What can I expect

jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
I just purchased a 500w solar panel kit for my rv. I have two 600ah 12v batteries that will be connected. I have determined that my average use will be 250w if the power is available. If the average charge is 400w for 5 hrs, how long can I expect to be able to continue with 250w during evening hours.

Or, another way to put it is - how long will the 2 600amp/hr batteries last with a 250w drain after solar charging is no longer available?
Thanks :-)

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,919 admin
    OK--Will give it a shot... But I have some questions too:
    • (roughly) where will the RV be located?
    • 5 hours of sun per day is a goodly amount of sun (non-winter, sunny area usage).
    • what season(s) will the RV be used?
    • what tilt will the solar panels be at (flat, tilted, summer/winter tilt)?
    • do you really have 2x 12 volt @ 600 AH batteries? That is a large/heavy battery bank of (roughly) 2x 500 lb batteries
    • do you have details about the solar panesl (Vmp and Imp)? And what brand/model of solar charge controller?
    • do you have genset backup charging?
    In general, I would suggest that you discharge a lead acid flooded cell battery bank by no more than ~50% state of charge (for longer battery life. A 250 Watt AC load load running from the battery bank to 50% state of charge:
    • 2x 600 AH batteries * 12 volts * 0.50 max discharge * 0.85 AC inverter eff * 1/250 Watt AC load = 24.5 hours (roughly)
    A 500 Watt, properly configured, solar power system on 5 hours of sun with 250 Watt load will run:
    • 500 Watt array * 0.52 solar system AC efficiency * 5 hours of sun * 1/250 Watt AC load = 5.2 hours of power per 5 hour sun day
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Raj174Raj174 Solar Expert Posts: 795 ✭✭✭✭
    Hi jw,

    Whoa, I had to google those 600ah 12v batteries to believe they exist. Sure enough, they do, at a whopping 2500 dollars apiece. Well if that is the case, 2 of these in parallel would be 1200 amp hour bank at 12 volts or 14.4 kWH.
    250 watts continuous draw would give you 30 hours to 50% state of charge, and of course about 15 hours to 75% SOC.
    A 60 amp MPPT charge controller and about 1000 watts of PV panels would be needed to charge the batteries. I would highly recommend going with a 24 volt system if possible to avoid the extremely high amperage levels of this setup. This would allow for a smaller charge controller also.

    Hope this was helpful,

    Rick   
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
  • BB.BB. Super Moderators, Administrators Posts: 31,919 admin
    Just to give you an idea of "hours of sun" per day (you can mount flat, tilted, vertical--such as for solar hot water in winter):

    http://solarelectricityhandbook.com/solar-irradiance.html

    Boise
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 47° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    3.21
     
    4.15
     
    5.28
     
    5.72
     
    5.92
     
    6.26
     
    Jul Aug Sep Oct Nov Dec
    6.56
     
    6.51
     
    6.14
     
    5.28
     
    3.49
     
    2.96
     
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
    edited May 2016 #5
    WOW thanks for all the help!
    First - let's be clear... I know nothing about solar other than what I have read the last week.
    I saw several people using 5hrs a day as a "realistic" value, maybe I am wrong.
    For now, I am stuck with a 12v system. I may have to replace the refrigerator and
    it might be possible to switch to 24v later.

    Humm. I have made a mistake some how.
    The batteries I just purchased are new 2x normal car batteries - I thought they said 600ah on them???
    They probably weigh 20-30lb each.

    The panel kit I bought is...
    http://www.ebay.com/itm/500W-Off-Grid-Complete-Kit-5-100W-PV-Solar-Panel-for-12V-Home-Solar-System-dd-/381133466767

    For altitude tilt I used http://aa.usno.navy.mil/data/docs/AltAz.php (location Boise, Idaho)
    It looks like 50deg (or the 47 mentioned) would be best all around.
    I will start with my own tilt support, when I get time I will make my own computer controlled sun tracker.(I use to be a aerospace engineer, )

    I have a 3000w inverter for using my computer and the microwave on the way too...
    http://www.sears.com/imax-power-inverter-power-inverter-3000-watt-12v/p-SPM13467712324#

    The RV hot water heater is broken so I will convert it to my own solar heater design.
    I have not researched designs, but I was thinking of finding or making a 10gal aluminum tank, or possibly
    convert a 10gal propane tank by coating the interior.

