# experiment for emergency lights



## budgetprepp-n

Hi,
This time I'm going to run 2 lights off a standard car battery to see how long they will run.
The bulbs will be SMDs they are sort of the next generation of LEDs. The SMDs give off a harsh light
that is they hurt your eyes to look at them (like a 100 watt bulb) But they are super bright and will really 
light up a room. I will be using a camper fixture for the bulbs. These bulbs are 12 volt and they will
fit in a standard automotive tail light socket. After this I will doing the same thing with a inverter and
one of the new cree led bulbs. They look almost like a standard light bulb but they take 13 watts to run and
they give off the same amount of light as a 100 watt bulb. Pricey $20 for one bulb but guaranteed for 10 years
The cree are 120 volts a used $20 inverter will be needed

After we see what happens with both tests we will figure out what to do with our new information for some 
emergency lighting.

For now the bulb on the left is the type we are using for the first test. It has 66 little SMDs for light.
these are available in 10 40 or how ever many SMDs you want. We will be using the biggest ones I could find. 
66 SMDs

The battery is a cheap Autocraft that I picked up from an auto repair shop in town it was taken out of 
one of there customers cars and replaced with a new one it is from the year 2009.
I don't know why it was replaced but it seemed to charge up OK.

If you guys want we can use a smaller SMD and see how long we can run after we are done with the
other two types of bulbs.

We can make this a forum group test/experimental thread and do what ever kind of experimenting
everyone wants just to see what works for emergency lighting. 
Like maybe using regular tail light bulbs from a car easy to find. 
Might as well play until the battery is burnt out. (I topped off the battery with distilled water it was low)



we will be using the bulb all the way on the left 2 of them at the same time.

Note: this is a prepper and survival forum. So lets not worry to much about deep cycle batteries
or anything technical.

Lets concentrate on what can be done after TSHTF and there are no stores or any place to buy
anything.

We also have a used 100 watt solar panel and a $6.99 controller at our disposal for experimenting.

Once we see what we can do you might want to ad some of these bulbs or controller
to your preps. The bulbs and controller can be had for under $20


To see how long these run you may want to skip to near the end to
see. There a lot of other stuff in this post but it's good stuff too.


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## alterego

Our Camper Has Some Nice Light Fixture That Run 12 Volt. They Are Fairly Bright. They Are Not Led For Reduced Consumption. You Might Look At Camping World For Light Fixtures That Run 12 Volt And Are Led.


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## Slippy

Excellent experiment. Looking forward to the results.


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## budgetprepp-n

alterego said:


> Our Camper Has Some Nice Light Fixture That Run 12 Volt. They Are Fairly Bright. They Are Not Led For Reduced Consumption. You Might Look At Camping World For Light Fixtures That Run 12 Volt And Are Led.


Excellent!! That is exactly what we will be using a camper light with an old 2 speed fan switch that I added and SMD bulbs 
with the two speed switch you can run 1 or 2 bulbs at a time. But if needed you could use old car tail light sockets. 
you could run just one bulb to conserve battery power.

The SMDs will replace the standard bulbs perfect 
I have one of these lights in every room in the house hooked up to my solar set up 12 volt


the smaller bulbs can had for $8.31 for 20 or $16.95 for 50
and up to $3.00 for the really big ones. All prices are with shipping
Do you guys want the prices on the stuff we are using? - 
Some people may be on a budget and want to know?
Some may want to get stuff for bartering later? 
Or does all the prices get annoy you?


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## budgetprepp-n

Ok we will see the lights have been on for 1 hour and 30 minutes


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## budgetprepp-n

Arklatex said:


> Budget, have you heard of the 500-1000 hour flashlight mods? It basically involves a camping lantern style flashlight and a 20 cent resistor. You guys can Google it. I would be interested in seeing you experiment with this concept as well. It ties in nicely with the application of emergency home lighting. Let's say you put in a resistor that dims you 100 watt equivalent to 50 watt. You would theoretically double battery life and still have plenty of light for everyday uses. Just a thought...


