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gova1467
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India - Member - New Member

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Location: India
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Battery Discharging

07/17/2009 10:39 AM

Dear sir

We have tubular Lead acid batteries(55 cells*2Volt) in our 110/33/11KV substation.Its capacity is 300AH.we commissioned it two years back.

My questions:

1) does periodical charging and discharging of batteries improve the performance and life of batteries?

2)At what interval of time,the above activity has to be carried out?

3)during discharging,how much the load to be connected for 55 cells *2 volts,300AH batteries(bank) and how much time duration allowed .

please share your views.

regards

gova
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mjb1962853
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Engineering Fields - Electrical Engineering - Analog and Digital Circuit Design Engineering Fields - Electromechanical Engineering - Transformers, Motors & Drives, EM Launchers Engineering Fields - Engineering Physics - Applied Electrical, Optical, and Mechanical

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#1

Re: Battery Discharging

07/17/2009 1:06 PM

Suggest you read this site...

http://www.batteryuniversity.com/index.htm
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StandardsGuy
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#2

Re: Battery Discharging

07/18/2009 11:45 AM

I my experience, lead acid batteries are best when continuously 'trickle' or 'float' charged. Discharging risks a cell reversal, so I would not do it.

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Panneer Selvam
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Join Date: Jul 2009
Location: chennai, India
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#3

Re: Battery Discharging

07/20/2009 6:11 AM

The specific Gravity of the individual cell shall in the range 1190-1200.

If all the cells are in this range, you can continue without any discharge cycle.

But It will not be in that range after Two Years of service for the following reasons

1. The internal loss of all the cells may not be same.

2. When ever 110 KV supply fails, all your dc loads (Indication lamps, Scada contactors, etc. )will drain the battery. To compenensate the same, you should have put the battery in boost charge at 30A or at 150 % of Load availed from battery, which ever is lower, for a period of 150% of hours for which battery was drained during power supply Failure

3. Failure to do and for the reason stated in Item 1., some of the cells in the battery will have Sp.Gr. in the range 1190 -1180

4. These cells shall be imroved with Sp. Gr.. It cannot be achieved by normal boost Charge.

5.the procedure suggested is Quaterly Equalising charge.

6.The Procedure for Quarterly Equalising Charge is as follows.

a.select a total Shut-down day,Or, If you have a spare battery, release the

battery to be discharged from service

b.dischrge the battery using a discharge kit at the rate 10Hr rating(i.e. at 30A

for 300 Ah Battery), for 3-5 hours till the the cells with Sp.Gr. 1200 are

reduced to 1190-1185. See also the cells with reduced Sp. Gr. are not gone

below 1175

c. Nou resume the battery to Boost Charge At the Rate of 10 hr current rating

( for 7-8 Hrs). Now allthe cells would have improved to 1195-1200.

d. The periodicity of this procedure Stands in the Name of this activity i.e.

Quarterly.

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gova1467
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Join Date: Nov 2008
Location: India
Posts: 72
#4
In reply to #3

Re: Battery Discharging

07/20/2009 10:54 AM

Dear sir

1)I cant get the point 2.please explain the same with numerical example for easy understanding.

2)whether this test kit is available in market?.

or please give me some idea to design it by own.

3)other points i got it.

Thank you sir

regards

gova
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Panneer Selvam
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Location: chennai, India
Posts: 55
Good Answers: 1
#5
In reply to #4

Re: Battery Discharging

12/19/2009 4:38 AM

Dear Mr. GOVA1467, Suppose your Substation is located on a radial 110 kV feeder , and the feeder trips on breakdown.Suppose your supply is resumed only after 5 hour after attending the breakdown, your battery would have been loaded without the Charger for indication lamps, SF6 Contactor etc . This discharge shall be compensated by boost charge, after resumption of supply. Mere trickle charge cannot provide enough recharge for your battery to compensate above spent up Quantum of charge during supply inturruption for Example you are having 64 Ah Battery in your Station and your station DC load is 5 amps. Suppose Supply Inturrupted for 6hours.Then your Battery would have been drained of 5x 6=30AH of charge. On resumption of supply, You should have put your battery in boost charge position with boost current level at 5 or 6 amps for 10 hours . Then you can change your charger to Trlckle position. Regarding discharge devices, it is available in convnient form for different ratings of battery. This is not the forum for communicating commertial details . If you contact me either in my mobile no 9444389547(Chennai) or in my mail Id panneer.rps@gmail com, i can guide you.

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