I have a parasitic drain so I charge my battery on a regular basis. The other day the battery had drain and I tried using my portable charger and it would not work. I used my large charger and was able to start the car. I had no problem starting it the rest of that day. The next day I used it to go to the store. When I came out the car would not start. It was getting power. The dash and radio came on, but nothing. No click ... nothing. AAA came and had one of those heavy duty charger, it was getting the 12 volts but still would not start. I had to have it towed. Any idea what the problem could be? Thanks for reading my post.