 That is a good thought. I will look into it,,,,,,,Thanks


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## DoubleA

Interesting and practical experiment, thanks. Subscribed.


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## budgetprepp-n

Good morning,
We just hit 12 hours and the lights are still bright. I'm doing this out side on the back porch and I
had the back yard lit up very nicely. 

You know I was thinking I bet I have the house of the future. No really a "Hybrid" part solar and part grid.
It doesn't cost that much to have a smaller set up to run the light weight stuff like lights, TV computer and what have you.
But I still need the grid for the big stuff well pump, Washer dryer, Refrigerator. 

Lights and little stuff don't cost that much to run but they a big part of your bill because we use them so much 
Am I off on this? What do you think?


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## dsdmmat

cool experiment, will be watching for your results. 

I have often thought of hooking up an alternator to a stationary bicycle for charging up 12 volt batteries which might be useful to keep the lights on.


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## budgetprepp-n

dsdmmat said:


> cool experiment, will be watching for your results.
> 
> I have often thought of hooking up an alternator to a stationary bicycle for charging up 12 volt batteries which might be useful to keep the lights on.


That's a good idea it would also keep you in shape if your stuck inside for a while. I just wonder how long and hard would you
need to pedal to charge up a battery?


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## LunaticFringeInc

yeah I have been using the leds that come in a fixture like Budgetprepper posted a pic of for about 3 years now maybe a bit longer. They are a definite improvement over the car tail light style bulbs for sure!


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## budgetprepp-n

LunaticFringeInc said:


> yeah I have been using the leds that come in a fixture like Budgetprepper posted a pic of for about 3 years now maybe a bit longer. They are a definite improvement over the car tail light style bulbs for sure!


Do you have the ones like on the left of the picture of bulbs? 
Are yours really bright like they hurt your eyes to look at them?
I got to get a new camera,, You guys need to see this to bleave it bleave < how do you spell that?

Up date: Cumming up on 20 hours and still bright


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## Prepadoodle

interestinG experimenT, leT uS knoW hoW iT turnS ouT.


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## dsdmmat

budgetprepp-n said:


> That's a good idea it would also keep you in shape if your stuck inside for a while. I just wonder how long and hard would you
> need to pedal to charge up a battery?


well a car usually has to run above idle for 30 minutes to fully charge a dead battery. So a 30 minute work out on a stationary bike should so it. Depending on the RPMs of the alternator I suppose.


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## budgetprepp-n

29 1/2 hours still bright


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## PaulS

An alternator connected to a bicycle. Lets make it easy and forget about all the losses in driving an alternator for this little thought experiment.

I'll use a 100 amp alternator that needs to turn 1800 rpm to start and has full output at 3600 rpm. (the speeds are optimum for automotive alternators)

100 amps at 12.5 volts is 1250 watts. 1 HP = 745 watts so 1250/745 = 1.678 HP

The average human can produce 1/3 hp for a period of just over an hour so you are going to get just under 248 watts for that hour. To charge a standard 60 AH battery (or 750 watt hours) will take three people each taking a one hour turn at the bike putting out all they can for three hours straight. During that time you will burn up an extra large meals worth of calories so you will have to plan for four meals for each person on the days you want to charge the battery. If you could find a way to chain five bicycles together then you could get it up to the maximum charge rate and cut your time down to about 45 minutes for a full charge. 

If you use an alternator off an older car - say a 65 economy car - it would only produce 40 amps then you could get the maximum 500 watts with just two people on the bikes. It would still take over an hour to charge the battery. It will be like climbing a 15% grade on your bike for an hour - can you do that?

A professional athlete can produce 1/2 HP for the same amount of time so if you get into really good shape you could get about 70% of maximum from the 40 amp alternator.

Considering the caloric costs it would be less expensive to buy solar charge systems.


