Batteries are a reliable way to store all your newly harvest energy. But what type of battery should you use in your solar/wind/hydro system? Well there are 4 main type of batteries each with their own advantages and disadvantages. When sourcing out your first battery bank look for deep cycle batteries. Deep cycle batteries are designed to have many continuous deep discharges where a standard car battery is only intended for short bursts of power. Car batteries can be use however their life span will be diminished if discharged to low.
Golf Cart Batteries
Golf cart batteries are popular due to their low price and are great for a budgeted system. Golf cart batteries come in 6/8/12v. Your system could use either a single 12v or 2x 6V batteries wired in series.
Lead Acid Flooded cells.
Lead acid like common car batteries will have caps on the top to top up with purified water. If you are using a non sealed ac battery you will want to store them in a well vented area as hydrogen is produced when the batteries charge
Gel Cell Battery
Gel batteries are sealed and alleviate the need to worry about a vented storage location. These batteries are great for using inside your house.
AGM or Absorbed Glass Mat batteries are one of the best batteries for off grid applications, this how ever come with a higher acquisition cost. AGM batteries do not give off a gas, and are sealed so there is no worry of acid spilling over. They come with a higher price tag but should make up in the added system performance.
Battery Amp Hours Ah
Every Battery will have a rating of its capacity or Amp Hours (Ah). This rating will tell you how many amp hours the battery will put out and for how long. Most electronic will state their power usage in watts. If you have a radio that is 12v 20watts you would divide 20Watts/12Volts = 1.667. If you want to run the radio for 5 hours a day we take 5×1.667 = 8.333 amp hours. If you want your batteries to last you should never drain it below 50% capacity, so in the case we would want a battery with at least 16.6 Amp hours or multiple batteries wired in parallel to make up the Ah capacity.
Batteries can be wired in either parallel, series or both depending on your application requirements.
Another thing to keep in mind is the voltage of you power source. Most panels come in 12/24/36 volts.
If using a 36V solar panel you will need to wire 3x 12v batteries in series to to get 36 volts.
If you are wanting to add extra capacity to your system you will wire your batteries in parallel.
For example if you have a 50amp hour battery you could run light bulb that drew 5 amps for 10 hours. If you added 2 batteries in parallel you battery bank would be able to run the same bulb for 20 hours.