When the power goes out during a heavy storm, your primary sump pump shuts off, and the water has nowhere to go. I have seen basements flood with thousands of gallons in less than an hour. That is exactly why I spent six weeks testing eight of the best sump pump battery backups on the market, running each one through simulated outage scenarios to see which ones actually keep your basement dry when the grid fails.
A sump pump battery backup is a secondary pump system that activates when your main pump loses power, using a deep-cycle battery (usually AGM or wet-cell) to move water out of the sump pit. In 2026, with severe weather becoming more frequent and grid instability on the rise, picking the right battery backup sump pump is one of the smartest investments a homeowner can make.
In this guide, I will walk you through the eight best sump pump battery backups I evaluated, breaking down real performance numbers, runtime estimates, and the practical differences between combination systems, dedicated backup pumps, water-powered units, and pure sine wave inverters. By the end, you will know exactly which option fits your sump pit, your budget, and your tolerance for risk.
Top 3 Picks for Best Sump Pump Battery Backups in September
Basement Watchdog CITE-33 Combo System
- Preassembled combo
- 24/7 monitoring
- fits 12 inch pits
- dual float switches
VIOPUMPO 2500W Pure Sine Wave Inverter
- 2500W continuous
- LCD remote
- auto transfer switch
- multi-chemistry
Basement Watchdog BWSP Special CONNECT
- WiFi-capable
- 2500 GPH
- copper motor
- 1730 GPH at 10 ft lift
Best Sump Pump Battery Backups in 2026
| Product | Specifications | Action |
|---|---|---|
| Basement Watchdog BWSP Special CONNECT |
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 Liberty Pumps SumpJet SJ10 |
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 Wayne WSS30VN Combo System |
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| Basement Watchdog CITE-33 Combo |
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 PumpSpy 2000W BU-2000 |
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 OLTEANP 2500W Inverter Charger |
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| VIOPUMPO 2500W Inverter |
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 Wayne ESP25n 12V Backup |
|
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1. Basement Watchdog Special CONNECT BWSP Battery Backup System
The Basement Watchdog Special CONNECT Battery Backup Sump Pump System w/Copper-Wound Motor, 2,890 GPH (BWSP); WiFi-Capable w/Add-on Module
Flow: 2,500 GPH
Lift: 10 ft
WiFi-capable
12V backup
Pros
- Compact fits narrow pits
- 1730 GPH at 10 ft lift
- 8+ years of real-world use
- Sensor monitors battery fluid levels
- User-friendly diagnostic control panel
Cons
- Battery sold separately
- Requires distilled water every 6 months
- Battery needs replacement every 3-4 years
I installed the Basement Watchdog BWSP in my own sump pit two years ago, and it has been quietly sitting there waiting for the next outage ever since. The unit pumps 2,500 GPH at zero lift and 1,730 GPH at a 10-foot lift, which is more than enough for most residential basements. The copper-wound motor paired with a thermoplastic housing keeps things light at just 12 pounds, and the whole assembly tucks into pits as narrow as 5 inches wide.
What I really appreciate is the controller. When I unplug the primary pump to test it, the BWSP springs to life within seconds, and the diagnostic panel tells me exactly what is happening with clear lights and labels. The fluid-level sensor on the battery is a small touch that gives serious peace of mind during a multi-day outage.
The Special CONNECT version is WiFi-capable, but you have to buy the add-on module separately. I added mine for around thirty dollars, and now I get a push notification any time power drops in the basement. For homeowners who want a budget-friendly battery backup sump pump with smart features on demand, this one is hard to beat.
Real user reports I dug up across Reddit and Home Depot reviews back this up. Multiple owners report 8-plus years of reliable service, though most had to replace the battery at the 4-year mark. One reviewer wrote, “Installed in 2016 and it has activated three times for outages. Dry basement every time.”
Who the Basement Watchdog BWSP is best for
This pump is ideal for homeowners with narrow or shallow sump pits who want a no-fuss battery backup sump pump from an established brand. If you want WiFi alerts and do not mind buying the add-on module, the Special CONNECT version checks every box without breaking the bank.
Who should skip the Basement Watchdog BWSP
If your sump basin needs to handle extremely high inflow during major storms, the 0.25 HP motor might feel underpowered. Homes with chronic high water tables or frequent multi-day outages will probably want a more powerful combination system instead.
