Deep Cycle Batteries For Solar Panels

Deep Cycle Batteries For Solar Panels

Installing a battery as part of your solar power system allows you to store the extra energy that the solar panels produce. This would otherwise go to waste or be fed to the grid. It also allows you to build a back up system in case of power failure and you can not access power from the grid. A deep cycle battery is the recommend type of battery to use in either a solar collector( photovoltaic), backup power, RV, or boat application. Deep cycle refers to the fact that they will be used for several hours continuously and then recharged over a fairly short period of time. To contrast a deep cycle battery with a Starter battery; Car Battery. The automobile batteries need maximum initial current for a brief period until the engine starts.

Automobile batteries or starter batteries have a large number of thin plates comprised of a lead sponge. This gives a very large surface which impacts ignition type starting but deep cycling this type of battery will ruin it quickly, perhaps as quickly as 150 deep discharges. The most important thing to consider before buying is the use to which you will put the battery once you own it. Then match the construction of the battery to its intended use.

There are two man types of deepcycle rechargeable batteries

  • Lead Acid Batteries
  • Lithium Ion Batteries

Lead Acid Batteries.

This traditional battery has been around for a long time. It’s typically used in cars as it is capable of delivering big, sudden surges of power. Lead acid batteries are quite heavy and difficult to carry around. They also have long re-charging times.  They cannot be disposed of in landfill and due to their internal make-up, are too dangerous to be sent through the mail. They tend to emit gas on charging and discharging, especially when they are older. As this gas will spill if the battery is turned over, they need to be well ventilated. Flooded Lead Acid batteries are also called “wet”. AGM batteries are also called “dry.” . A gelled battery is always sealed and also are valve regulated (slight positive pressure caused by a tiny valve).

Lead Acid Battery

Lead Acid Deep Cycle Batteries

There are different batteries in different voltages. The most typical are a 12 V and a 24 V battery. Any deep cycle battery can be discharged from totally charged down to 20% charged day after day This is because they have much thicker plates than other batteries and the plates are solid lead plates rather than sponge. In order to know what you are buying you need to know the thickness of the plates and whether or not they are solid.

How long do they last

The lifetime of any battery varies tremendously because of how it is used, maintained, recharged, ambient temperature, depth of discharge, how many times deep cycled and many other factors. So it is really impossible to put a typical lifetime on this battery . The deep cycle (L-. 16 type) average around six years. The gelled battery averages around four years. The AGM type 12 Volt deep cycle battery averages around five years. The premium type such as the Rolls-Surrette averages around 12 years. So when you look for a battery it is very important to know which type it is as well as its price in order to know what your lifetime cost of ownership will be.

Lithium Ion Polymer /Li Ion.

When people refer to Lithium batteries, they are typically speaking about this battery. It is used in applications such as laptop computers, mobile phones and other high-power electronic devices. The battery is much lighter compared to the lead acid battery. However, its ability to hold a charge deteriorates after time. This explains why laptop batteries die after only a few years, while car batteries do not need to be replaced for a very long time.

•    Lithium Iron Phosphate / LFP / LiFePO4. The Lithium Iron Phosphate (also known as the LFP and LiFePO4) is the newest battery on the market. It has a longer life span that the older types, is lighter for the same amount of power, and safer for the user and the environment. These batteries come in two different types: starter batteries and deep cycle cells.

Lithium Deep Cycle Batteries

The new Lithium battery is becoming the battery of choice for many reasons:

•    Lighter weight. When it comes to weight, the Lithium battery wins hands down. It is typically half to one third lighter than the original lead acid battery weight (for an equivalent run time/capacity lead acid battery bank).

•    Higher electrical efficiency. The Lithium battery has a much higher electrical efficiency compared with lead acid batteries. LiFeTech lithium batteries are typically 98% charge efficient compared to between 70% and 85% with the lead acid batteries. They also have significantly faster charging times than lead acid batteries. What this means is the Lithium battery will charge not only more efficiently, but    more quickly than a lead acid battery. This can be particularly important in situations  with limited charging methods available, such as from solar panels.
For example, camper van owners have reported that their LiFePO4 batteries are fully charged from solar panels by midday compared to 4 to 5pm using their old lead acid batteries.

•    Longer working life. While good quality Lithium batteries such as C&C Power Supply batteries are far more expensive to buy and set up initially, the actual cost of ownership is considerably cheaper than lead acid batteries (calculated in terms of cents per charge cycle).

•    Constant voltage.  In a lead acid battery, voltage will continue to drop over time as the internal circuit within the battery will self discharge. This forces the connected electrical device to eventually shut down at its minimum operating voltage. In the Lithium battery, however, voltage tends not to drop under load until the battery is almost depleted. For example, an ignition coil in a motor vehicle will have a consistent spark due to the battery’s ability to delivery a consistent voltage. This means electrical equipment tends to run more efficiently as they are receiving constant voltage. Ultimately, using Lithium batteries gives electronic equipment a longer working life before failure than the lead acid battery option.

•    Faster recharge. Expect to spend much less time recharging Lithium batteries than lead acid batteries.

•    More eco-friendly. Lithium batteries are the safest batteries for consumers and the environment.  Internally, they do not contain corrosive sulphuric acid or any toxic heavy metals such as lead or cadmium which can be environmentally harmful if leaked.