Potential battery over amp question

[Steven Mael]

Hello,

I purchased a bunch of stuff, that I am not too concerned with, but I do have one concern; I bought the below controller and battery.

EPEVER MPPT Solar Charge Controller 40A 150V PV Solar Panel Controller Negative Ground W/ MT50 Remote Meter + Temperature Sensor PC Monitoring Cable[Tracer4215BN]

VMAXTANKS VMAX V35-857 12 Volt 35AH AGM Battery Marine Deep Cycle HI Performance Battery (12V 35AH, Group U1)

The battery states that it requires a 7 to 30 amp controller, but the controller I bought is 40 amps. I do have the MT50 display. Can I set a charge amp limit of 30 amps, or do I not even have to worry about the amps as the controller should limit this.

I have attached a PDF of my set up. All I am doing is running four lights, two garage door openers (one as of now), and a 12VDC outlet and a 12v to 9v power converter.

Any help would be greatly appreciated.

Thank you!

 

[gnubie]

Can you post a link to your solar panels or the spec sheet from the back of the panel?

The manufacturer of your battery recommends charge current be 3 to 15 amps. Your battery is 35AH so as a rule of thumb you want to charge at somewhere around 1/4 of the AH rating, about 9 amps. You can charge at a higher rate but that sort of charging current is considered to be the best level for battery life vs time to charge. The Tracer lets you configure the maximum charge current to your battery (use the MT50 to do that).



Your SCC has a load output connector so it can identify current going to the battery separately from current going to the load so even though you set a limit of 9 amps into the battery the SCC will be able to provide more current from the panels to run the load during the day if the demand is there. If you run the load from the SCC's output take care to not exceed its current rating.

 

[Steven Mael]

Thank you for your assistance.

Richsolar All Black 100 Watt 12 Volt Monocrystalline Solar Panel with MC4 Connectors 12 Volt Battery Charging RV, Boat, Off Grid (2pcs)

When I talked to the guy at MidNight Solar he stated it would be best if I hooked up the PV cells in series, further stating "that is what the controller likes best." Therefore I did hook up the two 100w panels in series.

Here is a photo of the back of one of the PV panels.

 

[gnubie]

At a maximum of 200 watts into a nominal 12v battery the charge current would be 16.7 amps, at the top end of the scale but the battery would cope even if you didn't set a charge current limit in the SCC.

 

[Steven Mael]

Wouldn't my max amps be 100w / 12v = 8.33a (nearly the perfect 9 amps you suggested) since I am actually running in series then? Or would it actually be a max of 2.5 amps (100w / 40v, the max voltage output of the combined panels?)

 

[gnubie]

2 x 100 watts is 200 watts in series or in parallel. The current and voltage change between series and parallel configurations but the overall power remains the same. The SCC takes the power from the panels and converts it to 12v at what ever number of amps so watts in is approximately the same as watts out (the SCC has some loss etc). 200 watts at 12v is approx 16.6 amps.

 

[Steven Mael]

Okay, that helps, thank you!