    A little bit of my background might help.
    I am having to sue Social Security for disability and they are trying to starve me out - I am pretty much homeless.
    I sold everything I had and purchased a motor home. Since I do not have any income I am scrambling to live off-grid.
    I have been told the legal process averages 3 years and I have 2 years to go.








  • BB.BB. Super Moderators, Administrators Posts: 31,919 admin
    edited May 2016 #6
    600 amp rated starting current.

    Car batteries are the wrong choice. And depending on the size, each is probably 40-85 amp hours or so. Car batteries do not like being discharge deeply (more than 15% discharge is design) very much.

    If you have time, skim through this thread and follow the links about solar electric systems and batteries.

    http://forum.solar-electric.com/showthread.php?5556-Working-Thread-for-Solar-Beginner-Post-FAQ

    What solar panels/charge controller do you have (link to what you purchased is fine).

    I am not at a computer until this evening, so cannot give more info right now.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
    Yes... I understand the battery issue but time and circumstances are forcing some decisions.
    Thanks for the reality check, I am sure most folks don't understand the lead acid battery
    issue.

    I am starting with heavy duty light truck batteries and when finances allow, I will go to deep cycle.
    If the truck batteries last 2yrs, they will will have gotten me past my immediate homeless crises.
    The equipment is purchased and on it's way - for better or worse.
    You are right, the batteries are 60ah NOT 600 - oops.

    So, if I have done my calcs right.
    bat = [email protected] = 120ah (50% discharge = 60ah)
    w/v = a
    250w / 12v = 21a
    60ah/21a = ~3hrs

    I have a watt meter on my computer and it shows 250w. My laptop is 65w.
    This means I can only use my desk computer during peak hours and will have to
    switch to my laptop after 4-5pm :-(

  • PhotowhitPhotowhit Solar Expert Posts: 5,623 ✭✭✭✭✭

    First you came to the right place, we understand the battery issues.

    Second stop buying things! I'd suggest laying out what you want to power all your loads and let us describe a system that will get you there. You might tell us what you can live with out for a while, I've got a fridge at work I can use for a while.

    First see if you can return the batteries, sometimes chain stores will accept returns on these. Starting batteries are Lead Calcium and the Wrong battery for deep cycle use, Even "Marine" batteries often used for trolling motors usually last less a year or less in deep cycle daily use. You should be looking for "Golf Cart" type batteries. They are designed to be drawn down and recycled daily. 2 - 6 volt batteries can be had through Costco or Sam's Club for about $200. That will give you about 200 amp hours of capacity. We try to stay in the top 20% of that and use 50% as the maximum we would want to draw them down.

    The panels you purchased look like an okay deal, though I would have preferred you buy some UL rated panels, these might be but they don't state that. The 'Kit' has you connecting all 5 panels in parallel with out any fusing. I, personally, don't have a huge problem with that, it is against code for home use and there is potential for a problem to back feed the other panels and cause issues. People worry about fires, but there's not much to burn. The brackets might help you mount them to a wood frame off the camper or directly on the camper, though you have already stated a desire to mount at a proper angle for maximum annual collection. They offer a single extension wire, they talk about every thing but gauge in these (and the 'Y' connectors) I would want at least 10 gauge.

    The inverter is a MSW, and very large for your system, You would want 4/0 wiring and have it close to your batteries to run it near capacity. MSW may not work with you microwave, or may just shorten it's life. I lived with a MSW inverter for  quite a while, Most things work okay, but things with motors run less efficiently. Things like Microwaves, fridges, fans. Some electronics don't like a MSW (Modified Sine Wave) some wall adapters, TV's, computers (though most laptops should be okay)

    I'd suggest telling us what you need, can get by with and your goals and let the knowledgeable people here try to help you.

