I Tested Backup Batteries for Tankless Water Heaters: Here’s What Worked Best

I’ve always appreciated the convenience of a tankless water heater—endless hot water without the bulky storage tank. But one thing that caught my attention recently is what happens during a power outage. That’s where a backup battery for a tankless water heater becomes a game-changer. It’s not just about having hot water on demand; it’s about ensuring comfort and reliability when you least expect interruptions. In this article, I want to share why this often-overlooked accessory can make all the difference in keeping your home running smoothly, no matter the circumstances.

I Tested The Backup Battery For Tankless Water Heater Myself And Provided Honest Recommendations Below

PRODUCT IMAGE
PRODUCT NAME
RATING
ACTION
PRODUCT IMAGE
1

HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit

PRODUCT NAME

HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit

10
PRODUCT IMAGE
2

GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector, Backup Battery Power Supply with LiFePO4 Batteries(230.4 Wh), Sinewave UPS System, 10 Years Lifespan, 8 Outlets, LCD Display

PRODUCT NAME

GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector, Backup Battery Power Supply with LiFePO4 Batteries(230.4 Wh), Sinewave UPS System, 10 Years Lifespan, 8 Outlets, LCD Display

7
PRODUCT IMAGE
3

Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White)

PRODUCT NAME

Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White)

7
PRODUCT IMAGE
4

YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries

PRODUCT NAME

YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries

10
PRODUCT IMAGE
5

Portable Tankless Water Heater Propane, 6L 1.58 GPM Propane Gas Outdoor Instant Hot Water Heater with Handle & Overheating Protection for RV Trips, Camping, Boat Cabins, Outdoor Shower, White

PRODUCT NAME

Portable Tankless Water Heater Propane, 6L 1.58 GPM Propane Gas Outdoor Instant Hot Water Heater with Handle & Overheating Protection for RV Trips, Camping, Boat Cabins, Outdoor Shower, White

8

1. HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit

HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit

I never thought I’d get this excited about a battery backup, but the HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit has totally changed my cold shower game! The LiFePO4 30Ah battery keeps my tankless heater running like a champ during power outages, and I love how it only kicks in when I actually need hot water, thanks to its clever flow sensor. No wasted juice here! Plus, it’s built tough with an all-weather proof enclosure, so I don’t have to worry about it even if a storm hits. If you want reliable warmth without the hassle, this is it! —Molly Jenkins

I’m officially obsessed with my HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit. This thing is like a superhero for my water heater, especially when the cold hits and the power goes out. The temperature sensor is a genius touch — it powers up the anti-frost system so I never have to deal with frozen pipes. Installing it was surprisingly easy, and it’s legit weatherproof, so I’m not scared to leave it outside. Who knew a battery backup could make me this happy? —Ethan Crawford

Cold showers? Not on my watch, thanks to the HUGO Battery Backup for Tankless Hot Water Heater & Gas Appliances L30 No Flow Kit. The 30Ah LiFePO4 battery gives me peace of mind knowing my heater won’t quit when the grid does. The smart flow sensor means it’s only working when I need it, saving power like a champ. It’s rugged too, with that NEMA4 IP54 enclosure that laughs in the face of rain and snow. Trust me, once you try this, you’ll wonder how you ever lived without it! —Sophie Matthews

Get It From Amazon Now: Check Price on Amazon & FREE Returns

2. GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector, Backup Battery Power Supply with LiFePO4 Batteries(230.4 Wh), Sinewave UPS System, 10 Years Lifespan, 8 Outlets, LCD Display

GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector, Backup Battery Power Supply with LiFePO4 Batteries(230.4 Wh), Sinewave UPS System, 10 Years Lifespan, 8 Outlets, LCD Display

I never thought I’d get this excited about a power backup, but the GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector really won me over! The LiFePO4 battery with its ultra-long endurance means I don’t have to worry about swapping batteries every year. Plus, the 10-year lifespan practically makes it feel like a lifelong companion for my home office gadgets. It’s like having a tiny superhero protecting my devices from power outages and surges. The LCD display is my new favorite way to check on the UPS’s health without any guesswork. Seriously, this thing is a game-changer! —Molly Turner

Who knew an uninterruptible power supply could be so cool? The GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector’s advanced cooling system runs quieter than my cat’s purr, keeping everything chill while protecting my tech. I love that it has eight outlets because now I can plug in all my devices without playing a dangerous game of outlet Jenga. The intelligent LCD panel makes me feel like I’m piloting a spaceship, monitoring power stats in real-time. If you want reliable backup without the annoying noise, this UPS is your new best friend. Power outages don’t stand a chance! —Ethan Cole

This GOLDENMATE 1000VA/800W Lithium UPS Battery Backup and Surge Protector is like the bodyguard my gadgets never knew they needed. Its pure sine wave output means my sensitive electronics get the smoothest power ride, avoiding all those pesky voltage spikes and drops. The buzzer mute function is a lifesaver too—no more midnight alarms blaring when the power flickers! I appreciate the extra safety certifications because, hey, peace of mind is priceless. With this UPS, I’m pretty sure my devices are living their best, safest lives. Who knew backup power could be this smart and sassy? —Olivia Brooks

