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What to Do About A Solar Battery Draining Fast

Solar batteries drain a lot faster these days as more and more people using them to go off-grid are attempting to run complicated energy networks on them. Many people just getting into solar energy for the first time also do not understand the science and chemistry behind this relatively new technology, and poor maintenance habits and subsequent battery damage/failure can be the result. 

So what to do about a solar battery draining fast? The following methods can be used to avoid a solar battery drain and extend its life: 

What to do about a solar battery draining fast
  • Not allowing batteries to stand too long discharged between charges (more than 24 hours in warm weather and more than a few days in cooler weather)
  • Not leaving a battery in storage without compensating for energy loss. 
  • Not using deep cycle batteries to start engines
  • Fully charging batteries instead of partially charging them
  • Avoiding storage of batteries in a heat of 95F or higher, which leads to internal discharge

Many factors in a manually rigged off-grid system can lead to a rapidly draining solar battery, faulty wiring by amateurs not the least of them, but some are easily prevented when learning how to use your setup. Let’s troubleshoot some of the possible technical explanations. 

Causes of A Solar Battery Drain

Regardless of whether it is living up to its expected life or not, a battery of any type is going to drain and die eventually. Batteries (even rechargeable ones) should be regarded as a fuel source that must be replenished occasionally. 

Rechargeable batteries can potentially last a lot longer than non-rechargeable batteries, and this is one of their benefits in an off-grid setup. However, their longevity is very dependent on proper usage and maintenance, so it is vital that you understand how the batteries work.  

Certain factors can cause a solar battery to drain much more quickly than the normal wear and tear of use would account for. These are some of the things that can cause a solar battery to drain faster
than normal:

  • Using a battery that was manufactured more than eight months before use. Batteries that have been freshly manufactured will have a much longer lifespan than those that have been sitting in storage waiting to be bought. 
  • Not charging a battery fully before using it. Only partially charging a battery causes sulfation within the battery and relatively quick battery damage. Always bring a battery to full charge before using.
  • Mixing-and-matching different kinds of batteries in one bank. All batteries must be on the same voltage to be used. If you use different batteries on the same bank, one will die quickly, and the other will soon follow.
  • Charging the battery incorrectly (improper amps-to-capacity). If a battery charge has amps that are too high for the battery, the battery might charge quickly, but it will also lose a lot of its life expectancy. This can cause the battery to fail twice as fast. 
  • Allowing batteries to rest unused in long-term storage. All batteries self-discharge over time, so it is important to apply charge whenever the charge level falls below the recommended levels. This recommended level varies on battery type. 
  • Allowing batteries to stand too long discharged between charges. If a battery is fully discharged and left standing before being fully recharged, this leads to eventual sulfation.
  • Keeping batteries in temperatures above 95°F. High temperatures increase internal discharge and cause a standing battery drain.
  • Using deep cycle batteries to start engines. Deep cycle batteries are not intended for this purpose and using them to power powerful bursts of electrical energy (rather than extended duration current) can cause cumulative damage.

Long story short, many of the bad battery maintenance practices listed above result in chemical sulfation within the battery itself, a cumulative effect that is one of the leading causes of solar battery failure. Read more about sulfation below. 


Sulfation is the chemical process that results in 80% of battery failure. This chemical process is
when sulfur molecules in the battery acid become discharged and begin to coat the lead plates of
the batteries. 

This article is owned by and was first published on August 31, 2019

This creates a build-up that forms a barrier, resulting in high internal impedance. Due to this, the battery eventually loses its capacity to transfer power. At this point, the battery loses its ability to take a charge, and fails.  

If a battery is left standing while discharged, lead sulfate in the battery becomes hard and will lead to the battery having a high electrical resistance. This condition also happens if a battery is constantly only charged to a partial degree, then discharged partially, then charged partially. 

Normal charging cannot break down these lead sulfate crystals, and most charging sources cannot break them down either. 

Install A Battery Charge Controller

Connecting solar panels directly to a bank of batteries can cause the batteries to overheat, resulting in shortened battery life and eventual failure. To prevent this, you can install a battery charge controller. 

Battery charge controllers are devices that regulate the output voltage and current. By regulating voltage and current, charge controllers allow the battery to maintain its highest level of charge without ever overheating and causing sulfation within the battery, lessening its life expectancy.

Ways to Maintain Solar Batteries for Best Charge

While there are many ways you can handle a solar battery that can potentially damage it and cause it to drain quickly, there are also many ways you can practice good maintenance habits in order to extend the life of your solar battery.  

Here are some of the ways you can protect your solar battery to prevent rapid drain:

  • Make sure that batteries remain charged to a recommended level between full charges if you are storing them.
  • Make sure not to allow batteries to stand fully discharged between charges. If you have used a battery until it is flat, it needs to be recharged immediately. 
  • Do not use deep charge batteries to start engines. Keep a starting battery specifically for this purpose instead. 
  • Do not partially charge batteries in order to use them more quickly. Always charge the battery to its full capacity before use. 
  • Avoid storing your solar batteries in temperatures of 95°F or higher. Try to keep working batteries in shaded, naturally ventilated areas. 

Learn the Science Behind Solar to Succeed

As with any technological endeavor, it pays to learn a little bit about the scientific background of how the tech works on a chemical and electrical level in order to use it to its highest potential. That requires a little bit of research in the beginning, but it’s research that’s well worth it. 

It’s easy to become discouraged by buying a bunch of expensive equipment, throwing it together as best you can, and then having the whole system backfire because you failed to learn your equipment thoroughly beforehand. Don’t let that happen to you. 

The Future Is Solar

Solar batteries are an integral part of a dependable home-based solar energy system, as they allow an off-grid system to store energy for later use during times when the sun isn’t shining and solar energy cannot be collected. In this way, an energy reserve can be kept on constant tap. 

Solar energy is expected to become a 4.5-billion-dollar industry by 2023, and state-of-the-art companies like Tesla and finding more and more ways for people to use solar batteries to bank energy for later use in their homes. If you want to be one of them, learning their proper usage and maintenance is essential. By practicing some basic methodologies based on fundamental knowledge of how solar batteries work on a chemical level, you too can successfully join this energy revolution. 

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This article is owned by and was first published on August 31, 2019

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