SOLAR help 6 volt (20X) NEEDED

Re: SOLAR help 6 volt (20X) NEEDED

i will 3rdly say more info is warranted for any specifics, but beyond that some things can be said about charging in general. most will agree that regular charging on most general lead acid batteries can accept a charge in the 5-13% range based on the ah rating of the battery. that may even go lower or higher depending on the battery type, its manufacturer, and some other factors like loads on during charging. increasing the series voltages will lessen the amount of current you'll need to charge them with as compared to charging all of them seperately.
the maintenance charge should be handled by the pvs and a charge controller you wish to place at the cabin. though i've seen smaller figures on the trickle charge rate, i would allow for at least 1 amp of pv for every 100ah of battery capacity to be trickle charged to be on the safe side or a 1% rate of charge. rates as low as .1% have been know to be used too.
knowing what you wish to power is important because you must plan things out. will you be using an inverter and will it be powering any motors or power tool battery pack chargers or other wall wart chargers? what's the highest all at once power usage you believe you'll be using in watts or ?amps at ?volts? will you be able to run items straight from the dc only or in addition to an inverter? will you be able to keep the power usage from the batteries so as to not deplete them below 50% and will you be able to supply that much charge power as to replenish what you've used in a day?
again these are some generalities and that when specifics are known other questions may crop up. as it is now you must be sure of the battery condition of each of those batteries and if known to be good you must give them a charge sometime soon as batteries do lose some of their charge while sitting each month. this depends on the battery type and manufacturer, but a basic battery may have a typical loss per month of about 7% if memory serves correctly. older used batteries may be worse. other batteries may be rated better as agm style batteries do well on shelf life with as low as 1% per month from some concorde batteries.

Re: SOLAR help 6 volt (20X) NEEDED

It sounds like all you have is a 12v charger. Do 10 parallel strings of two batteries in series. Unless you have a really powerful charger it will take a long time to charge them with a 10 or 20 amp charger.

Before you do anything get a digital voltmeter you trust for accuracy and measure their unloaded voltage. The state of charge is as followed:

6.35 v = 100% specific gravity = 1.277
6.30 v = 90% specific gravity = 1.258
6.25 v = 80% specific gravity = 1.238
6.19 v = 70% specific gravity = 1.217
6.12 v = 60% specific gravity = 1.195

Below 80%, sitting for months, means sulfiding of plates has begun, meaning some capacity will not be recoverable on recharging.

If you don't know the battery Amp-Hr, tell us the size (length, width, and height) and we can give you an estimate of capacity.

Re: SOLAR help 6 volt (20X) NEEDED

here is a listing for Exide CA 9 that seems close, may help

http://www.eps-stl.com/telecom%20ref%20chart.htm

How big will the cabin be? Dock access? How will you get a 12.5 Kw genset off the boat?Electrical amenities planned? How is the amount of solar incidence ( hrs of clear sunlight)?

Assumimg the 160Ah rating is correct, you will need 5% of their capacity to maintain them
while sitting. Assuming you will arrange them in 12 v config. that will be 160Ah * 5%. or 8 amps per 12 v battery arrangement . therefore 10 batteries @ 12 v thus 80 amps of 12 v panels to maintain/ recharge. At about 7 amps per 12 v panel on average you are looking at a 10 or 11 panel array minimum.
hope this helps get the juices flowing.


Eric

PS we are also building in an isolated location and went for rechargable hand tools to start with a small Honda 1000 genset to recharge if needed. Get a 3000w + genset if you plan on using a table saw, chop saw or similar tool. Most will draw 12 amps plus and that is a fair load on a modest solar charging system.... will flatten your batteries quite quickly.on a day of heavy construction.
cheers

ej

Re: SOLAR help 6 volt (20X) NEEDED

maybe not a tree, but a tv tower or telescoping mast may be able to get them up high enough in the clear to get enough sun. it may also help to cut a few of the closest sun blocking trees down. the pvs you get should have a high vmp for the voltage class. for example getting pvs with 17.6v vmp as opposed to 17.2v vmp(volts max power). this minorly helps for some of the smallest shade in some instances, but overall any shade is detrimental. a plus is that winter has no leaves on the trees unless evergreen type and snows could amplify the amount of light with a slight increase in power from the cold temps. do have a good winter tilt angle to accomodate the south facing sun for the wintertime usages as this allows for more efficient collection and allows to let snows slide off easier or melt quicker. do size your wire for the run length and current you will need by using the calculator in the sticky at the top of this section.

Re: SOLAR help 6 volt (20X) NEEDED

though the trees are high i don't believe you'll need to take all of them down, but yes take some down even if only for the safety of you in the cabin as trees that big when they fall or catch fire would pose a danger to you and your property. having said that do realize that pvs hoisted up on a small tower or telescoping mast could possibly be enough to clear the shade of the trees. it is hard to judge your exacting circumstances from a pc. in addition a small wind generator rated for the battery system voltage could also work, but i have reservations on the wind genny only. that's because it is mechanical and many times more likely to fail and murphy says it'll happen in the dead of winter with nobody there. that wind genny may also need to be placed just as high or even higher than the pvs would need.

