Arno Smets, Nishant Narayan

PV Systems - Components and ConceptsBatteries II - Battery Parameters

Week 7.5.2

Battery characteristics

V

Rated voltage (lead acid): 12V, 24V, 48V, …

Cbatt

Rated capacity: Ah, mAh

QI

t

11 3600

CAh h C

s

Battery characteristics

V

Cbatt

batt battE C V

Wh Ah V

Significance of Amp hours

C = 10Ah

I = 1A

1010

1

Ahh

A

Charging and discharging

Capacity

Pb + PbO2 + 2HSO4- + 2H+ 2PbSO4 + 2H2O

C-rates

1batt

IC rate

Ch

I10* 1* 10

1 1battC AhI C rate A

h h

10* 2* 201 1

battC AhI C rate Ah h

Cbatt = 10Ah 10* 0.5* 51 1

battC AhI C rate Ah h

1h, 1C

0.5h, 2C

2h, 0.5C

1

*

batt

batt

Ct

C C rate n

battCt

Efficiency of storage

10kWh 8kWh

100out

in

E

E

8100 80%

10

kWh

kWh

Battery efficiencyarg

arg

100disch e

V

ch e

V

V

arg

arg

100disch e

C

ch e

Q

Q

batt V C

SOC and DOD

100available

batt

ESOC

C V

10 Ah - 2Ah SOC = 80%

arg100

disch ed

batt

EDOD

C V

DOD = 20%

Cycle life

Cycles

Cbatt

Cycle life vs. DOD

Battery overheating

Battery capacity vs. Temperature

Ageing of lead acid batteries

SulphationElectrode Corrosion Drying

Batteries : Hoppeke

Thank you for your attention!