25W of solar panel question

[ecusolar]

Maybe we should take the time to read the posts with enough attention, I wrote:

That's easy if it's right that all LEDs together have 5W.

You are forgetting the the 50W LED draw, for 10 hours, that's 500Whours.

This is an impossible situation. You cannot draw 500WH out of any battery, and replace with 25W x 5 hr = 120WH recharge.

The most the 8 LED 's can run, nightly, is .8hr. There are losses recharging the battery, so the solution is larger PV panel or less lighting.

I do agree with the least expensive battery, instead of buying a 40ha battery, get the cheapest battery, which might be a 60ah, but beacuse it's a common auto battery, mass production makes it cheap.

[ecusolar]

Thanks, will try not to post again.

I still think that he means that all 8 LED together have 5W and not 50W.

I also understand that the panel is working on 12V, anything else doesn't make sense.

If it's not like that I apologize about the BS

You're talking BS.

[greenHouse]

Thanks, will try not to post again.

I still think that he means that all 8 LED together have 5W and not 50W.

I also understand that the panel is working on 12V, anything else doesn't make sense.

If it's not like that I apologize about the BS

Batteries can't be trickled charged from "dead". There are minimum charging rates to bring a battery back to "full". Additionally, batteries really need to be chosen carefully, you can't just get a car battery and try to make it work. Sure, you can replace the battery every two years, but a proper solar system battery can be made to last 5, 10, 20 or more years. Who wants to replace batteries all the time?

In the OP's case, they've not stated the operating parameters of the solar panel. So all of this is just guessing.

Solar power systems need to be =designed= and not just thrown together. And that even applies to little systems that are just providing power for a few LEDs and a fan. For a 25 watt array on a 12 volt system, the largest practical battery is going to be between 25 and 50 amp-hours. 50 amp hours is really pushing it as the maximum charging rate is going to be about 3% of capacity (25 watts / 15 volts = 1.67 amps, 1.67 amps / 50 amp-hours is about 0.033) So, a 25 amp hour battery is a much better choice.

[lsy388]

i got it now, for stable and safety purpose, i need to put at least 320W of solar panel to support my 320wh led light, am i right? By the way, usually what is the average of recharge time for a watt? Thanks.

[hay4man]

lsy388, I think we need you to clarify whether your LED's and fan will be consuming 5W or 50W.

It would also be nice if you could tell us the specifications for your 25W panel, or give us a part number or something.

[Mike90250]

Who'd 'ave thunk a 25W panel would get a thread this big?

[lsy388]

Hi, may i know 1.8W mono 125*125 cell can charge how many watt per hour in Asia region? Kindly advice, thanks.

[Renewable Ray]

LOL...no kidding Mike. And I read this thread word for word????? Maybe it's a great story, newbie in Malaysia getting help from "engineers" from around the world. The internet is amazing.

[lsy388]

yeah!!! never shy to ask.......

[rmay635703]

I wonder how much a 48v 25 watt trickle charger solar panel combo would be for my mini van or if such a thing exists

[Mike90250]

I wonder how much a 48v 25 watt trickle charger solar panel combo would be for my mini van or if such a thing exists

Does not exist, you would have to string several panels together to make your own.

[lsy388]

Hi, can somebody tell me what actually mean 12V 7AH at lead acid battery reading? How could i know total load at watt for the lead acid battery? Thanks.

[Mike90250]

Volts x Amps = watts Your battery 12v x 7ah = 84watt hours.
of that, half is useable, or you begin to damage your battery.

84 watt hours = 84 watts for 1 hour, or 42 watts for 2 hours

[lsy388]

Thanks body, by the way, i still don't get the reading of (20 hour) at the battery, such as 12V 7AH (20hour). Kindly advice, thanks.

[rmay635703]

Thanks body, by the way, i still don't get the reading of (20 hour) at the battery, such as 12V 7AH (20hour). Kindly advice, thanks.

LoL, first of all a 7AHR battery isn't going to run much more than a flashlight.

2nd Batteries are rated by capacity OVER a specific amount of time. The faster you draw current the LESS capacity you get. Reason being that there is a lot of resistance and "losses" associated with drawing current quickly.

In other words that battery will provide .35amps for 20 hours and then will be permanently damaged and basically unusable after that amp draw.

If you were to draw much more current than .35amps you will not get 7ahr more like 1-4ahr depending on how fast you draw.

So to put it simply you only get the amount of capacity on the label if you draw the current over the rated period of time. Take longer you get more capacity, take less time you get less capacity.

And everything stated by Mike is correct, you can only use 50% of the batteries capacity if you intend on using the battery more than once.

So in reality you can draw .35amps for 10 hours and then recharge on that battery or it will be permanently damaged.

Cheers
Ryan