Sump pump backup - DC vs battery inverter?

Daox · 08-13-19, 01:12 PM

Story time. A few weeks ago I came home to the utility company cutting up one of my trees that had fallen on a power line. It didn't snap their line, but it did rip the mast off my house. To do that, they had to cut power to the house. Anyway, it got all fixed up, but it really made me think that I need to get off my butt and get some form of backup for my normal sump pump.

So, I am asking for advise. I know you can get 12v pumps out there. But, you can also just buy a battery and an inverter to power the pump too, right? Which way would you go and why?

jeff5may · 08-21-19, 04:29 AM

Ok so if you are going with a dedicated electric pump, use a battery backup DC pump. Why? It's a dedicated system. Low chance of failure, occasional use assures a long life. Also, a DC pump wired to a switch straight to the battery is the best you can do to avoid Murphy's law. A power inverter on a battery running an AC motor is going to burn a portion of the battery capacity. Not just because the inverter is always on, but the conversion from DC to ac eats some battery as well. Plus there's the same basic switch to cycle the motor anyway. Plus the same basic battery charger.

NiHaoMike · 08-22-19, 08:32 PM

12V bilge pumps are very common and quite cheap.

Xringer · 09-06-19, 01:40 PM

After a basement flood years ago, I installed a solar-battery-inverter system that could power my sump pumps for many hours.
You will never guess what happened.. It never flooded again, and the grid has never failed while it was raining, since then.

The 48v battery pack (car batteries) are getting very old. I'm thinking of replacing them, or just scraping the whole thing.
I can use a gas generator to power those pumps, if it ever becomes necessary.

All the extra CO2 is over-greening my backyard. I have to remove vegetation from the panels once a week now..

Aircommuter · 09-07-19, 11:12 PM

I suppose an overall assessment would be my plan. Do I want other things to work besides the pump. Maybe a generator would be a good overall choice. One has to think how often it happens and how long it stays off.
My basement has floor drains in case there is a leak but does not allow ground water in either because of the drainage system I installed when I built it.
Because we are rural and the power can be off for extended amounts of time I installed a 50KW 3ph Kohler on propane.

Xringer · 09-08-19, 01:21 AM

If a home has good water pressure from a supply that's not dependant on the grid,
you can get a water powered sump pump. I have one (1), but I have 4 sump holes.
(I have 4 because our basement floor is very near the local water table)..
So, my main anti-flood system is old 120vac sump pumps.

The water powered pump would still be useful during a grid-fail + heavy flooding.
Since the basement floor is level, a 1/2" of water is going to fill up the 4 sumps holes.
From Amazon:

08-13-19, 01:12 PM	#1
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Sump pump backup - DC vs battery inverter? Story time. A few weeks ago I came home to the utility company cutting up one of my trees that had fallen on a power line. It didn't snap their line, but it did rip the mast off my house. To do that, they had to cut power to the house. Anyway, it got all fixed up, but it really made me think that I need to get off my butt and get some form of backup for my normal sump pump. So, I am asking for advise. I know you can get 12v pumps out there. But, you can also just buy a battery and an inverter to power the pump too, right? Which way would you go and why? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

08-22-19, 08:32 PM	#3
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	12V bilge pumps are very common and quite cheap. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

09-06-19, 01:40 PM	#4
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	After a basement flood years ago, I installed a solar-battery-inverter system that could power my sump pumps for many hours. You will never guess what happened.. It never flooded again, and the grid has never failed while it was raining, since then. The 48v battery pack (car batteries) are getting very old. I'm thinking of replacing them, or just scraping the whole thing. I can use a gas generator to power those pumps, if it ever becomes necessary. All the extra CO2 is over-greening my backyard. I have to remove vegetation from the panels once a week now.. Attached Thumbnails __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

09-07-19, 11:12 PM	#5
Aircommuter Lurking Renovator Join Date: Jun 2016 Location: Greeley Hill Posts: 3 Thanks: 0 Thanked 1 Time in 1 Post	sump pump B/U I suppose an overall assessment would be my plan. Do I want other things to work besides the pump. Maybe a generator would be a good overall choice. One has to think how often it happens and how long it stays off. My basement has floor drains in case there is a leak but does not allow ground water in either because of the drainage system I installed when I built it. Because we are rural and the power can be off for extended amounts of time I installed a 50KW 3ph Kohler on propane.

09-08-19, 01:21 AM	#6
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	If a home has good water pressure from a supply that's not dependant on the grid, you can get a water powered sump pump. I have one (1), but I have 4 sump holes. (I have 4 because our basement floor is very near the local water table).. So, my main anti-flood system is old 120vac sump pumps. The water powered pump would still be useful during a grid-fail + heavy flooding. Since the basement floor is level, a 1/2" of water is going to fill up the 4 sumps holes. From Amazon: __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

08-21-19, 04:29 AM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Ok so if you are going with a dedicated electric pump, use a battery backup DC pump. Why? It's a dedicated system. Low chance of failure, occasional use assures a long life. Also, a DC pump wired to a switch straight to the battery is the best you can do to avoid Murphy's law. A power inverter on a battery running an AC motor is going to burn a portion of the battery capacity. Not just because the inverter is always on, but the conversion from DC to ac eats some battery as well. Plus there's the same basic switch to cycle the motor anyway. Plus the same basic battery charger.