Comparison of VRLA vs Lithium Batteries

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Dear sir ,
Chanced to browse your website and must say intrigued by the efforts this organisation is making in finding solutions to some of the vexing problems ,
Recently happened to read some of the work done by ” Green Mobile Services ” a London based organization who in association with “International Funding corporation” has done some good studies , Particularly Uganda in association with MTN, Haiti In association with Digi cell etc In all these cases it appears that reduction of Diesel consumption for powering telecom towers to power te BTS has been attempted
In all these cases the batteries used for back up power has been the VRLA ( valve regulated lead acid Batteries)
VRLA batteries have inherent disadvantages/ limitation
require reconditioning of the battery room thus consuming power for air conditioning provided by the DG set ( batteries do not power theA/c)
requires regular Maintenance adding to the man power requirement
capacity decreases as the room temperature goes up
Foot prints are higher
suffers from sudden death ( a common and inherent problem with lead acid batteries)
Ampere hour efficiency is low and watt hour efficiency is rather lower and so on
In the recent Months these have been astounding developments in regard to the ” Lithium ” Batteries , more so after the “OBAMA” President of USA advanced Huge grants for the development of batteries for “Electric Vehicle”. Safety issues which were once a concern have been dealt with and t o day it is not such a serious issue .
The attachment details the several advantages of Lithium over the conventional VRLA batteries , and would consider it a privilege to receive your views and feedback
Thanking you with best regards
G.Raghavan
Bangalore
Mob 91-0-9980512439




VRLA battery (valve-regulated lead-acid battery) vs Lithium



Sl no

Attributes

VRLA

Lithium

Remarks

1

Electrode Chemistry

Acid

Alkaline


2

Individual cell voltage

2.00

3.7o

Higher cell voltage

3

No of cells required for 48 v system

24 cells

13 cells

Lower no of cells

4

Current cell capacity

Generally 600 ah

Much lower

To be decided/sized

5

Approx Dimensions of cells LxWxHt

300x175x350mm

Tol +/-2mm

Much lower less than 60 % of VRLA

Lower size

6

Approx weight of cell in Kgs

~40 Kgs

Significantly lower say 55%

Less weight better for support structures

7

Approx  foot prints of 48 v system LxWxHt

1300x375x1300

Significantly lower

Saving of space

8

Wt of battery bank

~1050 Kgs

<500 Kgs

Lower weight

9

Float voltage/cell

2.25

4.2v


10

Charging current

~12-15% of rated ah ,72-90Amps

1 C is Fine no harm preferred is 0.3C

Lower charging time

11

Time taken to fully charge

10-12 Hrs

2-3 Hrs only

Saving in time

12

AH efficiency

~90 %

Better than 98%

Saving in power loss , reduction in opex

13

Watt hr efficiency

~70%

>93%

Power saving

14

Operating Temperature

Prefer 22-28deg C

Safe up to 55degC

No A/C required saving in cooling power requirement

15

Maintenance

Required

Not required

Saving in Man hours

16

Individual cell protection

Does not exist

Individually cell protection provided

Safe and reliable

17

Over charge issues

Detrimental

 cut off provided

Safe

18

No of cycles @80%DOD

~1200cycles

>3000 cycles

Longer life

19


No of cycles @50%DOD

~1600

>5000cycles

As above

20

Hydrogen liberation during operation

Yes liberated

None

Safer

21

Sudden deaths

Possible

None

Reliability enhanced

22

Self Discharge

High

Very low

Hardly any longer storage period

23

Sulphation issues

Applicable

 None


24

Capex

Low

Higher

Initially

25

Opex

High

Very low

Savings

26

Cost per cycle

High

 Very low

Lower total cost

27

Operation efficiency of SMPS rectifiers

Low since they operate at lower levels

High since they can operate/charge at higher currents

Savings in Opex estimated at 14 % 

28

Savings On A/c of no Air conditioners

None

Huge

Lower rated power requirements

29

Derating of cell capacity due to orientation

Yes applicable between vertical and horizontal positioning

None


30

Life expectancy

3-4 years Max

10 years minimum

Huge savings

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