Sizing 12v System [was: I can't find the thread or post I need....]

[Rugster]

And what usually happens when I am searching for something on a forum or the internet is that there are so many posts or threads, I get lost looking for the information I need

Here's the issue: I have decided to go with the 200 watt kit from Renogy for my Cabin. I do have a 110 plug I can use, so the AC and dorm fridge will use that. But, I was looking for the post or thread where it was explained what exactly Amp hours are and how they related to the solar kit and if I remember correctly it also explained how many hours of use you could get from a full charge based on what items you are using.

I'm looking to run a few led lights (led lightbulbs), a flat screen tv and a fan or two. And charge various tablets and a lap top. Would that be too much?

Thanks for any and all assistance.

 

[GotSmart]

Off the top of my head,  can only come up with this.

http://www.wholesalesolar.com/solar-information/how-to-save-energy/power-table

 

[Rugster]

Thanks! That is helpful and it is bookmarked so I can read more of the articles. I am pretty sure the info I was looking for was here on CRVL but that was good info as well.

It may have been a blog post, I'll go dig through there as well. If I remember correctly, it described how the watts from the solar panels translated into amp hours and then had a list of what certain van dwelling items took to run per hour.

Thanks again, tat site will be very helpful.

 

[GotSmart]

Thanks! That is helpful and it is bookmarked so I can read more of the articles. I am pretty sure the info I was looking for was here on CRVL but that was good info as well.

It may have been a blog post, I'll go dig through there as well. If I remember correctly, it described how the watts from the solar panels translated into amp hours and then had a list of what certain van dwelling items took to run per hour.

Thanks again, tat site will be very helpful.

I was on my way out so that was pulled from my bookmarks.  I remember that post.  From Sternwake I believe...

 

[SternWake]

I was on my way out so that was pulled from my bookmarks.  I remember that post.  From Sternwake I believe...

I remember  that thread but do not remember its title, I think AKrvbob posted the chart on what was expected from so much solar wattage and a consumption list of devices.

Since solar harvest will vary so widely depending on location/latitude/weather, and devices can draw different amounts brand to brand, and size of device, I'd feel uncomfortable trusting any such chart.

If you are getting 200 watts of solar, I'd not go for more than 232 AH of battery capacity.

232ah is the capacity of 2 gc-2 6 volt golf cart batteries.  This would not be enough solar for 50% discharges nightly, 200 watts is not going to return 115AH+10% more for losses+whatever the fridge and other draws consumes during sunup.

How much your dorm fridge actually consumes will make or break your system, but excessive laptop usage can also consume a lot of battery power.

Not only is a higher solar wattage/ capacity ratio needed just to return what is used overnight, but important that the max charge rate at noon can at least approach 5 amps per 100AH of capacity, but 10% would be way better.

It really depends on the depth of discharge.  the deeper one draws their batteries, the more important the charge rate becomes to overall battery health and longevity.


I have 200 watts on 90AH of  finicky AGM battery, and 50 or 100 more watts would be awesome.
I make regular use of alternator and plug in charging source to keep it as happy as can be with regular 50% discharges, this AGM can accept very high charge rates with ease, and it requires them every so many cycles when deeply discharged.

Flooded GC-2 batteries are much more tolerant of less than ideal recharging.

The Kill a watt p3 meter, used  on your dorm fridge in actual use, for a period of time(24 hours) will be enlightening.  it will give a KWH figure/  Divide this KWH figure by 12.2 for Amp hours, than add 20% more for inverter inefficiency.

http://www.amazon.com/P3-P4400-Elec...&sr=8-1&keywords=p3+international+kill+a+watt

If this number is much more than 55 AH, 200 watts is likely going to be borderline in less than ideal sunlight, and that does not include your other loads

Some dorm fridges are real power hogs, others not so much, but either will consume significantly more than a 12v compressor fridge that was built with efficiency in mind.

The 12v compressor fridge $ stickershock sends many down the path of dormfridge powered by inverter.  But usually this route requires 2x the battery capacity and 2x the recharge capacity(solar) so the savings is just not there once the first pair of batteries are cycled to their premature death.

