Review on SUNER POWER Waterproof Battery Maintainer Tools & Equipment and Jump Starters, Battery Chargers & Portable Power by Tony Wilson

Pretty easy to install. There must be a load to pull the tension. Note that if, like me, you use a standard battery service wire to connect directly to the battery terminals, the polarity on it will be reversed. If you are using a battery probe cable, the open end of the connector (on the cable connected to the battery) is negative and that side is positive, so you must reverse the cable going to the battery to use it. It would be nice if the manufacturer checked this closely so you can switch from a battery tender to this if you wish as the connector itself is compatible (just reverse the polarity); it should be universal, like all other batteries. The rest is working fine so far. Update: The first device I received stopped working after about 2 months (and outside the return period). I contacted the seller and they settled on their item and I was sent a replacement. So far so good with my updated device.