Thanks in advance

I’m thinking about setting up my BOV as an auxiliary power supply for our freezer and fridge.  

This would require a deep cycle capable battery installed in the BOV and an inverter.  I would put the inverter on the battery, and then run an extension cord into the house to the fridge, or freezer.

The fridge is a 3.6 amp, so that is 432W running and at 3X = 1296W startup.
The freezer is a 2.5 amp, so that is 300W running and at 3X = 900W startup

I’m considering the Optima Yellow top battery.  There are 2 models
D34/78:
CCA 750
Reserve Capacity 120
Capacity (C/20 rate) 55

D75/25:
CCA 620
Reserve Capacity 120
Capacity (C/20 rate) 48

I do not know what the Capacity (C/20 rate) means

This would cost about 300 after tax and installation
125 plus tax extra for the battery, up to 150 plus tax for the inverter and up to 20 plus tax for miscellaneous hardware.

So which is the better battery?  Or should I set the money toward a Honda quiet genny?

It is not so important to run the fridge If the power goes, but we keep milk in the freezer for the kids.  The milk is goat milk that I am thrilled to only have to pay $10 a gallon for when I can get it so cheap.  So keeping the freezer frozen in one event could offset the cost of the battery and inverter.

A single battery won't last long.  Also, I would not use any other battery other than a deep cycle type.

With the right setup, a set of batteries and an inverter are great.  However, for your immediate needs, I would buy the generator.

Your vehicle CAN recharge the battery but you will burn through a lot of fuel just to keep it charged.

Buy the generator.  Then, save your money to assemble a proper battery bank and inverter.

Honda EU2000i's are great. Easy as hell on gas too.

C/20 refers to the charge/discharge rate, in the case over a 20 hour period.

Automotive battery ratings are voodoo  and have little bearing on the real world.


Get the EU2000i.  You'll have to keep the truck idling and that is a huge waste of gas (half a gallon an hour or more and
your alternator isn't going to put out full power at idle.

Also, with inverters, you get what you pay for.  Run a cheap inverter near its capacity and they don't
last long, the power is extremely dirty, and they'll cause the compressors to run hot.




Car alternators also don't last very long when you are running them near capacity.

No.  This is an either or deal for now.  I don't have room for a battery bank.  As it is the genny or inverter could hide out in the bottom of the coat closet but the battery has to ride in the truck.  I have room for 2 batteries in the truck but that would get this project cost up to over half of the price of a new Honda.

My vote is for the Honda.

genny they are much more fuel efficient as well, if you stress your alt to much in will go bad,
save up and get the genny its portable and much easier to fix something happens to it.

+1 on the Honda, love mine!

Prepper

Deep cycle battery FAQ

...and I'd pick the Honda as well...

Generators and Batteries with an inverter are symbiotic. In true AR15 com fashion, you must get both. Of course money is the limiting factor, in my opinion, it is best to buy a generator first (assuming you do not have one) and then the battery(s)/inverter.

Lets do a little math using your figures.

The largest capacity battery at the c/20 rate is 55 which means it will supply a total of 55 amp/hrs of power over 20 hours of discharge.

55/20= 2.75 or a load of 2.75 amps for 20 hrs.

volts x amps = watts so a 12v battery supplying 2.75 amps would give us 33 watts or enough to power a cfl light bulb for around 20 hrs.
This assumes 100% efficiency which there never is converting from dc to ac. Figure around 85% to be safe. This would also completely discharge the battery.

The loads together total 742 watts which I take it was figured by looking at the plate on each appliance. It is probably a lot less than that as that is probably the max it draws during defrost. My fridge is a 26 c.f. Samsung which draws about 150 watts while running and around 475 watts while in defrost and my chest freezer is 15 c.f. and draws around 95 watts while running with no defrost. You should really get a kill-o-watt meter to figure a 24hr total for each appliance as it would be way more accurate.

Watts / volts = amps so 742 watts would consume  around 61.8 amps from a 12 volt battery.  Basically the battery would be completely dead in less than 1 hr with that kind of load on it.

Batteries do not like to be discharged below 50% very often especially if they are not TRUE deep cycle batteries. If you drain it dead once you will significantly shorten it's life. Do it several times in a row and it will kill it.

IMHO if you don't have the funds to buy the proper batteries and build a bank of sufficient size for the load then don't do it at all because you will be wasting a lot of money on dead batteries. Buy the EU2000 first and save up for the proper batteries later.

Well said.

Also agree that the figures posted by the OP for the refrigerator and freezer are too high for normal use.  My own experience closely matches yours as far as power draw for my refrigerator and freezer.

I, too, have been thinking of ways to be prepared for an extended power outage.  I've got a few 5,500 watt gasoline generators already, but I've been thinking about putting my freezer and well on a solar powered battery powered system like this one from mysolarbackup.

Get the generator.
You can move it around for other uses.

trkarl, thanks for a very informative post.  The whole point of this thread was to figure our how to get the most performance from my dollars.  Right now the generator wins.

i'm looking into this. don't really want to run a genny 24/7 how many batteries would it take for 24 hours?

I'd only run the genny long enough to keep the freezer frozen.  Maybe as little as an hour in the AM and again an o hour in the afternoon.

My vote is the generator as well. I have a larger one and a smaller one.

However I also have a 750 watt inverter for my truck for back up or small use needs. Power tools, pumps, aircompressors for on the go, that type of thing.
For long term use and larger appliances a generator will give you your best efficient use of resources. A battery bank is good but unless you are making power from solar, wind, water.... you are losing valuable energy in the production of electricity. For example, to use a generator to recharge batteries you will lose some energy because no system is 100% efficient, if you can use a windmill to turn an alternator to charge the batteries then you are gaining power.

A generator and small battery bank and inverter is the optimal backup power source combination.

This allows you to charge the batteries while you run the generator a few hours a day to power larger
appliances and then use the battery/inverter to run lights and smaller appliances.  

The rationale behind this is that it is very costly to build a renewable energy system sized to
meet all your need in an emergency.  If you built such a system you might as well go ahead and
use it all of the time.  The added fuel costs of charging a battery, while you are running the
generator to power larger appliances, is fairly small, and it buys you much more time to have
some power versus none when the generator is not running, which is much more cost effective
than running the generator full time, or in the case of the OP, idling the vehicle all the time.

This isn't armchair commando stuff for me, I've lived off-grid for almost two decades now and
have run  many different configuratons for power.  Before my housefire, I had a 1.1kw PV array and 12 kW battery bank,
small wind generator and 2 kW inverter, as well as generator.  Now my system is smaller, but
being rebuilt as I can afford it.

Sealed batteries can be used inside the house. A good charger $150-200. You could get both and use the batteries for lights/laptop/tv at night and use the genny during the day for fridge and charging the batteries. I have a couple large Honda gennys that are loud, I have a small 2500/3150 with a Honda motor for the small loads. I have a battery bank with 720AH, and am working on another 1000-1200AH.So a layered approach is where I am trying to be.

To get started go with the EU2000 from wise sales, the last price I saw was 869.00 shipped. Then you will need fuel. At least your getting started, but IMHO running a truck to use it to charge batteries and run a inverter is a waste of fuel.