charger safety device

Just got back from the bike shop, where they fixed my battery and found that a wire inside was burned.

While fixing the battery the electrician told me that one of his clients showed him a battery and charger, and he had found that the charger was not stopping when the battery was already full. He gave him an extra charger, and told him to check it out, because its dangerous. So he should keep an eye on the battery and charger during charging.

The guy left it charging during the night in his store which of course had been burnt down by the morning. This happened two weeks ago.

The store owner (and her insurance company) wants to know that her charger and battery did not cause the damage, and people want their safety and are willing to pay a lot for it.

The following device will sell like hotcakes. One part connects to the battery to identify it, and to confirm that our device is checking the battery's temperature. It also will not start until it can read the batteries voltage output. The identification device will also tell our safety switch device what the expected voltage from the battery should be. According to the current voltage it puts a time limit, as well as an extra reading limit, so that it will stop the electricity to the battery, even if the original charger failed to do so.

A small recording of the last use will be stored in a tiny "black box" safe from fire and water (from the fire extinguishers"). This will be proof to the insurance company that you had used the safety device, and the harm did not come from the charger or battery.