Battery Backup System

Most of the ideas I get for emergency power, I got from Steve Harris.  This is one of those stories.  I was listening to an interview he did on The Survival Podcast and he was explaining that even if you do not have a solar array on your roof, you can still have a battery backup system.

As it happens, I had everything I needed already just sitting in my garage.  Over the last year, whenever I would see something at a garage sale that I thought I might be able to use for solar power, I would pick it up.  Although, what I had was pretty weak.  It would be fine for a lighting system on the chicken coop but, I wanted to have a lot of power in the house if needed.  I decided to start finding everything I could on the cheap.

I went on eBay and found someone local who was selling everything from their old solar power system.  I was just in time to get the last two 12v 115amp deep cycle marine batteries.  They are flooded but, they were only $10 each that was a huge win.  He also had a power inverter left which I bought as well.  1500 continuous watts, 1800 watts for 20 min and 3000 peak watts.

The charger and wires are the only things I had to buy new and a month after I did, I saw the same charger at an auction.  It sold for $50 but, I think it was worth the extra cash to get one that was new.  I got the bigger charger off his list.  It is the Schumacher SE-1555A.  Not the one recommended for my small system but, for $10 more than the next one down, how could I not get it?  When I charge it, I keep it on the 20amp charge which works just fine.  I don’t dare try the 55amp charge with just these two batteries.  Maybe when I get eight or so.

Anyway, here is how it works.  You take the two 12v batteries and sit them next to each other.  + on one side – on the other.  You get a red piece of 2 or 4 gauge wire and connect each of the positive terminals.  (I used wire I bought at the auto parts store and they had connectors on then so this was easy.)  Then you do the same with the negative using black wire.  You then connect a longer (as long as it takes to reach your batteries) red wire and black wire to the inverter.  Take the other end of the red wire and connect it to the positive terminal on ONE of your batteries.  Now take the black negative wire coming out of your inverter and connect it to the negative side of THE OTHER BATTERY.  Positive on one battery and negative on the other battery.  Doing this will treat the batteries as one and drain them evenly.  Turn the inverter on and test it.  You now have emergency power.

Now for charging the batteries.  I wait until the evening when the power charges are less.  Take the cables from the charger and put them on the batteries the same way you did the inverter.  This will charge them evenly.  Now plug in the charger and turn it on.  My charger is smart and that is one of the reasons I got it.  It will not let me over charge my batteries.  I put is on 20amps if they are low and 2amps if they are almost full.

I have not had to use this system yet so, I don’t know how long it will last.  Here are a couple of key points to keep in mind.  You never want to run the batteries down past 50%.  When you have power, charge them up to 100% but, if the power is out, you can stop at about 90% of a charge.  That extra 10% and especially the last 2% take a long time to charge.  If you are powering your charger off the generator, the gas you use does not equal the power in the batteries.  While you have the generator running, power everything you can/want off of the generator.  When the generator is running, it runs at a few different speeds.  If you are not using all of the power that it is making, it is just being wasted.  The reason we charge the batteries then run off of them is that the inverter will only use the power it needs at that second saving you power.  Once the batteries are at 90%, turn off the big stuff and run everything else off the inverter.