12VDC or 120VAC (inverter) battery backup for a sump pump? - Page 1
Forum section: electronics / general

author: wblackledg
author_rank: Regular Contributor
timestamp: March 29, 2015, 04:25:49 am
content: I thought you guys would know the best way to approach this.I'm redoing my sump pump system in my basement here in the US.I have two choices for a backup sump pump.A 12VDC battery pump or a 120VAC pump running off an inverter with a battery charger float (like for an RV) and a deep cycle 100 Amp Hour marine battery.I'm leaning towards the 120VAC system because there are many more pump options, If the primary 120VAC fails I can just plug in the standby to the house power.I'm not married to the idea, so I welcome your thoughts and let me know if I'm stupid..Also, how would you hook it up so you could go on vacation and not have to worry about a power outage and a flooded basement?thanks.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 29, 2015, 04:52:30 am
content: 12V sump pumps are actually quite common, but it might be more helpful to search for "bilge pump".

author: Seekonk
author_rank: Super Contributor
timestamp: March 29, 2015, 10:15:12 am
content: I would do two pumps if it runs quite often, 120V for everyday and 12VDC for backup. Having a wooden boat I can tell you they don't last long. Have a camp and use a 12V for sewage pump up to the field. some last a couple monthe and some years because of the seals. Talk of variety. My house had a sump that would short cycle. When it went bad replaced it with a Little Giant the size of my fist. That worked great. Going inverter is a mighty expensive. I would go with a non powered pump that uses house water pressure to run as backup.

author: wblackledg
author_rank: Regular Contributor
timestamp: March 29, 2015, 02:13:03 pm
content: Quote from: NiHaoMike on March 29, 2015, 04:52:30 amlots of choices under bilge pump. thanks

author: wblackledg
author_rank: Regular Contributor
timestamp: March 29, 2015, 02:15:57 pm
content: Quote from: Seekonk on March 29, 2015, 10:15:12 amCost is a factor, but actually the 12v backup systems they sell as a package (which I had one of) aren't cheap either. One claims to test the battery but i found out that only tests 1 of 6 cells which means the testing is mostly useless. It does have a few big advantages too.thanks.

author: Seekonk
author_rank: Super Contributor
timestamp: March 29, 2015, 02:44:14 pm
content: It doesn't get more reliable, cheaper, or easier than this.http://www.righttoolusa.com/p/Water-Powered-Back-up-Pump-System-61408402.html

author: Ian.M
author_rank: Super Contributor
timestamp: March 29, 2015, 02:57:48 pm
content: You need at least two complete independent pump systems, with the backup system's automatic switch slightly higher so the main system runs first and unless that's overloaded the backup pump doesn't start. The water powered pump system looks like a good bet for the backup system.You also need a monitoring system, I would suggest a setup that logs the total time the primary pump runs + level switches between the main and backup trigger levels and above the backup level and also either a landline speach dialler (get one from any alarm company) that triggers on the extra level switches or a GSM/SMS alarm system that texts you on the same triggers.Make prior arrangements before vacationing so you have a keyholder who will also receive the alarm messages.

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 29, 2015, 04:49:30 pm
content: I would put a 120vac pump on an inverter-charger. Basically it's a UPS but it allows you to put as much battery capacity as you want. If you actually rely on the pump a lot, ex: if it runs a lot, I'd have a backup one that is set slightly higher in case one fails. Alarm points are not a bad idea too. Can be fairly easily done with float switches and arduino or similar board.

author: Seekonk
author_rank: Super Contributor
timestamp: March 29, 2015, 05:43:03 pm
content: I have a 100W fridge on an inverter. It takes 120A @12V to start it. Minimum inverter has to be 2000W to start a 1/4hp motor. I lived lived off batteries for years. This idea is NUTS!

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 29, 2015, 11:49:21 pm
content: Some of the better inverters do V/Hz soft start.

author: wblackledg
author_rank: Regular Contributor
timestamp: March 30, 2015, 12:07:36 am
content: Quote from: Seekonk on March 29, 2015, 05:43:03 pmthats what I'm looking for is honesty!Seriously, thanks. I decided I'm pretty much going with a 12VDC backup system. May also do the water powered back up as an aux.