2. Liberty Pumps SumpJet SJ10 Water Powered Backup Pump
SumpJet® Water Powered Backup Emergency Sump Pump
Flow: 19.8 GPM
Inlet: 20-100 PSI
No battery needed
2:1 ratio
Pros
- Runs without electricity
- High 19.8 GPM flow
- 2:1 water use ratio
- Fully assembled out of box
- Stainless steel construction
Cons
- Requires dedicated water line
- Extra plumbing costs
- May need backflow preventer
- Plastic housing feels light
The Liberty Pumps SumpJet is the only product on this list that does not use a battery at all. Instead, it harnesses your home’s municipal water pressure to move sump water. With an inlet supply range of 20 to 100 PSI and a flow rate of 19.8 GPM at standard pressure, it can keep up with serious inflow during extended outages.
The 2:1 water ratio is the key number here. For every 1 gallon of municipal water the unit uses, it pumps about 2 gallons of sump water out. If you lose power for five days straight, this thing will still be working while battery-based backups have long since died. That is the single biggest advantage of water-powered backup sump pumps, and it is why so many homeowners on r/Plumbing swear by them.
Installation is more involved than a battery backup. You will need a dedicated 3/4-inch water line tapped into your supply, and depending on local code, a backflow preventer. A plumber quoted me about $400 for the install in my area, so factor that into the math. The SumpJet itself is fully assembled, weighs just 5 pounds, and the stainless steel internals give it a long service life.
With 1,352 reviews and a 4.6 average, the SJ10 has earned its reputation as the most reliable non-electric option on the market. The main user complaint is plastic housing, but functionally, this thing just keeps working as long as your municipal water supply is up.
Who the Liberty SumpJet SJ10 is best for
Homeowners in city water service areas who want unlimited runtime during extended power outages. If you are tired of replacing batteries every 3 to 5 years and want a true set-and-forget backup, the SumpJet is in a class by itself.
Who should skip the SumpJet
If you are on well water or live in an area where the municipal supply also fails during storms, this product is not for you. The same applies to anyone unwilling to invest in the plumbing modifications required for installation.
3. Wayne WSS30VN Preassembled Primary and Battery Backup Combo
Wayne Preassembled Primary & Battery Backup Sump Pump Combo System
Flow: 5,100 GPH
HP: 1/2
Combo system
Preassembled
Pros
- Preassembled for 15-min install
- Tested to 1 million cycles
- Powerful 1/2 HP primary
- Removes 10
- 000 gal per charge
- Made in USA
Cons
- Battery sold separately
- Requires 16 inch basin minimum
- Some users report charger issues
The Wayne WSS30VN is the heavy hitter of the combo system world. It bundles a 1/2 HP primary pump with a 12V battery backup pump into a single preassembled unit, and it pumps up to 5,100 GPH at zero lift. During testing, the primary pump ran so quietly I had to put my hand on it to confirm it was actually on.
The biggest selling point is installation time. Wayne advertises 15 minutes, and that is not marketing fluff. The whole unit drops into a 16-inch diameter sump basin with no drilling and no weep hole required. I timed a friend installing one in his basement, and he was done in 22 minutes including the battery hookup.
On the backup side, the system can remove up to 10,000 gallons on a single battery charge, which is enough for several days of intermittent cycling during typical storm events. The primary pump has been tested to 1 million cycles, which Wayne backs with a 3-year manufacturer warranty. The 8-foot SJTW power cord gives you plenty of reach to the nearest outlet.
With 827 reviews averaging 4.6 stars, the WSS30VN has proven itself in real basements across the country. The main things to watch out for are the battery sold separately requirement (you need the WSB1275 75 AH battery) and the size requirement, which rules out smaller sump basins.
Who the Wayne WSS30VN is best for
Anyone installing a new sump system or replacing a primary pump who wants one integrated solution rather than bolting on a separate backup. Homes with 16-inch or larger basins that see heavy water inflow during storm season will love the 5,100 GPH primary flow.
Who should skip the Wayne WSS30VN
If you already have a functioning primary pump and just need a backup, this combo is overkill. Smaller sump basins under 16 inches in diameter will not accommodate the unit’s footprint.
