Solar Power System

Anything electric, AC or DC

Solar Power System

Postby Gunman9 » Sun May 31, 2015 8:55 am

I'm trying to stay on a "budget with the battery since it won't be used much. Would any of these work?

http://m.samsclub.com/ip/duracell-golf- ... rod3870120
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Re: Solar Power System

Postby MtnDon » Sun May 31, 2015 9:42 am

It is a good battery; made by Deka. Depends on how much capacity you really need though as that is a lot of battery at 90 pounds weight. Look after it and it should last you many years.
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Re: Solar Power System

Postby Gunman9 » Sun May 31, 2015 9:44 am

MtnDon wrote:It is a good battery; made by Deka. Depends on how much capacity you really need though as that is a lot of battery at 90 pounds weight. Look after it and it should last you many years.


Could it run a like a min fridge or window ac? I know it will run all my little stuff
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Re: Solar Power System

Postby lrrowe » Sun May 31, 2015 9:56 am

I want to try and answer this only to test my knowledge. I am learning about this stuff and can test my answer against what the experts here say.
My small 4.3 CF refrigerator uses .7 amps. So for a 24 hour day, not considering start up compressor demands, that would be 16.8 amp hours.
This battery is rated for 155 AH. If you only consider 1/2 of the battery power to be usable (so not to run it all the way down), that gives you 77.5 AH of available power.

So to me, if no other demands are made on the battery and charge it daily, you should be ok. So lets see how I did with my answer.

But the AC is another story. This battery will not be enough for a variety of reasons I will leave for others to answer.
Bob

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Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: Solar Power System

Postby MtnDon » Sun May 31, 2015 10:32 am

The battery info sheet from Deka.

Bob is correct regarding the 50% maximum discharge rule.

So, yes it all depends on the current draw of any device you wish to use. But if that fridge is one that operates on 120 volts AC there are also the inverter losses. If the inverter is left on all the time so the fridge can cycle on and off according to the thermostat there are substantial idle losses with most cheap inverters; as much as 15 - 20 watts with some. That is one reason we went with a fridge designed to work directly on 12 or 24 VDC. No inverter, no inverter losses.

Speaking of fridges and inverters... motors run most efficiently, run cooler and quieter on pure sine wave AC power. Cheap inverters are not PSW, they are modified sine wave, MSW. A fridge running on a MSW inverter will use more battery power.

Further note: the more accurate method of determining power use would be to actually measure it using something like a Kill-A-Watt meter for 120 VAC or something like a Watts Up for DC power. (there are many variations of the DC meters available with a Google search) That eliminates guessing how many hours a day the fridge runs when just multiplying the rated amps x time.

If you have solar input that will help make the battery last longer. Of course that is only true if the panel(s) are in the sun.

A small air conditioner will not run long off a single battery.

Oh, one last thing... some small fridges use thermoelectrics, not compressors. Do not consider a thermoelectric as they are power hogs and do not cool as well as a compressor type.
Our 6x12 deep vee nose cargo trailer camper conversion... viewtopic.php?f=42&t=58336

We have a small off grid cabin we built ourselves in the NM mountains; small PV solar system; 624 watts PV, Outback CC & inverter/charger ... http://countryplans.com/smf/index.php?topic=2335.0
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Re: Solar Power System

Postby Gunman9 » Sun May 31, 2015 10:34 am

Yes I have a 100w solar panel
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Re: Solar Power System

Postby lrrowe » Mon Jun 01, 2015 5:51 pm

MtnDon,
Help,me with understanding this one. Using the Watts-a-meter as you mention, for the 4.3 Whirlpool refrig that I just bought shows 25 Kwh for 25 hours of run time. Now the unit is in my garage with no contents.
Can you translate this to a hypothetical usage with a T105 dual 6 volt battery setup which would have a rating of say 205 AH?

Thanks,
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: Solar Power System

Postby MtnDon » Mon Jun 01, 2015 6:58 pm

Uh.... let's check that power use figure before carrying on with any battery calculations. 25 KwH for a 25 hour run time is way over the top. I think there is something wrong with that figure. For example our 4.3 cu ft 12 VDC fridge consumes less than 500 watt-hours, less than a half of one kilowatt hour in an average day. Some days it may only consume 350 watt hours. And our new home fridge, at 22 cu ft consumes about 1 KwH per day, according to the Energy Star label. I have not bothered to meter its actual use.

