Q-2 is isolated from the rest of the circuit (i.e. high-voltage components) using a photo-coupler. Battery-level LED indicators are provided for knowing the charging status.

EV Battery Charging Process

The change in charging voltage and current during the charging process is graphically illustrated in Fig. 4. If the battery voltage is too low when connected for charging, low charging current (i.e. trickle charge (TC)) will be set initially, and the charging process will start.

When the battery voltage increases to a pre-defined level (Vu), constant voltage (CV) and constant current (CC) are applied for charging and continued until the battery is fully charged. The battery is considered to be fully charged when the voltage reaches VOFF. When the charging current drops to Iu, the final voltage (FV) is set.

designing, electric, vehicle, battery

The voltage, current, and temperature control processes in this EV charger are explained below.

(a) Voltage Control

The charging voltage is decided based on the initial voltage of the battery when it is connected for charging. As the charging progresses, the charging voltage changes accordingly, and finally, when the battery is fully charged, the final voltage is set. The charging-voltage decision levels for the 48V/12A battery charger are explained below.

  • If Battery Voltage
  • If Battery Voltage
  • If Battery Voltage 40V, CC(12.0A) Charging, Voltage Setting CV(58V)
  • When fully charged, the voltage is set to FV(56V). If the battery voltage is lower than FV, the charging current will be reset to CC (12.0A).

(b) Current Control

The charging current is set depending on the battery voltage. Initially, if the battery voltage is too less, a trickle-charge current would be set for charging the battery. Once the battery voltage reaches a certain level, a constant current is supplied for charging, until the battery is charged fully. The charging-current decision levels for the 48V/12A battery charger are listed below.

(c) Over-temperature Protection

The EV charger has a negative temperature coefficient (NTC) thermistor to monitor the temperature and a fan to regulate the heat. When the temperature increases, the fan is automatically switched on to dissipate the heat; it gets switched off when the temperature is reduced to the lower set threshold. Also, the fan turns on when the charging current is high and turns off when the charging current is low.

  • When NTC temperature 110°C, the charging current will be reduced to 50% of the charging current and will be monitored periodically

(d) LED Indications for Charging Status

  • TC charge, red light flashes slowly (0.3 sec on, 0.3 sec off)
  • CC, CV charge, red light flashes quickly (0.1 sec on, 0.1 sec off)
  • When not charging, the green light is on
  • When charging time exceeds eight hours, red and green lights are bright

(e) Charging Duration

EV Charger Circuit Diagram

The schematic of the Holtek EV charger design for 48V/12A type is shown in Fig. 5 for reference and its PCB assembly is shown in Fig. 6.

The ASSP flash MCU HT45F5Q-2 can also be used for designing higher-wattage solutions. It offers a programmable option for setting parameter thresholds, which makes it very convenient for EV charger designs. Holtek provides technical resources such as block diagrams, application circuits, PCB files, source code, etc. to help designers in Rapid product development and speed up time-to-market.

EV charger development platform for the HT45F5Q-X series will also be available soon. Using this software tool, users would be able to easily select the charging voltage/current and other parameters to create a program. This application will also be able to generate a program containing a standard charging process, thereby significantly simplifying the development process.

Krishna Chaitanya Kamasani is the director – India operations at Holtek Semiconductor

34 Комментарии и мнения владельцев

I also worked on battery charging with ,24v alternator runnig with motor iwas getting 28v with 1800 rpm which I put on two wheeler vehicle for mr leon who apporach to me for vehicle charging in running

Sir i want to built a EV charger that can delivers 48V,12A output,but in the circuit diagram components values are not given.plz send a circuit diagram that has all the component values.

designing, electric, vehicle, battery

Sor The average capacity of the EV battery is 32 KVA. May you provide circuit diagram and details for 32 KVA battery. And also for on board (in vehicle) circuit diagram. I shall be very much thankful for your kind deed please.