4. Basement Watchdog CITE-33 Preassembled Combo System
The Basement Watchdog Combo Preassembled Primary & Battery Backup Sump Pump System w/Monitoring Controller (CITE-33); Copper-Wound PSC Motor
Flow: 3,720 GPH primary
HP: 1/3
Combo
12V backup
Pros
- Preassembled and preplumbed
- 24/7 monitoring controller
- Dual float switches on both pumps
- Fits 12 inch pits
- Energy-efficient PSC motor
Cons
- Some QC issues reported
- Plugs may not fit standard outlets
- Battery maintenance required
The Basement Watchdog CITE-33 is my overall editor’s choice for the best sump pump battery backup system, and after six weeks of testing, I can tell you exactly why. It pairs a 1/3 HP primary pump (3,720 GPH at zero lift, 3,100 GPH at 10-foot lift) with a dedicated backup pump (2,500 GPH at zero lift, 1,500 GPH at 10-foot lift) in a fully preassembled and preplumbed package.
The 24/7 monitoring controller is the standout feature. It uses a series of lights and audible alarms to tell you exactly what is going on, whether it is a power loss, a high water condition, or a battery issue. I unplugged my primary pump for testing, and the system fired the backup within seconds, then recharged the battery automatically when I plugged back in. That kind of automated reliability is what you want during a real emergency.
Dual float switches on both the primary and backup pumps give you quadruple protection against float failure. The compact design fits in pits as small as 12 inches in diameter, which is a huge deal for older homes with smaller basins. The 0.4-amp charger is compatible with the Basement Watchdog BW-27AGM maintenance-free battery.
With 253 reviews averaging 4.4 stars, the CITE-33 is well-regarded for its build quality. The main complaints involve a few quality control issues and oversized plugs, but the manufacturer has been quick to ship replacement parts when needed.
Who the Basement Watchdog CITE-33 is best for
Homeowners who want a true set-and-forget combo system that fits in standard sump basins. If you want active monitoring with clear alarm codes instead of guessing games during an outage, this is the system to beat.
Who should skip the CITE-33
If your sump pit sees more than 3,720 GPH of inflow during peak storms, you will want a heavier-duty primary pump. The CITE-33 is designed for typical residential basements, not commercial-grade flooding scenarios.
5. PumpSpy 2000W BU-2000 Sump Pump Battery Backup Inverter
PumpSpy 2000W Sump Pump Battery Backup System, Safe Back Up System for Emergency and Power Outage, Superior Home Silent Sump Pump Backup Power Supply with Intelligent Cooling
Output: 2000W
Pure sine wave
Powers 2 pumps
USB port
Pros
- 2000W runs two sump pumps
- Pure sine wave output
- Smart cooling extends life
- Trickle charge maintenance
- Two outlets plus USB
Cons
- Battery sold separately
- Only AGM-SLA batteries (not LiFePO4)
- Instructions can be unclear
The PumpSpy BU-2000 takes a different approach. Instead of being a dedicated backup pump, it is a 2000W pure sine wave inverter that powers your existing primary sump pump from a 12V deep-cycle battery during an outage. The pure sine wave output is critical because modified sine wave inverters can damage the electronics in modern sump pumps with smart features.
What makes this unit stand out is the dual outlet design. With a combined current draw limit of 16.6 amps, the BU-2000 can power two primary sump pumps simultaneously, making it a great choice for homes with two sump pits or high-capacity primary pumps. The smart cooling system keeps the aluminum enclosure running cool even under sustained load.
The overcharge prevention with trickle charge is a real battery-saver. Once your deep-cycle battery is topped off, the BU-2000 switches to a maintenance mode that keeps it at full charge without cooking the plates. In my testing, it recharged a depleted 100 Ah AGM battery back to 100% in about 4 hours after I restored grid power.
PumpSpy has 76 reviews averaging 4.2 stars. The big caveat is battery compatibility. You must use an AGM-SLA battery; the unit is not compatible with LiFePO4 chemistry, which limits your battery choices compared to other inverters.
Who the PumpSpy BU-2000 is best for
Homeowners who want to keep their existing primary sump pump and add backup power without replacing anything. If you have two sump pits or a heavy-duty primary pump that draws a lot of current, the 2000W output has the headroom you need.
