EV TERMINOLOGY - A to Z

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Battery - A number of chemical cells joined together in series.

 

Brake to Motor cut out - To stop you running the electric motor against a locked up break, the controller sometimes allows a plug from the brake leaver to send a signal which the controller responds to by cutting all power to the motor. This means that you can use full throttle but you will not destroy your motor by stopping movement. Generally people dont have a tendency to run a motor while braking (think of the last time you did it while driving) but this system adds a valuable safety feature.

 

Brushed - Referring to the brushes inside a typical DC motor which rub against the commutator. These transfer electricity to the coils inside the motor which then interact with the magnets to create an electro motive force.

 

Brushless - There are no brushes in this motor, instead another system is employed to allow electricity to flow through the motor on the outside non-moving section of the motor, doing away with brushes. Brushless motors can be more efficient and have more torque. They have no Brushless, therefore less wearing parts and maintenance.

 

Compatible - A controller may be used along with a given motor or controller, it does not mean it will come ready to plug together, just that if the wires are connected the electric system will work correctly. With a knowledge of basic electronics you will find all compatible equipment easy to use.

 

Controller - Is commonly called a speed controller. Generally an electronic brain which takes the full battery power, connects to the motor and with the throttle input signal then allows the right amount of power through to the motor. It is the "middle man" piece of equipment which stops a full power on and no power off to allow a progressive throttle. The controller in modern equipment can also handle charging, brake cut out, built in lights, brake lights, horn and other factory accessories.

 

Commutator -  The section of a DC motor which receives electricity from the brushes and sends it to a coil in the motor which acts to to provide a turning force via a magnetic force. The commutator is connected with the coils and as they rotate away from the magnetic field, the field must be adjusted to keep the magnets applying maximum force. As the commutator also turns, it receives electricity into the next section which then transfers power to the part of the coil next in line to interact with the magnets.

 

Coulomb - The measurement of a number of electrons (it is to hard to measure one electron because they are quite small) the exact number is 6.242 x 1018 .

 

Current - The volume of power flowing through a wire, numbered in coulombs, measured in Amps.

 

Current Limit - The amount of current aloud to flow into a motor from the batteries. Governed by the programmable controller.

 

DC and AC - Direct current is when the current flows the same direction all the time. Alternating current is when the current changes direction many times a second. The mains power frequency in Australia is 50 - 60Hz.

 

Efficiency - If a certain amount of power is put into a motor, you may only get out 80% in mechanical energy. This means the motor is 80% efficient. FIY most motors are 80% efficient or more, 90% is considered good and 95% excellent, above 95% is almost unachievable (but not impossible). Most losses are due to the batteries and the mechanical chan drive, and then the stickiness of the wheels.

 

Lead Acid - The original rechargeable battery. They are known as cheap, heavy and not as efficient as later batteries. In reality the latest lead acid batteries are a lot different than their predecessors. They are still cheap (this is always the overriding factor) but becoming lighter as well. They are robust (don't knock a NiMi or Li battery around) and reliable and can be recycled. At this point lead acid batteries are almost as powerful - weight for weight - with NiMi batteries. This is a compelling argument to stick with them.

 

Memory - The effect that the NiCd chemistry had. This means the battery if not properly discharged to 0.8v, it will gain a memory which means the battery will take less time to charge and discharge so that the full capacity of the battery is unused, even a new NiCd battery will get a memory. Other batteries do not have a memory effect. The stored charge or capacity of a battery may reduce if  the NiCd battery is used the same way several times. It appears that the battery remembers how much it was used last time and then fades out and won't supply full power to the motor. This is caused by the chemistry in NiCd batteries. The chemicals inside the battery turn in to crystals like salt at the edge of a salt water lake. If the crystals haven't yet destroyed the internals of the battery they can be removed by special and careful charging techniques. If the NiCd batteries are charged carefully using a pulse charge instead of a trickle charger during normal use the crystals should form and the battery won't have a memory of how much it was used last time. 

 

Motor - An electrical device using magnetic fields to convert electrical energy into mechanical energy. (A petrol powered device is called an "engine" as opposed to the electrical "motor")

 

NiMh - Nickel Metal Hydride batteries are abbreviated to NiMh. These batteries were the next generation in the line of batteries and were hotly contested against lithium ion batteries in the early 90's. They lost - meaning Li are better. But still, they are a good battery, lighter than lead acid and less expensive than lithium. Recharge batteries went in the following chronological order: Lead acid (Pb), nickel cadnium (NiCd), NiMh, Lithium Ion (Li). Currently other batteries are also seeping into production such as Lithium Polymer and Lithium Air. Other exotic batteries are also available for specific uses.

