Solar Charge Controller

steveh27 wrote:
I discovered why my multimeter wouldn't show the Short Circuit Current (SCC). The 20 amp fuse was bad. I did check behind both panel's black boxes & the connections are good. One registered Open Current Voltage (OCV) of 21.2 the other 20.8. It's rated at 21.8. The rated SCC is 7.2 amps with max output of 6.67 amp.

Results:

SCC from controller connection = 6.5
from 25' 18 ga = 6.7
from 22' 10 ga = 6.6

I need to make the final solder & heat shrink connections on the 10 ga. wire. I may shorten it a bit to 16-18' if that needs done & would help.

Now my battery has a SOC of 87% with 12.7 v and a draw of -0.2a. When connected with the various cords my Trimetric shows:
with 25' 18 ga = 13.1 v and +2.9a
with 22' 10 ga = 13.2 v and +3.0a the v went up a bit the longer connected
with 16' 18 ga battery clamped direct to battery = 13.3v and 3.0a.

Maybe all is well & I just do not drain the battery enough to allow all the amps to charge?

If you are at 87% SOC, then yes, the amps are going to drop quite a bit. The only way to get around that is to have an adjustable charge controller that you can set the bulk and absorption charge Voltages higher, to like 14.8 or 15.0V. If you do that, the amperage level will stay higher longer, and your battery's state of charge will get higher too, before going into maintenance mode and voltage drop to 13.4 -13.8V, for top charging.

Which is exactly what I did with my 120W portable solar panel. I bought a Solar 30 PWM charge controller on Ebay for $31, with adjustable voltage setting for bulk, temperature controlled, and I set it at 15.0V for my Trojan T-1275, a 12V 150 Ah Sweeper/golf cart battery. I will maintain 5.5 to 6.1 amps charge rate for a long time, and it does get my battery darn near topped off, almost every single day. 6 amps for 7 hours, is about 42 Ah, plus what ever else I get at sunrise and sunset, aiming the portable panel at the sun a few times a day.