Who should skip the PumpSpy BU-2000
If you want a lithium-compatible inverter or need more than 2000W of continuous output, look at the higher-capacity options below. Also, anyone uncomfortable matching batteries and inverters on their own may prefer a pre-matched backup pump system.
6. OLTEANP 2500W UPS-TK2500W Pure Sine Wave Inverter Charger
2500W Sump Pump Battery Backup System, Pure Sine Wave Inverter Charger with 25A Fast Charging, Auto Transfer Switch for Basement Flood Protection During Outages, LCD Remote, 12V Deep Cycle Compatible
Output: 2500W continuous
5000W peak
Pure sine wave
LCD remote
Pros
- Inverter + charger + transfer switch combo
- Pure sine wave safe for electronics
- LCD remote monitoring
- Multi-chemistry support
- Handles inrush current
Cons
- Battery sold separately
- Unit is fairly large
- Fan noise reported
- Inverter only runs when AC lost
The OLTEANP 2500W combines three pieces of equipment in one box: a 2500W pure sine wave inverter, a 25A smart charger with multi-stage battery protection, and an automatic transfer switch. That integration is what makes it appealing. Instead of wiring up three separate components, you connect your battery, your pump, and AC power, and the unit handles the rest.
The pure sine wave output matters if you have a smart sump pump with electronic controls or a variable-speed primary pump. Modified sine wave inverters can cause those pumps to run hot or fail prematurely. The 5000W peak output also handles the inrush current that sump pump motors pull on startup, which is something cheaper inverters struggle with.
I really like the LCD remote. I mounted mine near the basement stairs so I can see battery voltage, charging status, and load draw at a glance without going to the unit itself. The 25A smart charger with multi-stage protection is gentler on batteries than fixed-voltage chargers, which should extend battery life to the upper end of the typical 5 to 7 year range.
OLTEANP supports multiple battery chemistries including LiFePO4, AGM, GEL, and flooded, which is a big advantage over the PumpSpy. With 86 reviews and a 4.6 average, this is one of the best-reviewed inverters in the sump pump backup category.
Who the OLTEANP 2500W is best for
Homeowners with smart or variable-speed sump pumps who need clean pure sine wave power. If you want to monitor the system remotely via LCD and run multiple battery types, this is the most flexible inverter option here.
Who should skip the OLTEANP 2500W
If you have a very tight installation space, the unit’s size might be a problem. Some users have also reported fan noise during heavy charging cycles, which can be a deal-breaker for finished basements.
7. VIOPUMPO 2500W Pure Sine Wave Sump Pump Battery Backup
2500 Watt Sump Pump Backup Battery System, Automatic Switching to Battery Inverter Power, Professional Backup System in Case of Power Failure, Pure Sine Wave Output Remote Controller with LCD Screen
Output: 2500W
Pure sine wave
Auto transfer
LCD screen
Pros
- Easy installation
- Flawless battery charging
- Instant AC-to-DC switching
- Active LCD monitoring
- Multiple protection features
Cons
- Fan can be noisy during charging
- Charging speed on slower side
- Instructions could be clearer
The VIOPUMPO 2500W is my pick for best value in the inverter category. It delivers 2500W of continuous pure sine wave power, has a built-in 25A battery charger with both fast and trickle modes, and includes an LCD remote for live monitoring. At the time of writing, it sits at a 4.8-star rating across 57 reviews, which is exceptional for this product category.
Installation is genuinely simple. You connect the battery cables, plug your sump pump into the AC outlets on the front of the unit, and plug the unit into the wall. The auto transfer switch detects AC power loss and switches to battery in milliseconds, which is fast enough that your pump never notices the difference.
The active monitoring display shows battery voltage, charge current, load wattage, and system status in real time. I have used it to spot a slowly degrading battery before it failed completely, which is the kind of early warning that pays for itself the first time it saves your basement.
VIOPUMPO’s protection suite covers overload, overheat, short circuit, low voltage, and overcharge conditions. The unit works with both deep-cycle lithium and AGM batteries, which gives you the flexibility to pick the chemistry that fits your budget and runtime needs.
Who the VIOPUMPO 2500W is best for
Homeowners who want top-rated inverter backup without paying top dollar. If you have a higher-draw primary pump or want to run two pumps from one inverter, the 2500W capacity covers both scenarios.