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## budgetprepp-n

PaulS said:


> An alternator connected to a bicycle. Lets make it easy and forget about all the losses in driving an alternator for this little thought experiment.
> 
> I'll use a 100 amp alternator that needs to turn 1800 rpm to start and has full output at 3600 rpm. (the speeds are optimum for automotive alternators)
> 
> 100 amps at 12.5 volts is 1250 watts. 1 HP = 745 watts so 1250/745 = 1.678 HP
> 
> The average human can produce 1/3 hp for a period of just over an hour so you are going to get just under 248 watts for that hour. To charge a standard 60 AH battery (or 750 watt hours) will take three people each taking a one hour turn at the bike putting out all they can for three hours straight. During that time you will burn up an extra large meals worth of calories so you will have to plan for four meals for each person on the days you want to charge the battery. If you could find a way to chain five bicycles together then you could get it up to the maximum charge rate and cut your time down to about 45 minutes for a full charge.
> 
> If you use an alternator off an older car - say a 65 economy car - it would only produce 40 amps then you could get the maximum 500 watts with just two people on the bikes. It would still take over an hour to charge the battery. It will be like climbing a 15% grade on your bike for an hour - can you do that?
> 
> A professional athlete can produce 1/2 HP for the same amount of time so if you get into really good shape you could get about 70% of maximum from the 40 amp alternator.
> 
> Considering the caloric costs it would be less expensive to buy solar charge systems.


 Your math sounds about right but what if dsdmmat used a alternator size generator off a wind farm?
Your really good at math,, Look at the size of bike wheel and look at the size of a generator pulley every single rotation 
of the bike wheel has got to be a bunch of rotations on the generator. And there not that hard to spin.

Here is the chart for a small wind generator I got one of these in my yard. 
It's a lot different than a car alternator. 
can you reconfigure your figures for dsdmmat using this information? It might work you tell me


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## budgetprepp-n

budgetprepp-n said:


> Your math sounds about right but what if dsdmmat used a alternator size generator off a wind farm?
> Your really good at math,, Look at the size of bike wheel and look at the size of a generator pulley every single rotation
> of the bike wheel has got to be a bunch of rotations on the generator. And there not that hard to spin.
> 
> Here is the chart for a small wind generator I got one of these in my yard.
> It's a lot different than a car alternator.
> can you reconfigure your figures for dsdmmat using this information? It might work you tell me


,,,,,,,,,,,,,,,,,I would like to trade this silly thing for some solar panels

Note Experiment update: 38 hours and the lights are still bright


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## GTGallop

I'd like to do the same test only with a deep cell battery, an inverter, and a HAM radio.


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## GTGallop

Even more so than that HAM test is another one I'd like to do...

Test 1 - Battery, 150W inverter, one single LED bulb

Test 2 - Battery, 500w or 750w inverter, one single LED bulb

Looking to see if an OVERSIZED inverter will cost you more power if that extra capacity isn't being used.

And don't forget...
Volts times Amps = Watts.

I find a LOT of people don't know that when picking inverters.


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## paraquack

GTGallop said:


> I'd like to do the same test only with a deep cell battery, an inverter, and a HAM radio.


Why not go with a 12 volt Ham radio and eliminate the middle man. From my recollection (I'm and old fart) a lot of radios have a built in AC to DC power supply that can be or has built in bypass for 12 VDC. I know at least one of my radios had this.


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## budgetprepp-n

I have a 1500 watt / 3000 watt surge inverter for my house and I have a bunch of smaller ones that I have picked up
cheap that are like 500 to 800 watts you can pick them up all day cheap on ebay. 
My 1500/3000 surge pure sine wave inverter was only $149 with shipping new with warranty and shipping.
here you go 400 watt pure sine wave inverter used $20 with shipping 
new ones are cheap also.
Aims Power 400W 12V Modified Sine Wave Inverter 800 Watts Surge PWRINV400W | eBay

I gave $147 with shipping for this pure sine wave inverter 1500/3000 surge 
new with warranty. I been using it about 2 years to run my stuff in the house
from my solar set up.


