What Is a Deep Cell Battery and Why Is It Better for the Environment

There aren’t so many parts that make up a solar power system. In fact, it’s so straightforward that you could build your own solar grid in your home. However, in spite of the small number of components, it’s critical that each one of them is matched and up to the task. That means you will be faced with the multiple storage options, including a deep cell battery.

In previous articles on solar power, we’ve looked at solar rechargeable batteries and we’ve recommended you our top rechargeable batteries for a less polluting power consumption. We will explore today the insides and outsides of a deep cell battery, attempting to understand why this is one of your best options in terms of solar storage.

Storing Solar Power – Deep Cell Batteries

If you’re trying to run your standalone solar rig, you will soon realize you need somewhere to store the electricity. That way, you won’t be left powerless when the sun isn’t shining. What you need is a battery – better yet, a bank of batteries.

You could use car batteries, but they aren’t really up to the task. They will also cost you much more in the long run and create additional waste. In other words, car batteries are not something the environment needs more of. What you (and the environment) need is a deep cell battery bank, also known as deep cycle batteries.

Why Not Car Batteries?

The main difference between deep cycle batteries and car batteries is that car batteries are designed to spew large amounts of juice for a tiny fraction of time. Once they’ve turned over the engine, they the car’s alternator immediately recharges them.

However, when it comes to a solar power setup, the needs differ. On one hand, the draw of power is not as brutal in short bursts, and on the other, it can continue for a very long time. You might need them to power the home overnight, for example. Car batteries are simply not made for this type of application, which means they will wear out quickly.

If you set up a car battery bank, you will find out about its inefficiency the hard way. They will be done after just a couple of months of continuous use – difficult to charge and requiring a lot of maintenance. Luckily, you can still recycle the car batteries and invest in a decent deep cycle battery.

A deep cycle type allows you to reduce your needs down to one battery. This kind of battery is also rather good at doing its job, but you might want to invest in a bigger battery if you live in a sunny area. The solar panel usually recharges the batteries by lunch time, so you might need a bigger storage.

What Is a Deep Cell Battery?

What differentiates a deep cell battery from a car battery? In normal car batteries, the lead plates are sponge type structure and consist of many thin plates. This allows them to generate big amps for short periods (which is exactly what a car needs). In deep cycle batteries, the lead plates are solid and significantly thicker.

There are different types of deep cycle batteries; today, we’re going to help you choose the best one for your solar system.


These batteries are similar to car batteries, down to the issues presented by the latter when used in a standalone power system. They react the same to stratification, serviceable life, electrolyte dissipation, and the dangers of explosive gas. The only difference lies in the thicker lead plates that mitigate some of the transporting problems.


Gel deep cell batteries contain acid and silica, which turns the acid into a jelly. Even in this broken state, the acid won’t spill. This type of batteries is really good for deep discharge and daily use; they also perform well in high temperatures. There’s no serious battery damaged attached to partial recharge and the low internal resistance allows them to readily accept charging. However, avoid recharging gel deep cycle batteries with high voltages (such as the car’s alternator).


AGM – which stands for Absorbed Glass Mat – is made of a boron-silicate glass mat placed between the lead plates. The end product immobilizes the electrolyte, rendering it unspillable. This type of battery offers the same benefits as gel batteries. In addition, AGMs are fine with high voltage charging and they do not off-gas under normal usage.

Which Type of Battery is Best?

The debate is definitely between gel and AGM batteries. However, in spite of what people’s opinions might be, your choice depends on the application and your geographic location. If you’re unsure, consult an expert before buying any of the two.

When it comes to the battery life, deep cell batteries are meant to be discharged much lower than standard car batteries. At the same time, they are tolerant to being recharged many more times. Under normal conditions, a deep cell battery will have a lifecycle anywhere between 3 and 10 years.

Like any other device or piece of equipment, the more you strain it, the less it will last you. One of the secrets to getting the longest life out of your deep cycle battery relates to depth of discharge. If a battery is discharged to 50 percent (this can be measured with a cheap multimeter), it will last you about twice as long as if it was taken down to 80 percent discharge on the regular.

solar power cycle


How Many Batteries to Buy?

The rule of thumb is quite simple: The more, the better. For example, under normal weather conditions, a 100 AH (amp hour) battery will do you fine. Even if you’re going through one day of total overcast won’t cause any problems. The troubles appear after a couple of grey days back to back; that’s when the batteries reach their 50 percent discharge mark. At that point, you will have to fire up the generator.

As mentioned, a 130 watt panel will recharge the battery quite fast (by midday) given sunny conditions. With a smaller battery, this means you’ll waste the spare output. Therefore, you’re better off buying a larger battery (such as the 150 AH battery); it will help better carry you through overcast days.

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William E. Eubanks

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

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