Re: "Transformer" available to jump 6 volt car with 12 volt battery ?

Posted by Owen_Dyneto On 2010/7/2 11:26:46

Jumping a 6-volt car from a 12-volt source is commonly done and has been for decades, not a problem as long as some precautions are taken. 1st, forget polarity of the two cars, always jump positive to positive and negative to negative. As Phil points out, if both cars have the same polarity you can use a single cable between the hot posts and touch bumpers to make the ground connection.

Secondly, don't leave the cables connected for any more than is absolutely necessary, certainly no longer than 5 or 10 seconds at a time, at the most. If you're using 12-volt jumper cables they will get hot VERY fast and perhaps burn any plastic grips or insulators on them if you leave the connection intact any longer than that.

PS - wear safety glasses at an absolute minimum, full face shield and rubber gloves highly recommended. And I'd have a bucket of water handy; though uncommon, batteries do occasionally explode and the electrolyte in wet-cell batteries is approx. 20% sulfuric acid. And others may have alternative advice or actual experience, but I wouldn't jump a gel battery (Optima or similar) unless you could confirm with the maker that it's acceptable to do, whether from the same voltage or not.