 

[Suanne]

... Here's the issue: I have decided to go with the 200 watt kit from Renogy for my Cabin. I do have a 110 plug I can use, so the AC and dorm fridge will use that. But, I was looking for the post or thread where it was explained what exactly Amp hours are and how they related to the solar kit and if I remember correctly it also explained how many hours of use you could get from a full charge based on what items you are using...

Hi Rugster,

Could you clarify something?  When you say you have a "110 plug," does that mean that your cabin is on the grid (for your AC and fridge)?  And that you will be using solar to power other items?  Or, does it mean that you'll be converting your solar power to run items via your "110 plug"?

Thanks

 

[Rugster]

Hi Rugster,

Could you clarify something?  When you say you have a "110 plug," does that mean that your cabin is on the grid (for your AC and fridge)?  And that you will be using solar to power other items?  Or, does it mean that you'll be converting your solar power to run items via your "110 plug"?

Thanks

Oh, wow, I was not clear in my writing! Yes, the AC and refrigerator will be running off of shore power.

 

[Rugster]

Ok, trying to get everything completed on my cabin but keep running into problems with people close to me deciding I need something and then it quickly escalates into something complicated and expensive. So, when I am able to show up to work, there's all these new ideas and reasons why I can't continue to work on the cabin.

The big complication now is everyone is convinced I need to have full power run to the cabin. I showed up yesterday and as soon as I walked in the door was told they had a guy coming over who would say what was needed to set everything up....

So, for various reasons, I'm ready to get in the cabin now. ASAP. This is going to complicated things and cause delays, which I don't want for something I am not totally convinced I need.

My question here is: Can someone give me a general idea what I would need to run these items for (and this is a guess, but I assume with kids, times will be extended) 8 hours a day:

4 lights, typical dorm fridge (well, all day for the fridge), 32 inch flatscreen tv, Xbox 360.

I was planning on getting the Renogy 200 kit and ran across the tons of generators on Amazon. I do not know anything about generators but would be able to run one, if needed.

So, would the 200 watt kit and a small generator running fill my needs?

Thanks in advance for helping a newbie with beginner questions.

 

[GotSmart]

HOOO BOY!

What you are facing is not an easy thing.  Solar only works when the sun is shining.  In the winter where you are, You would need a lot of batteries to kind of meet your needs, and a 1,000 watt cabin kit.  $2,300 plus another $1,000 + for batteries.   Sorry for the bad news.  It can be done though.

http://www.renogy-store.com/Cabin-Solar-Kit-s/1903.htm

Remember you have to keep up appearances to keep custody of the kids.  Having been there, that is what is most important.  If the ex gets a bug, you have to prove habitability. 

The fridge, TV, and X Box will need over 20 Amps, so if you can get a 100 Amp service to the cabin, that would be best.  Then you can have AC to help with the humidity!  Pop in a couple outlets, insulate, and move in!

 

[Rugster]

Ok, with a 6500 watt generator, would I be stuck running it full time or would I only be required to run it for a few hours per day to help with the solar?

 

[VJG1977]

To get electric to a home you may need a certificate of occupancy, that could include an inspection of the electric and septic system.  To get electric to a shop or storage building you could still need an electrical inspection.  You might see if you can get a pole service or camper service set.  The service pole would have a meter on pole and a disconnect and outlets.  It would look like what you see at a campground.   A temporary service could be set, if you are close to a power line.  They are usually 60 or 100 amp.  Intended to be used to build a house, I have seen some up for over 5 years.

 

[Rugster]

Right and that's why I'm trying to figure out if there is a way to use a 200 watt solar kit and a 5500 watt generator to run those items for a period each day. I am a complete newbie to solar and generators and it is quite confusing. I'm trying to figure out if the generator and solar kit will work and if so, how long the generator may need to run each day, generally speaking. I am aware no one will be able to give a definite, specific answer but a general idea would be much appreciated.

 

[VJG1977]

A 200 watt solar kit and a 5500 watt generator sounds like a good combination.  run the generator whenever you use a high power draw item, like a micro wave or electric skillet. The generator running for an hour or two each day would bring your  battery bank up to that 80% state of charge and then the solar could finish bringing it up to 100%.

