Intelligent Octopus Go's 6-Hour Cap and Home Batteries

What changed in January 2026

Intelligent Octopus Go is Octopus Energy's flagship EV tariff. It gives you cheap overnight electricity for your whole home between 11:30pm and 5:30am, plus the ability for Octopus to schedule additional cheap rate slots outside that window to finish charging your car. The off-peak rate is around 7p per kWh, against a peak (Boost) rate of roughly 26 to 28p per kWh depending on region. The fixed off-peak window is 6 hours, the smart charging allowance on top is also up to 6 hours.

The 6-hour smart charging limit has always been in the small print. What changed in 2026 is that Octopus started automatically enforcing it. Octopus's own blog post confirms the change began at the end of January 2026 and rolled out across the customer base through March 2026. Octopus says around 80% of users were already inside the limit and have seen no difference.

Why this matters for home battery owners

Habo Energy's entire savings story is built on tariff arbitrage. We charge the battery overnight at single digit pence and discharge it through the peak window at 25 to 35p per kWh. Anything that changes the size or shape of the cheap window is a story we have to track, particularly for the large overlap between EV drivers and home battery buyers. Here is how the cap interacts with a battery:

A 5 kWh battery on a sub 3.6kW inverter (Habo's configuration, see G98 vs G99 for why we stay under 3.6kW) takes around 1.5 to 2 hours to charge from empty to full. The fixed 6 hour Intelligent Octopus Go window is comfortable. You set the charge schedule once and forget about it. A larger 11.5 kWh typical UK install still fits the same window.

Where the cap can bite: big EV charging needs

The cap is felt by households with very high EV charging requirements. The maths is the limiting factor:

Most UK households do well under 6 hours of EV charging a day. The average UK car covers around 7,000 miles a year, or roughly 19 miles a day, according to the Department for Transport's National Travel Survey. At typical EV efficiency that is well inside the cap with room to spare. The cap is a problem for very heavy commuters and for two-EV households running off a single charger.

Worked example: 5 kWh battery plus a 60kWh EV

Habo Energy installs a 5 kWh EcoFlow STREAM all-in-one from £2,499 fully installed, electrician-wired to the consumer unit (G98 / BS 7671). Not a plug-in battery. 0% VAT. Best case up to about £420 to £490 a year on Octopus Go (full daily cycle, all used at the day rate, so real savings will be lower). Best-case payback about 5.1 to 6.0 years. See how we worked it out.

Cheap charging needed:

• Battery: 5.556kWh ÷ an assumed 2.5kW charge rate ≈ 2.2 hours (whole-home window, not counted in EV cap)
• EV: 7.5kWh ÷ 7kW ≈ 1.1 hours (counted in 6-hour smart cap)
• Total inside 11:30pm to 5:30am window: about 3.3 hours, comfortably inside the 6 hour fixed off-peak window

Daily saving:

• Battery charging cost: 5 ÷ 0.9 = 5.556kWh × 7.6p = 42.2p
• Battery discharge: 5kWh a day that you would otherwise buy at your quoted day rate
• EV: 7.5kWh × 7.6p = 57p a day
• Each kWh moved into the cheap window saves your quoted day rate minus 7.6p. Real savings will be lower than a full daily cycle suggests.

The 6-hour cap never comes into play in this household. The customer is on the optimal tariff, the battery does its full daily cycle, and the EV gets a generous overnight top up.

When you should think harder about your tariff

The cap pushes a small slice of households to reconsider:

How Charge Cap actually works

Charge Cap is the new control Octopus added alongside enforcement. It is a simple toggle in the Octopus app with two positions:

1. Cap on (default). Octopus schedules up to 6 hours of cheap rate smart charging in a 24 hour period. If your target requires more, your EV stops at the cheap-hour limit and finishes the remaining percentage at Boost rate the next day, or you can top up manually.
2. Cap off. Octopus schedules whatever is needed to hit your target charge level. The first 6 hours are cheap, anything beyond bills at the Boost rate.

For home battery owners, the practical advice is to leave Charge Cap on. Your battery already smooths your daily energy needs, so if your car comes up a few percent short on a particular night, you can lean on the battery during the morning peak without paying Boost rates. The next overnight slot then catches up.

What about plain Octopus Go for batteries?

Plain Octopus Go is the older, simpler EV tariff. It gives you a fixed 5 hour or 5 hour 30 minute cheap window every night (the exact slot depends on your sign up date) at around 9.5p per kWh, and standard rate the rest of the time. No smart scheduling, no app required, and crucially no 6-hour cap because there is no smart layer at all. Both tariffs took a unit rate rise on 1 May 2026, so check your live rates in the Octopus app before doing maths off these numbers.

For battery owners without an EV, plain Octopus Go is the right tariff. For EV plus battery owners, Intelligent Octopus Go still beats it on headline rate and total cheap hours, even after the cap is enforced. The breakeven point sits at around 30,000 miles per year of EV use, which only a very small minority of UK households reach.

Are there alternatives to look at?

Agile Octopus. Wholesale linked half-hourly pricing. Often dips below Intelligent Octopus Go's off-peak rate in the small hours, but can also spike during winter peak periods. Suits people with home automation and a battery management system that can chase low prices.

Cosy Octopus. Designed for heat pumps, with three cheap windows including a 4pm to 7pm slot. We covered this in Cosy Octopus and home batteries. Not aimed at EV owners but useful if you have a heat pump plus battery.

Octopus Flux. Pays a premium for export at peak times and is the only tariff explicitly designed for solar plus battery export economics. Less useful for our battery only, no solar customers.

You can always model the trade off yourself with our home battery savings calculator. Plug in your tariff and battery size, and it will show the annual saving in pounds.

Quick checklist for Intelligent Octopus Go battery owners

1. Check your Octopus app to confirm Charge Cap is on (it is by default).
2. Set your home battery to charge in the fixed 11:30pm to 5:30am window. This is whole-home cheap rate, not counted in the EV smart cap.
3. Look at your average EV charge time per day in the Octopus app. If you are consistently under 6 hours, the cap will not affect you at all.
4. If you regularly hit the cap, decide whether to absorb the Boost rate cost or shift to Agile Octopus.
5. Re-run your numbers when the July 2026 Ofgem price cap is announced on 27 May 2026, since this also affects standard rate.

Where Habo Energy fits

Our 5 kWh EcoFlow STREAM all-in-one battery is sized to cycle inside Intelligent Octopus Go's 6 hour fixed window and to comfortably fit alongside a typical EV charging session. EcoFlow lists up to 2,500W grid-tied output for the main unit (EcoFlow specs), below the 3.68kW limit for a G98 notification. Total installed price is from £2,499 with 0% VAT applied. Octopus's own Nook battery, launched in June 2026, is the closest supplier-brand alternative, but it does not go on sale until 2027.