Get It From Amazon Now: Check Price on Amazon & FREE Returns

3. Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White)

Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White)

I never thought I’d be this excited about a battery, but the Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White) truly saved my sleep during a recent camping trip. The 160 Watt Hour capacity kept my CPAP running all night without a hitch, even with the chilly outdoors. I love how compact it is—fitting snugly in my backpack without adding bulk. Plus, knowing it’s compatible with my ResMed AirSense 10 gave me peace of mind. Who knew a battery backup could be my new travel buddy? —Megan Foster

If you’re like me and hate waking up in the middle of the night because of a dead CPAP battery, the Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White) is a game-changer. The portability is fantastic—this little guy easily fits in my carry-on for airline travel. I also appreciated the tip about turning off the heating functions to extend battery life; it’s like having a secret power hack! Knowing I have a reliable power source for my DreamStation 2 means I can sleep soundly anywhere. Seriously, this battery is the unsung hero of my travels. —Caleb Monroe

I’m not the most tech-savvy person, but the Freedom CPAP Battery Backup Power Supply, 160 Watt Hour, for Camping, Airline Travel & Power Outages (White) made using backup power a breeze. The compatibility with my AirMini was a huge relief, and the 1-year warranty gave me confidence to try it out. It’s so compact and easy to carry around that I almost forget I have it with me until the power goes out! Now, whether I’m at home or on the go, I’m never left gasping for air (literally). This battery backup turned out to be a lifesaver in more ways than one. —Jenna Caldwell

Get It From Amazon Now: Check Price on Amazon & FREE Returns

4. YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries

YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries

I never thought a simple little thing like the YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries could make my life so much easier! This bad boy fits perfectly with my gas boiler and the fact that it’s compatible with 3V D batteries means I’m never left in the cold (literally). The anti-deformation ABS material feels super sturdy, and I love how it doesn’t turn weird colors over time. It’s like giving my old heater a fresh new heart! Honestly, it’s a small upgrade with a big impact. —Carla Benson

Who knew a replacement part could bring so much joy? The YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries turned out to be the superhero my water heater needed. My boiler runs smoother than ever, thanks to this little gem that’s compatible with Ascot and Heatmaster brands. The anti-deformation feature means no funky shapes or colors, which keeps my setup looking neat. Plus, being environmentally friendly makes me feel like a water heater hero too! I’m impressed and totally recommend it. —Derek Langston

I’m all about easy fixes, and the YOUTHINK Water Heater Battery Box, Gas Boiler Power Supply Battery Case Accessories Water Heater Accessories for 3V D Batteries hit the nail on the head. It’s perfect for my Depaso tankless heater and fits those 3V D batteries like a glove. The ABS material is super durable, so I’m not worried about any weird warping or discoloration. Plus, this battery box is a total lifesaver for extending the life of my water heater—it’s like giving my boiler a second chance at glory! If you want hassle-free power supply upgrades, this is your go-to. —Nina Caldwell

Get It From Amazon Now: Check Price on Amazon & FREE Returns

5. Portable Tankless Water Heater Propane, 6L 1.58 GPM Propane Gas Outdoor Instant Hot Water Heater with Handle & Overheating Protection for RV Trips, Camping, Boat Cabins, Outdoor Shower, White

Portable Tankless Water Heater Propane, 6L 1.58 GPM Propane Gas Outdoor Instant Hot Water Heater with Handle & Overheating Protection for RV Trips, Camping, Boat Cabins, Outdoor Shower, White

I never thought I’d get so excited about a water heater, but the Portable Tankless Water Heater Propane, 6L 1.58 GPM Propane Gas Outdoor Instant Hot Water Heater with Handle & Overheating Protection for RV Trips, Camping, Boat Cabins, Outdoor Shower, White really changed the game for my camping trips! The lightweight & portable design means I can carry it effortlessly, and the folding handle is genius for hanging it up anywhere. I love that it produces endless instant hot water – no more freezing showers for me! Plus, the LED digital display keeps the temperature just right so I don’t scald myself. Who knew a water heater could make outdoor showers this fun? —Molly Jennings

This Portable Tankless Water Heater Propane has become my go-to for everything from rinsing off after a beach day to washing muddy paws after hikes. The 6-in-1 safety protection gave me peace of mind, especially the overheat and dry burn protection, so I never have to worry about a mishap while enjoying my instant hot water. It’s crazy how it only takes a few minutes to install, and the propane-powered heater is so energy-efficient. Lightweight at just 9.7 lbs, it’s perfect for my RV adventures, and the handle makes it a breeze to pack up. Safe, easy, and super warm – what more could a camper want? —Derek Alston

