- cross-posted to:
- loadbearingwisdom@sh.itjust.works
- cross-posted to:
- loadbearingwisdom@sh.itjust.works
Sump pumps are one of the most boring parts of home ownership. Until that one storm comes and suddenly they’re interesting.
After losing power one time this summer, I got paranoid and decided to build a battery backup. Home Depot had the basement watchdog systems, but they seemed high maintenance and I wanted something that would let me be lazier. I went with a LifePo4 battery system, that will (hopefully) get me 10 to 15 years. The battery charger has a float/storage mode so it can stay on 24/7. Doing some test runs, I think I can get about 400 cycles out of the battery before it hits 0%. I added some additional safety features (DC circuit breaker, GFCI with auto-on, Lithium fire extinguiser, etc), and added some battery powered lights and a basket of hand tools, so in the event the power goes out in the dead of night, something goes wrong, and I have to get my feet wet, everything is there ready to go.
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This board consistently has the most interesting posts on the fediverse lol. Well done. Makes me want to not rent even more ;s;
After finishing the project, I tried to show my wife and she was like -
“so this keeps the basement from flooding”
“yes”
“ok, you don’t need to bore me with the details”then this community popped into my head XD
She probably doesn’t even know which distro you maintain on her laptop.
No laptop…she only has a phone
At least it’s android… right?
Everyone around me knows that if they have a problem with an iPhone, don’t even talk to me, I won’t touch the hateful thing.
I’ve never seen a more disorganized UX mess than an iPhone’s Settings menu. It’s like every dev team in the company decided they needed their own top level menu item for their pointless little part of the walled garden, even if it had no relationship to a phone OS.
iphone :0
dios mio
We’re all standard nerds down here…,
There have been projects that made me wish I still rented. Home ownership is constantly dealing with the last guys fuckups.
But if you live in one place long enough, eventually the “last guy” is just you and if you do the job right, the volume of fuckups decreases over time. Some people like renting because they don’t want to deal with the maintenance. I like owning because it’s mine, I can do what I want with it, and I don’t have to put up with the “landlord special.”
You are a professional MacGyver.
We got flooded a bunch of times when the power got knocked out, because the town allowed development onto old swamp land that became a flood plain when the lake level was high and heavy rains came.
My dad installed a water based pump, it had a turbo type spool. City water pressure coming in on one side spun the pump shaft to pump out the sump. You are dumping city water into the sump too, but at a small volume x high pressure vs pumping out at low pressure x high volume.
So all was fine, just had to hope the town didn’t lose water pressure at same time as power outage.
And LAMINATED DOCUMENTATION!! Love the setup!!
Yessir, 'cause you know when I need to actually work on this thing…it’ll be in the middle of a storm, when the power is out, and the water is rising in the pit, and I’ll be stressed outta my gourd. So I’ll need battery powered lights, and tools sitting right there, and instructions on how to connect and disconnect everything, so I don’t actually have to think under pressure :D
I missed that, thanks for pointing it out.
I’ll have to get my dad to do this at his place. He’s on a well, water softener, and fancy septic tank, as well as sump and sewer being pumped up from basement level to ground level for removal.
The system looks impressive, but if he’s not around in an emergency I would not know what pipe or valve does what.
Every device and power cable has a label. So if the instructions say “disconnect ATS from Inverter”, you just look for for two devices with those labels.
I see the fire extinguisher is mounted in a convenient location should the board catch on fire. Easy to reach, you know, around all the flames.
There’s a second one 10 ft away.
Your concern of fire with the smoke detector and fire extinguisher, is something I strive for with my hobbies. Well done!
Since it’s on the basement, make sure it’s not “made in Briton”
Nothing against the British, it’s an it crowd reference
I’m going to put it there, together with the rest of the fire
To whom it may concern:
FIRE, FIRE, FIRE!!!
Yours truly Moss
Remember to place the monitor just so
at a sea parks?
“They died in a fire? In a sump pump pit?”
Are the seals alright?
Not the scene I was referring to be still applicable
Yeah, I had inverter feed cable just like the one in front of that board almost catch fire. The smell of melting insulation saved the day.
That’s why I have a circuit breaker on the positive feed line. Kills the circuit at the amperage that begins to melt the cable.
Jesus, you know they make 120 v sumps with a 12v backup right? :)
Indeed they do. But I’m lazy. I’ll explain:
The systems with the 12v backups only activate said backup when the main pump fails, typically due to a power outage. So if you live in an area with consistent power, the backup will hardly ever activate. Over time the backup atrophies due to never cycling and then when your main does fail, the backup is also dead too. Then you’re fucked.
To fix this, they recommend going down and unplugging your main, and running a hose or something to your pit to test the backup every 12 months or so, making sure it works. But who wants to do that.
