People don't routinely bother to make posts saying "My battery is still working fine." It's human nature; people post about problems. When you cite "all the reports here and on other forums of battery issues" you are using data from a self-selected group that have had problems. It should come as no surprise that you find a high incidence of problems on a car forum, and consequently, it is erroneous to assume that these reports are a good indication of overall reliability. Tom
I did not make any claims about overall reliability. Again, there are plenty of reports about battery issues, here and elsewhere. As I have already stated a couple times, I have no evidence that they are more common on Prius than other cars. Clearly, there are a number of people with concerns, and this type of product may be of interest to them. That is all.
In the Prius I used the clamps, as the charger in it did not have the 12v adapter, so not sure if the other one would have worked that way or not. It did work in the Highlander with the key in the accessory position. Anyway, I have used the chargers one time each over the last few months. The Highlander was my fault, but no idea what caused the Prius battery to drain. Maybe getting to be time for a new 12v battery as it's 4 years old now? Either way, very handy and saved a lot of hassle and in one case likely saved a tow. In retrospect they were worth the price of admission in my opinion, even though each one has only been used once in over 2 years. Good to know both maintained charge that long, too.