# Question about run time



## budgetprepp-n (Apr 7, 2013)

Without getting to technical If I'm using a standard deep cycle battery like what Walmart sells. How long
would it take for 8watt bulb to wear the battery down to the point of needing to shut it off before it is damaged?

working on building security light that would on solar


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## soyer38301 (Jul 27, 2017)

Would think that might depend on the amp hours of the battery....would vary some one type to another ..

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## Kauboy (May 12, 2014)

@soyer38301 is correct.
The math isn't too difficult to do once you know the total battery capacity.


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## Chipper (Dec 22, 2012)

Spend the extra couple bucks and get a Interstate battery.


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## soyer38301 (Jul 27, 2017)

I had decent luck with interstate batteries when I was running my wind genny. Worth the extra couple of bucks

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## Maine-Marine (Mar 7, 2014)

We install solar on gas pads all the time

a 105 amp hour battery will supply 12 volts at 1 amp for 105 hours, or 2 amps for 1/2 that, or 105 amps for 1 hour

divide the amps need by the size of the battery


ALSO - consider using a LOAD DISCONNECT device to turn off the load when power drops below the proper voltage


>YMMV<


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## soyer38301 (Jul 27, 2017)

+1 on the load disconnect . Consider a load diversion device also if you think you might produce more than the battery needs. Cooked a battery before i added diversion...

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## dwight55 (Nov 9, 2012)

Example, . . . a battery with a listed life of 75 amp hours.

That battery will produce 1 amp for 75 hours before needing to be fully recharged.

An 8 watt bulb uses 2/3 of one amp (watt = volts X amps, . . . in this case 8 = 12 X .666, . . . with the watts and the volts being the known factors).

Therefore if we have a 75 amp hour battery, . . . using 2/3 of an amp per hour, . . . divide 75 by 2 (37.5) and multiply it by 3 (112.5 hours).

Gotta remember, . . . this is ALWAYS all theory, . . . and will work the very first time you use it, . . . in a controlled environment, . . . but after the units are all a bit on the old side, . . . slight differences will come about.

May God bless,
Dwight


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## Maine-Marine (Mar 7, 2014)

Hint number 2

get some LED lighting... 

I had a 50 watt panel , a sunsaver, and 1 55 AH battery on my wood shed with a strip of led lights... you could leave it on for days - my kids often forgot to turn it off and it will stay running forever


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## budgetprepp-n (Apr 7, 2013)

Maine-Marine said:


> We install solar on gas pads all the time
> 
> a 105 amp hour battery will supply 12 volts at 1 amp for 105 hours, or 2 amps for 1/2 that, or 105 amps for 1 hour
> 
> ...


I'm using solar and a controller. That should take care of it.


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## budgetprepp-n (Apr 7, 2013)

dwight55 said:


> Example, . . . a battery with a listed life of 75 amp hours.
> 
> That battery will produce 1 amp for 75 hours before needing to be fully recharged.
> 
> ...


thank you


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## budgetprepp-n (Apr 7, 2013)

Maine-Marine said:


> Hint number 2
> 
> get some LED lighting...
> 
> I had a 50 watt panel , a sunsaver, and 1 55 AH battery on my wood shed with a strip of led lights... you could leave it on for days - my kids often forgot to turn it off and it will stay running forever


I was going to go with a corn row bulb I have had good luck with these. And they are really bright
I'll take pictures when I put this together maybe do a DIY thread.


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## paraquack (Mar 1, 2013)

Not sure BudgetPrepper if you are talking about a 8 watt bulbs at 12 volts or a 8 watt bulb running on 120 VAC from an inverter. Makes a difference.


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## budgetprepp-n (Apr 7, 2013)

paraquack said:


> Not sure BudgetPrepper if you are talking about a 8 watt bulbs at 12 volts or a 8 watt bulb running on 120 VAC from an inverter. Makes a difference.


8 watt 12 volt


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## Back Pack Hack (Sep 15, 2016)

Ambient temperature makes a big difference as well. Cold = less run time. Really hot = less run time.


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## budgetprepp-n (Apr 7, 2013)

Maine-Marine said:


> We install solar on gas pads all the time
> 
> a 105 amp hour battery will supply 12 volts at 1 amp for 105 hours, or 2 amps for 1/2 that, or 105 amps for 1 hour
> 
> ...


OK so how many watts does it to make 1 amp?


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## Back Pack Hack (Sep 15, 2016)

budgetprepp-n said:


> OK so how many watts does it to make 1 amp?


At 12 volts, 12 watts.


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## paraquack (Mar 1, 2013)

In theory a 12 volt battery with a capacity of 105 AH would be 1260 watts (12 times 105). So 1260 watts devide by 8 watt (LED) = 157.4 hours, in theory.


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## gvtoolsrepairs (Jan 1, 2018)

And remember you should not discharge a lead acid battery below 50% capacity before recharging 

Regards 
Bushpigv8


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## budgetprepp-n (Apr 7, 2013)

Ok well then it looks like to have a bulb that takes 8 watts to run all night one battery will do the job.


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## HerladWilly (Oct 7, 2019)

I'm a fan of combining solar+inverter+ LED lights and you can expect that you will have longer runtime for sure.


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## Grinch2 (Sep 12, 2016)

Maine-Marine said:


> Hint number 2
> 
> get some LED lighting...
> 
> I had a 50 watt panel , a sunsaver, and 1 55 AH battery on my wood shed with a strip of led lights... you could leave it on for days - my kids often forgot to turn it off and it will stay running forever


We run strictly L.E.D's for all of our lighting, it certainly helps with what we use, we use a wind turbine and solar panels and I couldn't believe the amount it saved, we sell excess back to the power company and the check difference in one month more than paid for the switch.


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## bigwheel (Sep 22, 2014)

The RV hobbyists say instead of buying a deep cycle 12 volt battery...buy two 6 Volt golf cart batteries and hook em together. The theory being they cant take the repepitive charging and discharging better than a single 12 volt. Who knows if thats a good or bad idea?


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## Elvis (Jun 22, 2018)

bigwheel said:


> The RV hobbyists say instead of buying a deep cycle 12 volt battery...buy two 6 Volt golf cart batteries and hook em together. The theory being they cant take the repepitive charging and discharging better than a single 12 volt. Who knows if thats a good or bad idea?


Two smaller 6v batteries vs one larger 12v battery there is no difference except the two 6v batteries require 2 more battery cables to connect then together. The advantage to lower volt batteries (6v, 4v, 2v) is they can weigh less when carrying them so larger capacity battery banks make for easier installations and since they weigh less huge battery banks can have fewer battery cells to monitor and water.


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## Back Pack Hack (Sep 15, 2016)

Elvis said:


> Two smaller 6v batteries vs one larger 12v battery there is no difference except the two 6v batteries require 2 more battery cables to connect then together. ........


Only 1 more if you're wiring them in series to make 12v.


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## Elvis (Jun 22, 2018)

Back Pack Hack said:


> Only 1 more if you're wiring them in series to make 12v.


Oops, your right.


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