I put together a little antenna tracker for my FPV hobby and it works great. It is currently powered by a 12V lead acid battery. The actual antenna tracker circuit is connected directly to the battery while the servos for the antenna tracker assembly are powered by a BEC which is connected to the battery as well. The reason for the BEC is that servos require 5V power. I would like to add a jack to the box so that I can charge the battery without having to take it out of the electrical box.
I purchased a Nextion touchscreen from ITEAD Studio and I would like to install it in the box and interface it with an Arduino Duemilanove and use it to monitor battery charge level and to power the unit on/off. I am also interested in the possibility of adding a jack to plug in an external power supply that can be used to charge the battery. This way, I don't have to open the box every time the battery needs to charge.
If someone could provide me with a schematic and a sketch that I can use to accomplish the above, I will be more than happy to pay for it.
Thank you
Lead acid charging is about as dead simple as battery charging gets: give it about 13.8 - 16V and it charges. Monitor with a voltmeter or "idiot light." Cars have been doing this for decades with nothing more than wires.
What do you hope to accomplish with a touchscreen and an Arduino that an off the shelf $5 voltmeter wouldn't provide?
Thank you for your reply.
I understand lead acid battery charging is easy but I would like to get a schematic to implement the circuit into my application.
I suppose that the touchscreen and the Arduino really have not much of a point other than to monitor the charge level and to tutn the device on and off. I am sure I could accomplish this some other way but I would like to have it done this way.
Are you interested in providing the circuit and the sketch?
Let's look at the first part: charging. From your description the battery, BEC and circuit are already connected together, no schematic or circuit change is necessary. You only need to replace the hard wired connection with a power connector so the battery is externally accessible.
Next, be sure what you mean by "charge level." That's a loaded statement. The only true way to measure charge level is to measure energy going into the battery and subtract energy coming out and a constant for residual charge. A similar approach is to measure the battery's internal impedance. Both of those are going to be pretty complex to implement. The actual algorithms are known, but getting everything working nicely is time consuming.
What I suspect you want is battery voltage reading, which really has very little to do with actual charge remaining but is trivial to implement. That, along with on/off control, I can do if you want it. However, bear in mind that a simple toggle switch and a digital voltmeter will cost about $6 to implement. Doing the same thing with a touch screen, etc will require much more and provide no benefit other than "looking cool."
Coloumb counting or battery impedance measurement may be more expensive than you feel is worthwhile.