Not a good product.
I all ready bought 3 of them and all stopped working after a while.
First I bought two (one for each bike). A year after, one of them stopped working. I got it replaced (guarantee) but just worked for few weeks.
Then, the other one stopped working as well.
Now i bought again again a Battery Tender Jr, and a Yuasa Smart Shot 900. Both at the same time.
After two weeks the Battery Tender stopped working and the Smart Shot still running.
It is not easy for me to ask for a warrantee because I live out side the US. It is not worth it because the shipping.
And when i talked with the people of battery tender, they told me that there was a problem with the electricity in my house, but every thing else I have works fine!