Selection of battery for E-cycle(part 1)

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Selection of battery and its comparison :

28/08/2021 ( Sunday )

The performance of an electric vehicle completely depends on the electric power train system of the EV which consists Motor, Controller, and Battery Pack.
It’s very well understood that lots of features of Electric Vehicles like travel range, charging time, cost per km charging/Discharging rate & motor performance, etc are related to the battery pack.

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Options available at present in India for battery packs :

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Various parameters consider during select of the right battery pack

Battery Size:

Smaller battery packs require less space to store the pack and less weight. Thus the availability of effective free space is more for other accessories.

Comparison of batteries are as follow

– LCO <   –LPO  <  LTO     <  Lead Acid

Availability: 

Easy availability of battery cells of good quality is also a very important factor to consider for the point of view of on-time delivery or shorter lead time for the required quantity.

LTO     <   –LPO  <   – LCO    <  Lead Acid

Voltage:

• For lithium cobalt LCO commonly known as lithium ion cell nominal voltage is =3.7V.  
• For lithium ferrous phosphate LPO cell nominal voltage is= 3.2V.
• For lithium Titanate  LTO cell nominal voltage is =2.3V.     
• For Lead Acid battery cell nominal voltage is =12V.

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• NOTE : Higher the voltage of the Battery cell means fewer cells require in series, thus smaller BMS (battery management system). Similarly smaller the voltage more cells required in series and bigger BMS. 

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Amp-hr:

• For lithium cobalt LCO commonly known as lithium ion cell nominal Amp-hr is =2.5 Amp-hr.  
• For lithium ferrous phosphate LPO cell nominal Amp-hr is= 6 Amp-hr.
• For lithium Titanate  LTO cell nominal Amp-hr is =45 Amp-hr .
• For Lead Acid battery cell nominal Amp-hr is =7 Amp-hr .

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• NOTE : Higher the Amp-hr of Battery cell means less cell requires in parallel.

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Charge /Discharging Rate:

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• NOTE:
  • Lower the charge rate of lithium cells in the battery pack requires higher time for charging. But it should keep in mind higher charging affects all lithium cell life.
  • A higher discharge rate allows lower battery pack capacity.
  • All cell life/ efficiency is affected by a higher charge and discharge rate. 

For more information on the C rating click on the below link :

https://www.power-sonic.com/blog/what-is-a-battery-c-rating/

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Cycle Life

Cycle life denotes the cell or battery pack charging life. A battery pack cell has high charging life sustained for a long time thus low replacement cost and slow rate of efficiency fading.

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Overlook of cells charging life :

• For lithium cobalt LCO / lithium ion cell nominal 800 – 1000 Cycles 

• For lithium ferrous phosphate cell 1500 – 2000 Cycles

• For lithium titanate cell or LTO cell 8000 – 12000 Cycles (Yinlong LTO cell)
• For lead Acid cell 150 – 300 Cycles

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Cost/pc:

Here is the costing of battery price in India and running cost of battery packs

Cost of a Li-Ion/ LCO cell  – ₹60-₹120/ pc

Cost of a phosphate cell  – ₹140 – ₹220 / pc

Cost of a lithium titanate cell  -₹ 2800-₹3500Rs/ pc

Cost of a Lead Acid cell – ₹850-₹1000/ pc

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Calculations for Design of 24V battery for 250W BLDC Motor, Range of 100km With Above cells. With 40% Assistance.

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1.  Lithium ion battery or Lithium Cobalt or  LCO :

Calculations for the cost of LCO battery :

• Cost of a LCO cell 
  • -= ₹ 80 / pc 3.7V 2500mah
• Battery Pack of 24V * 20ah
  • = 480 watt-hr
• Cell require in series
  • = 24v/3.7 = 6.486486486 ~7 Nos
• Cell require in Parallel
  • = 20/2.5 = 8 Nos
• Total Cells required in pack
  • = 7×8 = 56 Nos
• Cost of cells
  • = ₹ 56 x₹ 80 = ₹4480  
• BMS and other accessories
  • = ₹ 2000 
• Total Cost of battery pack
  • = ₹ 4480  + ₹2000 = ₹ 6480

Calculations for milage for LCO battery :

• Given speed range for E cycle with BLDC motor of 250 W  is 20-25 kmph
• Motor take 10amp/hr if run 20kmph
• Max discharging time for 250 Watt Motor to consuming 480 watt-hr Energy of Battery
  •  Battery life /charge= Battery capacity /load
    • = 480 watt-hr / 250 Watt 
    • = 1.92 hrs.

• Maximum distance travel by e cycle at ( 20kmph  )  per charge :
  • Dist.  = speed * time
    • = 20 kmph * 1.92hr
    •  = 38.4 km approx

• Total distance travel by cycle throughout battery life :
  • = Distance /charge *charging cycle life
    •  = 38.4 km * 800
    •  = 30,720 km

• Cost of charging battery per cycle :
  • = battery unit *₹10 /KW                                        —— ( 1UNIT=₹10 / KW )
    • = 0.480kW *₹ 10/KW
    • = ₹ 4.8

• Cost of charging battery throughout battery life:
  • = Cost of charging battery per cycle* charging cycle life
    • = ₹4.8 * 800
    • = ₹3840

• Running Cost with LCO battery:
  • = ( Total Cost of battery + cost for charging battery through life ) / Total distance travel     
    • = ( ₹6480 + ₹3840) / 30720 ) km
    • = ₹0.3359375 /Km

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•  Lithium ferrous Phosphate battery or LFP

Calculations for the cost of LFP battery :