Can the circuit be modified to charge Lithium battery of E-rickshaw from 90 V solar panel at roof to boost range of travel ? If yes, please share circuit idea and codes.

Sir, I am also in a startup to design Battery array charging circuit for EV batteries (Li-ion) Request you to share the Circuit diagram with component list and quotation of the same.

EV Charging Explained: How to Make Your Home EV Ready

About to buy a new EV? Make sure your home electric system is up to scratch first!

Readers like you help support MUO. When you make a purchase using links on our site, we may earn an affiliate commission. Read

EVs are seemingly everywhere now. However, it wasn’t uncommon a while back to go days without seeing an EV, but now the EV craze is making EV sightings more common than ever. With this explosion of EVs, many people ask themselves if they should buy one.

The great news is that buying an EV is simple, especially the charging aspect, which many people are reluctant about. Still, many people wonder how you can charge your EV at home and what steps are required to up the ante and charge your EV in a faster manner from home as well.

What Is EV Charging?

Electric vehicles run off of electricity that powers their electric motor. In contrast to gasoline-powered cars, you can charge your vehicle at home and never have to worry about refueling pit stops (especially if your commute is local). An EVs lithium-ion battery pack allows the vehicle to store power, which is later used to power the electric motor (or motors in the case of vehicles like the amazing feature-packed Rivian R1T).

designing, electric, vehicle, battery

Electric vehicle charging is quite simple. At the core of it, you’re basically getting power from your home’s grid and supplying it to your vehicle via a cable. Of course, charging times vary, depending on the type of outlet you’re using. But the great thing is that EVs include a basic 120V charging cable that you can connect to your conventional outlets at home and get charging immediately.

Level 1 Home Charging

Depending on your needs, you might need to make some modifications to your home, or you might simply be able to use the supplied 120-volt cable to charge your car without any additional work. EV manufacturers already supply a cable to charge your vehicle, so why not try this out before modifying your home.

The supplied 120V charging adapter is known as an L1 (level 1) charger. This adapter will charge your vehicle using your home’s standard 120V infrastructure and can recharge your vehicle at a rate of approximately five miles of range per hour of charging.

This doesn’t sound like much, but you can recuperate about 50 miles of range if you leave your car charging overnight. If your commute is less than 50 miles per day, then you really don’t require an L2 charger, which is great news. Charging a lithium-ion battery to 100% constantly isn’t the best for its battery life, so using the L1 charger overnight also ensures you can protect your battery long-term.

Not only this, it can’t be overstated how convenient it is to have a charging solution for your vehicle that you simply plug into a conventional outlet and can immediately begin charging your car. It truly is plug-and-play. The fact that most EVs allow you to program when your vehicle begins charging is also a huge advantage because you can schedule your vehicle’s charging to begin at the cheapest rate hours on your local grid.

Level 2 Home Charging

On the other hand, if you need to charge your vehicle faster due to a more demanding daily commute, the answer is an L2 (level 2) home charger install. The L2 system actually uses 240V power, and as an example of how fast it can charge your vehicle, Enel X Way says their JuiceBox charging stations can add anywhere from 12 to 60 miles of driving range per hour. L2 chargers can also be found for public use, and if you’re lucky, you might be able to charge your EV for free.

Even at the minimum end of the range, this is way faster than the conventional L1 charger and can top your vehicle off to 100% during the same timeframe an L1 charger would fail to do so. However, the installation procedure for an L2 charger and charging station for your home is more involved, and it’s recommended that you consult an electrical professional in your area, so they can inspect your home and determine the necessary installation procedures.

If you already have a 240V outlet (the same type of outlet your washing machine plugs into) in your garage, then you likely have almost everything you need. Regardless, it is still recommended that you talk to a professional, so they can let you know if it’s safe to install the L2 charger and run it off of your home electrical infrastructure.

