5 Best Battery Backups for Existing Sump Pumps in 2021

Power outages are troublesome but when you rely on sump pumps to protect your home, they can become your worst enemy. Thankfully, we now have multiple ways to ensure that our pumps run even in such occasions. 

The easiest way to do so is by using batteries. You can install a battery backup sump pump that runs directly off them or you could use a device called an inverter that converts the power from the batteries into the type your main pump needs. This can give you extra protection without having to install another pump in the pit.

In this article, I’ll share with you the best battery backup for existing sump pumps for both types. I’ll also be answering a few questions you might have about them. So, let’s get on with it.

Wayne ESP25 Zoeller Spin508 PumpSentry 822PS

Best for average flooding

Best for heavy flooding

Best power inverter

1680 GPH @ 10'

2040 gph @ 10'

Depends on your main pump

Audible alarm

Audible alarm

Audible alarm

Editor Rating: 4.7

Editor Rating: 4.6

Editor Rating: 4.7

The Best Battery Backup for Existing Sump Pumps

Best battery backup sump pump for average flooding

Wayne ESP25 with case and accessories

The Wayne ESP25 is the best battery backup sump pump you can get to take care of your basement while the primary pump is out of commission. It’s powerful and sturdy — exactly what you want for a backup sump pump.

This pump is an upgraded version of the old ESP25 that had a thermoplastic construction. Now it’s equipped with an epoxy coated steel housing and a cast iron bottom for that added protection against the elements.

It has a pumping capacity of 1680 gallons per hour at 10 feet, about the same as your typical ⅓ HP sump pump. You can expect it to last for 26 hours on a single charge of battery if you have around 5 gallons per minute of water coming into your basement.

It has all the bells and whistles you need for a solid backup sump pump including an audible alarm and a status indicator panel. If you have water coming in that’s not too light nor too strong, this one’s just right.

Best backup sump pump for heavy flooding

Zoeller Spin508 with the battery case and control panel

It’s hard to talk about sump pumps without adding Zoeller, one of the most trusted brand in the industry. The Zoeller Aquanot 508 is a proven fully-automatic 12 volt backup sump pump. It can pump 2,100 GPH at an elevation of 10 feet and can last for 6 hours of continuous running. 

A controller takes care of the automatic charging and protection of the system. It even has the self-testing technology that will make sure the sump pump is in good order every single day of the year.

Like the Wayne, this one has a low battery indicator and alarm to notify you when it needs some help. It’s a bit pricier but it also gives you a bit of extra pumping capacity which could make all the difference for your basement.

Black pumpspy with battery case

The PumpSpy PS2000 is a powerful battery backup sump pump that can take over the job of  ½ HP primary sump pumps when needed. It can pump a whopping 2400 gph at 10 feet and still last for 5.5 hours on a single charge running continuously.

PumpSpy is known for its sump pump monitoring system and it’s a given that this one is at the top of the game. You can connect it to your WiFi to get instant alerts on your phone for complete peace of mind even if you go on vacations.

It does a test every 48 hours to check if everything is okay so you can react to problems before flooding can even occur. In case your connection goes down, their server automatically sends you a message that they can’t get to your pump, which is probably the case when there’s an outage.

It will also logs daily pump cycles, last cycle time, estimated gallons pumped and total cycles by date giving you a much better understanding of your system. The catch is that it comes at a higher price compared to the previous two. Is the extra cost worth it to gain that peace of mind? That’s up to you.

Best power inverter for sump pumps

Compact power inverter Pumpsentry 822 PS
If you need to backup your pump but you can’t find extra space in the pit, take a look at power inverters. They allow you to run your primary pump even when there’s a power outage. 
 
The PumpSentry 822 PS is the best one you can get for your average sump pump. It’s a very reliable 1200W power inverter with charger that can support up to 1/2 HP sump pumps. A leading choice for emergency backup power favored by pros and homeowners alike.
 
It has battery status indicators and a low battery alarm you can hear from your kitchen. It’s not exactly cheap but what it brings is a complete peace of mind even in the midst of thunderstorms. Something only a top-quality product can give.

Best budget-friendly power inverter

If you want to use an inverter but just can’t stomach the price of the PumpSentry, you should check out this new release from RayBend. It’s a much cheaper alternative yet it’s able to power up larger pumps (up to 3/4 HP) with pure sine wave power. That means power supply as clean as what you get from the outlet, ensuring your pump runs smooth and quiet. The only drawback is the slower charger but if you’re not expecting back-to-back power interruptions in your area, it shouldn’t be a problem. 

