Constant Current Lead Acid Battery Discharger(Help)

[KrizEE]

I need to design a constant current Lead acid battery discharger to test battery capacity.
Specifications
12V Lead Acid Battery discharger
discharge current rating 0-8A
We need to get the constant current from the battery through out the discharge period until terminal voltage 10.8V.
I want to know about a suitable circuit diagram and parts for this design.
Can anybody plz help me.....

[eevblogfan]

hey

can you tell us the budget ?

I dont know you . so I'll ask , do you have basic knoledg ? (and the apropriate tools ? )

the load will run continusly at 12V@8A (ie , ~96W ) ?

[KrizEE]

The budget is around $200
I have appropriate tools but dosen't have much knowledge abut electronics.
the load will not run continusly at 12V because battery voltage(12V) would drop when it is discharged.
the current drawn from the battery depend on it's capacity.if it is 100Ah battery i have to draw 5A constant current from it for a 20hour period.
I'm glad if u can help me with this.
thnk u..

[T4P]

When a battery is fully charged it's around 14.4V
when it's about 50% is about 12V
When it's discharged it wouldn't move much unless it drops below 30% but eventually recovers