If you don’t have a 240V outlet at the ready, an electrician will need to modify your electrical system and install an outlet that supports 240V, so the charging station can plug into it. There are also charging stations that can be hardwired into your home electrical system instead of simply plugged into a 240V outlet. These hardwired stations are sometimes mandated if you install them outside.

Even though L2 chargers are not a necessity, many people will decide to install them for peace of mind. It’s a great feature to have, even if you don’t use it every day. An ideal scenario for one of these L2 chargers is in preparation for a long road trip. You can simply charge your vehicle overnight and be ready for the road with 100% battery. After you leave home, you can schedule your trip through a charging app like ChargePoint and plan accordingly to see where you want to make charging pit stops.

L2 Chargers Will Become the Norm for Home EV Charging

As more and more EVs are sold, the dilemma of installing an L2 charger in your home will slowly become a problem of the past. EVs will be standard fare transportation in a few years, and most new homes will be constructed with electric vehicles in mind.

It’s not farfetched to imagine most new homes will include L2 charging infrastructure, or perhaps even L3 charging in luxury homes. A good way to increase the market value of an older home is to implement EV-friendly electrical infrastructure in your home, and adding an L2 charger is a great start.

DIY Solar EV Charging Station Design | Charge Electric Cars With Solar Panels

If you already own an electric vehicle (EV) or plan to do so, you should seriously consider charging it with the sun. Solar power is fast becoming the good guy on the block as far as clean energy is concerned.

If at the moment you charge your electric vehicle with electricity from the grid, your utility expenses will definitely increase and also you’ll be putting more demand on the grid. It´s often said that EV driving is completely green but of course this isn´t true.

All of the raw material that comes out of the ground to manufacture an EV has to be mined and processed, which at the moment is done using machines powered by hydro-carbons. If the electricity grid in your country is fired by hydro-carbons as well, then the problem is compounded.

In fact it’s been calculated that an electric car running from a ‘dirty’ grid is about as eco as a modern diesel car – there’s a long way to go! The future may see electric vehicles with solar photovoltaic panels embedded in them but at present plugs and sockets are used to charge EVs so that’s what we have to deal with.

When did electric cars become popular?

Electric cars early 1900s

The heading is a bit of a trick question. Most people think of electric cars being a modern inventions, but not so.

If we look back at the records from Dept. of Energy, USA, from the time when vehicles were powered by horses, patents using electricity to power vehicles were filed initially in Hungary, the Netherlands and the USA during years 1828-1835.

Five decades later the first electric vehicle built by William Morrison was shown to the amazed public in the USA. During the end of 19th century electric vehicles actually gained popularity against gas and steam powered vehicles because of their environment friendly nature and ease of driving.

At the beginning of 20th century around 1900-1912 about one third of all vehicles in the US were EVs. During the same time Thomas Edison actively worked on batteries for electrical vehicles and Ferdinand Porsche built the first hybrid EV. In around 1920-1935 petroleum-based vehicles overtook the EV share and EVs went extinct from the roads.

“Dr. Evlyn Farris and her Electric Car in 1919” by jurvetson is licensed under CC BY 2.0

Three decades later when gasoline touched their peak, EVs were again considered as worried industrialists could foresee a time when hydrocarbons disappeared.

The first electric rover on moon in 1971 made also an impact, many people realizing that the vehicles were viable in all kinds of environments. Since then the momentum has gather pace until we can see a time when all vehicles will be electric.

Warming of the planet and dirtiness of fossil based fuels is enticing automobile manufacturers and buyers to turn their heads more and more towards EVs, but this uncovers another problem – how are we going to charge millions of EVs with our national grids? Solar energy has to take up the slack!

What types of EV are there?

In general, electric vehicles are categorised as follows:

Hybrid electric vehicles (HEV) in their pure form are those which use regenerative braking and a gasoline engine to charge the battery. There are different types of HEVs but none of them charge their batteries from an external charge point or socket. Specifically, in full HEVs an electric motor assists the engine to drive the wheels. This makes it more energy efficient than conventional vehicles and also more environment friendly.

