Battery Backup

[Mortblanc]

If working off mains for recharging then there is a device called a "float charger" that trickles current to the battery and keeps it topped off without overcharging. They are inexpensive and worth the effort.

Look for deep cycle marine batteries in the amperage rating you desire. Most of the proper batteries are going to be rated in amp hours. How many amps does the device draw and how many hours will the battery power it. Amps become more important and easier to calculate than converting it to watts and such. Most of your 12v appliances have amp hour ratings for this reason.

I have one deep cycle battery that is nearly 15 years old and still takes and holds a charge. It has been used in my caravan as primary power source for two years, in the house for emergencies and in the boat as a starter motor and to power the electric fishing motor. As of this summer it was still providing current on call.

One or two batteries are not going to power your house during grid down situations for more than an hour or two. It's a waste hooking them up like that. That use requires big battery banks with big solar panels. Dedicate your small system to lighting with 12v LED or florescent type lights and recharging the computer devices and phones and they will keep you operating for several days. You can recharge most devices right off the battery using an automotive plug. My 12v tv would pull my 180 amp battery down at an alarming rate. I missed the end of several GP races due to that.

Place your batteries on a wooden frame, not on the dirt or concrete of a basement floor. Even a board between the battery and floor is better than nothing.

A good panel for charging is handy, especially in the summer months. Not so much in your winters at the higher latitudes. Do not waste time with the small panels used for automotive dashboards. Go straight to a 45w pannel. It will actually charge the battery rather than just teasing it.

I lived off grid for two years in a self contained caravan and for one summer I had a 45w panel hooked up. All appliances were 12v and I was working a lot outside, only coming inside due to weather or darkness. I would keep the lights on for a couple of hours, read a little then go to bed. I did not have to recharge off mains power from April until October. When the daylight hours got short I needed mains for a recharge.

If you are running an inverter then you will pull down the batteries more quickly than if using 12v appliances. The inverter uses a lot of power to cool itself during the conversion. However, a high load inverter is handy for emergency use of power tools.

Remember that there are several tricks you can do with batteries of this type. One is that you can run jumper leads from your vehicle to the batteries and recharge them off your vehicle alternator. At one time I had a battery rack in the back of my pickup and a wiring harness that allowed me to shut off the car battery and transfer recharging power to the marine batteries. I would recharge the batteries on the trip to work and back each day, then plug the caravan into the battery bank when I arrived home in the evening.

You can also recharge off of a garden tractor pulled up next to the basement window.