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## budgetprepp-n

GTGallop said:


> Even more so than that HAM test is another one I'd like to do...
> 
> Test 1 - Battery, 150W inverter, one single LED bulb
> 
> Test 2 - Battery, 500w or 750w inverter, one single LED bulb
> 
> Looking to see if an OVERSIZED inverter will cost you more power if that extra capacity isn't being used.
> 
> And don't forget...
> Volts times Amps = Watts.
> 
> I find a LOT of people don't know that when picking inverters.


 Hi
Hey I had the same worries about the inverter using up extra juice also but I have a 1500/3000 watt inverter
and it doesn't use enough juice to even be a problem if it has no load it doesn't really take any power. 
I was really surprised to find this.
150 watt inverter or 1500 watt inverter -pretty much the same -- I have tested them

Test no 1? we can do that one next -- you got it 
I will be using a cree bulb 100 watts of light. and a small inverter will that work for you?

Test no 2? One led? well the test I'm running right now has a little over 200 LEDs or SMDs built into the 
bulbs and they have been running for over 42 hours with no sine of weakness so far.
I'm afraid that 1 LED or SMD would take months to drain a battery.

As you wish you git the next experment. Only using a 100 watt cree. 
sound ok?

I'm starting to think I should have used a lot more lights for this test it's been a long 
time and the bulbs are still bright as can be. This is getting a little boring

we can do the regular light bulb after we test the smaller stuff this battery is sort of junk and I
don't want to burn it out until after we test the small stuff. 
Ok so we already know what we will be doing next.

my LEDs and SMDs are 12 volt bulbs no inverter is needed.
we will use the inverter in the next run


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## GTGallop

If you want...
Your current test could flow into the next one.
In your OP, you state that for the 2nd part of the current test you will


> After this I will doing the same thing with a inverter and
> one of the new cree led bulbs.


If you use a small inverter for that, then you finish your initial test and actually do Pt1 of the test I suggested.
Then follow it up doing the same thing with a large inverter and a Cree LED of the same size.

Make sense?


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## budgetprepp-n

Ok it's been 48 1/2 hours and we are still lighting the porch and back yard the lights are still bright. 
I didn't think the lights and junk battery would last this long. I'm pleased and surprised
at least this experiment isn't a bust this could lead to a project I bet one 100 watt solar panel and a deep cycle
battery could really light up my yard. I could run a dozen of these lights on an independent system.
Hummmmm.


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## budgetprepp-n

GTGallop said:


> I'd like to do the same test only with a deep cell battery, an inverter, and a HAM radio.


 all I got to play with is a CB radio and it's already 12 volt what else would work to take the place of a short wave radio? 
might useful to see how long a short wave would run on 1 charged battery.

Update 50: hours and still going strong about 9:00 pm
So this is like the third day on one car battery


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## paraquack

Here's the link to change out a regular 6 Volt flashlight bulb to a LED. Looks easy enough
$3.50 Flashlight + 20 Cent Upgrade = 500 Hour Run Time


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## budgetprepp-n

paraquack said:


> Here's the link to change out a regular 6 Volt flashlight bulb to a LED. Looks easy enough
> $3.50 Flashlight + 20 Cent Upgrade = 500 Hour Run Time


 That's pretty cool I wonder if you really can get 500 hours run time. 
why don't you give that shot and see? Or later I might even try that one myself 
I wonder if you can pick that stuff at radio shack?

Up date: about 54 1/2 hours still bright and strong about 1:30 am 
this going a lot better than the hydrogen generator when I tried to get a weed eater
to run on water. I burned the motor up in about 120 seconds those 2 cycle engines 
do not like to run on hydrogen. My dad was really mad I had to buy him a new weed eater. 
I told him I was trying to save the world from it's dependence on oil but he was still not impressed. 
On the second test I must have gotten a spark or something to close to the generator
it went off like a 10 pound fire cracker. I never built another one to costly. This was when gas 
weed eaters first came out they were really expensive.


