Vacuum will not start; display shows E1 shortly after pressing the power button.

Safety first: Turn the main power switch off (if equipped) and remove the battery pack from the vacuum. Do not attempt to open the battery pack case.

• Check battery charge level: Insert the battery into the original Hitachi charger. Confirm that the charger’s indicator LEDs behave normally (steady or blinking charge light). If the charger shows a fault or no lights, unplug it for 1 minute and try again.
• Allow recovery time: If the pack was heavily discharged, leave it on the charger for at least 30–60 minutes even if the vacuum previously showed E1. Some Hitachi packs need a pre‑charge period before normal charging resumes.
• Inspect battery contacts: With the battery removed, visually inspect the metal contacts on both the battery and the vacuum handle for burns, pitting, or heavy oxidation. Clean gently with a dry, lint‑free cloth. Do not use liquids or abrasives.
• Test with another battery (if available): If a second compatible Hitachi battery pack works normally, the original pack is likely defective and should be replaced.
• Do not bypass protection: If the battery becomes hot, swollen, or emits odor, discontinue use immediately and recycle it according to local regulations. Do not attempt to reset or short the pack.

If E1 persists with a known‑good battery, the vacuum’s battery detection circuit on the main control PCB may be faulty and professional service is recommended.