Battery life on full load help?

4000 mah / 0.2 ma = 20000 hours = 2.283 years!!!!!!!

Are you sure?

Is it really 0.2 miliamps? Do the amp and speakers run off of 12 volts or is there voltage conversion circuitry. The above equation is far too over simplistic, also to factor in are:
Self discharge rate of the battery
Voltage discharge curve of the battery
Current draw of the amp and speaker under different conditions
Voltage supply of the amp and speaker and any voltage conversion circuitry (eg buck, boost, linear regulator, switching regulator OR other)

There are probably other factors as well. A worst case scenario is a short circuit, in which case your circuit and battery will overheat, allowing you to power your amp and speaker for very little time at all.

Please check your current draw.

 

Battery chemistry, safe discharge level.

 

I suspect it is 0.2A not mA.

Bob

 

Please could you supply us with your circuit diagram along with the specifications of your amp and speaker.

Also set your multimeter to an amp range rather than a miliamps range, look at bobk's suggestion.

Thanks,

 

So the amp is an integrated unit? There is no more circuitry work to be done?

8 Ah/ 0.2 A = 40 hours.

Remember that our electrochemical cell are all prototypes, the battery will age, leading to a lower capacity over time.

Thanks,