Are rechargeable gel batteries obsolete? In the solar energy storage system, the common rechargeable battery, the gel battery appeared earlier than the lithium-ion and flow battery, put into mass production.
A look at history:
The lead-acid battery was invented by the French scientist Plante in 1859, and the battery has been in use for 140 years.
In 1938, the American A.Dassler proposed the gas complex rationality of sealed lead-acid batteries, which laid the theoretical foundation for the VRLA battery.
In 1957, Germany’s Sunshine company invented the thixotropic SiO2 gel colloidal sealed lead acid battery.
Gates invented the absorption AGM separator in 1971, a breakthrough in lead-acid battery “sealing”, more commonly known as a “gel battery “.
Lithium batteries and flow batteries are emerging hot types. But, we need to admit that rechargeable gel batteries are the most affordable, oldest, and most compatible with solar energy storage systems.

Gel batteries come in two types —2V and 12V.
2V is mostly used in large-scale solar energy storage systems, such as the 500kW Solar Power Plant Project here. 12V is mostly used in homes and small PV energy storage systems.


Watch the process of producing gel cells at PVMARS Solar’s factory for more production information.
Is the gel battery capacity really only 70% used? Is it even lower?
Before we dive into this topic, let’s understand what capacity is.
In the world of solar energy systems, there is theoretical capacity ( the highest theoretical value ).
Actual capacity ( the amount of electricity that can be output under certain conditions, which is equal to the product of discharge current and discharge time, unit AH )
Rated capacity ( the minimum capacity that should be released under certain conditions stipulated by national standards ).
And rated reserve capacity ( often used in automobile batteries regardless of the battery size, the discharge time from 25A current to 1.75V termination voltage is calculated by species ).
Back to the original 70%, we clearly have 100% capacity. Why can we only use 70% or lower? – Technical reasons.
For example, our older mobile phones are getting shorter and shorter, because battery life is reduced by constantly cycling to 0% capacity.
In other words, if you want to extend the service life of the gel battery, then you can’t use 100% of the capacity.
So many manufacturers set the inverter output battery capacity at 50%-70% before leaving the factory to maintain battery life.

PVMARS Solar has 16 years of energy storage technology. We use 80% to 90% of the capacity of our gel batteries here, which is one of the reasons for the price difference.

Is there a relationship between battery voltage and discharge speed?
There is a certain relationship. The current through the battery’s internal resistance reduces the battery voltage.
As the battery voltage decreases, the discharge rate increases.
The PVMARS Solar factory uses different resistance materials, such as graphite, carbon black, conductive polymers, etc., to reduce this resistance, so that your battery can discharge slower and last longer.

Are gel batteries maintenance-free?
Gel batteries are maintenance-free.
For example, diesel generators or other generators, they need to regularly add oil for maintenance.
Gel batteries, on the other hand, don’t require you to add electrolytes for maintenance, but they still need to be cleaned regularly, as solar panels do.
Keep an eye out for dirt and debris on your battery, which can accumulate on the battery’s terminals and increase resistance.
When cleaning, remember to cut off any battery hookups to the inverter, or the load. Then, clean the battery terminal stain with a rag soaked in mild soapy water.

More tips to extend the life of gel batteries:
1- Use the right charger: Applying a charger not designed for gel batteries can damage the battery and increase resistance. Make sure to use a charger designed for gel batteries.
2- Proper battery storage: Gel batteries should be stored in a cool, dry place. Storing the battery in a hot or humid environment increases electrical resistance.
At last
As technology advances, it’s imperative to choose what suits your needs.
For example, space in my home is limited, so a small lithium battery is very suitable for you. Please click here to learn more about lithium batteries.