Confuse about solar charger controller

[mrel]

Hello
I notice people who sell solar charger controller list ,there controller from 20 ,30,40,50,60,70,80,90,100,etc amperage.
When seller list solar charger controller the amps (example 20 amps) and person has 100 amps hour lithium battery.
If person purchase 20 amps controller and person have 100 ah lithium battery,does that mean battery get charge to 20 amps and controller shut down at 20 amps.
And battery don't full charge
El

 

[Rednecktek]

No, the ratings are for the maximum amperage the SCC can pump out to your batteries continuously. If you had a 20a controller with 10zillion watts of panel for 30 hours of sun every day, the controller could only feed 20a to the batteries for as long as the sun was out and your panels were producing.

The battery not charging thing is usually because you've used 30 amps an hour every hour of the day and are only putting 20 amps per hour back in for the 4 hours of good sun you got that day. If your panels and controller can't produce more than you draw then your batteries will never get fully charged. This happens a lot in winter when there's just not enough sun to fill the batteries back up because of clouds and rain and sun angle.

The Amp Hour rating of the battery is how many hours it could feed 1 amp, or how many amps you could draw in 1 hour, or a balance of those 2 (50a for 30min, etc) and is a measure of how much capacity it will hold. If you were draining it empty every day, your panels and 20a controller would need to charge full tilt for 5 hours to make up those amps (5 hours at 20a = 100 amp hours). If you only got 4 hours of sun you could only produce a max of 80 amp hours and wouldn't fully charge your battery.

However, if you only used 10 amp hours of that battery in a day, then your 20a controller would have it topped back up in half an hour. That's where sizing your array and controller really come into play.

Tl;Dr: A battery is a bucket full of amps, the controller is rated by how fast it can refill that bucket.

 

[owen69420]

thank you for that reply. I am learning here as well.

 

[mrel]

No, the ratings are for the maximum amperage the SCC can pump out to your batteries continuously. If you had a 20a controller with 10zillion watts of panel for 30 hours of sun every day, the controller could only feed 20a to the batteries for as long as the sun was out and your panels were producing.

The battery not charging thing is usually because you've used 30 amps an hour every hour of the day and are only putting 20 amps per hour back in for the 4 hours of good sun you got that day. If your panels and controller can't produce more than you draw then your batteries will never get fully charged. This happens a lot in winter when there's just not enough sun to fill the batteries back up because of clouds and rain and sun angle.

The Amp Hour rating of the battery is how many hours it could feed 1 amp, or how many amps you could draw in 1 hour, or a balance of those 2 (50a for 30min, etc) and is a measure of how much capacity it will hold. If you were draining it empty every day, your panels and 20a controller would need to charge full tilt for 5 hours to make up those amps (5 hours at 20a = 100 amp hours). If you only got 4 hours of sun you could only produce a max of 80 amp hours and wouldn't fully charge your battery.

However, if you only used 10 amp hours of that battery in a day, then your 20a controller would have it topped back up in half an hour. That's where sizing your array and controller really come into play.

Tl;Dr: A battery is a bucket full of amps, the controller is rated by how fast it can refill that bucket.

Rednecktek
Thank for reply to my post.
In reading your reply post, have question (example) if person have solar panel that put out 30 ampere and solar charger controller is 20 ampere does that mean 10 ampere will not put to the battery ,because 20 ampere charger controller limit the amount to 20 ampere feed to the battery.
EL

 

[mrel]

Rednecktek
Thank for reply to my post.
In reading your reply post, have question (example) if person have solar panel that put out 30 ampere and solar charger controller is 20 ampere does that mean 10 ampere will not put to the battery ,because 20 ampere charger controller limit the amount to 20 ampere feed to the battery.
EL

 

[Rednecktek]

Rednecktek
Thank for reply to my post.
In reading your reply post, have question (example) if person have solar panel that put out 30 ampere and solar charger controller is 20 ampere does that mean 10 ampere will not put to the battery ,because 20 ampere charger controller limit the amount to 20 ampere feed to the battery.
EL

Exactly. Fortunately it's hard to get 30a out of panels, most 100w panels top out at about 5a. By the time you're doing strings of multiple panels you've (hopefully) stepped up to a MPPT controller.