• Cost of a LFP cell 
  • – =₹150-₹300   / pc 3.2V 6000mah

• Battery Pack of   24V * 24ah
  • =576 watt-hr

• Cell require in series
  • = 24v/3.2 = 7.5 ~8 Nos

• Cell require in Parallel
  • = 24/6 = 4 Nos

• Total Cells required in pack
  • = 4×8= 32 Nos

• Cost of cells
  • = 32x 180
  • =₹5760

• BMS and other accessories
  • = ₹2000 

• Total Cost of battery pack
  • = ₹5760  + ₹2000
  • =₹ 7760

Calculations for milage for LFP battery :

• Given Speed range For E cycle With BLDC motor of 250 W  is 20-25 kmph

• Motor take 10amp/hr if run 20kmph

• Max discharging time for 250 Watt Motor to consuming 480 watt-hr Energy of Battery                                                                        
• Battery life /charge
  • = Battery capacity /load
    • =576watt-hr/250 Watt  .
    • =2.304hr

• Maximum distance travel by e cycle at ( 20kmph  )  /charge    
  •   = speed *time
    • =20kmph*2.304hr
    •  =46.08km approx

• Total distance travel by cycle throughout battery life life
  • =Distance /charge *charging cycle life
    •  =46.08km*1500
    • =82944km

• Cost of charging battery per cycle
  • =battery unit *₹10 /KW                                       —— (1UNIT=₹10/KW)
    • =0.576kW *₹10/KW
    •  =₹5.7

• Cost of charging battery throughout battery life
  • = Cost of charging battery per cycle* charging cycle life
    • =₹5.7*1500
    • =₹10368

• Running Cost with LCO battery
  • =(Total Cost of battery + cost for charging battery through life)/ Total distance travel     
    • =(₹7760+₹10368)/ 30720km
    • =₹0.218557099/Km

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• Lithium Titanate battery or LTO.

Calculations for the cost of LTO battery :

• Cost of a LTO cell 
  • =-₹2800-₹3500 / pc 2.3V 45ah

• Battery Pack of   24V * 30ah
  • =720 watt-hr

• Cell require in series
  • = 24v/2.3
  • = 10.43478261 ~11 Nos

• Cell require in Parallel
  • = 30/30
  • = 1 Nos

• Total Cells required in pack
  • = 1*11
  • = 11Nos

• Cost of cells
  • = 11x  ₹2500
  • =₹27500

• BMS and other accessories
  • = ₹2000 

• Total Cost of battery pack
  • = ₹27500  + ₹2000
  • = ₹29500/-

Calculations for milage for LTO battery :

• Given Speed range For E cycle With BLDC motor of 250 W  is 20-25 kmph

• Motor take 10amp/hr if run 20kmph

• Max discharging time for 250 Watt Motor to consuming 720 watt-hr Energy of Battery
• Battery life /charge
  • = Battery capacity /load
    • =720watt-hr/250 Watt  .
    • =2.88hr

• Maximum distance travel by e cycle at ( 20kmph  )  /charge   
  •    = speed *time
    • =20kmph*2..88hr
    • =57.6km approx

• Total distance travel by cycle throughout battery life life
  • =Distance /charge *charging cycle life
    • =57.6km*8000     —–(for second hand cell)
    • =460800km

• Cost of charging battery per cycle
  • =battery unit *₹10/KW                                       —— (1UNIT=10Rs/KW)
    • =0.720kW *₹10/K
    • =₹7.2

• Cost of charging battery throughout battery life
  • = Cost of charging battery per cycle* charging cycle life
    •  =₹7.2*8000
    • =₹57600

• Running Cost with LCO battery
  • =(Total Cost of battery + cost for charging battery through life)/ Total distance travel     
    • =(₹29500+₹57600) / 30720 km
    • =₹0.189019097/Km

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• Lead Acid battery

Calculations for the cost of Lead-Acid battery :

• Cost of a cell  Lead Acid batter
  • =-₹850-₹1000 / pc 12V 8-10 ah

• Battery Pack of   24V * 20ah
  • =480 watt-hr

• Cell require in series
  • = 24v/12
  • = 2 Nos

• Cell require in Parallel
  • = 20/10
  • = 2Nos

• Total Cells required in pack
  • = 2×2
  • = 4Nos

• Cost of cells
  • = 2 x ₹1000
  • =₹ 4000  

Calculations for milage for Lead-Acid battery :

• Given Speed range For E cycle With BLDC motor of 250 W  is 20-25 kmph

• Motor take 10amp/hr if run 20kmph

• Max discharging time for 250 Watt Motor to consuming 480 watt-hr Energy of Battery
• Battery life /charge
  • = Battery capacity /load
  • =480 watt-hr/250 Watt  .
  • =1.92hr

• Maximum distance travel by e cycle at ( 20kmph  )  /charge    
  •   = speed *time
    • =20kmph*1.92hr
    •  =38.4km approx

• Total distance travel by cycle throughout battery life life
  • =Distance /charge *charging cycle life
    •  =38.4km *150
    • =5760km

• Cost of charging battery per cycle
  • =battery unit *₹10 /KW                                       —— (1UNIT=10Rs/KW)
    • =0.480kW *₹10/KW
    • =₹4.8

• Cost of charging battery throughout battery life
  • = Cost of charging battery per cycle* charging cycle life
    • =₹4.8*150
    • =₹720

• Running Cost with LCO battery
  • =(Total Cost of battery + cost for charging battery through life)/ Total distance travel     
    • =(₹4000 +₹720)/ 5760km
    • =₹ 0.819444444/Km

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• Overall  Lithium ferrous Phosphate battery or LFP is better option  than other cell battery packs , the initial investment is higher as compare Lithium Cobalt battery pack.

 Exel shit of specification of battery,

https://docs.google.com/spreadsheets/d/1ca7FjyXy6rBUKRvfX2M81yZ4ftzRWJFM/edit?usp=sharing&ouid=112002993528878283233&rtpof=true&sd=true