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## alterego

Ok Budget. Just So I Understand How Many Actual Bulbs Are You Running On Your Test Here. One Two Or What. The Other Question Is. When You Notice Substantial Dimming Please Take A Digital Multimeter To The Terminals And Report Haw Many Volts The Battery Is Showing If You Have One Available. I Would Like To Know If An Led Will Continue To Emit Light At Less Than Ideal Voltage.


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## Smokin04

Could always rig the bulb to a baghdad battery and save the solar for something else.


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## budgetprepp-n

alterego said:


> Ok Budget. Just So I Understand How Many Actual Bulbs Are You Running On Your Test Here. One Two Or What. The Other Question Is. When You Notice Substantial Dimming Please Take A Digital Multimeter To The Terminals And Report Haw Many Volts The Battery Is Showing If You Have One Available. I Would Like To Know If An Led Will Continue To Emit Light At Less Than Ideal Voltage.


Oh,, Ok If you look at the picture I am running two of them. Each one has like 120 bright little 
SMDs or LEDs built into it. I thought that if I ran two it would cut down on test time. But darn we are coming up on 4 days of straight
running time and they are still bright as can be. I had no idea lights this bright would run for so long on one junk car battery.

Boy that's a great question, But I don't have a Digital Multimeter I should pick one up. 
I too am interested in seeing how low the voltage can go and still have bright lights.
I'm also wondering if they will get dim with low voltage or just go out all at once or will this damage the bulbs?


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## budgetprepp-n

GTGallop said:


> I'd like to do the same test only with a deep cell battery, an inverter, and a HAM radio.


 yes as preppers this the kind of stuff that is important to know before TSHTF. 
I'm to cheap to spring for a deep cycle battery and burn it up just to get some information that may save our life someday.

But fear not I have some Morgan silver dollars for trade. I met guy from the local short wave club that wants to 
trade a short wave radio for 3 of the coins. I'm going to get the make a model number and post it somewhere and 
ask if it is a good one or not. Do you think it might damage it if we used it for a test on a 120 volt inverter till the
battery is dead?

If your looking for a great deal on a used short wave radio check with the local short wave clubs.
They got all kinds of good used stuff laying around for a great price.


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## budgetprepp-n

Uses for this experiment just some passing thoughts. 

1,,If I can can find a photo cell that works on 12 volts to shut the lights off at dawn and on at dusk this could be
A great thing I have a telephone pole in my yard with a big mercury light on the top .
What if I mounted a small solar panel on it and a true deep cycle battery and controller lower on the pole where I could get
to it for maintenance if ever needed. Put like 4 of these bright lights up there on at dusk off at dawn with no grid involved.
Light that yard up at night for many years for about $225 the point is not really to save money but rather to have lights when the
grid goes down for a long time when TSHTF. Or put those lights in the house. I think we have proven that it is easy possible.

2,, In the winter most people with chickens (and cocks) put a light in the chicken coupe so the chickens will keep laying in the 
shorter winter days. What if you did the same thing here? " Chickens living off the grid" sounds like a good post to me. 

3,, Even if you didn't have any solar power if you live where there are hurricanes or what ever. keep a deep cycle battery on a trickle charger
or "battery tender" on the battery to keep it fully charged. Use a 60 foot extension cord put alligator clips on one end for the battery
and mount the lights like the ones we are using in a camper fixture on the other end. Think of how many hours of light you could have 
with no grid. If you used a new deep cycle battery. Or if you only used one bulb I bet you could at the least get 150 hours of light easy.
That could come in handy. Put the battery on a battery tender and have the cord made and ready and forget about till you need it
(check on the battery water level every few months.) It's been my experience that if a battery is just sitting there fully charged up
it usually doesn't need any water added. Emergency lights for $150? 150 hours of lights dived by 8 hours of light per night = 18 to 19 days
of lights. And if you need to recharge just use jumper cables and run the car a while. Or just pinch the battery out of the car and use it. 
due to the low amp draw I'm sure a extension would be heavy enough. 
Good for a 12 volt radio also.

