# battery backup for sump pump?



## ilyaz (Dec 7, 2009)

We are not quite ready to install a generator, so in case we lose power the most important piece of equipment that we might want to keep working is the sump pump. Can I buy a battery backup for it? How do I determine how long this backup will last? In other words, if I have specs for my pump, how do I calculate what type of backup I need for the pump to operate, say, for 24 hours?

Thanks.


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## mpoulton (Jul 23, 2009)

ilyaz said:


> We are not quite ready to install a generator, so in case we lose power the most important piece of equipment that we might want to keep working is the sump pump. Can I buy a battery backup for it? How do I determine how long this backup will last? In other words, if I have specs for my pump, how do I calculate what type of backup I need for the pump to operate, say, for 24 hours?
> 
> Thanks.


You'll not get 24 hours of battery backup. It would be cheaper to install a generator. For a shorter duration of battery backup, you might consider using an uniterruptible power supply (UPS) intended for computers. They are compact self-contained units that you can just plug the pump into. You can only reasonably expect an hour or so of backup, if the pump were running frequently (as in a major rain storm). The UPS manufacturer will provide the backup capacity in watt-hours or volt-amp-hours (these are roughly the same thing). Just look at the data plate on your pump for the power requirement. It will probably be given in horsepower. One horsepower is about 750 watts or volt-amps. So, a 750 watt-hour UPS could run a 1/2 HP pump for about two hours.

The drawback to this solution is that the UPS could fail, leaving you with no pump.


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## baum (Jul 14, 2009)

your big box store carry back-up battery sump pumps. when power is lost these will kick in. they start in price about 200 and up. they can work for up to 12 hours.


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## McSteve (Dec 8, 2009)

If you get a 12v battery powered back-up pump, the advantage is that if you ever really have to, you can power it with your vehicle, for as long as you have gasoline.

That said, do you have city water or well water? If city water, you can look into getting a water-powered backup pump. They'll keep pumping as long as the city water system keeps flowing.


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## Red Squirrel (Jun 29, 2009)

I have not tried one of these but I plan to build myself a computer UPS out of something like this, eventually:

http://www.canadiantire.ca/AST/brow...1%252C000W%2BInverter%2BCharger.jsp?locale=en

I think this could probably work, and you can put as many batteries as you want in parallel for longer life.


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## moondawg (Dec 17, 2008)

I have one of these: 

http://www.basementwatchdog.com/

which has been quite nice. It has a feature which monitors the electrolyte level in the battery and sounds a warning when it gets low. 

Of course, since I bought and installed it we have not had a significant power outage. It's been about a year.:furious:

You can test all of the features of course by manually manipulating the float, or buy pulling out the battery sensor, and by pulling the plug on the charger every once in a while. 

You can also force it to pump by pressing the yellow button on the control panel.

If you get one, save yourself some $$$ and don't buy their battery. Buy a maintainable marine battery at walmart for $20 cheaper, and drill a hole in the top cap (it tells you in the manual which cell the sensor should be in) and put the sensor in. Been working great. 

If you decide to go with a water-based system, you should know a few things:
1. They use a pretty good amount of water while pumping. (something like one gallon for every 2 gallons pumped.)
2. They won't pump NEAR as much water as an electrical pump (neither volume or static head pressure) so if you have a large volume of water when it rains, you might not have enough pump capacity to remove it. 
3. If you're in an extended regional power loss situation, you might start using a very limited resource (fresh water) to empty your sump. This is a low probability, but figured I should mention it. 
4. Water-based pumps are great solutions for low-volume, low-downtime power outages.... they're much less maintenance than battery systems.


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## jimmy21 (Jul 2, 2008)

somebody just offered to give me one for a computer and i turned it away since i had no use for it. This thread makes me think of a perfect use. My pump is used in my basement for a washing machine and a bathroom. Would have provided plenty of backup since the pump only runs for seconds at a time


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## Red Squirrel (Jun 29, 2009)

Keep in mind most of the cheaper UPSes are only meant to run for 5-10 minutes to give time for the computer to shut down properly. Though if you have a standby generator it should be good enough.


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## homerb (May 7, 2010)

I think that "basement watchdog" system is the best way go to, given what you want to accomplish with this. It's designed specifically for your application. 

However, if you're looking to do more of a DIY approach, you could search craigslist for a commercial grade battery backup. You could get a 1500W or 3000W system with bad batteries for around $100. All you have to do is replace the batteries with bigger car batteries and you'll get a longer runtime. Just make sure to wire the batteries in the proper series or parallel configuration for a 12, 24 or 48V system. 

But I don't think a battery backup sump pump is a good idea.. Here's why: What if the power goes out during the early stages of a storm, the battery pump kicks in and keeps the basement dry for a few hours. But what if the rain hasn't really come yet? What if the snow hasn't melted away yet? If that's the case, you've got a sump pump with a dead battery and no way to charge it until the power comes back on. Most outages that have to do with floods are extended outages. 

I think a generator is probably the best idea because you'll never have to worry about the battery life for extended periods of rain. You can just put more gas in it. 

Homer


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## WillK (Aug 29, 2010)

I'd add my vote to suggesting a water-powered backup sump pump system. My parent's house is situated where the sump needs to operate frequently, the basement is below the water table, so having a working sump at all times is essential. They have a water-powered backup and it's been needed for outages that would've been too long for any battery backup system.

I suppose the recommendation is going to vary by your situation, but relatively inexpensive city water (is there anywhere that the cost of city water would really be more than the damage to a basement that flooding could do?) typical longer duration of power outages and frequent sump pump use make for a combination where it makes sense for my parents.


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## homerb (May 7, 2010)

WillK said:


> I'd add my vote to suggesting a water-powered backup sump pump system. My parent's house is situated where the sump needs to operate frequently, the basement is below the water table, so having a working sump at all times is essential. They have a water-powered backup and it's been needed for outages that would've been too long for any battery backup system.


I've never heard of a "water powered" system before, but after doing some researching, it looks like a good idea! Simple, makes sense. Only thing is that you need the water flowing to get it to work. 

9 times out of 10, you'll have water from the supply flowing. For a real bad outage or flood, they might shut off the water to keep from contaminating the supply. 

Good for the short term or intermediate outages, (like what you want it for), but not as good for when you realllly need to pump out the basement during emergencies. 

Interesting.

Homer


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## operagost (Jan 8, 2010)

I don't think any consumer-grade UPSes are suitable for use with sump pumps. They draw far too much. UPSes aren't designed to support motors (other than the relatively small ones found in computer fans and disks). If you did decide to go this route, you definitely wouldn't want to use a car battery as someone suggested, as I'm sure all of us have seen what happens to a car battery once it's been drained a few times. Deep-cycle marine batteries cost a little more, but can tolerate being totally drained.


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