Looking for DIY Battery Backup Sump Pump controller - Page 1
Forum section: electronics / general

author: rvmeush
author_rank: Contributor
timestamp: December 18, 2013, 02:05:01 pm
content: I've been using a Basement Watchdog BW4000 battery backup sump pump system for a while and have had issues with its operation. I thought it might be an interesting DIY project but haven't seen any designs posted online. I found discussion of a project athttp://talk.newagtalk.com/forums/thread-view.asp?tid=220317&DisplayType=flatbut was wondering if anyone might know of a published design? Thanks.

author: dr.diesel
author_rank: Super Contributor
timestamp: December 18, 2013, 02:25:54 pm
content: My last house had a basement and I built a simple backup system:- (4) Trojan T105 6v batteries, series parallel for 12v system voltage.- Statpower 3000VA modified wave inverter- 1.5A trickle charger- 3/4HP sump pump (this was absolutely necessary in the EXTREMELY high water table area I lived in, pump would run constantly for 6-8 hours on heavy rains)- Super simple relay logic to swap the pump from AC mains to inverter and switch it onWorked great for the 11 years I lived there, swapped batteries every ~4 years or so. Then I got smart and moved to a new house without a basement!

author: Skimask
author_rank: Super Contributor
timestamp: December 18, 2013, 03:18:24 pm
content: Not quite the same thing, but I've got a low-ish flow 12v pump placed about 1/2 way down my septic tank access hole with a 12v batt & really small trickle charger 'permanently' plugged in sitting in a box next to the cover.If my froggie water alarm in the basement drain sounds off, or if power goes out, or the main pump takes a dump, go out, put the 12v pump the rest of the way in the hole and let it go until everything else is back to normal.And if the battery takes a dump, just pull up one of the cars and hook up the jumper cables.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 19, 2013, 06:02:34 am
content: Take a look at bilge pumps. They run directly from DC and use surprisingly little power to move a lot of water.

author: Bored@Work
author_rank: Super Contributor
timestamp: December 19, 2013, 08:26:41 am
content: Quote from: Skimask on December 18, 2013, 03:18:24 pmThe dump can't be done if the pump doesn't run

author: Skimask
author_rank: Super Contributor
timestamp: December 19, 2013, 08:43:28 am
content: Shit don't flow if the pump don't go.

author: ConKbot
author_rank: Super Contributor
timestamp: December 19, 2013, 01:10:57 pm
content: Quote from: NiHaoMike on December 19, 2013, 06:02:34 am+1 from a 12v battery a bilge will draw 15A to do what an inverter and induction motor sump pump need 70-80A to do.I have 2 ~360AH 6V flooded lead acid cells in series for a battery bank, and IIRC they have enough juice to pump ~12' of water out of the basement, depending on the head of course.I'd put the johnson pumps L4000 up against a 1/2 or maybe even 3/4 HP sump pump any dayI'm even working on a overly fancy control panel, but IVe been lazy on completing it.I wouldnt waste your time on one of the 'basement watchdog' kits unless you wanted to shell out for the big one. The little one with the dinky pump would ring in even with a 1/10 - 1/8 HP pump. Ive had times when its really, really wet outside and a 3/4 HP pump runs at a ~25% duty cycle. That little guy would have to run constantly, and IIRC the battery in the basic kit is rated for 6 hours of run time. Better than nothing, but 6 hours isnt much time.

author: rvmeush
author_rank: Contributor
timestamp: December 19, 2013, 01:28:53 pm
content: What I've really been looking for is a circuit to replace the control circuitry of the BW4000. The parts I'd like to retain are the AC pump, the smaller DC pump, and the float switches for the two pumps.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 19, 2013, 03:01:18 pm
content: Use capacitive sensing. No moving parts so very reliable. I have used it in an air conditioner (for controlling the condensate drain pump) with great success.