Battery/Solar

[yakas]

I have recently purchased a marine deep cycle battery and have hooked 3 very old solar arrays to it all in parallel. I have a 700watt inverter connected to that and it's used to power a laptop and some computer speakers and the occasional phone charge. I don't have a charge control or a system monitor. I do have a voltmeter but don't really know how to find out how much power is remaining in the battery. the volts are around 12.37 when nothing is plugged in and drop to around 12.13 when everything is on. I guess i don't really know what I should be asking so if anyone has any input on my system and if there are things I need to know about it please let me know. I don't want it to break, but it was all fairly cheap so I do consider it my test egg.

[Bruce S]

Yakas;

  Just from reading the little you put in. I would say you need to let the system fully charge the battery before connecting the inverter.

Most Lead-acid battery types should be sitting fully charged around the 13Vdc mark while on the panel set.

Since you have a meter. one at a time pull a set off and while the sun is on the panels, measure each panel, unloaded. This will first tell you the panel is working.

Then grab a battery, first measure it's current voltage.

Then with the meter set to current, correctly connect it to the panel and attach that panel to the battery.

The meter will then tell you if it's working "loaded" this will tell you the state of each of the panels.

Unloaded, you sould see a pretty high voltage, my Harbor Freight panels reads between 21 & 22 volts open voltage.

Then if attach the working panels to the battery and let it charge.

You could also come back with those voltages and let us know. This will help us help you further on what to do about charge controllers.

IF you already know the make/model of the panels let us know this too. Will help a bunch.

BTW: This can be a wondeful sickness for which there isn't a cure wanted :-()

Cheers

Bruce S

 

[yakas]

The battery was brand new so I assumed it was fully charged.

This is going to be a stupid question but when you say read the current for each panel and the battery what should I turn the dial on my voltmeter to to get that reading? I did test the panel (volts) individually and there readings were all over the place. Is current and volts the same thing? I have had an electrical engineer explain all of these terms to me because I really want to grasp them, but I was still confused.

Thanks

[jonas302]

The meter can be a tough one to help with they are all different try measuring things you have an idea what it should read

 Here is a ton of reading on batterys

http://www.fieldlines.com/story/2008/4/22/142649/842

your inverter probly has a low voltage cutout to might not want to run that low though

[Bruce S]

Taking current readings on the meter is different from reading volts.

With volts you're reading voltage drop across (i.e.Across the pos and neg sides of the panel's connections) .... current you're reading through (i.e. pos(+) connected first to the neg leg of the panel's connection and then the neg (-)of the meter to the neg side of the battery (or) load. This will tell you the current flowing through the wires.

Becareful though , don't try to measure current while the meter is set to voltage, if it's a cheapo it'll more than likely let go of the magic smoke :-()

On most meters there should be a 3rd port for which to plug in the RED or Pos+ test wire. It will have something like 10dcA marked on it. Plug the pos(+) into it and turn the meter dial or however your's is selected, ( old Flukes had a button for each type of measuring being done, MOST new ones have a dial.

If money is not too tight, go find an outlet store and find a $3.00 unit to learn with , that way if it goes poof you're not out good money.

On the panels, you say the readings were all over the place? what were those readings? could it have been due to cloudy day? were they all above say 12Vdc?

If those panels has a tag on them with model or maker it'll go a long way to telling what they should be working at.

IF not and Harbor Freight ones do not, then testing is about the only way to tell. PLUS on the bright side you get experience in using meters and knowing the health of the panels.

Good luck and let us know.

Bruce S

ALSO : Pics of the panels could help as well, there's a ton of people on here who can tell the model just by looking.

[Bruce S]

jonas302;

 You are correct , those are very good online readings. The battery University is one that helped soldified my knowledge of batteries. AND along with that and the tester they sell (NOT CHEAP!! over 6Gs) helped save our company many more thousands the 1st month just bay being able to tell the good ones from the bad, in one easy test.

Cheers

Bruce S

[yakas]

Thanks for the info. The batteries were at 13.37 volts last night after being hooked up to the panels all day, although the exposure for the panels isn't ideal it still seemed to add to the power of the battery. The panels are made by arco - like the gas station, but i didn't get the model # yet. I will tonight.

[Bruce S]

Good to read the battery is coming up on charge.

Depending on the power output of the panels and the Amp rating of the battery, it could take a while longer to fully charge the battery.

Also, the resting voltage will tell you more. Most of the time when charging , batteries will have a higher "surface" voltage reading, than true "resting" voltage.