Or to save money liberate the battery out of the guys car next door and barrow his extension cord.
and if he has a camper with good lights now you are really in luck. Just joking,, maybe 



4,, Hunting cabin or BOL shack in the woods? You could berry the solar panel and everything needed to hide it. 
I could think of many uses for this set up in different forms. Short wave radio?

Your thoughts or ideas on this? 

berry < Whats the right way to speel this? 

Up date: 5/5/2014 3:00 P.M. 56 hours all is well and bright.


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## PaulS

budgetprepp-n said:


> Your math sounds about right but what if dsdmmat used a alternator size generator off a wind farm?
> Your really good at math,, Look at the size of bike wheel and look at the size of a generator pulley every single rotation
> of the bike wheel has got to be a bunch of rotations on the generator. And there not that hard to spin.
> 
> Here is the chart for a small wind generator I got one of these in my yard.
> It's a lot different than a car alternator.
> can you reconfigure your figures for dsdmmat using this information? It might work you tell me


12V x 1.5 amps = 18 watts
25V x 4 amps = 100 watts
43V x7 amps = 301 watts = too much for one person to make on the bicycle 
60V x 10 amps = 600 watts
70V x 11 amps = 770 watts

The rpm is not important - the hp it takes to make the power is what you are limited to. The wind has a lot more power - even with the small turbine - than you can produce yourself.
Wind power is effective if you have winds that are higher than 7 mph. Around my place it would easily generate power most days. I also have quite a bit of sunlight so solar panels would be another excellent choice. Some places have more wind than sun some more sun than wind. I pity the places that have neither and am blessed to have both.

All alternators are easy to spin when they are not producing power but when you start generating power it takes more power in to make the power that it is putting out. Typically if you want 1 hp out you have to put in 1.1 hp in order to achieve it. (think of it like pulling an oar through the water - if you pull very slowly it doesn't take much to move it but the faster you pull the oar the harder it becomes)


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## budgetprepp-n

Update: 7/5/14 3 days and 19 hours and the lights are still running. 
Man that's 91 hours of light so far from an old car battery. If you only ran one light for 10 hours a night 
That would be over 18 days of light. If you had two batteries you could have light for over a month.
I bet one of the solar battery charges from Harbor Freight could keep up if you charged it everyday with the light
coming a window or something. Or have two batteries and charge one while you use the other. 
thoughts?
I'm I over posting? Or are a bunch of people sitting on there hands looking at the monitor screen like a dear in the headlights? 
Get involved and help everyone get ready. If you got any good ideas that might help someone post it. 
I'm not in charge of anything but I thought that's the way it worked here.


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## GTGallop

Here is what I really want to find out...
Take a battery, any battery - like this battery for a 20 year old Toyota Pickup. Common, cheap, generic, you get the point.

If I have an appliance that runs X watts, lets call it 10 watts and I'm running an inverter (some loss), then how long will that battery last me on a full 10 watts of drain? Or Maybe 50 watts? Or maybe 100 watts?

Is there a formula that lets me put in some criteria about the battery and the drain and see what it will do?

Because, if so, I'd like to run that formula against this type of battery ==> A Golf Cart Battery.
Or this ==> A Big Honkin Marine Battery!

I think someone, some where, some how should be able to lay this down in a formula that we can put into Microsoft Excel and fairly accurately calculate what we would be able to do with one battery - roughly...


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## StarPD45

If you use a timer, the timer will require juice to run, unless you use a windup type. But then you would have to constantly wind it up.


