Not a mechanic- but since this is a situation I have experienced myself: Here my thoughts- The Miata has a small battery, that for some reason or another empties within four to six weeks when car is not used. It is not unusual that a battery still has some juice left and works the radio but is not able to crank up the engine. So best bet would be to jumpstart or buy charger and leave the battery on "trickle" charger during the time of low or no use, which is also much better than totally letting it run empty and then recharge quickly, which may shorten the battery life. Another thing could be of course the age of the battery. They typically last about 5 years, depending on usage.
This reply is a courtesy only. No explicit or implicit warranty for correctness.
Saturday, April 19th, 2008 AT 6:47 PM