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Batteries, The big deal.

The batteries world is in constant change nowadays with the electric vehicles take off , the new and improved power storage, super capacitors, and the new kid on the block, graphene.

Lead batteries and AGM or gel are a thing of the past. We are now having the Li-ion present going to the new Li-air future.

The necessity of longer trips, fast charging times a better performance are a must in electric vehicles, and more and more, those demands are the big deal in EV.

Fresh air, still to come.

Till now, the obvious technology in the batteries department has been lithium-ion. But since some time ago, a new technology based in air is the real interest for manufacturers and EV developers. The new Li-air promises up to 10 times the energy density of their cousins li-ion. IBM´s project 500 has the aim of driving 500 miles in one single charge  in a family car using those new batteries. Although this has been achieved already by the Metron Institute (Slovenia) with LiFePo4 technology.

Li-air cells

The way it works is, a Li-air cell uses cheap carbon as a cathode (instead of cobalt), a molecule of a oxygen pivots through the cathode and gives the battery its name. But it has remained theoretical because of its big challenges. Among them: the other electrode in such batteries—the anode—is pure lithium metal, which provides a lot of energy but also ignites when exposed to water, carbon dioxide, or other contaminants.

Such is the challenge, that IBM and JCESR (Joint Center for Energy Storage Research) have decided to step back from the LI-air project, and IBM has turned his favour to a Lithium Sodium technology.

Li-Na cells

But with all these changes, a new development continues, and metal chemistries are also under development, in particular Aluminium-Air. An Israeli company (Phinergy), has claimed to solved corrosion, and recharging issues with a silver based catalyst. A prototype EV claimed to have 1600km range with Al-air batteries. However those cells cannot be electrically re-charged having to re-load them mechanically and topped up with water.

It smells sulphur.

Lithium Sulphur cells are another energy dense technology that could solve the needs for the EV in a near future. This new chemistry tends to solve issues like life cycle and stability. Based around a carbon based electrode, those cells are said they could go ahead Li-air technology.

Li-S cells

Many studies and research from Imperial College (London)  to German company BASF are putting their efforts into Li-S. They said this could be the 4th generation of batteries, expecting ranges of 400Kms in the next decade. Scientists at Lawrence Berkeley Labs (California) have introduced graphene oxide into Li-S cells that are said to deliver 1,500 charge cycles without deterioration.

Other researchers from ETH Zurich are working with Sodium-ion cells, stating that are much cheaper than Li-ion. But they have two major problems; they are three times heavier than lithium and tend to lose capacity when not in use.

Lithium Ion are here to stay.

Despite all the development in the power storage field, one thing is clear, most of EV at the moment go for Li-ion, and the fact that manufacturer are offering cheaper prices and even Tesla is building a new Lithium batteries plant, makes you think that in the long term this technology is here to stay.

Li-ion cells

Li-Ion developers, Bosch, GS Yuasa and Mitsubishi, claim that the could reduce the prices to half in the Li-ion filed, and double the capacity, that would make EV much more approachable to normal consumers.

There are also many new promising developments with carbon, but the gap between the lab and the factories is too big to stop producing Li-ion for EVs.

graphene cells

The magazine “Electric & Hybrid Vehicle Technology International” writes in their July 2014 issue about the carbon:

“The real deal?. A new type of dual-carbon battery technology that could potentially be a game changer for EVs has been launched by a Japanese R&D company. Called Ryden, the new battery is said to offer energy density that’s comparable to Li-ion products, but over a much longer functional lifetime with far improved safety and cradle-tocradle sustainability, says Power Japan Plus, which will begin production of the cells later this year at its manufacturing facility in Okinawa, Japan. The Ryden battery makes use of a completely unique chemistry, with both the anode and the cathode made of carbon. “Power Japan Plus is a materials engineer for a new class of carbon material that balances economics, performance and sustainability in a world of constrained resources,” says CEO Dou Kani. “The Ryden dual-carbon battery is the energy storage breakthrough needed to bring green technology such as electric vehicles to mass market.” Kani says that the Ryden battery balances a breadth of consumer demands previously unattainable by a single battery chemistry. In terms of performance, the new battery is not only energy dense and operates at above four volts, but also offers a charge time that’s 20 times faster than that of current Li-ion designs.

