Electric vehicle battery question

[akueddy]

Hi,
i really hope someone can help me with this...
what type of battery that is suitable for an electric vehicle(slow walking speed,electric wheel barow)? is it a deep cycle marine?
I have a problem on how to choose the correct battery.
i have choose a motor which can produce a max mechanical power output of 400Watts.
http://www.boschmotorsandcontrols.c...2/kennlinie.htm

if you look at the characteristic curve, my working torque would be around 2-3Nm, the corresponding current required is about 100A. The problem is due to the fact that the vehicle need to be as compact as possible, i can only choose one 12V battery 100Ah battery. i initially try to pick the right motor by using the assumption that, stall torque>torque require.This i know is not efficient+the rpm is slower near stall torque.
Right now the motor that I've choosen got the right working torque(2-3Nm) and rpm, and is >50% efficient but the power source could not supply more than (2-3Nm), what happens if the required torque is more than 2-3Nm??

 

[Panda]

There are two solutions. One is to use cells with high peak currents such as Li-Ion or Molibnium, but these are expensive and generally only used in Electric Cars as opposed to Electric Wheelbarrows unless weight is a driver above cost.
The other option is to use motor control circuits to deliver the very high starting currents from resevoir capacitors whilst keeping the average current drawn from a Pb-Acid cell near the optimum for capacity. This slows your acceleration but gives you good running times.
The motor control solution also protects the motors when the going gets tough as they can be used to limit the average current seen by the motor and switch out if a dead stall occurs.
Unless you are looking for a lightweight wheel barrow with good 0-60 times I would look at building a motor controller using IGBTs such that peak current is delivered to the limit of the motor and average current is delievered at no greater than 2-3C of the Battery.

 

[ravenprp]

Choosing the correct battery for an electric vehicle can be a complex process, as it involves considering various factors such as power output, torque requirements, and efficiency. In your case, it seems like you have already chosen a suitable motor that can produce the required power output for your electric vehicle.

When it comes to selecting a battery, the type of battery that is suitable for an electric vehicle depends on several factors such as the vehicle's size, weight, and the distance it needs to travel. Deep cycle marine batteries are commonly used in electric vehicles because they have a higher capacity and are designed to withstand repeated charging and discharging cycles. However, they may not be the most suitable option for a slow-walking speed electric wheelbarrow.

In your case, since you have limited space for a battery, it is important to choose a battery with a high energy density (amount of energy stored per unit volume). This will allow you to get the most out of your limited space. Additionally, it is important to consider the battery's discharge rate and the motor's power requirements. A battery with a higher discharge rate will be able to provide the necessary current for your motor to produce the required torque.

It is also important to keep in mind that the battery's capacity and power output may decrease over time, so it is important to choose a battery with a higher capacity and power output than what is currently needed. This will ensure that the battery can meet the vehicle's requirements in the long run.

In terms of your concern about the motor not being able to produce more torque than 2-3Nm, it is important to note that the motor's torque output is directly related to the amount of current drawn from the battery. As long as the battery can provide the necessary current, the motor should be able to produce the required torque. However, it is always recommended to have some margin of safety and choose a slightly more powerful motor and battery combination.

In conclusion, selecting the right battery for an electric vehicle involves considering various factors and making trade-offs. It is important to carefully assess the vehicle's requirements and choose a battery that can provide the necessary power and energy for optimal performance.