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someshsinha
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Join Date: Nov 2007
Posts: 1

Lead Acid Battery

11/03/2007 7:15 AM

Dear Friend,

  1. Qs.How to calculate the back up time expected from a fully charged 150AH lead acid battery?
  2. Qs.How is c20 calculated for lead acid batteries?
  3. Qs.How to calculate the REDUCTION in back up time over a fixed period of usage on constant load,and charging cycle.
  4. Qs.What is the energy out put effecency standard of a lead acid battery.
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user-deleted-1105
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Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
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#1

Re: Lead Acid Battery

11/03/2007 7:35 AM

These things aren't precise..but as a rough answer.

1. Divide 150AH by the average current drawn by the load..that will give you hours of back up time.

2..Dunno what c20 is... probably refer to battery manufacturers data

3 .. see 2

4. No such thing as 'standard battery'... calculate efficiency of your battery by refering to manufacturers data for both battery and charger and doing the arithmetic.

(This is not a flippant answer)

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Electroman
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#2

Re: Lead Acid Battery

11/03/2007 8:45 AM

As Del says plus C20 is the discharge or chargeing current, so in your case with a capacity of 150Ahr the charge / discharge current will be at 150/20 = 7.5 Amps.

As for the other questions refer to the manufacturer.

John.

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lordravindran
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Join Date: Oct 2007
Posts: 43
#3

Re: Lead Acid Battery

11/03/2007 8:59 AM

1. (battery voltage x 150Ah) divided by load power in watt will give the back up time in hour

2. 150Ah divided by 20 gives the optimum current that the battery can deliver for 20 hours. C20 is a parameter decided by the manufacturer of the battery. This factor may be different for different manufacturers.

3. 20 hours' of charging @7.5A will bring the battery to full capacity. Depending on the age of the battery you may have to charge for an additional time of one or two hours. Capacity to which battery is charged is not a linear function of time. In the same way the remaining capacity of the battery after using for a certain period of time is not a linear function of the period of use capacity

4. Only the supplier of the battery under discussion can provide you with the information on efficiency. Efficiency depends on the technology employed.
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sail4evr
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Join Date: Jul 2006
Posts: 295
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#4

Re: Lead Acid Battery

11/03/2007 11:20 PM

I believe they generally use 1/2 of the battery capacity to calculate the battery discharge time. The theory is you shouldn't discharge the battery more than 1/2 way in order to maximise battery life.
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eefourn6
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Join Date: Nov 2007
Posts: 4
#5

Re: Lead Acid Battery

11/04/2007 6:59 AM

Go to the Trojan website. They have most of the information that you need.

Load duration depends on load, but the relationship is not linear.
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ca1ic0cat
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#6

Re: Lead Acid Battery

11/05/2007 9:36 AM

C is the discharge capacity of the battery. If you have a 150AH battery the c/20 value is 150Ah / 20h = 7.5A

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