Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Lack of automatic switching

The 3300 has provisions for motorcycle, auto, and boat batteries. The case becomes warm, but not hot, with use.The manual implies that the unit will automatically switch to maintenance mode when connected, and that if it does not, the battery may need replacing. This is misleading, as the manual also states that after 3 days that the unit should be manually switched to maintenance mode. I used the 3300 on 3 different batterys that were only a couple of years old, and it failed to switch automatically in each instance.