Which battery backup to choose for your home

Before we start, in case you’re not familiar, DC power is basically what you get from a battery while AC is what you get from your electrical outlet. There are 2 common setups available for adding a battery backup to your existing primary pump:

1. Battery backup sump pump

This setup only comes with the 12V sump pump, perfect if you already have an existing sump pump installed. You will need to fit the second pump inside the basin so make sure there’s enough room down there for this. 

The backup pump’s float switch is usually placed a few inches higher than the on point of the primary so it runs only when the water gets too high. Since you’ll be running it when the main pump is down, you have to make sure it has the same capacity as the original. Otherwise, the water will eventually overflow. 

There are also combination sump pump systems where both the backup and primary are pre-assembled in a single package. This is great if your original pump is getting old and you want to make sure that two pumps fit inside the basin since these are usually more compact.

2. Power inverter

The first setup comes with limitations. First, you need to have enough extra space in the pit. Second, you need to hire a plumber or do a bit of work yourself. Lastly, you need to have less than 2500 GPH of water coming in since most DC backup pumps are rated below that.

Power inverters solve all those three problems by having your primary pump itself powered up even during power outages. When choosing an inverter, it’s very important to pick one with an auto switch and charger like the ones above so they operate automatically without you having to go down the basement every time.

Need to look at more sump pump inverters? Check out our complete review.

What if a power outage lasts for days?

As the sump pump battery only lasts for hours to days at most, you can’t rely on it to keep the basement dry for long. There are essentially 2 things you can do to prepare for such cases:

Prepare a spare battery – possibly the easiest and cheapest way you can prepare for a longer power outage. Keep a battery in storage or line it up in parallel with the other.

Use a sump pump generator – if your area is prone to having blackouts that last for days, the best you can do is to get yourself a generator. That way, you could run your pump indefinitely as long as you have fuel. You could even use it for the fridge and the AC.

What type of batteries can I use with this?

The type that’s ideal for sump pump use is a deep cycle marine battery, the best you can use is the AGM type battery which doesn’t need any maintenance. It works well with the power demand of sump pumps. 

A battery backup sump pump usually requires at least a 75 ampere hour battery to last at least 5 hours of continuous running for the typical pump. Of course, I’d recommend the 100 AH models for longer run hours at your disposal.

Buyer's Guide

1. Build Quality

The build quality of the battery backup sump pump and inverter has to be top-notch. Before we consider their features and performance, we need to make sure it has a sturdy build quality with no obvious design flaws. The pumps must be resistant to corrosion and build-up while being strong enough to resist impact and erosion. In case of the inverter, they should be able to withstand the moisture in the basement.

Individual parts must be made of materials that are appropriate for their purpose. For example, aside from protecting what’s inside, the motor housing should also encourage heat transfer to keep the motor cool at all times. The pump’s float switch must also be made resistant to punctures and dirt accumulation. Also, the battery box must be sturdy enough to keep the insides safe.

2. Performance

We want a powerful backup sump pump that can keep the water supply from overflowing the pit. It must be able to move nearly as much water as the primary to maintain the same amount of protection even as the primary pump fails. Which is why you should also choose a backup pump that’s close in capacity to your main pump.

Since the battery power is limited, it must also have high efficiency which means being able to run longer on a single battery charge. You don’t want the battery juice to run out before you can even do something.

3. Features

A battery backup sump pump needs to be fully equipped to deal with different possible scenarios. That’s why it’s usually equipped with a few more tricks up its sleeve compared with the primary. 

Aside from the float switch, it could have sensors, alarms, chargers, and indicators that allow you to get a good idea of the current status of the system. There are also remote alert systems from much more sophisticated pumps such as the PumpSpy which could be a lot of help to people who have to go away often.

4. Ease of Installation

Installation is the final consideration. Plumbers and other specialists (you can hire one from TaskRabbit) can do the the job of installing backup sump pump systems if you need help. But since a lot of us are installing the pump on our own, a pump or inverter that’s easy to install is a huge bonus.

A battery backup sump pump should easily fit inside the basin beside the existing pump. You may need to modify the position of the primary as needed. 

On the other hand, inverters are much easier to install and will probably cost you less in installation fees if you have to hire someone. All you need is to mount it on the wall or an elevated space then connect the batteries and the plug to the outlet.

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