Re: SOLAR help 6 volt (20X) NEEDED

I agree with Neil, but when I first joined the forum and proudly shouted my 1.6 kw array with a massive 2100 ah 24v battery bank Neil was the first to deflate my ballon although gently about my lack of solar recharge capacity for my bank. around 3% against the reccomended minimum of 5 % Hope thats right This was a new statistic I hadnt encoutered and was a little peeved with my lack of knowledge. Neil Im not knocking you in fact Im applauding you for introducing me to this accepted fact. But I had a generator back up and an expensive XBM monitor which told me very accurately what level of discharge my batteries were at. I never let my batteries gobelow 90 % before I ran the generator and with an input of 100 amps from my SW3024E it would take a minimum of 2 hours to get my batteries back to full from 90% . I now let them go lower pending on the forecast for the following day. But still have never dropped below 80 % charged.

So i was able to look after my batteries on a daily basis. Im soon to increase my array to 2.4 kw in about 3 weeks now which will double my battery bank charging capacity taking my standing loads into account ! This will take me over 5%. but Ill still watch the XBM and switch on the genny accordingly. By next spring summer up to 4 kw.

Because your not going to be ther full time and thus be able to add gen power Neils comments are relavent, but also if your not there your loads are probably zero, so have a large battery bank as you wish that can be maintained with out loads by the correct level of PVs to start with when your not there ! Then burn some hydro carbons for your deficent when you are there. As time goes by with the beauty of PVs scaleabilty you can grow like Im doing and kick the noisey smelly unreliable internal combustion engine in the garbage ! (but with on onstandby in the basement )

Re: SOLAR help 6 volt (20X) NEEDED

No offense intended but I think that you should do a bit more reading up on solar system and thier installations. You run into the trap that many of us have, that is Ready, Fire, Aim!

For a variety of technical reasons most battery banks run in multiples of 12vdc, ie 12,24, or 48 volts. I have never heard of a bank running at a higher DC voltage. There are few devices that can run on 120vdc. By contrast there is lots of equipment for 12vdc multiples, inverters, chargers etc.

As to panels, the are sized based on watts. In short, larger panel, more watts, more net power for use, either load or charge. The number of panels relative to battery size is irrelevant, but what is important is the amp capacity factored in with average insolation.

It will pay you big dividends if you avoid the ready, fire, aim. Understand how stuff works, and the interrelationships between the components. You have a battery bank to start with. Now work in the expected loads, the average insolation and figure out what hardware you need to make it happen.

Icarus

Re: SOLAR help 6 volt (20X) NEEDED

slow down here. before i get into it here pvs are rating in watts (several varieties, but here we'll just deal with stc or standard test conditions), volts max power(vmp), and amps max power(imp). some of these do vary as to their terms like vpm instead of vmp and is basically the same. for simplicity know that watts stc= volts max power x amps max power.

ok on the 160ah (amphours). now looking back i see that your batteries are indeed 6v each and should have 3 water caps. to get 12v you need 2 in series. to get 24v you need 4 in series. the current will stay the same on the seriesed batteries as what just 1 would be rated at until you start putting them in parallel.

now i have no idea what you would run with a 120vdc battery bank.

now back to the kc130s applied to charging a 160ah 12v battery bank. a 1% trickle would be 1.6amps needed. the 3% mark is 4.8amps needed. so that is a maintenance charge for over winter at 1% and a 12v pv will have typical operating voltages at around 17.0-17.6v and are good for charging a 12v battery bank through a charge controller. the 3% is the absolute minimum we recommend to charge without and loads connected to the batteries at the time of charge and this will take conciderably more time to reach full charge. that 3% is 3 times the current capacity as needed by the 1% trickle. keep in mind that this is 2 of your batteries in series. we would now need to parallel more series sets with at total of 10 for 1600ah for a 2x10 battery bank and the 1% is now 16amps and the 3% is now 48amps.

now for regular charging rates this goes between the rates of 5%-13% and possibly more if the manufacturer says you can without harming the batteries lifespan. naturally the higher charge rate will charge the batteries quicker, but too high of a charge rate can fry your batteries of their electrolyte so water levels do need to be watched and maintained more often with adding only distilled water when low. too high can also be more expensive as in more pvs used. now i recommend that once you settle on a battery voltage for your system that you will have to match the pvs to the batteries as we discussed already. there are other losses that do occur and we'll just call them all charge efficiency losses and round that to another 20% capacity needed. other factors do figure in this, but you will need to read up more as I'm giving you quite a bit here as it is.

now the 2x10 battery bank will need at the trickle rate of 16ampsx1.2=19.2amps. 3 kc130 pvs in parallel will yield over 21amps so this will work fine for that rate and being it is a 12v pv configuration charging a 12v battery bank no pvs in series will be needed. if you change the battery voltage higher you will need pvs in series, but half as much capacity needed in parallel. you can't cut 3 in half so 4 other pvs of lesser current at 12v would be in order here.

for the minimal charge rate of 3% rate for 48ampsx1.2=57.6amps and divide that by the 7.39amps of the kc130 means you need 8 of them at that rate. for better charging rates you see how things go upward and i hope you got the trend of what i was doing. i'm sorry for the book, but once in a great while envelopes, i windup doing this as i hope it lets others see too. i also hope this hasn't confused you any as i'm very tired at this point due to health problems at this time. do note that once you have the proper voltage on the pv that you can address the current. some like to do everything in watts, i think it gets more confusing that way.