How to Choose the Best Battery for Backup Sump Pump System.

Choosing the Best Battery for Backup Sump Pump Use

A battery backup sump pump system plays an important role in ensuring that your basement remains free of water. The battery for a sump pump that is used to power such a system is equally important. If the battery you use is of poor quality, even the best backup system available will be utterly useless.

Whether you have had to at some stage clean up a flooded basement or simply prefer to be prepared, you know that prevention is always better than cure.

When there is a power outage, a sump pump won’t work without backup power provided by a sump pump battery.

The problem is that there are many types of batteries available and very few are labeled as a battery for backup sump pump use.

This makes it very difficult to select the best one.

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It is possible to buy a backup sump pump that already has a battery included. However, if you don’t have one or need to replace a battery, this article will help you decide which one is best for your needs.

Terms Used to Describe Batteries

When you want to buy a backup battery for your sump pump, you’ll come across many terms being used such as:

  • wet-cell
  • gel-celled
  • deep-cycle
  • maintenance-free
  • marine
  • solar

As these terms are used interchangeably to describe lead-acid batteries. Finding the right one to buy can be very confusing.

Let’s look at battery terminology to help you distinguish one battery from the next. Then you’ll be able to select the perfect type of backup battery for your sump pump.

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Maintenance-Free Batteries

Batteries labeled “maintenance-free” can be a misnomer depending on the type of battery.

For wet-cell batteries, maintenance-free means that the battery is sealed and sometimes valve-regulated (VRLA).

With this type of battery, the oxygen and hydrogen produced by the battery are recombined back into water, and this reduces rapid evaporation and leakage.

Although they are called “maintenance-free”, it is really misleading as they still need maintenance to avoid the cells from drying out and losing their cycle capacity.

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Deep-Cycle Batteries

A deep-cycle battery is not a type of battery but describes the battery’s charging cycle. This term is important to be aware of when shopping for a sump pump battery.

This type of battery is made to constantly charge and discharge (cycle). This doesn’t reduce the expected life of the battery. Although they can’t deliver as high a current as wet-cell batteries can, they have thicker plates that can be discharged to a much higher degree.

Marine and RV type batteries are often a compromise between the higher starting capacity and the lower discharging capacity characteristics.

These types of batteries are rated in ampere-hours (AH). The AH rating indicates the number of amps the battery can provide for more than 20 hours. If a battery for example has a rating of 100 AH, it would provide 5 amps an hour (100/20) for 20 hours. The AH rating is normally printed on the battery.

Types of Lead-Acid Batteries

People are generally familiar with lead-acid vehicle batteries used in cars. This type of battery is designed to provide a big current for a short period.

The capacity and output of the battery is rated in CCA (cold cranking amps). The number of CCAs is often printed on the battery. This type of battery is not suitable as a battery for sump pump use except in emergencies. For example: If the backup battery has failed, then a car battery could be used temporarily.

Gel Batteries

A gel battery is filled with a gelled electrolyte that uses silica gel. The small satchels often found in vitamin bottles use the same type of gel as these batteries.

These batteries are “maintenance-free” as the gel won’t evaporate, making them ideal in situations where there are extreme vibrations and temperatures.

They are therefore most often used in off-road and racing vehicles, as well as solar and wind applications. As the gel design prevents fast movement of electrons, maximum current capacity and ion exchange are reduced. Also, the time to recharge the battery is slowed down.

Wet Cell Batteries

Wet-cell or “flooded” type batteries are inexpensive and are mostly found in automotive applications. They provide short bursts of current to start a car but are not suitable as battery for backup sump pump use. Generally, they are not suitable for use over extended periods. However, the deep-cycle versions can be used, but they are not the best choice.

Wet-cell batteries have lead plates that are submerged in an acid electrolyte and come in unsealed and sealed versions. Both versions need a periodic inspection to prevent the lead cells from drying out.

Maintaining these batteries is dangerous as it exposes you to noxious gas, acid, lead, and the risk of explosion.

AGM Battery For Backup Sump Pump Use

Absorbed Glass Mat (AGM), no-maintenance batteries are the best battery for backup sump pump use.

AGM batteries really are maintenance free. That is because homeowners don’t have to check or replace the water (acid electrolyte) levels.

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Although they are generally more expensive, their better performance and safety features are well worth the price.

The unique design of AGM batteries surrounds the lead plates in a glass fiber material which absorbs the acid electrolytes. So, the plates are not completely submerged in liquid acid, but only kept wet. Which also means that the batteries won’t leak when punctured, meaning they are relatively safe to use.

This design also allows the cells to be stacked together closer, enabling faster charging times and increased energy capacity.

As previously mentioned, gelled batteries silica gel and acid. AGM batteries provide all of gelled batteries’ advantages but without exhibiting their disadvantages.

An AGM battery’s acid is contained by the fiberglass mat but is still available for the battery plates, resulting in faster acid migration. This means the battery has a higher rate of absorption and delivery of current.

Most gelled batteries need to be charged at slower rates to prevent excess gas from damaging cells. However, an AGM battery is charged at standard voltages. Without needing to buy special chargers.

There is also no discharge or charge current limits. With its low internal resistance, the buildup of heat is virtually non-existent during heavy and normal charge and discharge currents.

Other gel type batteries could potentially lose capacity due to gaps developing in the gel if they are overcharged.

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An AGM battery’s self-discharge is typically between a low 1% and 3% on average per month, allowing them to be stored for longer periods without charging. AGM batteries can be recharged to almost full capacity even after being discharged for a month or more.

An AGM battery for backup sump pump use preserves water through electrolysis as it charges. This is done by oxygen and hydrogen recombining to convert to water while inside the battery. Water loss in other types of gelled batteries is common, especially in hotter climates. Which often times results in the premature death of a battery after only a few years. As water loss is not a problem with an AGM battery, it is truly maintenance-free.

Acid won’t spill or leak from an AGM battery due to the glass fiber material between the lead plates. As the plates are tightly packed, they can withstand vibration and shock.

AGM batteries are also non-hazardous, making them a cheaper and more viable option for shipping.

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When wanting to buy a battery backup sump pump system, purchasing one with an AGM battery is by far the best battery for backup sump pump use. An AGM battery provides maximize sump pump effectiveness and value for the money spent.

Checking A Backup Battery

The backup pump must start running to protect the basement from water ingress when the primary pump can’t work due to a malfunction or an interruption of power. As emergencies don’t occur often, ensuring the backup battery for sump pump use is in good condition and fully charged is important.

Which is why having the best battery backup sump pump system with Wi-Fi and text alerts is highly recommended. These systems will alert homeowners if a pump or battery is about to fail or needs replacement.

Many sump pump backup systems only have locally audible alarms.  So, it is good advice to check your system before the alarms go off.

Even a maintenance-free battery must be checked occasionally to ensure it will perform as it should. The easiest way to check a sealed battery is if it has a sight glass that will show when electrolyte levels are low.

Another way is to check a battery’s performance with a multimeter. If the battery is not holding a full charge, it may need some distilled water, or acid electrolyte added. Otherwise, the battery might need to be replaced.

Conclusions For: Battery For Backup Sump Pump Use

So, now you have the knowledge to choose the best battery for backup sump pump use.  Let me remind you that the AGM batteries are the best choice.

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Related article: Why Is My Sump Pump’s Alarm Going Off? What Must I Do?

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