The quick table
| Error | Meaning | First move |
|---|---|---|
| Charging Error 1 | Battery not detected | Reseat the battery; on a brand-new robot, pull the battery tab |
| Charging Error 3 | Internal charging fault | Reboot; reseat on dock; service if it persists |
| Charging Error 5 | Dirty contacts | Clean robot and dock contacts (dry cloth or eraser) |
| Charging Error 6 / 7 | Battery overheated / won’t cool | Cool for 1+ hour somewhere cooler; recurring = replace battery |
| Charging Error 8 | Can’t talk to the Li-ion battery | Usually a defective or non-genuine battery — replace with a compatible genuine pack |
The pattern behind them
Errors 1 and 5 are mechanical (seating and contact cleanliness) and fix in minutes. Errors 6, 7, and 8 are battery-health errors — if they recur after the basic fixes, the pack is telling you it’s done. Error 3 is the genuine “internal” one: reboot once, and if it returns, that robot needs service, not more dock cleaning.
Buying the replacement battery right
Two facts that prevent wasted money:
- Chemistry and shape differ by family. Older 500–800 series used NiMH packs; 900/e/i/j/s are lithium-ion, and older packs do not fit the square-battery i/e/j/s machines. iRobot’s official compatibility chart is the authority — check it before ordering.
- Genuine packs are still sold first-party post-bankruptcy: $99.99 for the e/i/j-series Li-ion, $109.99 for the 1800 pack (600/800/960), up to $169.99 for j-series Combo packs. Third-party batteries are cheaper but are a documented trigger for Charging Error 8 — and iRobot’s guidance notes non-genuine parts can void the warranty.