Battery Draining and Charging?

You're ruining the battery: If the battery is allowed to run down (leaving the lights on, low charging output, slipping drive belt, frequent short-trip driving, long periods of inactivity, etc.), sulfate can form a barrier on the surface of the plates that makes it difficult for the battery to accept a charge. Over time, this can ruin the plates and cause the battery to fail.

And also the computer can lose its memory so you are going to have a bigger problem with the engine management system.