Off Grid Home Forums Technical Discussion Using capacitors instead of a battery Reply To: Using capacitors instead of a battery


I couldn’t watch the video, but I can tell you that super capacitors are a poor choice for off-grid power storage. As Chowan has said the energy density is far less than a lead acid battery. But the real problem is that unlike a battery a capacitor will have a voltage drop that is unexceptionable. A fully charged 24v battery system will have 25.46v when fully charged (Trojan T-105’s) and at 50% DOD the voltage will be 24.2v and at 90% DOD it will still have 23.02v. The capacitor will go from 25.46v (or whatever voltage you choose to store) down to 0v when fully discharged.

Capacitors store electricity, but batteries produce not store electricity. The way a battery works is that the sulfur atom in the electrolyte (sulfuric acid) bonds to the lead alloy forming lead sulfide. This releases Hydrogen and Oxygen from the electrolyte and produces (releases) two electrons. When a load is applied to the battery terminals these electrons can flow and the chemical reaction can continue. When you charge the battery, you reverse the voltage and “Push” electrons back into the lead sulfide causing the sulfur atoms to return to the electrolyte. This is why you don’t want to discharge your batteries to far as that would allow the acid to degrade the lead plates. It is also why the most accurate method of measuring the state of charge of a lead acid battery is by measuring the specific gravity of the electrolyte with a battery hydrometer.

OK, I’ve rambled enough, the short answer is that the voltage will drop below what your inverter can use. To date, there is no more efficient way to store power than a good quality deep cycle lead acid battery.