 

[akrvbob]

I'd go with 500 watts of solar and a Honda 2000. It will keep your batteries charged and run any one single item.
Bob

 

[GotSmart]

I'd go with 500 watts of solar and a Honda 2000. It will keep your batteries charged and run any one single item.
Bob

And be a lot less expensive.

How much battery capacity Bob?

 

[akrvbob]

And be a lot less expensive.

How much battery capacity Bob?

4 golf carts and an Iota charger.
Bob

 

[SternWake]

Iota is good as it seeks 14.7v for absorption voltage, close to trojan's 14.8v recommendation.

The key to minimum generator run times is a high amp charger.

trojan recommends 10 to 13% when using a plug in charger, but upto 20% should be OK.

10% on 464Ah of batteries is 46 amps, So get a 50 amp or larger charger.

One other way to minimize generator run times is to have a high amp manual charging source that will seek and then hold absorption voltage the whole time the generator runs.

The Iota will hold 14.7 for 15 minutes then drop to 14.2 which will slow charging to some degree.

Powermax converters offers a adjustable voltage manual charger upto 120 amps.

Progressive dynamics is also offering their converters with a preselected absorption voltage. PD converters are nice as one can choose the voltage the unit will seek and hold. Press the button for boost and it seeks 14.4v and will hold it for 4 hours.

Short generator run times in the morning when most depleted, followed with a high amp charger and then solar to finish off the absorption stage will yield excellent battery life. Run the generator until the solar can maintain the voltage at absorption levels.

I use a meanwell RSP-500-15 adjustable voltage power supply. it will seek and hold any voltage from 13.12 o 19.23v and provide upto 40 amps. The meanwell rsp-750-15 should be good for 60 amps.

I've modified it with a better voltage potentiometer, and more heatsinking and fans:
https://vanlivingforum.com/Thread-My-newest-electrical-toy?page=3

A good high amp charging source to run on the generator is pretty key. Ensuring it will seek a higher absorption voltage when desired is also key. Some will just shrug and seek 13.8v instead, vastly increasing recharge times.

Disregard Grandpa's 'trickle charge every battery every time' mentality. this is only a good option when there is no limits on time to recharge. When the next cycle begins late afternoon, it is healthier for the battery to get closer to 100% at a high rate, tan babying it with a slow easy trickle charge.

Some AGM batteries, like Lifeline, Northstar and Odyssey have no upper limit on charging amperage and actually need huge recharging currents. These AGMS can be very quickly charged to 80%, but that last 20% will still take 3 to 4 hours when held at absorption voltage. it is nice to have a battery that can accept huge recharge currents without protest/damage.

Do note lesser$$ AGMS all say a 30% maximum charge rate, 30 amps per 100Ah of capacity, which is still higher than flooded Trojans 10 to 13% recommended and 'acceptable 20% rate'

But flooded trojans will outcycle most any lead acid battery if you treat them right.

 

[Rugster]

Ok, using Bob's article for me to run these items 8 hours per day:
4 led lights = 4 amp hours (.5 an hour)
energy efficient tv = 32 amp hours (4 per hour)
laptop = 32 amp hours (4 per hour)

would equal 68 amp hours, so to keep from damaging my batteries would need at least 136 amp hours in my batteries. Am I right so far?

So a 200 watt kit with 200 amp hour batteries would run that with good weather conditions , correct? I'm learning but I get completely lost when you guys start talking about anything but the most simple information.

 

[akrvbob]

A big part of the equation is WHEN will you be running things? If mostly at night then it might be enough in the summer, but in the winter I don't think so. I'd want at least 300 watts and prefer 400.
Bob

 

[Fivealive]

The TV laptop and Xbox are redundant. You can get a USB game controller for the laptop for playing games and a USB TV tuner to watch TV with the laptop. You can also by battery powered led lights and buy rechargeable batteries for them. Charge the batteries when the sun is out so you can have light when it's not. Also but a spare battery out two for the laptop. Again when the sun comes out charge everything up. With this strategy you could get by with 100 watts.