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How big is the Base battery?
This is the battery Base installs in Illinois. Everything below comes from Base's spec sheet unless it says otherwise.
| Item | What Base lists |
|---|---|
| Energy it stores | 39.2 kWh |
| Width, height, depth | 30.68 in, 35.9 in, 22 in |
| Voltage | 120/240 V, 60 Hz (the two levels homes use) |
| Works in | −22°F to 122°F |
| Noise | 55 dBA at 1 meter |
| Main panel limit | Up to 200 amps; call Base above that |
| Switches on | Within seconds of an outage |
| Safety tests | UL 1973, UL 9540, UL 991, UL 1998, UL 1741, IEEE 1547 |
| Service | Base handles service and upkeep for the life of the battery |
kWh is how much energy the battery holds, like the size of a gas tank. kW is how fast it can hand out power, like how fast fuel flows. Base's spec sheet lists no kW number. Ask for it in writing, because it decides how many big appliances can run at once.
How loud is the battery at your window?
Base lists 55 dBA at 1 meter, which is about 3.3 feet. That is quieter than normal talk, which the National Institutes of Health puts at 60 to 70 dBA. Sound also fades as you move away. Type the distance from the battery spot to your bedroom window, patio or fence.
This calculator could not start. Rule of thumb: every time you double the distance, the sound drops about 6 dBA.
This is an estimate for open air with no walls or fences, from Base's own number. Real yards differ. Ask Base where the battery will go, and check your village's noise rules.
Open-air math from Base's 55 dBA at 1 meter: each time you double the distance, the sound drops about 6 dBA. Everyday sounds from the National Institutes of Health. Bars start at zero.
Will it work in an Illinois winter?
Base rates the battery for −22°F to 122°F. That covers almost every day in Illinois. But Chicago has been colder than −22°F on 8 days in National Weather Service records. The record is −27°F, on January 20, 1985. The latest was −23°F, on January 30, 2019.
From the National Weather Service's Chicago temperature records, read October 25, 2026. The bars show degrees below zero.
Base does not say what the battery does when it is colder than −22°F. Ask before you sign.
How does the install work?
Base says it installs the battery in two visits.
- Check your addressYou enter your address. Base engineers check that your home qualifies, and whether it needs one battery or two
- Visit 1Base puts in the electrical gear and gets the home ready. It may add a soft start to help a large air conditioner
- Visit 2Up to three weeks later, Base sets the battery outside near your meter. No one has to be home, and your power stays on
- After the installBase handles the paperwork and works with your utility
Base's Illinois page lists a $295 one-time install fee, down from $695. The $95 offer for the first 2,000 homes ended September 30, 2026. In Illinois, Base serves homes in ComEd's area only.
What can stop an install?
Base checks every home before it books the work. Know these limits before you spend time on it.
- Your panel. Base supports main panels up to 200 amps. Above that, you must call Base first.
- Electrical clearance. The BBB lists Base installs turned down because a home did not meet clearance rules.
- Rooftop solar. Base warns its offer may cost you more than ComEd if you have solar or plan to add it.
- Where it can sit. The battery goes outside near the meter. If the spot is tight, ask Base to show you the plan.
- Sprinklers and wiring. The BBB lists complaints about crews hitting sprinkler wiring and air conditioners. Mark them before the crew arrives.
Thinking about solar too? A Base deal and rooftop solar pull in different directions, and our Base vs Energywell guide explains why. What customers say about Base installs is on our Base Power Illinois reviews page.
How long will it run my home?
Base says the battery runs an average home for 12 to 18 hours, and up to 36 hours if you cut back. It is not promised to be full when an outage starts. Base aims to keep at least 5 kWh in reserve, but says it can't guarantee that.
From Base's Illinois page, read October 25, 2026. Real backup depends on how full the battery is, the weather and what you run.
Our backup calculator turns your own monthly kWh into hours for both offers.
Questions, answered
How big is the Base Power battery?
The Base Core is 30.68 inches wide, 35.9 inches tall and 22 inches deep. It holds 39.2 kWh, according to Base's spec sheet.
Is the Base Power battery loud?
Base lists 55 dBA at 1 meter, about 3.3 feet away. That is quieter than normal talk, which the NIH puts at 60 to 70 dBA. At 10 feet, open-air math gives about 45 dBA.
Does the Base battery work in extreme cold?
Base rates it from −22°F to 122°F. Chicago has dropped below −22°F on 8 days in National Weather Service records, most recently in 2019. Base doesn't say what happens below its limit, so ask.
Where does Base put the battery?
Outside your home, near the electric meter. Base picks a spot that meets code, and no one has to be home for the battery visit.
Can my home take the Base battery if I have a 200-amp panel?
Yes. Base supports main panels up to 200 amps, and it checks your address and home before it books the work.
What does the Base battery cost to install in Illinois?
Base's Illinois page lists a one-time $295 install fee, read October 25, 2026. The $95 offer for the first 2,000 homes ended September 30.
What do you want to do next?
Want a battery you own instead?
Solar with your own battery can qualify for ComEd's battery rebate. See in about a minute if solar fits your roof.
Free eligibility check · ComEd & Ameren · No obligationThe Day Company is an independent solar, battery and electricity information resource. Information you submit may be used by our review team and authorized partners to contact you about your request. Checking eligibility creates no obligation.
Sources and updates
Sources (8)
- Base Power, Base Core home battery specifications: Size, noise, panel limit, temperature range, voltage and safety tests.
- Base Power, How it works: The two-visit install, the soft start, one battery or two, and where the battery goes.
- Base Power, Base Power in Illinois: The $295 install fee, 39.2 kWh, ComEd's area and backup hours (updated October 1, 2026).
- Base Power, Illinois Battery Services Agreement (May 4, 2026): The 5 kWh reserve Base aims for and does not guarantee.
- National Weather Service, Chicago, Chicago temperature records: Chicago's coldest days on record, read October 25, 2026.
- National Institutes of Health (NIDCD), How Loud Is Too Loud?: A whisper at 30 dBA and normal talk at 60 to 70 dBA (NIH Publication No. 18-DC-6431, May 2018).
- Better Business Bureau, Base Power complaints and profile: Install damage, and installs turned down for clearance, read October 25, 2026.
- Citizens Utility Board, CUB Q&A: Battery and electricity supply offers in Illinois: Base installs it outside, no backup guarantee, and the solar warning.
Changelog · last updated October 25, 2026 · 1 update
- October 25, 2026: Guide published.
How to cite this page: The Day Company, "What is the Base Power battery, and what does it need?", updated October 25, 2026, https://theday.company/answers/base-power-battery-illinois.
We have no partnership with Base Power, and it does not review or edit this page. Specs and fees change, and your signed agreements control. The noise figures are estimates from Base's own number, and the cold figures are weather records, not tests of the battery.