dual carbon cellsThe Ryden technology has been created so that it can slot directly into existing manufacturing processes, requiring no change to existing manufacturing lines. Furthermore, the battery enables consolidation of the supply chain, with carbon being the only active material used. As a result, manufacture of the Ryden battery is under no threat of supply disruption or price spikes from rare earth materials, rare metals or heavy metals. According to Power Japan Plus, its technology is the first high-performance battery that meets consumer cycle-life demands, being rated for more than 3,000 charge/discharge cycles. The breakthrough also eliminates the unstable active material used in other high-performance batteries, thus greatly reducing fire and explosion hazard. Furthermore, the new battery experiences minimal thermal change during operation, eliminating the threat of a thermal runaway. Finally, it can be 100% charged and discharged with no damage. Adding to the sense that the Ryden battery could be a key moment for EVs is that it is 100% recyclable, vastly improving the cradle-to-cradle sustainability of battery technology. As an add-on to this, Power Japan Plus is testing the battery with its organic carbon complex material, working toward the goal of producing the battery with all-organic carbon in the future. Made of naturally grown organic cotton, the carbon complex exhibits properties not seen in other carbon materials. By controlling the size of the carbon crystals during production, Power Japan Plus can engineer the carbon complex for a variety of applications.”

Which vehicles are best to convert to electric.

There are hundreds of thousands of cars out there waiting to be converted. The best cars to be converted to electric are small old cars. The older is de car, the less electronic components it has and the easier will be the conversion.

As the batteries are still the big issue in a conversion project, regarding the weight and the price, the only way to minimize this aspect is by installing the less battery modules possible, and this can only be achieve nowadays by using a donor car that needs little electric power to drive, therefore it will need few batteries to run.

Another advantage in this philosophy is financial cost in the project. An old car will always cost you less than the equivalent two years old car. The Mini may be the exception in this case, but hey, it is a Mini.

Here are some examples or perfect old cars easily convertible, and examples of their prices in the second hand market.

o    Renault twingo

 30_renault_twingo30_renault_twingo_precio

o    Fiat Punto

31_Fiat_Punto

31_Fiat_Punto_price
o    Citroën AX

 32_Citroen_AX

32_Citroen_AX_price

o    Ford Ka

39_Ford_ka

39_Ford_ka_price
o    Mini

33_mini

33_mini_price
o    Nissan Micra

 34_nissan_micra

34_nissan_micra_price

o    Open Corsa

35_Open_Corsa

35_Open_Corsa_price
o    Peugeot 205

36_Peugeot_205

36_Peugeot_205_price
o    Seat Ibiza

37_Seat_Ibiza

37_Seat_Ibiza_price
o    Volkswagen Polo

38_Volkswagen_Polo.jpg

38_Volkswagen_Polo_price

How to convert your car to electric?

quien mato el coche electricoWhen I had the idea of converting my own car to electric, I had two goals in mind. To be able to drive a novel car, that wouldn´t make any noise and the cost for the fuel be little or nothing.  The other goal was to stop once for all contributing to dirt our environment and be able to tell the rest of the people “Yes, we can”, now days you also can have an electric vehicle exactly as it was at the beginning of the 20th century in New York (See the documentary “Who killed the electric car?” ).

Little by little, this idea was more and more real, asking other people, researching on the net and other countries where this was already a reality, I started the project of building an electric car.

Choosing a donor car.

The first step, once everything is clear, was to choose a cheap car and appropriate for the project The best cars are old vehicles o classic cars. The reason for this is because they are not complex in their design and electronics are not playing an important role in the car functions.  There is no need to be afraid at this point, nothing anyone can overcome reading a bit about the chosen car.

01_renault_twingo_elelectricAnother important requirement is the car to be light in weight, less than 1000 Kg is more than adequate, and 800Kg is ideal.  The reason behind this is the resistance the car has because of the friction in the roads, the more resistance, the more electric energy it will need to drive.

There is also other elements that a high speed affects the performance as the Aerodynamic coefficient, but this will leave it for the time being.

The old Renault Twingo is a car that weights very little, it doesn’t depends much on electronics (it doesn’t come with power steering or automatic gearbox). So I decided to get a cheap second hand Twingo and I spent 500€.

 

 

And now, the motor.

The motor is something you need to spend some time researching on it to take the correct decision. By choosing a small car, the motor doesn’t have to be very powerful, so a 7 to 15 Kw motor can be just perfect. There are two kinds of motors:  DC motors (direct current) and AC motors (alternating current). The first ones are cheaper, more accessible in second hand markets or scrap yards, but they are less efficient. The second ones are more expensive; they weigh less and are more efficient. Then according to other technical aspects are synchronous motor and asynchronous, also other with permanent magnets, which supposed to be top of the list. As examples, there are 7 Kw motors from China that cost less that 1000€, while in Europe or USA you can have 15 to 25Kw motor between 2000 and 4000€. I decided to go for an Slovenian 14 Kw motor, branded Letrika. I knew this provider at the electric car fair EVS27 in 2013.