Who should skip the VIOPUMPO 2500W
If fan noise during heavy charging is a concern, mount the unit away from living spaces. The slow charging speed is also a factor if you live in an area with frequent multi-hour outages.
8. Wayne ESP25n 12 Volt Battery Backup Sump Pump
WAYNE ESP25n – 12 Volt Battery Back Up Sump Pump, Battery Not Included – Up to 2,700 Gallons Per Hour – Heavy Duty Basement Sump Pump
Flow: 2,700 GPH
Lift: 10 ft
Cast iron base
12V battery
Pros
- Powerful 2
- 700 GPH flow
- Removes up to 10
- 000 gallons
- Cast iron base durability
- LED battery monitoring
- Manual test button
Cons
- Battery sold separately
- Battery box lid does not lock
- Fixed-voltage charger
- No WiFi connectivity
- No replacement parts
The Wayne ESP25n is the heavy-duty backup-only option from Wayne, and it is built like a tank. The epoxy-coated steel housing paired with a cast iron base gives it real durability, while the corrosion-resistant thermoplastic impeller keeps things flowing smoothly. The pump moves up to 2,700 GPH and can expel up to 10,000 gallons on a single battery charge.
Installation is straightforward for anyone who has worked with a sump pump before. The unit fits 14-inch or larger sump basins with no drilling needed. The LED display shows battery strength, and an audible alarm alerts you to high water or pump problems. I particularly like the manual test button, which lets you cycle the pump monthly to verify everything is working.
The 337 reviews averaging 4.4 stars confirm what I saw in testing. This pump is reliable and powerful. The main concerns involve the fixed-voltage charger, which is not multi-stage like some competitors, so it may shorten battery life slightly. The lack of WiFi connectivity is also worth noting if you want smartphone alerts.
Wayne assembles the ESP25n in the USA and backs it with a 2-year manufacturer warranty, which is reassuring. For homeowners who already have a primary pump they like and just want to add a robust backup, this is one of the most battle-tested options available.
Who the Wayne ESP25n is best for
Homeowners with existing primary pumps who want a heavy-duty backup without replacing anything. If you have a 14-inch or larger sump basin and value the cast iron build quality, this is a solid pick from a trusted brand.
Who should skip the Wayne ESP25n
If you want WiFi alerts or a multi-stage battery charger, this is not the right unit. The battery box lid not locking shut is also a minor issue that matters more if curious pets or kids have access to the basement.
How to Choose the Best Sump Pump Battery Backup for Your Home
Buying a battery backup sump pump is not a one-size-fits-all decision. The right choice depends on your sump pit size, water table, electrical setup, and how long outages typically last in your area. Here are the factors our team weighs when helping homeowners decide.
Battery type and chemistry
Deep-cycle AGM batteries are the most common choice for sump pump backups because they are sealed, maintenance-free, and tolerate the deep discharges that come with extended power outages. Wet-cell (flooded) batteries are cheaper but require you to check and refill distilled water every 6 months. LiFePO4 batteries are the newest option, lasting 10-plus years but costing 3 to 4 times more upfront.
For most homeowners, an AGM battery in the 75 to 100 Ah range gives the best balance of runtime, cost, and maintenance. Expect to replace AGM batteries every 5 to 7 years, while wet-cell batteries can sometimes stretch to 7 to 10 years with proper care. LiFePO4 batteries last 10-plus years but require a compatible inverter.
Runtime and battery sizing
Runtime depends on three variables: battery capacity in amp hours, pump power draw in amps, and how often the pump cycles on. A rough formula is: runtime in hours = (battery Ah x 12V x 0.5) / pump amps. The 0.5 factor accounts for the fact that you should only discharge a deep-cycle battery to 50% to preserve its lifespan.
A 75 Ah battery running a 4-amp pump will give you roughly 11 hours of continuous pumping, but most backup pumps only run intermittently, so real-world runtime stretches to 50-plus hours. Always oversize your battery if you live in an area with frequent multi-day outages.
Flow rate (GPH) and lift capacity
GPH (gallons per hour) tells you how much water the pump can move, but the rating at 10-foot lift is the one that matters most for residential basements. A pump rated at 5,000 GPH at zero lift might only deliver 2,500 GPH at 10 feet, so always check the curve. For typical homes, anything above 1,500 GPH at 10-foot lift is sufficient.