Plug-in hybrid electric vehicles (PHEV) are those HEVs which can be plugged in to be charged. They also have a gasoline engine and battery powered electric motor to move the vehicle.

Additional battery charging makes PHEV an all electric vehicle when it runs only on battery and the engine assists when the battery capacity is exhausted. It is better than HEV for its energy efficiency and environment friendly design.

All Electric Vehicles (AEV) do not have a gasoline engine in them and are totally dependent on an electric motor and batteries to drive them. Regenerative braking and other energy efficient features with external charging equipment make it an all electric vehicle or AEV.

In conventional vehicles the engine and its capacity defines the power of that vehicle and that capacity is to explode gasoline or diesel with force and speed to drive the shafts turning the wheels of that vehicle. The gasoline or diesel is required to be poured in the vehicle to store it there and use it while driving.

Similarly in EV, electricity is to be poured in and stored in batteries. This electricity or electrical energy is stored in form of chemical energy in batteries. This chemical energy is again transformed to electrical energy to turn the electric motor which drives the shafts turning the wheels of that EV.

The battery is the most important component of an electric vehicle if it is an all electric vehicle (AEV). HEV and PHEV still have combustion engines in them so that makes engine and battery both essential components depending on usage. If we just concentrate on the EV and battery part of the subject, there are different types of batteries.

Electric Vehicle Battery Technology

What type of batteries are in EV cars?

The number and types of batteries available makes a long list indeed, all with different chemical compositions, usage and design.

Out of that list lithium ion batteries currently power the ‘All Electric Vehicles‘ or AEVs. The lithium ion batteries are again split into various types depending on their mineral components.

The chemical symbols are used as identifiers, like Lithium Manganese (LMO) and Lithium Nickel Cobalt Aluminium Oxide (NCA) batteries which are currently the best rechargeable batteries in use in AEVs today.

What technology is used in electric car batteries?

Nickel Metal Hydride (Ni-Mh) batteries are used in hybrid electric vehicles or HEVs because of their performance but are not very good if used as rechargeable battery in AEVs because of high cost and high self discharge.

Lead acid batteries and Ultracapacitors are also used in EVs to take care of electrical load other than the main drive train of the vehicle – they do so in a very efficient and cost effective manner. Ultracapacitors also help in additional power boost to the vehicle, if designed to do so.

Electric Vehicle Battery Capacity Comparison

Let us have a look at some basic characteristics of Nickel Metal Hydride (NiMH), Lead-acid and Lithium ion (Li-ion) batteries in the table below.

EV Charging Installation

The next generation of EV charging has arrived, giving customers clean, reliable, and efficient power to recharge their battery vehicles.


When you install an Electric Vehicle Charger (EV) in your home, you can enjoy the convenience of “refueling” at home every day. With your personal electric car charging station you will ALWAYS be ready to go.

We offer a Free Home Evaluation to determine the best location and type of installation that would best fit your needs and budget.

You made a great choice to purchase an Electric Vehicle and DIY Go Green can assist you with any electric vehicle chargers on the market. We have experience with all charger manufacturers and offer chargers which work with every electric vehicle. If your vehicle has a plug we can provide you with a solution to “refuel” your vehicle at home.

How It Works

  • #1 One of our EV Consultants will come out to your home and consult on the best place to install your car’s charger.
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A Reward for Fueling With Clean Energy

If you drive a new or used Electric Vehicle (EV), you may be eligible to receive a 450 Clean Fuel Rebate. By driving an EV, you’re contributing to a cleaner energy future.

The Clean Fuel Rebate is funded by the State of California’s Low Carbon Fuel Standard Program, which helps combat climate change by encouraging the use of clean fuels, like electricity, in vehicles. Read Here

Install an EV charging station

Having the option of charging your electric car at home is crucial to ensuring that you’re fueled up and ready to go whenever you need it. There are three types of electric car charging stations. Each has their own installation process.

