Help with adding a solar charge controller to my small DIY battery box

[MikeL219]

I built a few battery boxes just for fun and basically as an intro to all this battery and solar stuff. Right now, I am charging them via leads from my bench power supply.

My question is: If I wire in this cheap ebay solar charge controller, can I still charge in this manner?

I assume yes, but I have no idea if the current flowing back through the charge controller and to the battery will do any harm.

Thanks for any insight!

 

[snoobler]

You can have as many independent charging sources running concurrently provided they are programmed properly.

Important that the sum of all charge currents do not exceed the recommended max charge current.

Might consider a comparably priced yet well rated PWM charge controller on Amazon if that's an option for you. I see that Prime box after all...

 

[MikeL219]

You can have as many independent charging sources running concurrently provided they are programmed properly.

Important that the sum of all charge currents do not exceed the recommended max charge current.

Might consider a comparably priced yet well rated PWM charge controller on Amazon if that's an option for you. I see that Prime box after all...

Thanks for the reply! Noted about the max charge current.

That cheap $20 10A Renogy controller does look pretty good!

 

[MikeL219]

As a follow up to this, I received the controller and connected it (properly, I believe). Initially, things were looking good with my Paxcess/Rockman 120W panel, but then things got weird. After a minute or two, voltage at the battery shot up to 20V! Looks like the controller was allowing full voltage through to the battery.

Odd because I thought this controller would regulate the incoming voltage. Was I wrong to assume that?

In any case, the Renogy Wanderer is coming tomorrow!

 

[snoobler]

You thought right. A solar charge controller should never provide significantly higher voltage than the battery. The moment before charging starts, you might see 20V @ the PV terminals, but they will drop to very near battery voltage as soon as current starts flowing.

Sounds like a bad or improperly configured controller.

 

[mccuistion]

I did almost exactly that (but with the Renogy Adventurer); I just added the Renogy to to battery box. Remember to connect the controller to a battery before you connect the controller to solar (so it warns in the Renogy literature).

 

[MikeL219]

I did almost exactly that (but with the Renogy Adventurer); I just added the Renogy to to battery box. Remember to connect the controller to a battery before you connect the controller to solar (so it warns in the Renogy literature).

View attachment 40210

Thanks for the reply! I started over with the connections and, this time, made sure that I connected the charge controller to the battery first. Maybe that was the problem because it's been working fine for the past hour with the panel in full sun. No overvoltage events so that's promising.

Question about your setup, since the controller is connected to the battery, is it then always on? Should I wire another switch so I can only turn it on when I want to charge?

 

[mccuistion]

Thanks for the reply! I started over with the connections and, this time, made sure that I connected the charge controller to the battery first. Maybe that was the problem because it's been working fine for the past hour with the panel in full sun. No overvoltage events so that's promising.

Question about your setup, since the controller is connected to the battery, is it then always on? Should I wire another switch so I can only turn it on when I want to charge?

That amber switch above the Renogy turns it off. I have to remember to turn it on Before I connect the solar panel. But I turn it off otherwise cause it empties my 18amp batteries in about ten days if I don't.

 

[MikeL219]

You thought right. A solar charge controller should never provide significantly higher voltage than the battery. The moment before charging starts, you might see 20V @ the PV terminals, but they will drop to very near battery voltage as soon as current starts flowing.

Sounds like a bad or improperly configured controller.

You were right about a more well reviewed controller. I picked up an open box Renogy Wanderer 10A and at the very least, it being more descriptive and having an actual manual makes it easier for me. I just set it up and the numbers coming in are looking great.