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## budgetprepp-n

I used one before on a set of yard lights and it was really easy to it just look like a little black box
with an eye. You spliced it into the line and it worked. I had a timer but I had to keep resetting it as the amount of 
sunlight changed. 
And yes the timer ran on 120 volts


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## budgetprepp-n

Hi
OK I finally got a picture of this experiment someone stopped over with a cell phone and snapped a picture for me. 
Sorry it's such a crappy picture but that all I got for now. I know it doesn't look real bright with the sun shinning on
it but it is quite bright.


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## budgetprepp-n

GTGallop said:


> Here is what I really want to find out...
> Take a battery, any battery - like this battery for a 20 year old Toyota Pickup. Common, cheap, generic, you get the point.
> 
> If I have an appliance that runs X watts, lets call it 10 watts and I'm running an inverter (some loss), then how long will that battery last me on a full 10 watts of drain? Or Maybe 50 watts? Or maybe 100 watts?
> 
> Is there a formula that lets me put in some criteria about the battery and the drain and see what it will do?
> 
> Because, if so, I'd like to run that formula against this type of battery ==> A Golf Cart Battery.
> Or this ==> A Big Honkin Marine Battery!
> 
> I think someone, some where, some how should be able to lay this down in a formula that we can put into Microsoft Excel and fairly accurately calculate what we would be able to do with one battery - roughly...


Thing is if you do experiments like this you don't even want to use a deep cycle stay with a car battery.
A deep cycle won't stand up to this kind of punishment like a car battery will. 
Budget said that

Up date: in 1 hour and 45 minutes it will be 4 days non stop running
I got my hours screwed up some how. I started on the 1st at 7:00 PM and now it is the 5th that's 4 days
it should be like 96 hours at 7:00 PM on the 5th - is my math right here? 
4 days is 96 hours right?


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## budgetprepp-n

OK this experiment is done the lights are starting to show sines of starting to grow a little dimer so the battery must be about dead.
I'm going to give this one a %100 thumbs up success
lights for 4 days and 2 hours. Using two SMD bright bulbs and one car battery. 
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Total of 98 hours of light on a car battery with no recharge,,,,,,,,,,,,,,,,,,,,,,,,,,,

I have been emailing back and forth with GTGallop and next we want to see how long it takes to recharge the battery
with a small harbor freight gas generator and a small Montgomery Wards battery charger.

It's nice to use less than top class stuff to simulate what it will be like after TSHTF.
So i guess for me the thread is closed on to the next one,,,,,,,,,,,


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## PaulS

GTGallop said:


> Here is what I really want to find out...
> Take a battery, any battery - like this battery for a 20 year old Toyota Pickup. Common, cheap, generic, you get the point.
> 
> If I have an appliance that runs X watts, lets call it 10 watts and I'm running an inverter (some loss), then how long will that battery last me on a full 10 watts of drain? Or Maybe 50 watts? Or maybe 100 watts?
> 
> Is there a formula that lets me put in some criteria about the battery and the drain and see what it will do?
> 
> Because, if so, I'd like to run that formula against this type of battery ==> A Golf Cart Battery.
> Or this ==> A Big Honkin Marine Battery!
> 
> I think someone, some where, some how should be able to lay this down in a formula that we can put into Microsoft Excel and fairly accurately calculate what we would be able to do with one battery - roughly...


It is relatively easy to calculate how long you can drain a battery as long as you know the amp/hour rating of the battery and the drain that you will have in watts.
Lets say you have a battery rated at 60 amp hours. 12V x 60 amps = 720 watt hours. since you are running it through an inverter you will lose 10% so 720 - 72 = 648 watt hours. You can only drain the battery 80% so 648 x .80 = 518 watt hours. If your device uses 10 watts then you can run it 518 / 10 = 51.8 hours.

To charge that battery you have to put in about 1.1 times the amount you used so you would have to charge it at say 10 amps for over 6 1/2 hours (6.6 hours) and then you let it sit idle for at least half of the charge time and up to the full charge time. sitting allows the battery to degas and equalize the charge on the plates. It also allows the battery to cool.


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