With my system, I have a pump alternator (silver box, bottom left in pic). So I have two primary pumps, and it flips between 'em. So each pump runs half as often as normal. If one pump fails, the alternator flips to the other one and triggers an alert. This alert emails me saying “yo something is fucked up with the pump”, and from there I have to diagnose and fix it. But it’s asynchronous and I don’t have to worry about it until I get that email. Only thing I really need to check on an annual basis is the battery health, which is bluetooth’d to my phone.
If your sump pump moves any amount of water consistently you could automate it with your home assistant (or whatever because I see the zooz high power switches). Just automate the switch to go off and monitor the other one. You could even have it run every month or something.
I’m using them to monitor via Grafana
Honestly very cool setup. I’d love something like this if I get a house that needs a sump.
Basement watchdog brand. 12v activates on a higher water level. they both use the same output line. There’s a test button you can use to test the 12v if youwant, but the instructions do not reccomend “exercising” the 12v pump. https://basementwatchdog.com/wp-content/uploads/2025/06/CITE-33-US-manual-05-15-25-Web.pdf
So the Watchdogs are legit systems and I won’t dog on them (har har).
That said, for myself, I wanted a LifePo4 system. The Watchdogs are AGM. Additionally, with Watchdog you are putting all your eggs in one basket, and you really gotta swap the whole thing if one part fails other than the battery.
They do have the advantage of being ubiquitous, and most plumbers know them well, so it’s easy to hire help if you need it.
You do need to replace both pumps if one fails. but… it does have 2 independent pumps. If the power goes out, or the primary fails, you’re still dry.
More importantly, the upside to your setup, the lead acid / AGM batteries on mine need to be replaced every 3-4 years, your battery will likely last many years.
The downside, you have a long dependency chain with a number of single points of failure.
to each their own.
It’s the same number of points of failure. The watchdogs have an automatic transfer switch, a power inverter, a fuse or circuit breaker, etc - it’s just all embedded in a single box instead of being parted out.
Watchdog can lose all things out of one of the following lines and still run, and it will let you know if either line fails with an audible alarm.
120v->Fuse->120v motor->120v impeller->120v float
or
12v battery -> 12v Fuse -> 12v motor->12v float
The only shared point of failure would be a crack or hole in the exit line
The 12 and 120 sides are completely seperate except the water exit path.
The 120v side doesn’t get anything from the “control box,” it’s just a float pump.
If you filled the some faster than the 120 could pump, they’d both run at the same time. (and it would complain audibly about it)
Gotta love showing off your great work and someone coming in with “UM AKSHULLY THIS IS BETTUR”
There’s a lot of variables involved in sump pump systems. I don’t have any qualms with rumba’s comments, they’ve added to the conversation.
If you’re on city water that doesn’t lose pressure during power outages they also make water powered sump pumps.
Venturi pumps are awesome, but with the risk of basement flooding, i’ve never trusted them enough. the risk of no flow+power out is low, but not zero. I have a 12v bilge pump and a float in a tackle box for emergencies and 2 cars of fully wokring 12 batteries :)
LiFePo4 batteries are awesome. Much less (but not zero) fire potential than standard lithium, many more cycles than lead acid, and can drain to zero without not getting damaged like lead acid and standard lithium batteries. I’m pretty sure they’re better with low temperatures as well.
The primary con is their weight and size for how much energy they can deliver.
I’m sure you know all of this already, I just love batteries. I use LiFePo4 batteries in my UPS for my homelab because I got tired of having to replace the lead acid ones every couple of years.
Edit: is your fire extinguisher of F-500 type? An ABC extinguisher would also work in most cases since this is LiFePo4, but F-500 (or AVD) is the best way to put out metal fires, if you’re paranoid about it. Most likely though, if your battery has a thermal event, it’ll just off gas some nasty vapor for a bit since this battery chemistry doesn’t self-oxidize and cause a cascade of failures. As long as there’s not something sparking to ignite that vapor, you’re probably good.
Having used LA batteries for years on watering and fencing, the day I discovered LFP batteries was a glorious day.
They last forever, they discharge down to nothing with no damage, you don’t get corrosion on the terminals. You can’t boil them, you don’t need to check water level, they weigh half as much for the capacity.
Even though initially expensive, I calculated they’re about a quarter of the cost over the long term than LA because of the cycle count and amount I need for the extended capacity. I get about 30-40% of a LA battery’s capacity without doing lasting harm to it, with LFP I can abuse that thing all the way down until it’s completely exhausted and it charges right back up again.
Only thing I have to watch is charging them below freezing, so I have to run them in an insulated and heated box in the winter.
It gets very cold where I live. I should look into an auto shut off of the battery charger if it dips too cold in my basement. Unlikely to go below 32F but you never know. The BMS will do it itself, but I’d rather not rely on it.
If your basement goes below freezing, you have a lot bigger problems than if that battery gets borked because it was trickle charging. You’re probably right to not trust the BMS though, unless you can get into it and confirm the cutoff temperature. I think the JKBMS comes from the factory set to -6C which is bullshit.