Why don't you check that out again?
Our 6x12 deep vee nose cargo trailer camper conversion... viewtopic.php?f=42&t=58336

We have a small off grid cabin we built ourselves in the NM mountains; small PV solar system; 624 watts PV, Outback CC & inverter/charger ... http://countryplans.com/smf/index.php?topic=2335.0
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Re: Solar Power System

Postby lrrowe » Mon Jun 01, 2015 7:24 pm

:oops: :oops:
Embarrasing....
I did just check it again. The Kill-a-Watt meter's Kwh button is a dual use one. One push for the clock and one push for the KWh. I reported the clock time.
Just now it reads 27.27 hours and .64 kwh.
Is this better (no wonder my stab at the calcualation would not work for me)?
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: Solar Power System

Postby MtnDon » Mon Jun 01, 2015 8:04 pm

Okay. 0.64 KwH is much better! 27.27 hours at 0.6 KwH per 24 hours. That works out to 0.563 KwH per 24 hours. Let's be pessimists and call the usage 0.60 KwH per 24 hours, or 600 watt hours.

If you have two genuine Trojan T105's, in series, they are rated at 225 amp-hours. You have a total capacity of 225 AH x 12 volts = 2700 watt-hours. Using a maximum of 50% of that means you have 2700 / 2 = 1350 usable watt hours.

1350 WH divided by that 600 WH = 2.25 days at 24 hours a day. Conservative me, looks at that as 2 days. Not too bad. That is doable as long as there is AC power or a generator available sometime during the later parts of day two. Solar input would help with that.
Our 6x12 deep vee nose cargo trailer camper conversion... viewtopic.php?f=42&t=58336

We have a small off grid cabin we built ourselves in the NM mountains; small PV solar system; 624 watts PV, Outback CC & inverter/charger ... http://countryplans.com/smf/index.php?topic=2335.0
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Re: Solar Power System

Postby MtnDon » Mon Jun 01, 2015 8:40 pm

BUT. If that 120 VAC fridge is running off the batteries, and you are measuring the AC use then the inverter loses have not been taken into account. That could be an easy 10%. Possibly more; that can vary a lot between brands and types.

At the very least watch the battery voltage in use, but try to catch the reading when there is no immediate draw. A good hydrometer like hydrovolt will give accurate specific gravity readings with ease. That can be a better guide to state of charge than just voltage. You can get a feel for the way your system performs with comparing hydrometer to voltage.
Our 6x12 deep vee nose cargo trailer camper conversion... viewtopic.php?f=42&t=58336

We have a small off grid cabin we built ourselves in the NM mountains; small PV solar system; 624 watts PV, Outback CC & inverter/charger ... http://countryplans.com/smf/index.php?topic=2335.0
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Re: Solar Power System

Postby lrrowe » Mon Jun 01, 2015 9:00 pm

Thanks very much MtnDon. That is about what I was anticipating, but I was not sure how to convert the thought into numbers. It gives me a good base to start from and I hope that you, Gunman9, do not believe this was hijacking your thread. It sort of addresses your most recent question regarding a refrigerator.
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: Solar Power System

Postby Gunman9 » Mon Jun 01, 2015 9:01 pm

lrrowe wrote:Thanks very much MtnDon. That is about what I was anticipating, but I was not sure how to convert the thought into numbers. It gives me a good base to start from and I hope that you, Gunman9, do not believe this was hijacking your thread. It sort of addresses your most recent question regarding a refrigerator.


Lol I'm just still drying to get the math down hahaha
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Re: Solar Power System

Postby OverTheTopCargoTrailer » Tue Jul 14, 2015 6:13 am

I just gotta say I really LOVE SOLAR MATH.
Most folks assume if you have a 100 watt panel you will get 100 watts in power. That's dead wrong !! First the panel will mostly only give you up to 80% max. Second you loose about 15-20% with the charge pmw controller , next you loose 20-28% adding that to your flooded or jell battery and finally you loose another 15-20% going back from 12 volt dc to 120 ac with your inverter. AND..... that does not even include you should only drain your flooded battery around 50%. So I really admire the guy who can run EVERYTHING on a 100 watt panel with a 75 ah battery. :lol: :lol:


In my humble opinion, "& real life experience" I don't leave home without 250 in solar going into a 225 ah L16 solar battery. :thumbsup: :thumbsup:
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Solar Power System

Postby Gunman9 » Sun May 15, 2016 8:32 pm

Gunman9 wrote:I'm trying to stay on a "budget with the battery since it won't be used much. Would any of these work?

http://m.samsclub.com/ip/duracell-golf- ... rod3870120


Reviving my old thread... But does this battery need to be vented? I'm trying to find something around this price range that doesn't need vented. Also should I be concerned about leaving a battery in the CTC in the middle of the Virginia summer? Will the heat effect it any such as it leaking etc...
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