FIELD NOTES · JULY 2026
Roomba battery replacement, generation by generation
Batteries are the one Roomba part guaranteed to fail. Not because of a defect — because that's what batteries do. Every pack has a finite number of charge cycles, and a robot that once cleaned three rooms starts dying in the hallway. The good news: on every Roomba generation, the battery is a user-replaceable part sitting behind a few screws. The catch: iRobot has used several different packs over the years, and putting the wrong chemistry in the right robot is how swaps go bad.
First, know what's in there
iRobot's own compatibility documentation splits the fleet roughly in two. The older generations — 500 and 700 series — shipped with a 3,000 mAh nickel-metal hydride (NiMH) pack. The 600 and 800 series are the messy middle: depending on the exact SKU, they left the factory with either a NiMH pack or a lithium-ion one. Everything from the 900 series onward — including the e, i, j and s series — is lithium-ion only. Same-capacity packs are not automatically interchangeable across lines; the shapes and connectors differ, which is iRobot's stated reason, not ours.
| Series | Chemistry | Original pack |
|---|---|---|
| 500 / 700 | NiMH | APS 3.000 mAh |
| 600 | NiMH / Li-Ion (SKU) | 3.000 mAh / 1.800–2.130 mAh |
| 800 | NiMH / Li-Ion (SKU) | 3.000 mAh / 1.800–3.300 mAh |
| 900 | Li-Ion | 1.800–3.300 mAh |
| e / i | Li-Ion | 1.800 mAh (some i / algunos i: 2.210) |
| j | Li-Ion | 2.210 / 4.460 mAh |
| s | Li-Ion | 3.300 mAh |
Original battery by series, per iRobot's battery compatibility documentation (verified July 2026).
The practical rule: don't shop by series folklore, shop by what's in the bay. Flip the robot, open the battery door, and read the label on the pack you're removing. That label — chemistry, capacity, part number — is your shopping list, and it settles every "will this fit" question before it starts.
The swap itself
Details vary by generation — on most models the side brush has to come off first because its screw anchors the bottom cover — but the anatomy is the same everywhere: flip, unscrew, lift, swap, close. Keep your model's manual open beside you (the battery procedure is always illustrated) and give yourself ten unhurried minutes. There is nothing to solder and nothing under spring tension.
Battery swap, start to finish
- Power off and undock. Work on a towel so screws don't wander.
- Unscrew the side brush and set it aside, then remove the bottom cover or battery door screws (a Phillips #1 covers every generation).
- Photograph the old pack in place before lifting it out — the photo answers every orientation question later.
- Check the new pack's label against the old one: chemistry, capacity, part number. If they disagree, stop and re-check compatibility, not the forums.
- Seat the new pack, refit the door and side brush, and dock the robot for a full, uninterrupted first charge before the first run.
- Tape over the old pack's contacts and take it to a battery recycling point within the week — not the someday drawer.
OEM or third-party: the honest version
An OEM pack costs more and removes every variable: correct chemistry, correct protection circuitry, correct fit, and no arguments if the robot is under warranty. Third-party packs range from perfectly decent to actively dangerous, and the price tag won't tell you which you're holding. The failure pattern with the bad ones is consistent: capacity claims that exceed the label physics, missing or minimal protection electronics, and runtimes that collapse after a few months. A battery is the one component in this robot that stores enough energy to matter, which is why we treat it as safety-critical in our parts library while happily recommending aftermarket filters and brushes.
If you do go third-party, do it deliberately: an established brand with a track record, realistic capacity claims, a stated protection circuit, and a warranty someone will actually honor. And know your rights: under the US Magnuson-Moss Warranty Act, a manufacturer can't void your warranty merely because you used a third-party part — only if that part caused the damage. The wider fit-versus-OEM question has its own guide.
After the swap
Give the first charge all the time it wants, then run the robot to near-empty once so you learn the new pack's honest runtime. If the robot won't charge on the fresh battery, resist blaming the pack first — nine times out of ten it's the same dirty contacts and dock issues that plague old batteries, and the not-charging walkthrough sorts them in order of likelihood. A new battery in a maintained robot resets the clock by years; pair the swap with the maintenance schedule and the rest of the machine will keep up with it.