    So realistic loads, list devices and we're sure to ask you to try them out with a Kill-A-Watt meter if possible to get an actual load in use.


    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • PhotowhitPhotowhit Solar Expert Posts: 5,623 ✭✭✭✭✭

    Forgot to say that the pwm charge controller is of an unknown variety, though they are pretty simple. I would want to check voltages and if possible current, and be there for a day or 2 before letting it run when you aren't there. Might feel if it's getting too hot during the day as well. Looks like a fixed system since you are angling your panels, so You might setup the system away from the camper and pipe the AC current to the camper.

    Also check outthis thread, where a lady is trying to do the same thing;

    http://forum.solar-electric.com/discussion/350743/small-effective-off-grid-rv-system-for-1-full-timer-experience-with-off-grid-living#latest

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
    edited May 2016 #10
    Thanks for the concern and advice.
    I have to start living in the RV in two days so I did not have the luxury of doing much research or shopping. It is what it is. I will have a little more money to spend in about 4mo. (I hate doing things twice, but life does not always cooperate!)

    I understand the battery issue - I had $1000 dollars and have to go with what I knew and could do on that budget. Over the next year I will be able to bargain hunt and upgrade and watch craig's list; but that is not an option at this time. I got the $1000 3 days ago. I'm down to $50 and still need a tire!

    The inverter says it's pure sine wave and that was a major consideration because computer switching power supply's do not like MSW. I got the 3000w because cheap inverters (and power supplies) will not run even close to their advertised rating. I am hoping I can heat a cup of coffee and not have to shut my computer off. The two of them will be about 1000w and then add a small light or fan and I am pretty close to 50% of rated capacity which is about all your going to get out of cheap equipment..

    It looks to me like I will end up needing 200amps if I want to use a refrigerator and maintain my life style in the winter - but that's down the road.
  • PhotowhitPhotowhit Solar Expert Posts: 5,623 ✭✭✭✭✭

    I'm just worried "What you should expect" will be disappointment.  You likely have more than $50 left just to connect things up and make some mounts for the panels. Connecting to the camper might require an adapter, thoughyou could take apart the 30 or 50 amp connector and wore it in, but I would want a heavy 10 or 12 gauge extension cord to take the electric from the inverter to the Camper. I WOULD NOT PUT A $125 "3000 WATT" INVERTER INSIDE MY CAMPER!!!

    So you did your math sorta correct;

    • So, if I have done my calcs right.
      bat = [email protected] = 120ah (50% discharge = 60ah)
      w/v = a
      250w / 12v = 21a
      60ah/21a = ~3hrs

    But you forgot that the inverter is NOT 100 % efficient, also that the battery is rated at a discharge over 20 hours, you would be discharging it at a rate of 5 hrs (after adding the inverter efficiency). The effective capacity of the battery bank will be considerably less at this high a load. I don't know what the effect is on Lead Calcium batteries, but on a deep cycle battery you would loose 20% of the capacity in Ah rating so your 60 Ah would become 48 Ah! I would NOT consider using your desktop system, unless your batteries are full and the sun is shining directly on them.

    Your panels are rated at 100 watts, but this is NOT what you can expect from them. A 100 watt panel during the 2 hours either side of solar noon with a VMP of 18 volts. Will Provide about 4.5 - 5.5 Amps of charging current. So with a fixed array, on sunny days you might be able to replenish the amount you are thinking about drawing the battery down. But what do you do on a cloudy day? Battery will need to be replenished. Do you have a generator? If you leave the battery at 50% of capacity for any length of time it will start to sulfate (die).

    Not trying to scare you, just trying to be realistic.

    I suspect you have other lifestyle needs, some light. LED lights are very efficient. I mostly use an Mp3 player for listening to music, books and even the radio. You could charge it while at work or driving to work. My new version runs 20 hours on full charge (Sandisk clip sport) about the only thing I like about it over the earlier versions. They will work with a pair of unamplified speakers pretty well.

