Hello all once again! I have been tinkering with another project (of course) which involves charging a 12V 7AH Sealed battery using a 24V 18W solar panel. Sounds simple enough? Use an LM317 set to 13.8V and let it sit..... Well, I have already done this, but the battery takes WAY too long to fully charge. I am hoping to make something much better without spending a small fortune. I would also like to be able to add onto the current capabilities so I can add more solar panels and more batteries in the future. I know there are MPPT controllers which are extremely expensive, and there are other charge controllers on Amazon which are less than $50 which would work for now, but what is the fun of buying someone else's project :p
So...where do I start...? First off, I have basic electronics knowledge, enough to be dangerous. Second, I don't know how to properly charge a battery except connecting a premade charger to it. I understand a little, but I probably need to learn more about it. Reading these "informational" posts about how to charge batteries are not very informational to me since 90% of the information is gibberish to me. I am a hands on learner and will probably learn this better if I just jumping in and started building it. But...before I can start, I have some questions base on my current research. Please keep in mind I am trying to build a very inexpensive
charge controller..... I would prefer to use what parts I have on hand in my electronic collection to keep cost as low as possible. I know it may not be as efficient as a $100+ controller, but if it works for what I need, great!
First Question :
Since I have a 24V solar panel and a single 12V battery, I am sure 24V pulsed or directly connected into the 12V battery is probably not a good idea for battery life. What is the best method of charging an SLA battery? PWM, constant voltage / current, other?
Once question 1 is answered, monitoring battery voltage and maybe even charge current will be needed. I know that an ADC circuit is needed to monitor voltage, but what about current? I have read using a very low resistance resistor can work and so can a [url href="http://www.reuk.co.uk/Make-a-Shunt-Resistor.htm"]DIY
shunt resistor[/url], but once I have the resistor or shunt resistor, what do I do then?
I am sure Mosfets will come into play in my circuit somewhere but the problem is, I don't know much about them nor how to "properly" activate the gate without
a mosfet driver. I have several Mosfets on hand only because i wanted to tinker with them and learn how to not blow them up in a circuit. Is activating a Mosfet the same as a standard transistor?
That's all I can think of right now. I am sure there will be plenty more questions!
EDIT * The reason this is in the Prop forum is because I plan on using the Prop to control the entire controller.