This, like car batteries ,is merely the surface charge. You should read the voltage of the battery after it's been disconnected from the panels and let rest for about 1/2 hour.

Since this is a lead-acid based battery Marine batt., is it a sealed battery or can you take the tops off to add water if necessary? If you can add water, then in the long run you should begin to learn how to take SOC readings. Basically this is the State of Charge and gives a much better overall reading of the battery's health.

What are your long term plans for this setup? Learn? short times when no power? camping or long term to begin pulling stuff from Mains?

All of these can make for slightly different paths..

Oh and when purchasing new batteries :-() back when fuel was $0.49 and full service they used to, as normal everyday service do a charge on the batteries, same as they did with car batteries. NOT to day, sorry...

Some places might if you ask, NTL, Batteries Plus, but most others will not , Sam's club usually gives you a funny look when asking.

Cheers ;

Bruce S

[yakas]

Thanks again for your input.

Basically I am living off the grid and have no real need for electricity except to run my laptop and some speaker with the occasional cell phone charge. I have solar landscaping lights set up that are a complete system in themselves, and those I use for lighting my home. No fridge, but am looking for a propane one that's reasonable. I was just flung into this situation but I am completely happy to be using so little and getting by completely fine. I am using this small system to get one creature comfort (music) and mainly just learning from the experience. I intend to add on later but can get by with this little setup. The one other thing down the road would be to get the furnace fan functioning so I can have heat. But I do live in a very comfortable climate so I have several months until it would become nice to have, but still not necessary.

[Bruce S]

Where might you be located? :-)

Couple things to help with getting as much out of everything as possible.

Cell phone, if you haven't already, go find a car type charger, 10 times better for charging directly than the wal wart and inverter.

Same goes for Laptop, unless it's real new, there's car adapters that will charger laptops much better directly connected to 12Vdc source than setup DC/AC inverter then step down AC/DC adapter.

Furnance, go see if it has a startup cap on it and what the hp rating is.

If it's an older unit that uses a pulley, then you can certainly find a 1/10hp DC powered unit to replace OR put an inverter at it for startup. These are easier to startup than a fridge, but barely. IF using a DC motor there could be a problem if your unit has a thermocouple.

If these are truely ARCO panels; then they at one time, were at the top of the heap. Those panels have a pretty good 20 year life span.

Now the Battery: Marine batteries are pretty good for getting your feet with and will last a long time on good loads, however if you can, go find some of the golf cart batteries They're likely 6Vdc and you'll need two. Sam's has them pretty cheap, and the ones a neighbor just got are 220Ahr, so for the price he got a much better deal than expected.

AND they'll give longer creature comforts :-/

Above all else have fun with it!

Bruce S

[wooferhound]

Yes I agree that all of your items should be able to run off of the 12 volts directly using car adapters or direct connection to the battery. I have a system very much like yours and all of my stuff runs directly from the 12 volt battery

http://www.fieldlines.com/story/2008/3/4/6303/63451

Here is a good chart to help you decide how charged your battery is

State of Charge (SOC) Chart:

% of Charge- - - - - - - - Charging- - - - - - - At Rest - - - Discharging

100. - - - - - - - - - - - - - 14.75 - - - - - - - - 12.70 - - - - - - 12.50
     
90. - - - - - - - - - - - - - 13.75 - - - - - - - - 12.58 - - - - - - 12.40
    
80. - - - - - - - - - - - - - 13.45 - - - - - - - - 12.46 - - - - - - 12.30
    
70. - - - - - - - - - - - - - 13.30 - - - - - - - - 12.36 - - - - - - 12.25
    
60. - - - - - - - - - - - - - 13.20 - - - - - - - - 12.28 - - - - - - 12.15
    
50. - - - - - - - - - - - - - 13.10 - - - - - - - - 12.20 - - - - - - 12.00
    
40. - - - - - - - - - - - - - 12.95 - - - - - - - - 12.12 - - - - - - 11.90
    
30. - - - - - - - - - - - - - 12.75 - - - - - - - - 12.02 - - - - - - 11.70
    
20. - - - - - - - - - - - - - 12.55 - - - - - - - - 11.88 - - - - - - 11.50
    
10. - - - - - - - - - - - - - 12.25 - - - - - - - - 11.72 - - - - - - 11.25
    
    

http://solarjohn.blogspot.com/2007/03/measuring-battery-state-of-charge.html

[yakas]

I am in Santa  Barbara county on a north facing hillside, I live in a trailer but I have the view of a lifetime. I didn't have a chance to write down the equipment models but I will try this afternoon. Thanks for that charge chart. That is exactly what I was looking for