    I don't know your location, but suggest, as I did with the linked thread, that you park in the shade and have your panels, charge controller, batteries and inverter parked in the sun, well, with the panels shading the batteries, inverter, and charge controller. Run an extension cord to you camper. This will keep the camper cooler during the day. I personally like O2cool 10" fans they draw very little electric and will help you feel more comfortable. I know you can't afford to buy anything right now, but keep your eyes open, a camper in the heat can be miserable.

    Something else to remember, is that the inverter will use some electric it's self, even good inverters may use 20 watts in stand by mode, the best can 'sleep'. but they let you know that this will always have a fan running. Something to think about.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
    edited May 2016 #12
    You point out good considerations.

    The inverter is rated at 93% efficient which I thought was impressive and played a substantial part of of my purchase decision. Either the electronics have gotten better or the manufactures are bolder about lying. I think the last inverter I bought 12 years ago was rated at 80%; it was rated at 1500w but could only do 1000w and that was no more than 500w on each of two sockets (it was a disappointment).

    I already swapped out all the bulbs with led. and I think each is is 2-3w, yet good enough to read with. I also bought a new replacement 18ft awning canvas and started replacing it today.

    I had hoped to be able to watch TV but it looks like I will be listening to the radio until I can get the proper batteries. I do have a generator for stormy days but I have to replace the shore power transfer relay - the contacts welded and short circuited last year. The reason I went with solar is because running the generator 3-4hrs a day is $100 per month.

    My plan is to mount the panels on the roof which places them 6ft from the battery box. The panels will provide some shade to the roof and I made a couple brackets that allow me to hang a tarp 18inchs above the roof for shade. There is space for the inverter and anything else next to the wheel well 12 inches from the batteries.

    Why wouldn't you suggest the inverter be in the RV?
  • PhotowhitPhotowhit Solar Expert Posts: 5,623 ✭✭✭✭✭

    I guess that last line is a joke?

    I WOULD NOT PUT A $125 "3000 WATT" INVERTER INSIDE MY CAMPER!!! I did a quick search looks like others are hedging on the "pure sine" statement, calling it a corrected wave or some such. You might do a search. The manual at Amazon doesn't state the cabling size. Those cable that come with it should likely be thrown away. Though a 3000 watt inverter that weighs 7 lbs might well be very fuzzy on the correct size. I have the light weight version of pure sine inverters and my 1800 watt weights @20lbs. I often recommend a cheaper version of Xantrex 1800 watt inverter and it weights @12 lbs.

    For some reason I can't open PDF files one my computer right now, likely uninstalling a trial pdf writer. As I recall with my faulty memory, The 1800 watt 12 volt Prosine recommends 4/0 cable between the battery and the inverter up to 3 or 5 feet, then the cabling gets bigger. 4/0 is likely the thickness of your thumb.

    ...and no unless you are traveling, I would park the camper in the shade and put the array/panels in the sun and run AC to the camper. Campers are hot by nature, keep them as cool as possible. This advice might change if you are in the UP or Wisconsin some where. but in general, once you have heat gain, you won't have a way to cool down the camper. so keep it cool. I've actually done this in Mid Missouri. I was building an 'A' frame, and took a job 70 miles away, so purchased a lot and put a small camper on it to stay 4 nights a week. My camper was sufferable. Missouri has coolish nights during most of the summer. My small system ran a fan, tv, and VCR radio laptop.

    After I was robbed badly at the 'A' frame, I purchased a camper for $50 and rebuilt it. I don't know who got the better end of the deal. 16 feet of floor, and wall, and 20 feet of roof. I lived in that for a couple years, until I decided I was too fat and old and wanted AC. I understood what it takes to cool using solar and built specifically to me needs, built in the shade, 6" walls, 8-10" roof and floor. I put my array in the sun and ran AC to the cabin and air conditioned with a small system.

