Even so they won't shut-off automatically. A voltmeter or hydrometer is necessary to check the battery situation periodically and swap off the charger, when the batteries are absolutely charged. Although all you need to do is disconnect the battery terminals, we advocate eradicating the battery totally to forestall any accidents. https://hukums.com/products/heavy-duty-car-foam-washer-gun-fg-23-by-painter-for-cleaning