Next step for small outdoor lighting system.

Ks Solar · July 2014

Hello all, I am new to the forum. I have been interested and using solar for a few years. I started a business early 2013. Doing sign service in a bucket truck.
I really want to start installing small solar systems. However I have a lot to learn I know.

My current system is maintaining well so far. I want to make sure I can rely on it all year.

Right now. 1-130w panel= 17.4vmpp- 7.49Impp
Sunlight 10-amp pwm controller w lighting controller
1- gp -24 car battery. Maybe 70 ah. I am guessing. I had the battery from my camper so using it for now.

Right now it is running appr. 30 watts of lights in the yard. It started to go into lvd about 4am. I removed 2 incandescent lamps and finished modding
Fixtures for led. It is currently running all lights all night again.

I want to upgrade this system as I can afford. My question is should a deep cycle battery be next and should I go for agm? Right now the battery sets
on a shelf near an entry door in a drafty old garage. I should put it in an enclosure vented. I was thinking a PVC pipe through the wall. Also should I just get
another gp -24 =75ah. Or can I go ahead and get a gp-27 = 100-105 ah. Thinking ahead or will my system never fully charge a bigger battery?

Thanks. Any help would be awesome. I want like to run my lights through the winter . I will be shutting down the lights around my pool in the fall which should drop
10 watts.

Cariboocoot · July 2014

Re: Next step for small outdoor lighting system.

AGM and deep cycle are not alternatives. AGM (Absorbed Glass Mat) is a type of battery construction; deep cycle is a type of battery use. You can have AGM's that are deep cycle or AGM's that are not deep cycle. The alternative to AGM is FLA (Flooded Lead Acid), which also may be either deep cycle or not. Beware the Marine/RV "deep cycle" which is a compromise between a true deep cycle and a standard automotive battery.

For Renewable Energy use you want a deep cycle, whether FLA or AGM.

Your single 130 Watt panel capable of around 7 Amps is not going to fully charge much more than a 100 Amp hour 12 Volt battery.

The Wattage isn't what matters to battery capacity so much as the Watt hours. Running 30 Watts for 1 hour is 30 Watt hours. Ignoring all the loss factors that's about 2.5 Amp hours @ 12 Volts. If you were to try and run that much lighting for 10 hours it would use 10 times the power; 300 Watt hours or 25 Amp hours. For a 100 Amp hour battery that would be 25% Depth Of Discharge. Once you add in the losses a system inevitably has it will probably be closer to 40% DOD. The SunLight controller will turn off the LOAD terminals when battery Voltage falls below a set level. This is why the lights go off at 4:00 AM.

This is why we repeat the litany about figuring out the loads first, sizing a battery to accommodate those loads, and then the PV & controller to recharge the battery.

Ks Solar · July 2014

Re: Next step for small outdoor lighting system.

Thanks for the answer. I may have to look at adding solar before I worry about the battery. I know I need a deep cycle but it may not help with only 7.5 amps available.

Cariboocoot · July 2014

Re: Next step for small outdoor lighting system.

Ks Solar wrote: »

Thanks for the answer. I may have to look at adding solar before I worry about the battery. I know I need a deep cycle but it may not help with only 7.5 amps available.

That depends.
An automotive battery is not meant to be steadily drawn down over a long time and then charged back up. A deep cycle is. With the same Amp hour capacity the deep cycle will last longer in that type of use than the automotive battery will. If you've noticed a change in performance over time it is because the battery is dying (becoming sulphated from extended discharge time), and not necessarily due to the amount of charging it is receiving.

The best way to tell a battery's condition is to measure the Specific Gravity with a hydrometer. This can only be done on non-sealed batteries though.

Ks Solar · July 2014

Re: Next step for small outdoor lighting system.

Picked up a OReilly deep cycle battery. It is a DCM27 90ah It weighs 53 lbs. A little bigger than the gp-24 starting battery I had. $85.00 Hopefully this will hold up better.

Ks Solar · July 2014

Re: Next step for small outdoor lighting system.

A couple pics to go with my thread. Since getting the deep cycle have moved the small battery to a small 40w panel system. Attachment not found.

jcheil · July 2014

Re: Next step for small outdoor lighting system.

Ks Solar wrote: »

Picked up a OReilly deep cycle battery. It is a DCM27 90ah It weighs 53 lbs. A little bigger than the gp-24 starting battery I had. $85.00 Hopefully this will hold up better.

That's still not a real deep-cycle battery. It's better than what you had, but this one is a hybrid battery which provides CCA/MCA to start the engine and extra reserve time (deep cycle part) for running powered devices. Basically if the battery says CCA (Cold Cranking Amps or MCA Marine Cranking Amps) then it is not a TRUE deep cycle. But you Might get a year out of this one using it in your deep-cycle application (maybe).

If you can return it and get a REAL deep-cycle (only) battery you would be better off.

Ks Solar · July 2014

Re: Next step for small outdoor lighting system.

Damn, And here I thought I was getting this stuff

And I checked too. OReilly showed 2) gp-27 marine. One starting and one deep cycle. And the deep cycle has about half the cranking amps and shows a 90 ah rating. I thought with lower cranking amps it should have thicker plates. And it may. I just did a little more reading and the dang starting battery in same physical size weighs 4 lbs. more than the deep cycle. haha idk

My little gp-24 has been in service for almost a year and has not even used much water and only showed its limits when I added more lights so like you said "it is better than what I had"

jcheil · July 2014

Re: Next step for small outdoor lighting system.

Ks Solar wrote: »

Damn, And here I thought I was getting this stuff And I checked too. OReilly showed 2) gp-27 marine. One starting and one deep cycle. And the deep cycle has about half the cranking amps and shows a 90 ah rating. I thought with lower cranking amps it should have thicker plates. And it may.

That is certainly better than the first one. And not the end of the world. Just in your application a TRUE deep cycle would be the optimum choice. It's tough because you have limited panels. Otherwise (2) 6-volt golf cart batteries in series (12v) at $180 total at Sam's Club would likely work perfectly for 5+ years.

Ks Solar · July 2014

Re: Next step for small outdoor lighting system.

That is pretty good . Only seen them for that price a piece.:) I have learned a lot just joining and reading a lot and asking a lot of questions. My little system will have to do for now. Any upgrades now would might as well be a start over. At least my controller has a lot of lighting options so I can cut my" time on" to 8 hrs. a night or less If I need to this winter.

I know from reading here I have really changed my view and understanding of PV. I always thought about totally off-grid being so great when in fact it is the least cost effective setup it seems. I still want a system that will run my fridge and maybe tv and a few lights/fans for a few days but in 20 yrs. have only seen the power out for more than a day once. Still would like to be prepared for major events...Even it took 20 yrs. to pay back. Saving on power and the peace of mind seems worth it to me.

I think next I will get a hydrometer and see if I can use my Turnigy wattmeter or get a "watts up" meter ( I think it is) to get some low budget means to keep track of what I have now.

Thanks for all the help ..

Next step for small outdoor lighting system.

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