    Pictured are my cabin in the shade with air conditioner and the second picture is the electrical center and battery box with some of the cedar tree that shaded my cabin, which is in the first photo with hanging baskets. It was a neat trick, running an air conditioner on 4 golf cart batteries. but the idea of parking in the shade is even more critical if you have no way of cooling your place down...


    bb.jpg 74.9K
    it.jpg 108.9K
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
    edited May 2016 #14
    Your place looks nice.
    In a year I will start looking for cheap property I can build a 700-800sqft home. I have looked at some land adds already but the only cheap land I have found is in Arizona, Texas, or Florida. I would like to find 2-5 acres for $5-10k and water less than 100ft down.
    How many watts are your solar panels and how many amps is the battery storage... what did you pay for the batteries?
  • PhotowhitPhotowhit Solar Expert Posts: 5,623 ✭✭✭✭✭

    Sounds like you're retired?

    The Ozark region has reasonable land, wish I had purchased 20 years ago, when you could find tracts at $200-400 an acre. Still can find some in the $1000-1500 an acre. You would want 3+ acres here, or there are extra hardship for waste water.

    My current system is in my footer, I purchased a 2000 - 16x60 mobile home, setup on 3 acres that a guy had to sell quick so he could purchase a home with his fiancé. $12,000, the pay off of the mobile home. I had recently purchased a "800 Ah" 24 volt, forklift battery so I set up a 4000 watt array, and later got a great deal on another 2700 watts of panels ($900), which I hope to setup.

    I found out through the forum that the manufacturer of my battery over rates their batteries in the 20 hour rate, so I really have about a 660Ah battery. It's 5 years old and I paid $2550 delivered, 5 years ago it may last 15 years. So I'm 'over paneled' now. I heat with wood, don't have a generator so must manage my power wisely, over paneled helps, and I may yet add the 2700 watts. I have also picked up 4 - 250 watt panels ($400), which will go onto the current array and max out my 2 charge controllers.

    Since I have looked for land, the Cheap Land that is barren does not appeal to me, you might find some in Texas and other states in the south west, even Colorado. I lived in Florida, high taxes, restrictions would keep me from buying there. though there are a few places that might be okay. The Dead Lake area is quiet, and there are areas around Niceville, and Ponce Deleon have artesian wells. I don't think they allow you to 'spike a well' any more, and due to contaminants they want you to go down 100 feet or so, use to be and may still be that you can spike a well, drive a pipe into the ground for a well, water table is less than 10 feet down in some areas, so you could use a hand pump. But Florida is hot and humid.

    Arkansas, Missouri and Oklahoma have the best balance for me of cheap arable land, low population density, minimal restrictions.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 31,919 admin
    edited May 2016 #16
    In my earlier post, I forgot the link (sorry). Here it is:

    http://forum.solar-electric.com/showthread.php?5556-Working-Thread-for-Solar-Beginner-Post-FAQ

    Ignoring the A/C usage at the moment... A basic system would be:
    • 500 Watt array * 0.77 panel+controller deratings * 0.10 rate of charge * 1/14.5 volts charging = 385 AH @ 12 volt "nominal" battery bank
    • 500 Watt array * 0.77 panel+controller deratings * 0.13 rate of charge * 1/14.5 volts charging = 296 AH @ 12 volt "minimum" battery bank
    Battery wise, 6 volt @ ~200 AH "golf cart" batteries (around $90 each) in series (for 12 volts), and 1-3 parallel strings would be a good start for small/cost effective system.

    5% rate of charge is OK for a seasonal/weekend usage system. 10% to 13% rate of charge would be much better for a full time off grid living condition.

    So--With the array you have, roughly 2x 6 volt batteries in series * 2 parallel strings would be a ~12 volts @ 400 AH battery bank.

    Inverter wise, the maximum size "reasonably useful" AC inverter would be ~1,000 Watts... And for your usage, "efficient" DC lighting + radio + other stuff can work OK... However, I would suggest a smallish 12 VDC AC inverter like this one from MorningStar--It includes "search mode" and a remote on/off connection--Much easier to keep your power usage low to preserve your battery life and "live" within the available power from your solar array.

