How to freplace dead battery in sump pump?

March 8, 2008 11:32 PM

Clueless homeowner question: Our sump pump (which has a battery for backup) is beeping and blinking, telling me to replace the battery. It looks like a car battery, but my son (he who knows how stuff works) is away ay school. What kind of battery do I get? Where do I get it? And, most scary, how do I (safely) unhook the old one and replace it with the new one. Don't assume I have even the most basic skills or knowledge.
posted by mmf to home & garden (11 comments total)

Generally those batteries are marine deep cell batteries, which are available at your local marina or plumbing supply store. To disconnect, follow the battery cables to the charger and then unplug the charger from the outlet. Get yourself an adjustable wrench that can handle up to about 1/2". Locate the negative battery cable and terminal (noted by a - on the battery and a black cable generally), loosen the nut that holds the cable to the terminal, remove cable and repeat on the positive (+ or red cable) side. Do not let these cables touch. Bring old battery to marina or plumbing supply store and they'll sell you the proper replacement one and dispose of the old one. Installation is reverse of removal.
posted by moitz at 11:40 PM on March 8, 2008

Seconding what Moitz said, and you definitely want to take the old battery with you to be turned in, since it has recycling value... The plates in the battery contain about $10 to $15 worth of metals.
posted by thewalrus at 12:12 AM on March 9, 2008

It's preferable, but not critical, to use a box wrench to remove the cables. This avoids the possibility of rounding off the nuts.

Also be very, very careful not to let the wrench touch both terminals of the battery at the same time. If you can avoid that, you have very little chance of hurting yourself. Unless, of course, you drop the battery on your foot.

But are you sure that the battery must be replaced? I would try cleaning the terminals first. Remove the cables as described above, then give the terminals and the ends of the cables a good scrub with a bit of steel wool. They don't need to be shiny-clean, just get 95% of the gunk off. Then re-attach the cables. If the pump-gizmo still complains, then go spend money on a new battery.
posted by kc8nod at 4:56 AM on March 9, 2008

Also, don't let it tip, it is filled with very nasty acid, and yes it is a marine battery you are looking for. A car battery is not designed to go into deep discharge as may happen when the power is out and you are running the pump off of the battery.
posted by caddis at 6:23 AM on March 9, 2008

re: not tipping it over

It is likely (although not a sure thing) that the battery is the sealed lead-acid type, and tipping it over wouldn't be a problem. That's not to say you shouldn't be careful, though.

If you can scrounge up the manual for your pump, it should have the requirements for your battery. If you bought the house with the sump pump installed, it could be placed somewhere in the vicinity. I recently found the instructions for the water heater that was installed when the house was built in the 1950's on top of some heating duct.
posted by ArgentCorvid at 8:26 AM on March 9, 2008

Thank you all so much, I feel like I can safely try this now!
posted by mmf at 9:09 AM on March 9, 2008

So I got the battery unhooked, thank you all for your simple to grasp instructions.
We don't have a marine supply store here, and plumbing supply places are closed. Can I find something like this "Nautilus" battery at Home Depot?
Also, can I buy an extra one so that I have a backup in case this happens again, or do they die if not used?
And finally is there some kind of other system that keeps the backup battery charged and can recharge it? I'm thinking what if there was a power outage while we were away for a long weekend, and the battery (which says it goes for two hours) used itself up but the power was off for a few days, we would not want to come home to a big flood.
posted by mmf at 9:27 AM on March 9, 2008

We don't have a marine supply store here, and plumbing supply places are closed. Can I find something like this "Nautilus" battery at Home Depot?

Probably. I think that particular brand is fairly common. maybe even at Wal-Mart.

Also, can I buy an extra one so that I have a backup in case this happens again, or do they die if not used?

I wouldn't recommend that. batteries like this require some maintenance to keep their charge.

And finally is there some kind of other system that keeps the backup battery charged and can recharge it?

That should be built into the system. It might be that the charging circuit is what is really the problem here. If I had to guess, I'd say the part that is "beeping and blinking" is actually the charging/maintenance circuit. Try looking on that part for a manufacturer and/or model #. finding the manual for your specific equipment will be much more helpful than anything we can come up with here.
posted by ArgentCorvid at 10:06 AM on March 9, 2008

Other options that I know of include getting a bigger battery that can pump for more hours, or installing an emergency generator outside your house that is wired to switch on when the power gets cut; or you are on city water there is a backup pump that uses the vacuum power from city water to suck the water out. The problem with that is that for every gallon of water pumped out you use a gallon of city water.
posted by any major dude at 10:09 AM on March 9, 2008

If you buy a spare battery and leave it on the shelf, it will degrade and be of no value when you want it. You can, however, buy a much larger battery that will run the pump for longer and likely have a longer life. Make sure it's the same voltage as the old one but a larger one will often have more plates, e.g. 13 instead of 9.

You can also connect multiple batteries in parallel but that requires cables and special tools so we'll ignore that.
posted by polyglot at 7:10 PM on March 9, 2008

mmf writes "Also, can I buy an extra one so that I have a backup in case this happens again, or do they die if not used?"

You can buy dry storage batteries. They come in two parts; the cases with installed plates and a container filled with acid. To use you just pour the acid into the battery case. The battery is in a charged state immediately. Automotive batteries used to be distributed this way to little Mom and Pop service stations because of their essentially infinite shelf life and instant readiness. You might be able to buy them still from an independent battery supplier.
posted by Mitheral at 6:50 PM on March 11, 2008