Installing a Level 1 electric vehicle charger

Level 1 EV chargers come with your electric vehicle and don’t require any special installation – simply plug your Level 1 charger into a standard 120 volt wall outlet and you’re ready to go. This is the biggest appeal of a Level 1 charging system: you don’t have to deal with any extra costs associated with an installation, and you can set the entire charging system up without a professional.

Installing a Level 2 electric vehicle charger

A level 2 EV charger uses 240 volts of electricity. This has the benefit of offering faster charging time, but it requires a special installation procedure as a standard wall outlet only provides 120 volts. Appliances like electric dryers or ovens use 240 volts as well, and the installation process is very similar.

Level 2 EV charger: the specifics

Level 2 installation requires running 240 volts from your breaker panel to your charging location. A “double-pole” circuit breaker needs to be attached to two 120 volt buses at once to double the circuit voltage to 240 volts, using a 4-strand cable. From a wiring perspective, this involves attaching a ground wire to the ground bus bar, a common wire to the wire bus bar, and two hot wires to the double-pole breaker. You may have to replace your breaker box entirely to have a compatible interface, or you may be able to simply install a double-pole breaker in your existing panel. It is essential to make sure that you shut off all power going into your breaker box by shutting off all breakers, followed by shutting off your main breaker.

Once you have the correct circuit breaker attached to your home wiring, you can run your newly installed 4-strand cable to your charging location. This 4-strand cable needs to be properly insulated and secured to prevent from damage to your electrical systems, especially if it is being installed outdoors at any point. The last step is to mount your charging unit where you will be charging your vehicle, and attach it to the 240 volt cable. The charging unit acts as a safe holding location for the charge current, and doesn’t let electricity flow through until it senses that your charger is connected to your car’s charging port.

Considering the technical nature and risk of a Level 2 EV charger DIY installation, it is always Smart to hire a professional electrician to install your charging station. Local building codes often require permits and inspections by a professional anyways, and making an error with an electrical installation can cause cause material damage to your home and electrical systems. Electric work is also a health hazard, and it is always safer to let an experienced professional handle electric work.

Professional installation can cost anywhere between 200 and 1,200 depending on the company or electrician you work with, and this cost can rise higher for more complicated installs.

Pairing your EV with rooftop solar is a great combined energy solution. Sometimes solar installers will even offer package purchase options involving a full EV charger installation with your solar installation. If you’re considering upgrading to an electric car sometime in the future, but want to go solar now, there are a few considerations that will make the process easier. For example, you can invest in microinverters for your PV system so that if your energy needs increase when you buy your EV, you can easily add extra panels after the initial install.

Installing a Level 3 electric vehicle charger

Level 3 charging stations, or DC Fast Chargers, are primarily used in commercial and industrial settings, as they are usually prohibitively expensive and require specialized and powerful equipment to operate. This means that DC Fast Chargers are not available for home installation.

Most Level 3 chargers will provide compatible vehicles with about 80 percent charge in 30 minutes, which makes them better suited for roadside charging stations. For Tesla Model S owners, the option of “supercharging” is available. Tesla’s Superchargers are capable of putting about 170 miles worth of range into the Model S in 30 minutes. An important note about level 3 chargers is that not all chargers are compatible with all vehicles. Make sure you understand which public charging stations can be used with your electric vehicle before relying on level 3 chargers for recharging on the road.

The cost for charging at a public EV charging station is also diverse. Depending on your provider, your charging rates may be highly variable. EV charging station fees can be structured as flat monthly fees, per-minute fees, or a combination of both. Research your local public charging plans to find one that fits your car and needs best.

Install an EV charger at home at home with Qmerit

EnergySage partners with Qmerit, a home EV charging installation leader who works with a trusted network of certified installers. They can help you quickly and easily install your home EV charger.

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