Around the House: Back-up battery system can help in power outage

Cohen_Zolton.jpgZolton Cohen

Q I have a natural gas steam boiler in my basement that I would like to be able to operate when the power goes out during winter storms. The boiler has an electronic ignition and an electrically operated flue damper that operates at the beginning and end of the heating cycle. There are no other electrical needs of which I am aware.

I have asked both electricians and my furnace company to rig up a back-up battery power system for emergency use, but both have been unable to do so. Have you any suggestions, short of installing a gas generator?

— B.N., Kalamazoo

Q Following a recent round of storms, I couldn’t help but notice the buzz of generators in our neighborhood. I know that portable and whole-house generators are available, but I wonder if there is such a thing as an energy “bank” that also could be used for that purpose, such as a set of large batteries with the appropriate trickle charge and circuitry/inverter. This would be like a bigger version of an uninterruptible power supply for a home computer.

— P.S., Portage

A Battery backup and power supply systems do exist, though, in this area, they are relatively unusual. Mostly, they’re designed to be used as part of an “off-the-grid” alternative energy storage setup.

In that arrangement, power generated from a sporadic source, like a wind turbine, is stored to use during periods when the wind dies down and power isn’t being produced. When electric needs exceed the power generated by the turbine, the battery bank is tapped.

In the outage scenario about which you two are inquiring, grid power would keep the battery bank charged and topped off. So, it is possible to do what you’re asking; the technology exists. But getting there is a pretty steep climb. 

First, you’ll need to identify the circuits you want to power during outages. These will usually include the furnace or boiler, refrigerator and freezer, and maybe a lighting circuit or two. The more extensive the requirements, the more expensive it is to store enough electricity to get through an extended outage.

Next, you’ll need to hire an electrician to install a transfer switch so those circuits can be isolated from the grid when you’re operating them with the battery backup. Without a transfer switch in place, electricity from the grid can blow up your system when it comes back online.

An inverter/charger (one manufacturer is Outback, is needed to charge the batteries and to convert the stored DC power into the AC required by your appliances and fixtures. Deep-cycle lead-acid batteries, like those used in golf carts, complete the system.

You’ll need a place to store the batteries where they won’t get too cold, since their capacity diminishes as the temperature drops. Plus, you’ll need space to check them and do periodic maintenance.

At current prices, figure on spending $2,000 to $2,500 on equipment for a minimal system. Labor would be extra, and would vary widely depending on how much work is required to get everything up and going.

Also, budget money each month to charge the battery bank, and some more to replace the batteries, in five to 20 years, when they can no longer hold a charge.

Zolton Cohen is a Kalamazoo-based columnist and former American Society of Home Inspectors-certified home inspector. Write to Zolton Cohen, Around the House, P.O. Box 2007, Kalamazoo, MI 49003.