G+_Rud Dog Posted September 3, 2017 Share Posted September 3, 2017 What solar panel would I need to charge a 12V Battery with 5Ah rating? Link to comment Share on other sites More sharing options...
G+_Akira Yamanita Posted September 3, 2017 Share Posted September 3, 2017 I'm certainly no expert, but I think that someone who could help would need to know the use case and the environment. Trickle charging for maintenance in the tropics will be different than wanting to recharge the battery in a day in the arctic. Link to comment Share on other sites More sharing options...
G+_Ben Reese Posted September 3, 2017 Share Posted September 3, 2017 I'm not an expert either, but I play one on the Internet. So here's my made-up expert advice ? You have a few things to determine: How long do you have good sunlight exposure or how quickly do you want to charge the battery? How much additional load will be on the circuit besides just charging the battery? How much amperage can the battery safely charge at? If your battery can safely charge at 2A, it will theoretically take 2 hours to charge from 25% (if my math is correct). If also has a 6W load on it while charging, your charger will need to supply at least 2.5A. From what I'm reading, you'll typically only get half of the rated amperage from your solar panels, so that would be a panel capable of providing 5A (plus overhead for the charge circuit). A quick search on Amazon and found this: _https://www.amazon.com/dp/B017OMTAV6/_ It claims to provide 5.7A at 17+V, so should be able to fit that made up scenario. If you have a bit more time in good sunlight (5-8 hours?) or only need to charge from 50%, something like this 20W panel may be enough. https://www.amazon.com/dp/B00PFGP0EA/ I hope this helps. Sometimes "it depends" is the only right answer. Link to comment Share on other sites More sharing options...
G+_Rud Dog Posted September 3, 2017 Author Share Posted September 3, 2017 Ben Reese Akira Yamanita the load, in this case, will be light, NPI'd. The setup is for an outdoor sprinkler controller with plans of expanding it to more than the original design which is 3 solenoid valves and one Spark Core. The solenoids will be active for about 15minutes 2 to 3 times a week. Depending on the weather the time the solenoids are held open is dependent on the weather. The solenoid current can be reduced if I can find latching relays in the same small form factor as the current relays. In this case, I am leaning towards the combo pack of one panel and one controller. The final addition will be either rotate or tilt mechanism to improve sun harvesting, this might require a bit more power but it will be once a day. Not planning on tracking the sun. Thanks guys. Link to comment Share on other sites More sharing options...
G+_Rud Dog Posted September 3, 2017 Author Share Posted September 3, 2017 Well felt my search was over but of course the wrench has made contact with the wheels. Probably my own damn fault for reading the reviews on Amazon. I do a lot of shopping on Amazon and enjoy finding out what others think of products, pros and cons. But it has stopped me in my tracks will have to make a decision based on how many stars out of five were given. Or how many out of 10 liked and had no problems with the product. What I find interesting is the cons make a solid point. Guess I will sit here and stare at the screen getting nothing done. Link to comment Share on other sites More sharing options...
G+_Dan Hockey Posted September 3, 2017 Share Posted September 3, 2017 I have 2 of these.... https://www.amazon.com/MOHOO-Controller-Intelligent-Regulator-Protection/dp/B0191QN7OO/ref=sr_1_60?ie=UTF8&qid=1504456088&sr=8-60&keywords=mppt+charge+controller and 2 of these https://www.amazon.com/Docooler-Battery-Regulator-Charge-Controller/dp/B01HCL7LEW/ref=sr_1_9?ie=UTF8&qid=1504456038&sr=8-9&keywords=mppt+charge+controller The MPT-7210A is programable 15-72 volts and up to 10 amps. The down side with this one is you cannot charge a 12v battery with it. The Mohoo is 12 or 24v. You have to hook it up to a battery first before the solar panels. The battery voltage is what sets it mode, so make sure your battery is charged before hooking it up. One of those things I learned the hard way, is don't waste your money on cheep non-MPPT charge controllers. I've lost track of how many i've burned up. Are far as solar panels go I would suggest getting the largest you can afford. Because before you know it you'll end adding more loads than your system can handle. Link to comment Share on other sites More sharing options...
G+_Rud Dog Posted September 4, 2017 Author Share Posted September 4, 2017 Dan Hockey Thank you for the links and information. Was wondering how long have the units been in operation under working conditions? Link to comment Share on other sites More sharing options...
G+_Dan Hockey Posted September 4, 2017 Share Posted September 4, 2017 I got those about 2 months ago. One Mohoo has been running 24/7 since I got it. It's hooked up to 3 64 watt panels charging a 50ah starting/deep cycle battery. It runs a 100 watt inverter with 5 watt led controller by a photo cell. It's sort of an outdoor night light. I have one of the MTP-7210A setup to charge an 8 cell 60ah LifeP04 battery pack I made for my franken mower. I can use the 192 watt setup to charge it from solar when I'm not in a hurry to mow again. Link to comment Share on other sites More sharing options...
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