How Many Hours Does a Sump Pump Battery Backup Last?

  • By: Monica Shulz

A sump pump’s battery backup can last about 4-8 hours of continuous operation.

Its battery life depends on the battery’s capacity, age, and several other factors.

A battery backup sump pump is a great investment to have in your home because floods and rains often come with power outages.

These pumps remain operational even after power outages, ensuring your basement doesn’t get flooded.

A big concern among homeowners buying a battery backup sump pump is how long their batteries last.

How Long Does A Battery Backup Last For A Sump Pump

Battery Capacity (Ampere Hours)Expected Life (Hours)
Note: This table is for a sump pump continuously operating and drawing current from the battery.

These values will be much different in real life as the pumps do not operate continuously for long.

How Long Should a Backup Battery Last?

The backup battery should last about 4-6 years.

After this period of time, it will not be able to hold enough charge to power the sump pump for long operating periods.

In some cases, the battery might even become a safety hazard.

So, it’s advisable to replace your pump’s batteries at most, every 5 years.

However, sump pump owners often find themselves getting less than this from their batteries.

This is because the life of your backup battery depends on several factors.

These factors include:

  • Battery capacity
  • Pump power
  • Battery age
  • Charge level

Battery Capacity

The battery capacity is the single most important spec you should look at when buying a backup sump pump.

It determines how much charge your sump pump’s battery will be able to hold.

A battery with a higher rating will deliver power to the battery for longer.

The battery’s capacity is usually rated in Ampere Hours.

You can check out the table above to compare different battery capacities and their estimated battery lives.

Pump Power

Pump power (rated in hp) also determines how long the battery will last.

A pump with a higher power rating will pump a higher volume of water at a faster rate from the sump.

However, this comes at the cost of battery life.

Pumps with higher horsepower will draw more current from the battery, leading to it being exhausted quickly.

Battery Age

As the sump pump’s battery ages, it gradually loses its ability to hold a charge.

For example, a battery that offers you about 6 hours of continuous pumping when brand new might only offer you about 3.5 hours after three years.

To combat this, most homeowners often find themselves replacing their batteries after about five years.

Charge Level

Sump pump battery chargers are designed with a trickle charge system.

This means they will keep the pump’s battery at 100% by slowly charging it when it’s not in use.

However, due to unforeseen circumstances, you might have a situation where a spoilt charger or battery might result in a low charge level.

And since the pump is an emergency aid, most people might not detect the fault in time.

So, this will significantly reduce the charge level available to the sump pump when it is time to work.

This is why you should constantly monitor your backup sump pump’s health and battery levels.

Why Does My Backup Sump Pump Keep Beeping?

  • Pumping alert
  • Low battery
  • High water level
  • Overwhelmed primary sump pump
  • Low power input
  • Low water levels in wet cell batteries
  • Loose battery connections

Pumping Alert

One of the main reasons a backup sump pump starts beeping is to alert the user that it is in operation.

So, if your power is out and you start hearing beeping noises from the backup pump, you should first investigate.

If the pump is running and the basement isn’t flooded, then it means the pump is just doing its work.

Low Battery

Another cause of beeping is a low battery.

If the pump has been running for a while and starts beeping, it’s a good idea to check the battery level.

If the battery level is low, then the pump’s alarm is warning you that the battery backup sump pump will soon give up.

High Water Level

If the water in the sump reaches a certain level, the battery backup sump pump might have trouble keeping up.

In this situation, the pump will not be able to evacuate enough water from the sump to keep the basement from flooding.

So, the alarm will alert you that flooding might be imminent.

Overwhelmed Primary Pump

The battery backup for sump pumps are usually installed in tandem with normal AC sump pumps.

In cases of extreme flooding, the water in the sump can reach the backup pump even while the power is on and the primary pump is operating.

In this situation, the backup pump will begin working with the primary pump to evacuate the water.

As a result, its alarm will start beeping to alert you that it has begun operation.

Low Power Input

The battery backup for the sump pump is set to trickle charge through a wall outlet.

If the battery is receiving little or no power from the wall outlet, it can trigger the alarm.

To fix this, check if the wall outlet is providing power for the battery’s charger.

You can test this using another appliance.

You can try resetting the outlet’s circuit breaker if it’s not providing power.

If the outlet is providing power, then you might need to check the battery’s charger.

Low Water Levels in Wet Cell Batteries

If your backup battery for the sump pump uses wet cell technology, you’ll need to keep a certain level of distilled water in the cells.

If the water level drops to a certain level, it will trigger an alarm to remind you to refill the cells with distilled water.

If the alarm persists, you should also check the placement of the water level sensors in the cells.

Loose Battery Connections

A tight connection between the sump pump and the battery’s terminals is needed for optimal operation.

If the connections are loose, the pump won’t be able to draw power properly from the battery.

So, check the connections at the terminals to ensure the cables are snug and tight.

Also, inspect the battery’s terminals for any corrosion.

What To Look for When Getting a Battery Backup for Sump Pumps?

The battery of the backup sump pump will play a big role in the performance of the sump pump.

So, whether you’re looking for a new battery or buying a new system, here are some things to look out for.

  • Battery capacity
  • Battery technology

Battery Capacity

The battery capacity determines how long your pump will last on a single charge.

So, if you’re planning on using it for extended periods, you should get one with a high battery capacity.

It would be best to look at a battery with at least a 75AH rating for regular pumps and >100AH for larger pumps.

Battery Technology

The battery technology influences how long the battery will last and how fast it will charge and discharge.

It also determines the maintenance costs associated with running the battery.

For the best performance, we recommend you go with deep-cycle AGM batteries.

These batteries are relatively maintenance-free, safe to use, and last longer than conventional wet cell batteries.

You can also charge them from wall outlets with regular voltages without needing special, boxy chargers.

Is a Battery Backup Sump Pump Worth It?

Yes, a battery backup sump pump is worth every penny.

It helps ensure the basement and lower levels of your house are safe and dry in the event of unforeseen power outages.

Also, the initial investment involved in buying a backup sump pump is way less than what you’ll have to spend on water damage.

While the average water damage bill is about $300, it can run into thousands of dollars in some bad cases.

So, it’s better to install a battery backup sump pump and be safe than sorry.