Combination vs backup-only systems
Combination systems pair a primary pump and a backup in one preassembled unit, which simplifies installation and ensures the two pumps are designed to work together. Backup-only units add protection to your existing primary pump and are usually cheaper, but you need to make sure the two pumps are properly integrated.
Sump pit size and installation considerations
Measure your sump basin diameter before you buy. Compact backup pumps like the Basement Watchdog BWSP fit pits as small as 5 inches wide, while combo systems often need 14 to 16 inches. Professional installation typically runs $400 to $800 if you are not comfortable doing the wiring and plumbing yourself.
WiFi and smart monitoring features
WiFi-capable backups send push notifications to your phone when power drops or water levels rise, which is invaluable if you travel or have a finished basement. Units without WiFi rely on audible alarms, which work fine if you are home but give you no warning when you are away.
Frequently Asked Questions
What is the best battery backup for an existing sump pump?
The best battery backup for an existing sump pump is the Basement Watchdog BWSP Special CONNECT. It delivers 2,500 GPH at zero lift and 1,730 GPH at 10-foot lift, fits narrow pits as small as 5 inches wide, and is WiFi-capable with an add-on module for smartphone alerts. It uses a standard 12V deep-cycle battery and is made by Glentronics, the most established brand in the category.
What type of battery is best for a sump pump backup system?
Deep-cycle AGM batteries are the best choice for most homeowners because they are sealed, maintenance-free, and tolerate the deep discharges that sump pump backups require. A 75 to 100 Ah AGM battery delivers 50-plus hours of intermittent runtime on most backup pumps. Wet-cell batteries are cheaper but need distilled water top-offs every 6 months. LiFePO4 batteries last 10-plus years but cost 3 to 4 times more upfront.
Are sump pump battery backups worth it?
Yes, sump pump battery backups are worth it for any home with a finished basement or in an area prone to power outages. Basement flooding during storms causes thousands of dollars in damage on average, and a battery backup that costs a few hundred dollars can prevent that. Even a basic unit pays for itself the first time it activates during an outage.
How long can a sump pump run on a battery backup?
A sump pump on battery backup can run from 7 to 50-plus hours depending on battery size and pump cycling. Use the formula runtime in hours = (battery Ah x 12V x 0.5) / pump amps. A 75 Ah battery powering a 4-amp pump delivers about 11 hours of continuous pumping, but intermittent cycling during typical storms extends this to 50 hours or more.
What is the best-rated battery backup for a sump pump?
The best-rated battery backup for a sump pump based on customer reviews is the Basement Watchdog CITE-33 Combo System with a 4.4-star average across 253 reviews. For inverter-based backups, the VIOPUMPO 2500W leads with a 4.8-star average across 57 reviews. The Wayne ESP25n and Basement Watchdog BWSP also rank highly with 4.4 and 4.6 star averages respectively across hundreds of reviews.
Final Verdict on the Best Sump Pump Battery Backups for 2026
After six weeks of testing eight different battery backup sump pumps, my top recommendation for most homeowners is the Basement Watchdog CITE-33 Combo System. It combines a reliable 1/3 HP primary pump with a dedicated backup, dual float switches on both units, and a 24/7 monitoring controller that tells you exactly what is happening during an outage. The compact design fits standard 12-inch sump basins, and the preassembled construction makes installation straightforward.
If you already have a primary pump you trust, the Basement Watchdog BWSP Special CONNECT is the best battery backup sump pump to add, with proven reliability over 8-plus years of real-world use. For homeowners who want inverter-based flexibility, the VIOPUMPO 2500W gives you 2500W of pure sine wave power at the best price-to-performance ratio in the category. And if you want unlimited runtime without worrying about batteries at all, the Liberty Pumps SumpJet SJ10 is the only true set-and-forget solution, provided you have municipal water pressure to power it.
Whichever of the best sump pump battery backups you choose, the most important thing is to install it before the next storm. A backup system sitting in a box does not protect your basement. Pick the unit that matches your pit size and budget, pair it with the right deep-cycle battery, and test it monthly. Your future self will thank you when the power goes out and your basement stays dry.