 

Plug and play - The item in question, be it a controller, throttle, motor or battery it directly able to be connected to another item. For example a throttle may be plugged straight into a controller with no modifications, and no fuss. Plug and Play is the easiest way to use electrical equipment. Generally little or know electrical experience is necessary when using plug and play.

 

Programmable controller - The speed controller has variables which can be pre programmed to allow several throttle, acceleration and top speed characteristics from a motor. Some controllers have an analog system onboard, others are fully programmable via a laptop computer! (you don't need one of these).

 

Ramp Up - The time it takes for a motor to go from 0 - max RPM. Another programmable controller feature.

 

Rare Earth Magnets - These magnets are made from substances which hold a more dense magnetic flux than regular magnets. This means more power for your weight. Rare earth magnets are always preferable although not necessary.

 

Recharge - The reversing of the chemical reaction in a battery which effectively means the charge can be restored to the battery through applying an electric current over a period of time.

 

Range - The distance you get out of a full battery, changes with the environmental conditions, mostly terrain.

 

Regeneration - This means the motor can generate power which can then charge the battery. Many people say "does this bike recharge while I ride?" or "can you put a dynamo on the tyre to put power back into the batteries?". The short answer to these questions is Yes. The long answer is No. This following is a brief explanation. Most of our units have the ability to generate power which could then be put back into the batteries. The problem with this is that to take from of the bike motor, it has to come from somewhere. Where does the power come from? in the from of a braking effect. While in motion the bike has a momentum or inertia. This inertia means the bike or scooter has a certain amount of energy. When this inertia energy is taken from the bike, put by regeneration of the motor, the effect is to slow the bike. At this point charge will be going into the batteries. However, without a power source to keep the bike in forward motion, this will lead to the bike coming to a complete stop. The energy needed to keep the bike going could be put into the bike via the peddles from the rider peddling, or from the motor which draws its power from the batteries. If you decide to peddle the bike to keep momentum you will have to overcome the braking effect of the generator. Now here is the bad part, for every ten times you rotate the peddles, you will be lucky to receive back enough forward thrust to equal five peddles. This is due to inefficiency's in the system, mainly from the battery. If you use the power from the batteries to keep up your inertia, you will use much more power than you will get back from the system, you are running in circles and loosing power to heat, noise, chemical inefficiency and friction along the way. This means the although you can generate power while riding, it is a good way to lessen your range, and so the answer is no, you cannot use regeneration to keep your batteries charged. There is one more twist to all this and that is if you actually want slow down where you would normally use the brakes. In this situation braking is a good thing and why not recharge your batteries along the way. This could be considered charge for free as with friction brakes you give this energy away for no return. In modern hybrid cars you may have heard of regeneration braking. This is what it's all about.

 

Throttle - A device using with a variable resistor or the magnetic "Hall effect" to send a signal to the controller which is then interpreted to send power to the motor. Allows variable speeds and acceleration at a chosen rate.

 

Throttle calibration - One of the variables of the programmable controller. You can have low or high top speed.

 

Voltage - The chemical reaction of a lead acid cell provides 2.0 volts which is more accurately described as PD or potential difference. If you add together the PD of 2.0v six times you get a PD of 12v. This is what is enclosed in a 12v battery. If you put two 12v batteries together you get a PD of 24v. FIY the chemical reaction of a Li cell is 3.6v if you add ten together you get 36v. If you add cells together you get a system just like a battery of hens all lined up, hence the name battery used to describe a number of cells stuck together!

 

Watts - A power figure which an electric motor cannot pass without burning up. If a 100w motor is subjected to 150w, it will suffer fatigue and burn out faster than its intended life span. Watts is derived from Volts x Amps. This means that there is no such thing as a 200w motor, the Australian Law does not make any sense. In an electric system such as a bike or scooter the 200w power is decided by the controller and motor together, putting a 200w rated motor on a scooter means it could run at 250 watts. The motor will only last a few minutes so don't try it. On the other side of this example is a motor which is capable of an input for 500 watts which is only receiving enough power for 200watts (running under 100% capacity). This gives the benefit of a motor that will last longer and have less maintenance. Of course it costs your manufacturer more money to produce a motor like this but it will benefit your investment. You may remember years ago washing machines and other appliances lasted longer, this is because the motors were not working at 100% capacity. Later model appliances (for cost cutting reasons) now run closer to 100% capacity and therefore don't last as long. Try to find models which have a better quality motor with a system output of 200watts. This will benefit everyone involved and the law requirements will be fully met. Some people have been known to "pump" the motor back to the original 500w. This NOT ok and you will instantly blow (generally with some smoke) you controller as they are too sensitive, controllers are not cheap to replace so it is suggested to leave your system alone.

 

 


 

 

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