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The battery is no longer 7.5 Ah. If you've routinely run it below 12 V, and have not been charging it as PN Junction described, the capacity has been degraded. As he pointed out, if running it just two nights without charging took it all the way down to 11.5 V (almost definitely damaging it in the process), either your load is much higher than the 0.2 A you are thinking, or the battery is in very bad condition. -
Am I understanding this:
Battery is 7.5AH 12V
Light uses .2 amps...so thats 2.4W. If I run for 6 hours, then that is 14.4 WH.
14.4WH is 1.2AH at 12V. And 1.2AH is .16 or 16% discharge?
If I assume a safety factor of 50% for the battery, then that leaves me with a 3.75AH battery, effectively which means I have discharged 32%.
Is that right?Leave a comment:
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That tells me that your load is much larger than you're claiming or the battery was shot to begin with. A voltage of 11.5 would be less than 20% charged. So each night you used over 35WH. Your panel cannot supply that this time of year. Being December and living someplace that has bobcats leads me to believe you have less than 1 hour of solar insolation available.
WWW
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Sure enough, 7.5ah * 12v = 90 watthours. BUT only half of that is usable for a 50% DOD to get any cycle life out of it. So you really have 45 watthours to play with.
This is winter. 6 hours of direct sunlight are not the real solar isolation hours that count . Depending on where you are, it is more like 2 - 4 hours. Solar isolation hours are different than sunrise to sunset.
To make matters worse, to fully charge an agm battery, that means you need at least 6-8 hours of float!! Each cycle! If you dont, the capacity walks down progressively from sulfation of the little bit that never gets charged and hardens.
What you are looking at is at least doubling your battery capacity, and quadrupling your panel power.
And unfortunately your 7.5ah battery is toast now.Leave a comment:
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What? A 7.5AH/20Hr battery is 90 Watt hours. No?
Light is .2A, 12V for 6 hours....thats 14.4 Watt hours ...but thats not what you came up with.
Walk me through this. I need to know exactly how to make the calculation.
I'm lost because I thought a 7.5AH battery can handle .2A light for 37 hours....and that seemed reasonable considering I used the light on this battery two nights in a row WITHOUT a recharge, and that left me at 11.5V (or something really not that much). But apparently, that is not all there is to the equation.
Let's work with a .2 Amps for the light, running 6 hours per night max, 12v SLA 7.5AH/20Hrs battery and the 10W panel. Help me through it. I can't get my head around a fully charged battery dropping less than 1V after TWELVE hours of full light use and the 10W panel not being able to essentially top that off. That may be where my hangup is.Leave a comment:
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This is super easy to figure out. Like 90% of the people who come here, your system is grossly undersized.- You have a 10 watt panel at best generates 20 watt hours a day on a really good day if you are lucky
- You have a battery that can only supply 20 watt hours a day.
- You have a light that takes 100 watt hours per day.
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I can't remember the exact numbers for the light, but when I ran a test for a few nights, the voltage on the battery dropped less than 1V in a 12 hour period. That was from a FULL charge. The light is not currently on 6 hours. Battery is a 7.5AH. I didd run a test with the light to measure the amp draw, but I cannot remember. I THINK i remember it being somewhere in the ballpark of .2A. But I cannot be sure now and I dont have my notes. I tossed all of that once I decided that a single SLA battery was more than enough to handle the task. Not sure if that helps.
The light is a 10W light, but even at 12V, it did not pull the 10W. I measured curent with my multimeter. Moreover, its a light that has multiple colors. The only way it pulled 8W was using the WHITE function. I use RED, and that was pulling .2A I THINK...that kind of makes sense considering 1/3 of the LED are on when using RED.Leave a comment:
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How many watts does the LED flood light pull? How long is it on each day? How many Ah is the battery?Leave a comment:
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Panel not charging my SLA 12V battery
I have a strange setup, but I think it will apply here. I have a 10W solar panel hooked to a solar charge controller. Then I have a small LED flood light hooked up to the battery via a photo sensor. This is actually used to illuminate a wildlife feeder to watch bobcats and coyotes.
Anyway, the solar controller has a shutoff and diagnostic LED and it indicates that my battery is 'low'. Its currently at 11.5V. It wont let the light come on at night. The light doesnt draw much. ITs a 12v SLA battery. The issue is that the panel is 10W and in DIRECT sunlight facing south for at least 6 hours. It should EASILY charge this battery, but for some reason, it is not doing it. I have another charge controller that is also not working for it, so I don't think its the controller. The battery is in good shape and will take and keep a charge if charged with a trickel charger.
Is there something I can check? Its frustrating. I have a tiny 5W that has NO controller that charges the exact same battery for the camera, and its holding a solid 12.7V. So...something isnt right with my big panel.
What can I do to troubleshoot this?
Here is the controller:
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