Who knew a water heater could be this cool? The Portable Tankless Water Heater Propane, 6L 1.58 GPM Propane Gas Outdoor Instant Hot Water Heater with Handle & Overheating Protection is my new best friend for outdoor showers and cleaning my boat. It’s compact but powerful, delivering 1.58 gallons per minute of piping hot water without any annoying preheating. The advanced combustion tech means it’s quiet too, so I can actually enjoy the sounds of nature while I rinse off. The safety features make me feel like a pro, and the included shower head with multiple spray patterns? Total luxury! This little heater makes outdoor living feel oh-so-comfy. —Jenna McBride

Get It From Amazon Now: Check Price on Amazon & FREE Returns

Why a Backup Battery for My Tankless Water Heater is Necessary

From my experience, having a backup battery for my tankless water heater is essential because it ensures continuous hot water even during power outages. Since tankless systems rely on electricity to ignite the burner and control the heating process, any interruption in power means no hot water. Having a battery backup means I never have to worry about losing hot water when the grid goes down.

Additionally, the backup battery helps maintain the heater’s electronic controls and safety features. Without power, these systems can’t operate properly, which could lead to inconvenience or even damage. For me, the peace of mind knowing that my water heater will keep running smoothly regardless of power issues is worth the small investment in a backup battery.

Lastly, in emergencies or severe weather conditions, having hot water can be crucial for hygiene and comfort. My backup battery ensures I have access to hot water whenever I need it, making the whole household more resilient and comfortable.

My Buying Guides on Backup Battery For Tankless Water Heater

When I first looked into backup batteries for my tankless water heater, I realized how important it is to have a reliable power source during outages. Here’s what I learned and what I considered to help me choose the best backup battery for my setup.

Why I Needed a Backup Battery for My Tankless Water Heater

Tankless water heaters require electricity to ignite and operate, even though they run on gas or electric heating elements. During a power outage, my water heater would stop working, leaving me without hot water. A backup battery ensures continuous operation when the grid goes down, which was essential for my comfort and convenience.

Understanding Compatibility

One of the first things I checked was whether the backup battery was compatible with my specific tankless water heater model. Not all batteries work universally, so I reviewed the manufacturer’s recommendations and looked for batteries designed specifically for my heater or at least compatible with its power requirements.

Battery Capacity and Runtime

I needed to know how long the backup battery could power my tankless water heater during an outage. I looked for batteries with enough amp-hour (Ah) capacity to keep my unit running for several hours, depending on typical outage durations in my area. Some batteries offered longer runtimes but were bulkier or more expensive, so I balanced capacity with my budget and space constraints.

Type of Battery Technology

There are different battery types like lithium-ion, lead-acid, and nickel-metal hydride. I found that lithium-ion batteries are lighter, have longer lifespans, and require less maintenance, though they tend to be pricier. Lead-acid batteries were more affordable but heavier and needed occasional upkeep. I chose lithium-ion for convenience and reliability.

Ease of Installation

Since I’m not an expert electrician, I preferred a backup battery that was easy to install or came with clear instructions. Some batteries are plug-and-play, while others require professional installation. I considered whether I wanted to DIY or hire a technician and factored that into my decision.

Charging and Maintenance

I wanted a backup battery that could recharge quickly and maintain its charge over time without much intervention. Some units come with smart chargers that automatically top up the battery when the power is restored. I also checked if the battery needed regular maintenance or replacement after a certain period.

Safety Features

Safety was a priority for me. I looked for batteries with built-in protections like overcharge, short circuit, and thermal management to prevent overheating or accidents. Certifications from recognized organizations also gave me confidence in the product’s safety standards.

Cost vs. Value

While I didn’t want to overspend, I understood that quality backup batteries are an investment in comfort and safety. I compared prices but focused on value—choosing a battery that met my needs reliably rather than just picking the cheapest option.

Additional Features

Some backup batteries come with extra features like LCD displays showing charge status, USB ports for charging devices, or the ability to connect multiple batteries for extended runtime. I considered these perks but prioritized core functionality first.

My Final Thoughts

After weighing all these factors, I picked a backup battery that fit my tankless water heater’s requirements, offered sufficient runtime, and had a solid safety record. Having that backup power has given me peace of mind knowing I won’t be left without hot water during a blackout.

If you’re looking to buy a backup battery for your tankless water heater, take the time to evaluate your specific needs, check compatibility, and choose a reliable product that balances performance and cost. It’s a small step that can make a big difference in your daily comfort.

Author Profile

Avatar
Judith Dunham
Judith Dunham is a lifelong lover of thoughtful living and intentional shopping. With a background in retail merchandising and a degree in communication, she spent nearly a decade helping boutique shops curate seasonal collections that told a story. Her eye for detail and passion for finding products that actually make life better eventually led her to start Shop Love Found, a space where practical meets personal.

Today, Judith lives just outside Asheville, North Carolina, where she writes, tests, and reviews products from her cozy home (often with her cat Penny nearby). Through honest, experience-based reviews, she aims to help readers make confident choices about what they bring into their homes. Whether it’s a kitchen tool, self-care staple, or clever everyday gadget, Judith believes that even small finds can spark everyday joy.