Nevertheless They won't shut-off automatically. A voltmeter or hydrometer is necessary to examine the battery situation periodically and change off the charger, when the batteries are totally charged. buttons: 1 to select the cost mode, and A further to initiate charging. We had little issue attaching the TOPDON to the https://hukums.com/products/hukums-24v-automotive-or-commercial-multi-battery-charger-c1224