# Off Grid Question???



## junkman (Jan 14, 2010)

Deep cycle battery rated at 100 ah?If used at 4 amp will it last 25 hours?


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## Big Frank 25 (Feb 21, 2002)

https://planetcalc.com/2283/


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## junkman (Jan 14, 2010)

So sounds like I will be ok if i pickup a 100 ah battery.my furnace draws 4 amp while it is running.If it only runs 15 minutes out of the hour it should last a weekend.Plus running the engine will also charge the battery.


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## grapestomper (Jan 9, 2012)

Maybe hook a solar charger up to it to help out. 
Drain your battery to zero all the time and it won't last very long.


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## Gamekeeper (Oct 9, 2015)

Batteries have an actual yield that is a functional percentage of rating.I
So, 100 amp/hrs is probably about 75 actual.


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## junkman (Jan 14, 2010)

Gamekeeper said:


> Batteries have an actual yield that is a functional percentage of rating.I
> So, 100 amp/hrs is probably about 75 actual.


I know that part.I'm just talking the theory.And I will also be charging by running the engine from time to time.


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## Gamekeeper (Oct 9, 2015)

On my motor home, once I got rid of every incandescent bulb, a modern digital charge controller, and totally replaced every light with LED's, I doubled my battery bank time.

My goal, was to be able to use the furnace over the weekend without running a generator. I couldn't do it with the old furnace, it's sail switch and can motor was too Inefficient, but the new replacement furnace with a more efficient electronics Can make the weekend.


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## fishrod (Oct 3, 2008)

You should never go below 50% of any deep cycle battery other than Li ion. It will significantly shorten the life span.


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## MossyHorns (Apr 14, 2011)

Go with 2 6 volt golf cart batteries hooked in series. I converted my camper over to them 10 years ago. They are true deep cycle batteries and will outlast 12 volt ones.


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## Ronnie D (Dec 8, 2020)

junkman said:


> So sounds like I will be ok if i pickup a 100 ah battery.my furnace draws 4 amp while it is running.If it only runs 15 minutes out of the hour it should last a weekend.Plus running the engine will also charge the battery.


The furnace runs on a/c current. The battery produces d/c current. In order to get a reference on run time you will need to get the V.A rating on the inverter. Then access ugly's electrical manual and do the math. The values will change as the battery discharges so a solar charger would help out bigtime


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## junkman (Jan 14, 2010)

Ronnie D said:


> The furnace runs on a/c current. The battery produces d/c current. In order to get a reference on run time you will need to get the V.A rating on the inverter. Then access ugly's electrical manual and do the math. The values will change as the battery discharges so a solar charger would help out bigtime


It runs off of DC.The furnace came from an RV.


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## ArrowFlinger (Sep 18, 2000)

fishrod said:


> You should never go below 50% of any deep cycle battery other than Li ion. It will significantly shorten the life span.



If go over 12hrs usage you will ruin the battery. Buy Lithium, generally higher capacity and you can use nearly 100%. They are lighter and easier to transport to your charger. In the long run they are cheaper as you will not ruin them like Lead Acid batteries.



Gamekeeper said:


> On my motor home, once I got rid of every incandescent bulb, a modern digital charge controller, and totally replaced every light with LED's, I doubled my battery bank time.


I did the same and i think it is way more than double, 3x-4x



MossyHorns said:


> Go with 2 6 volt golf cart batteries hooked in series. I converted my camper over to them 10 years ago. They are true deep cycle batteries and will outlast 12 volt ones.


This is another option.


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