Okay, I am working on EMG controlled prosthetic arm with 5 active DoF and 5 Driven DOF. Designing an elbow, a wrist and 3 active fingers. All is done but I need help in choosing an appropriate battery.
Like how will I choose the battery and I want the battery to last for a day at least...
I read a few articles where they said lithium ion or lithium polymer batteries are being used for this purpose and battery needs to be recharged daily; however in certain cases it may last for 3 days or so...
Please can anyone suggest how to choose an appropriate battery according to the use of my design? I am using 3 feather servo motors and 2 other servo for elbow and wrist plus I have a small PCB for EMG acquisition and classification...
Lithium-ion-polymer (LiPo) cells if you want high energy per battery weight (specific energy). Lithium-iron-phosphate (LiFePo or LiFe) if you desire many hundreds of cycles (charge-discharge) and long calendar life of the battery and you accept lower specific energy. Any lithium-ion powered device need a battery protection circuit disallowing too deep discharges. Servo-driven RC models use LiPo/LiFe for many years. Please visit any RC webstore and take a look.
In order select the optimum battery for your application, where you want the battery to last for one whole day, initially you have to take two important measurements.
1) average power (Pa) consumed by the device
2) maximum power (Pmax) consumed by the device
Moreover, note down the supply voltage (Vs) of the device.
Then when you select the battery,
*Always make sure that the battery pack is providing the right voltage (this is basic stuff)
If maximum discharge current of the battery is Imax
*Make sure that the maximum power supplied by the battery (Vs*Imax) is greater than the maximum power consumed by the device (Pmax).
* Make sure that the maximum storage capacity of the battery is larger than the total energy consumed by the device over a day (Pa*24*60*60).
this way you should be able to find the right battery for your device.
Moreover, additional margin on energy and power capacity may increase the life time of the battery.
Ok thnk u so much for the details i will chk all ds n dn gt bacj to u
Lithium-ion-polymer (LiPo) cells if you want high energy per battery weight (specific energy). Lithium-iron-phosphate (LiFePo or LiFe) if you desire many hundreds of cycles (charge-discharge) and long calendar life of the battery and you accept lower specific energy. Any lithium-ion powered device need a battery protection circuit disallowing too deep discharges. Servo-driven RC models use LiPo/LiFe for many years. Please visit any RC webstore and take a look.
@Manaz
Hi
I checked out all the stuff but still a little confused
Ok i hav three micro servo motors and 2 other servo motors
All operate at 4.7 to 6 volts and the micto servo motors draw current from 550 mA to 750 mA and the other two draws a current of 1 amp each
Now can u tell me how much is my total power consumption and which battery would be good?
well, let's assume that you have a 6 volt battery pack. Then from the values you have given, to find the maximum power consumption, it would be ok to assume all motor are working at 6 volts and are drawing maximum current that they can.
Thus all three micro servo motors would draw a maximum of 750 mA each and the other 2 servo motors would consume 1A each. Hence,
Pmax=3*(0.750*6)+2*(1*6)=25.5 W
therefore to supply this power from the battery,
Imax= Pmax/Vs = 25.5/6 ~= 4.4A.
To find the required energy capacity of the battery, you may have to do some tests and find out the average power consumption first.
Let's say you found out that the average power consumption is 10W. Then, the average current consumption Iavg,
Iavg=Pavg/Vs=10/6 =1.67 A
thus the battery should be able to supply 1.67 A for one whole day. thus the battery capacity ,E should be
E=1.67*24 Ah =40Ah
Gr8 thnks man
Now all i need to do chk my average current consumption
My best regards
- Badges
- Science topic
- Similar topics
- Electrochemistry
- Battery