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Monday, January 26th, 2009 by Prarthana Sharma
If a pump cycles once per minute, that's a 6% duty cycle. So, if you have a battery back-up pump that pumps 1,000 gph, can you back the primary up? Yes, since the backup runs at 41% the gph rate of the primary, then the duty cycle has to be 59% more than the primary-pump - or a 9.5 duty cycle. In other words, the backup pump is running 9.5% of the time instead of 6% of the time like the pump it's backing up.
That being said, you won't catch me trying to say that more gph isn't better - it is. But do the new wave of the backup pumps do what they say they will? Well, lets see. We have test results that a Little Giant top-of-the-line-way-high-priced systems says it pumps 2,620 gph at only 4.5 amps - but in an actual test it it pumped 1,740 gph, or 30% less than claimed. But wait - that's only a fully charged battery. This unit uses an inverter that converts DC to AC, which is a very inefficient process. When the battery was fully charged it did a 1,740 gph rate, but when it drew the battery down for a while, it ran at a 1300 gph rate. And then the battery went dead in 2.5 hours, and the unit pumps a total of only 3,227 gallons out ( about a third of the volume of an UltraSump).
A new-to-the-market unit now being marketed from Glen-tronics says it pumps 2,200 gph at a 10-foot head. In fact, it does 1,300 gph at an 8-foot head. Today, we saw our Ultra-sump Pump 1,480 gph at an 8-foot head because it does 1,480 gph at an 8-foot head. More than that, it's DC to DC and will pump out 9,500 total gallons off a 100 amp battery, which we claim as over 7,000 gallons to be safe.
In about 4 weeks after you read this, the Ultra-Sump will pump 2,016 gph out using the 120 amp battery. It will get over 13,000 gallons out of a basement before going dead, which we will advertise as over 11,000 gallons. These numbers are right on.
I must say that for a short time our pump supplier changed changed their motors without our knowledge, which reduced the gph capacity to 980. When we found about it ( by accident) we took action immediately, and switched suppliers and got our capacity up to 1,480 where it is today. We think this went on for less than one year. The good news is that since the amperage of those wayward pumps was down, the total gallons out capacity was unchanged.
In most, so long as the gph is reasonable, the most important number is the total gallons out, which tells the homeowners how long the backup pump will run before they get flooded.
I don't know how pump manufacturers sleep at night while misinterpreting these products. I think it has become a market issue more than anything. If their brochure says one number, then we have to have a higher number to win.
Once manufacturer, Glentronics, has a wet cell battery that your installer has to fill each cell with acid to the proper level, and then the homeowner has to check the battery and add distilled water every 6 months. The distributor has been known to say that he thought that was great because it gives him more maintenance visits he can charge for.
Sealed batteries are the way to go. The UltraSump battery is a maintenance free sealed lead acid battery that is leak proof, and has deep discharge recovery. It is not a marine battery as most of these are not maintenance free.