Re: starter need 2 batteries?
Your starter motor is not getting the power it needs when on one battery.<br /><br />Either the starter demands extraordinary amounts of power due to a defect or it demands the rated amount but the supply-line somehow is restricted.<br /><br />If the starter is OK (not drawing too much power to crank the engine), you should start by looking battery connections, cables and battery selector/switch over. If the switch is defective it may prevent sufficient power over one set of breakers thus only starting the motor when two are engaged. Look for points that have been extremely hot as this will happen when the starter demands more power than a certain supply-line offers.<br /><br />If you connect the motor directly to one battery and it works, your switch/connections are the problem.<br /><br />If all is OK and your starter still needs the power of two batteries to work, your starter and solenoid needs checking.
