need help, not charging my battery.

[robbie0201]

Ok so I just bought a 100 Watt solar panel, I bought it to power a modem and Point of sight router. I did this so be able to get internet to my house. Well I got the panel and a PWM controller. I hooked it all up and the load works perfectly. But it is not charging the battery. I have between 20.1 and 18.1v coming in from the panel. But the light is not coming on to charge the battery. At first I thought it was because I had the load on, but nope it still will not charge. If anyone could help me I would be grateful!
I attached a picture of the setup. I am just testing it right now, before I put it out. So I know it looks sloppy right now

[wayne23836]

robbie, If your charge controller has load terminals they are not for the battery connection. On some charge controllers the load terminals are for night lights or to be used as a photo switch.
Just a thought, may not apply.

Wayne

[robbie0201]

Had a brain fart and had the lead from the box to the panels backwards..... So I have it charging now. But in reference to what you said. Do I just connect my inverter straight to the battery? What would be the difference between connecting to the battery and connecting to the load on the controller? I am just wondering? I am just trying to get a better understanding. Thank you for responding!

[Sunking]

Connect the loads to the battery, and keep polarity straight.

Having said that there is a good chance your battery and panel wattage are too small. If after a couple of days you notice the battery voltage falling, then you know your system is too small. 90% of all DIY battery system are grossly undersized.

[robbie0201]

All I am running on this system is a cable modem and a Power Over Ethernet device. Both combined use 1.5A. Which is not much at all! I was thinking that the 100 Watt panel could keep up with that. The amount of amps coming in a day would be more than the amount going out.

[Sunking]

Did you run any numbers to design the system? How many hours per day are you running?. Forget Amp Hours, use watt hours.

Example let's say you use that 1.5 amps 24 hours per day. I assume 12 volts. That would be 36 AH or 450 watt hours per day. The minimum requirement with a 20 amp PWM controller is:

12 volt battery capacity = 180 AH
Panel Wattage = 325 watts.

With MPPT:

Battery = 180 AH
Panel Wattage = 225 watts

Point I am trying to make here is most DIY fail to plan and just assume. That is a plan to fail. It is rare you can guess correctly unless you have a fair bit of experience. A 100 watt panel with PWM at best can only support a 12 volt 50 AH battery and supply up to a maximum of 125 watt hours of usable power per day. That only applies if you live in an area with excellent solar insolation. Same panel with MPPT can support up to a 80 AH battery and supply up to 200 watt hours per day.

So if you run that gizmo 24 hours per day. your panel is not capable of generating 450 watt hours per day year round even under best solar insolation conditions. You will know for sure soon enough when you have a dead battery in a week or less. It may work now depending on how long you run your gizmo. If 24 hours per day. 3-5 days until dead battery.

[Amy@altE]

The inverter should never be connected through the charge controller. It should go through a fuse or breaker to the battery. The inverter has the potential to pull too much power in, and blow up the charge controller.