Review on CTEK (40-149) CTX Battery Sense - Smart Battery Monitoring via Mobile Phone by Jason Olguin

I charged my battery to 100% with the CTEK charger and it was great. Unfortunately, after connecting this Battery Sense, my battery went from 100% to 78% within 12 hours. I have used this in another car and drained my battery from 29% to 23% in the same period. As you can see in the graph, I drove one of the cars for about 30 minutes and jumped from 3% to 26%. I'm not sure about the accuracy of this device, or it's just drawing too much current when connecting the battery clip. It's probably best to plug it into a cigarette lighter, which only lights up when the car is in motion. I would not recommend this product or connect it directly to the battery terminal. UPDATE: I drove the cars for about 30 minutes, the reading went from 26% to 100% in about 5 minutes drive, while the other car went from 78% to 100% in about 5 minutes. travel time too. After overnight parking, the battery now shows 85% and 88% respectively. CONCLUSION: I just can't trust this device to get accurate readings.