Battery charger/maintainer connection question

[EMBPilot]

Why is it, everywhere you read, if your going to hook up a automatic battery charger or battery maintainer to your car, they say not to hook up the negative lead to the battery? they always say to attach it to the block.

Why is that recommended? is it just a matter of keeping sparks clear of the battery? or is there some other reasonable theory behind it?

What is the best way to use a maintainer on our cars and minimize any 'jolts' or over currents to old computers that are in our cars (ie DMEs ect)?

[911pcars]

Sparks near a battery that has been charged can ignite the gases and cause an explosion. If the jumper/charger cable is connected to a common ground connection a distance away from the battery, their is less risk of this occuring even if a spark happens.

The safest method is to plug the charger to its power source only after making sound connections to the battery. Connections should be clean and firmly attached.

A true battery maintainer is a low current charger so connecting it to a the vehicle shouldn't cause any harm. However, the safest method of ensuring charging voltages won't harm vehicle electronics is to disconnect the ground cable from the battery, then connect the charger directly to the battery. The aftermarket has quick-disconnect switches for this purpose. I would disconnect the battery when using a regular charger.

Sherwood