That’s a good point…I have a new furnace, and I’ve been here several years without pipes freezing (knock on wood).
It’s AVD. Bro, do you know of consumer level F-500? That seems like pro shit you’d have to have a contractor install AFAIK lol.
Nice! There’s a few distributors near me that sell F-500, I actually can’t find AVD where I live.
Nice try. I know a flux capictor when I see one.
Am I not understanding something, why not just a UPS?
A UPS with that capacity would likely be 5-10x the cost of what OP built.
Thanks for chiming in because yes - the answer is “money”.
Parting out the system as individual components saved me a ton of it. In addition, it will be easy to identify and replace problematic components if and when they fail (for a fraction of replacing a UPS that meets the power requirements).
How much did this cost you? Just trying to compare a my Ecoflow which I use for a network UPS. It’s got a capacity to run steady for an hour or two I think.
For the core backup system with the battery, inverter, ATS, charger, circuit breaker, etc. Right around $900 or so.
I’ve calculated it to do 400ish cycles. So if my pumps turn on every 5 minutes, it’ll go about 33 hours.
Sounds pretty good. I’d spend that much for that length of operating time
When I was a kid, our sump pump was like the #1 thing that would get fried in a thunderstorm. Our power would go out every fucking time it rained. We’d sit there in the dark watching the outlets arc.
Yup, it’s hard to see in the photo, but at the wall power I put a Southwire #41008.
It has a high joule rating, but the nice thing is that if a surge occurs and it fries the 41008, it cuts off power (i.e. system goes to battery) and it sounds an alarm like a smoke detector. So then you go down and either replace it or remove it to get wall power again.
I do know that surge protection in front of a pump is a highly debated topic among electricians, so YMMV
Idk shit about fuck about electricity, but that sounds good I guess?
It’s a tradeoff. You can “raw dog” the wall outlet, and hope that a surge doesn’t fry your shit.
I have a little widget that absorbs electricity and basically kills itself and sounds an alarm if there’s a significant surge in a thunderstorm. The tradeoff is that I have to resolve the situation by either swapping in a new, unkilled widget or remove the dead one and plug everything directly into the wall, before the battery back up runs out of power.
I have that same victron smart charger.
Nicely done, tho less than a dull result for a dull home component
Ty friend, I will strive to be more dull <3
I hate the need for them. My fathers house had a basement with windows that if water was against would 100% flood in if not from somewhere else. never flooded and no sump pump. would not be surprised if it would flood a basement nowadays on the property though.
I’d say a cheap charger-inverter like a Sungold or SRNE would clean this up quite a bit. You’d also not have to size a surge suppressor to withstand the inrush current since the inverter would be supplying the load. It would have a generator input on top of all that. And IDK what sort of inverter you have there, but a lot of those style are modified sinewave and not very good on motors. You’d also get a good data feed off the CI for monitoring, and a dry contact for an alarm siren if the battery hit critical.
But I like the DIY route, those purpose built backups seem ridiculously expensive to me.
The all-in-ones are nice, but expensive. I specifically went with high quality (but individually purposed) components, to save some money and also make repairs and replacements easier & cheaper.
The inverter is an AIMS pure sine wave (not modified) rated to 2000w continuous and 4000w peak. I chose it so that I could safely throw any consumer sump pump rated for a 15amp receptacle at it without worry. If you’re careful and considerate, you could downgrade to a 1500w/3000w or even 1000w/2000w inverter if you’re positive the pumps won’t exceed the limits (would work on smaller 1/3hp systems, etc).
The current setup handles my Zoeller M95 that peaks at 16.5A with ease.
Regarding monitoring, the white cables are ZWave devices, I have set up to measure current and power draw.
Mad respect. However if i was a child or grandchild of yours i would unplug this squirrel’s nest and ask you about the fire hazard in the basement (until educated about the functioning parts).
Oh you are so right…there’s a reason the battery is 6.5 feet off the ground, and the frame is hanging from the joists with structural screws so nothing can get knocked over… kids man…yea, if they unplug all the stuff at the bottom, I’ll get an email stating as much. And I’ve screwed everything to the board, so at least they won’t be able to pull anything off.
Or ya know, a siphon jet back up. Maybe not an option if you are on a well pump. But a much cleaner fix for power failure AND main pump failure. Its a good thing you can maintain the pumps yourself because ain’t nobody gonna touch that.
I mentioned in another comment but I have two pumps and an alternator that swaps between them, so I’m not overtly concerned with pump failure, more-so power failure.
The siphon’s are dope but yes wasn’t an option. I was a professional plumber in a previous life, so yea, I’ll be maintain this thing lol.
This is the first time I’ve heard of siphon jet backup pumps. That looks like a really great option and I wish I had known about those years ago when I put in my own battery backup.
