Post on 13-Feb-2018
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How to calculate how much batterycapacity (SLA Battery) you need.
Example:- Equipment draw 1.2A and we need to run for 12
hours
Step 1
Determine Capacity needed :- Capacity= 1.2 amp x 12 hrs = 28.8 A
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How to etimate how much batterycapacity (SLA Battery) you need.
Step !:- Cycle li"eConideration:-
!o extend the cycle of lead acid "attery# we
shouldn$t run the "attery past 8%& of its capacity.
!hus#
Capacity = C'%.8
= 28.8 ' %.8= () A
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How to etimate how much batterycapacity (SLA Battery) you need.
Step #:- $ate o" Dichar%econideration:-
*ome "attery chemistries +i,e much lesser fewer ampere
hours if we dischar+e them at a hi+her rate. E+:-
f a *A "attery rated at 1%%A# 2% hrs dischar+e rate
1/ f it is dischar+ed at 0A for 2% hours# the "attery will a"leto deli,er the rated capacity of the "attery# i.e 1%%A
2/ owe,er# if it is dischar+ed at 1%% A # the "attery will "edepleted within half an hour instead of the calculated 1hour . !his is called the euert E3ect.
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&eu'ert law#presented "y the 4erman scientist 5ilhelm euertin 1867# expresses the capacityof a "attery in termsof the rate at which it is dischar+ed. As the rateincreases# the "atterys a,aila"le capacity decreases
euerts law is as follows:
Cp = 9tCp = is the capacity accordin+ to euert# at aone-ampere. dischar+e rate# expressed in A = the dischar+e current# expressed in
Amperes#a. = the euert constant#t = the time of dischar+e# expressed in hours# h.
https://en.wikipedia.org/w/index.php?title=Wilhelm_Peukert&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Wilhelm_Peukert&action=edit&redlink=1https://en.wikipedia.org/wiki/Battery_(electricity)https://en.wikipedia.org/wiki/Battery_(electricity)https://en.wikipedia.org/w/index.php?title=Wilhelm_Peukert&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Wilhelm_Peukert&action=edit&redlink=17/23/2019 Est Battery Capacity Calc
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Examples:-
* 1 At 0A 1%% A 2% rs rate/
!=1%%'0;1.(/
= 12.( hrs
*. ! At 10.8A 76A 0 rs rate/
!= 76'10.8;1.(/
= 2.18 hrs
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REVISED PEUKERTs LAW
The capacity at a one-ampere discharge rate is not usually given for practical cells. As such,
it can be useful to reformulate the law to a known capacity and discharge rate:
where:
is the rated discharge time (in hours,
is the rated capacity at that discharge rate (in ampere-hours,
is the actual discharge current (in amperes,
is the !eukert constant (dimensionless,
is the actual time to discharge the battery (in hours.
https://en.wikipedia.org/wiki/Ampere-hourhttps://en.wikipedia.org/wiki/Dimensionless_numberhttps://en.wikipedia.org/wiki/Dimensionless_numberhttps://en.wikipedia.org/wiki/Ampere-hour7/23/2019 Est Battery Capacity Calc
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Examples:-
* 1 At 0A 1%% A 2% rs rate/
!=2%1%%'0 x 2%/;1.(
= 2% hrs
*. ! At 10.8A 76A 0 rs rate/
!= 076'10.8 x 0/;1.(
= 0 hrs
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&eu'ert Law Limitation
euert$s law is a ,alua"le tool for estimation. owe,er# ithas limitations. Amon+ them are