The system is designed to be used with a 12V "deep discharge" battery, different from a car battery becomes unusable after being completely discharged a few dozen times. The battery which comes with the pump has to be filled with acid and topped off periodically. The acid is hard to handle, it gives off fumes while one fills the battery, and each cell has to be filled to precisely the right level which is hard because the acid is completely transparent.

I live in an area where years pass between power outages of any duration. I would have preferred to use a car battery which requires no filling or refilling. However, part of the BW system is a needle dipping into one of the acid-filled cells. If the needle is not in the acid, an alarm goes on and it can not be turned off. So one has to use the BW battery.

At least, you might think, you can be sure the battery is good for hours of emergency use, but that is not so. I did not have a blackout since I installed the pump but every few months I turned it on for 20 seconds to check it. 4 or 5 years after I installed it, the battery alarm went on the moment I started the test. The battery would probably not have been able to drive the pump for long. In fairness, the instructions tell you the battery lasts only 5-7 years but what it does not tell you is that your pump can work for 6 hours only when the battery is new, and you have no way of knowing how long it could work when it is some years old.

One more thing. The instructions say drill a one-eight inch hole in the outlet pipe 3 in. above the outlet of the pump itself to prevent an air lock. A leak in the outlet pipe of course reduces the effectiveness of the pump, especially if it has to pump the water several feet up. I found that at a height of 3 in. a one-sixteenth inch hole suffices to let out air trapped under the valve.

The system is designed to be used with a 12V "deep discharge" battery, different from a car battery becomes unusable after being completely discharged a few dozen times. The battery which comes with the pump has to be filled with acid and topped off periodically. The acid is hard to handle, it gives off fumes while one fills the battery, and each cell has to be filled to precisely the right level which is hard because the acid is completely transparent.

I live in an area where years pass between power outages of any duration. I would have preferred to use a car battery... more