    Nominal usage, assuming fixed array in Boise:
    http://solarelectricityhandbook.com/solar-irradiance.html

    Boise
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 47° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    3.21
     
    4.15
     
    5.28
     
    5.72
     
    5.92
     
    6.26
     
    Jul Aug Sep Oct Nov Dec
    6.56
     
    6.51
     
    6.14
     
    5.28
     
    3.49
     
    2.96
     
    You will get a minimum of 4.15 hours of sun for 9 months a year, the minimum "average" useful AC energy per day would be:
    • 500 Watts * 0.52 off grid AC eff * 4.15 hours of sun per day = 1,079 Watt*Hours per day
    And if you assume 2 days of storage and 50% maximum discharge (longer battery life) and 5 hours of usage "per night" and/or day of bad weather from a fully charged battery bank:
    • 12 volts * 400 AH battery bank (4x golf cart batteries) * 0.85 AC inverter eff * 1/2 days storage * 0.50 max discharge = 1,020 Watt*Hours per day average recommended usage
    • 1,020 WH / 5 hours per day = 204 Watt @ 120 VAC "average supported load"
    During summer, you will have more power (get an efficient/small DC fan to move air for now--some folks here can give you links to good options, or find a surplus computer fan). And during winter, you will either have to cut back on power usage during poor weather/and or use a small genset + AC battery charger to get through the dark days.

    A 1,000 WH per day system should be enough to power your daily needs... However, you will need to be very energy efficient... No desktop computer, just an efficient laptop (250 Watts vs 30-60 Watts). LED lighting--120 VAC LED lighting is not bad... Many times, the AC bulbs are cheaper and much easier to put your solar power system in the sun and a relatively small AWG extension cord to your living quarters in the shade (sending 12 VDC anything more than a few 10's of feet can be very expensive because of high current and voltage drop). Use a 12 volt RV water pump (if needed)--Will not use much power.

    At some point, you may want to add some panels, and a new charge controller (many inexpensive ones don't seem to last very long).

    For now, using propane Fridge + Cooking + Heating (and/or wood other alternative fuels if available) for the rest of your power needs.

    The next step will be a closer to 3,300 Watt*Hour per day system to support refrigerator+(possible) A/C and clothes washer (like photowhit's 1,600 Watt solar array system).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jwzumwaltjwzumwalt Registered Users Posts: 10 ✭✭
    edited May 2016 #17
    Thanks Photowhit and BB,
    This helps me plan. I will run my current equipment until it dies and replace with better stuff. It looks like the first thing to plan for are golf cart batteries. It will be interesting to see how long these new car batteries last.
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    The cranking amps you see on car batteries is pretty much useless for powering a continuous load. Cranking amps just means that's how many amps you can get for 30 seconds with out the battery dropping below 7.2 volts. A 600ah 12 battery would weigh some where around 400 to 500 pounds.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • CountyMountyCountyMounty Registered Users Posts: 6 ✭✭
    Is it too late to return the batteries, exchange for something different.  I'm not sure where you purchased them if at a local auto parts store or ?    Like you I am brand new to the solar world and I'm trying to set up a system for my father at camp.   Also like you I was in a hurry (because he needs to use a CPAP machine at night and was bummed about not being at camp), so I started buying before researching.  After reading on here I returned the two deep cycle 12v batteries I had bought and got 2 6v deep cycle batteries to start with.   I was able to find them quite reasonably priced at a national chain auto parts store (dont think I can post that here) using their discount codes and actually ended up spending less.  If you have the space available for the 2 6v golf cart batteries and can return the 12v's that may be a better option to start with.  
  • BB.BB. Super Moderators, Administrators Posts: 31,919 admin
    CountyMounty (and everyone else),

    You are more than welcome to post details of purchases (and links) to move conversations forward.

    What I try to avoid is turning the forum into a constant stream of "there 50% off sale this week on xyz" stuff.

    Our host, Northern Arizona Wind and Sun, has been very kind to offer this forum free of charge (and ads) for the solar community. And has always been supportive of open and complete discussions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Sign In or Register to comment.