Epever 5415an can’t get full charg amps

[Simonbr2]

Upgraded my 40a SCC to 50a so that I could charge my batteries at their rated 42a + run my loads at the same time. My array is 2x 350w in series.

For some reason I can only still get the SCC to output 40a, panels are getting 100% sun. Any idea why I’m not getting more?

 

[DJSmiley]

Which battery and SOC? Especially with lead acid, current decreases at high SOC.

And what do you mean by 100% sun? Have you been able to verify this? (Did you measure the actual sun power so it's radiation power is equallly to the specs - thus 1000W/m2), on the same angle as the panels?

In my experience, 80-85% of the rated capacity is generally about the best I can get with a flat mounted panel. This might be different for your latitude.

 

[Simonbr2]

Which battery and SOC? Especially with lead acid, current decreases at high SOC.

And what do you mean by 100% sun? Have you been able to verify this? (Did you measure the actual sun power so it's radiation power is equallly to the specs - thus 1000W/m2), on the same angle as the panels?

In my experience, 80-85% of the rated capacity is generally about the best I can get with a flat mounted panel. This might be different for your latitude.

I have 2x l16 interstates that I’m told are made by is batteries, link bellow. I have not measured the sun power, I mean they are not shaded and are on a slight degree pointing at the sun.

maybe my math is not correct but i am taking the full watts and dividing by 12v to get my estimated max amperage. If this is correct that’s 58.33a, 80% of that would be 46.66a.

https://www.usbattery.com/wp-content/uploads/2019/11/usb_L16xc_data_sheet_11_2019.2.pdf

 

[DJSmiley]

12V is almost empty battery. Voltage will rise pretty fast, thus the amps will be lower.

13V is a more average voltage to calculate the current with.

 

[mikefitz]

When the batteries are charging, the voltage at the controller will be near 14 volts not 12. The power losses, cable losses, loss due to temperature of the panels and perhaps not ideal angle, will reduce panel output somewhat, say 80%.
(700 x 0.8)/14 = 40 .

Mike

 

[Symbioquine]

Agreed that it sounds like you're hitting your batteries' charging current limits. Check out https://www.sevarg.net/2018/04/08/off-grid-rv-lead-acid-maintenance-charging-failure-modes/ which has a good description of how lead acid batteries behave over their charging cycle.

 

[Simonbr2]

Ok that makes sense, so depending where the charge is at the voltage will be higher and I can see that changes the results. I have a third panel I will connect to see if I can get more amps out of the array

 

[Symbioquine]

For a 12v battery, the size of the PV array probably isn't your limitation here so adding that third panel won't help. The solar panel voltage is (mostly) independent of the battery charging voltage. You just need more hours for the absorb phase of charging to complete - over that time the charging amps will slowly drop to (near) zero.

 

[Simonbr2]

For a 12v battery, the size of the PV array probably isn't your limitation here so adding that third panel won't help. The solar panel voltage is (mostly) independent of the battery charging voltage. You just need more hours for the absorb phase of charging to complete - over that time the charging amps will slowly drop to (near) zero.

Actually the third will help with the bulk for sure. I need 42a for battery bulk and about 8 to 10a for loads that I can’t remove while charging. 40a has not been cutting it for me because the load is taking away 1/4 of the charge current

 

[Symbioquine]

Oh, yeah that makes sense. I didn't read your original post carefully enough. For the bulk phase + loads you were a little under-paneled to get the full initial charge current. That said, the way I'm doing my math the 50A charge controller is a little small if you're expecting 42A going to your batteries and 10A going to loads at the same time.

 

[Simonbr2]

Oh, yeah that makes sense. I didn't read your original post carefully enough. For the bulk phase + loads you were a little under-paneled to get the full initial charge current. That said, the way I'm doing my math the 50A charge controller is a little small if you're expecting 42A going to your batteries and 10A going to loads at the same time.

No problem, always appreciate the answers. It is still too small but I had ordered the 50a before really doing all the math and having more knowledge. I am currently aiming to return it and purchase either a classic 150 or victron 150/100 (or 250/100) with a shunt for controlled current delivery to the battery. I’m planning on adding a second bank and I know I will need more amps.