Motor electrico

Motor electrico

Lets go to the motor controller.

This is one of the main components, it is also one of the most expensive and it goes paired with the motor for two reasons: One, it is the one in charge to convert the batteries electric power to the correct voltage necessary for the motor, and the second, to regulate the speed of the motor, so the controller needs to be designed for it. As with the motor, there are DC controllers and AC controllers. The good news is that most of the motor manufacturer they also do the controllers, and if the don’t, normally the motor can be configured for generic configurable controllers.

Controllers are also classified according to the maximum current they can feed, the more current and voltage, the more powerful l the motor will be. There are several brands as Brusa, Curtis, Sagem, ..

 

03_curtis_controllerI got a Curtis controller, medium range for AC motor, the Curtis controller 1236. Most of the controllers are programmable, so you can adapt it to your own motor. You will have to study a bit about variety and features of the controller best suits you.

 

 

And we get to the batteries, the queens.

Batteries are the most important element in a electric vehicle, as they will define how much power and how much range the electric car will have. I hope one day this element will be the less important, but for the time being, this technology is more complex than we may think. The appropriate batteries bank is conditioned by the maximum distance the car will drive in one single char and also the charger and the BMS (Battery Management  System).  Not all kind of batteries can be charged or discharged in the same way, if you don’t follow the manufacturer requirements and limits, batteries can be affected and their life span be reduced.

There are several technologies in the market right now, but in practical terms we can talk about 3 or 4 types. Lets start by the cheap ones.

04_lead_batteryLead Batteries. They are the cheapest ones, but the least suitable  ones because its design, as they are not design to provide a constant current all the time, but to provide a very strong one in one go, and this is not what a controller for a electric motor needs. The good news for a budget car, is that even dead, you can re-acconditionate them or de-sulphate them. This is a delicate process as the content inside the batteries is sulphuric acid, so if you are a bit un-sure of what you are doing, better not to try. I have done it being very careful, and following all the security precautions and using protecting gloves, glasses and mask (in an open environment), at the end you need to neutralize the acid with sodium bicarbonate before wasting it to the sink. You can also buy them to avoid all this hassle. They are very heavy, but can be charged with any standard charger.

 

05_72V_agm_batteriesAGM or gel batteries.  Those are deep cycle batteries, they are lead batteries with more efficient electrolyte gel. They are a bit more expensive but they are designed for electric cars. They are very heavy too, and there are manufacturer that assure up to 1000 cycles before losing charge capacity. The charger has to be specially design for gel batteries to follow a correct charge parameters for gel or AGM. They are not very expensive, I bought 6 of them, 12V at 100Ah for about 900€.

 

06_lithium_battery Lithium batteries. This already more expensive, but they weight about half and they have double capacity. Those are the standard option for electric cars. They use to come in 3.7 cells, so you have to get many of them to achieve the desire voltage. Another VERY IMPORTANT issue is that lithium batteries need to be managed (charged and discharged) by a BMS (Battery Management System). The reason is that these batteries cannot be charged or discharged outside the recommended limits by the manufacturer. As an example, 18650 lithium cells can only be charged at a maximum of 4.1V and discharged at a minimum of 2.5V.
–    Pyrophosphate batteries (LiFePO4). They are the most expensive of all but also they have the more energy capacity.

comparacion_densidad_energia

Enough batteries for now..

 

07_dc_dc_converter_72vAnother very important component is a current converter for high voltage to 12V.
When we remove the IC engine (Internal combustion), one of the components that also disappears is the alternator, the one in charge of keep the battery always at the proper voltage (in this case we could call it the auxiliary battery) for lights, electric windows, radio, etc. So, as the alternator is missing, we need a system have it always charged, for example, a DC converter  72V to 12V.

 

 

 

Well, that´s it, isn’t ?. No, still something important, the brakes.

For the brakes, you need to supply the vacuum that the IC engine use to make for the brake booster. So we need to install a vacuum pump in order to replace the missing one in the IC engine.

08_iruna_vacuum_pump

Then you need other small components, but equally important as a pedal accelerator, a contactor, some relays, fuses, etc.

09_pot_fuse_relay_contactor

Those small components are as relevant as the big ones, because even with the motor and controller, with no cables, there is no use. Also, you need to see the high voltage requirements that the motor manufacturer recommends. Also the signal cables are also important in following no just the diameter but the isolation.

Now the adventure starts… just install everything in the car.

10_full_assembly

 

If you are interested in converting your car to electric and need more information, support, documentation or just someone who share your hobby, you can contact with us by clicking here.