I got this little charger because sometimes I don't start my car for 10 days or more. Thanks to this, I can plug it in and make sure my battery is fully charged every few days. I've connected the o-ring clamps and all I have to do is plug them into the main unit and I'll know right away if my battery has been completely changed or not. If not, I just switch it to charging and after a short while it's fully charged again. I recommend this to anyone who doesn't drive every day because it's so easy to use that anyone can do it.