need help explain mppt data

[brahmon]

i have 3 280w panels connected to an mppt charge controller.    it is currently showing the following output:

26v 3.6a under the pv icon and 14.2v 6.6a under the battery icon?

is this good, bad or normal?

the instructions that came with the mppt are in chinglish so no noncomprendo.  
thx!

 

[tx2sturgis]

The 26v number sounds low...if those are 40v panels and wired in series your voltage should be much higher...if your panels are wired in parallel that number might be about right under a high charging demand, but the current reading does not match with that scenario.  

Is this a new installation, or one that has been working fine until now?

 

[brahmon]

tx2, it's a new array. i have 2 other arrays on the same vehicle. these 3 panels are on the rear and both sides so not in full facing toward sun. also, the data was taken at 8:00am. here are current readings at 12 noon:

pv 28.5v 4.6a
battery 12.7v 10.1

(currently under load with 5000btu ac)

 

[highdesertranger]

so are you getting these numbers with one of the panels in the shade? highdesertranger

 

[brahmon]

not fully facing sun.  here is actual location

 

[tx2sturgis]

If those panels are wired in series, and the panels face different directions...Houston, we have a problem.

The shaded panels, in series, will act like a 'roadblock' to the current from the other panels UNLESS they have bypass diodes installed. 

We need to know if they are wired in series.

 

[brahmon]

sorry.  they are wired in parallel

 

[tx2sturgis]

Ok...then you are getting about 130 watts input from that controller and whichever panels are producing power.

The numbers may be low compared to the maximum possible, but with 3 panels angled like that, it may be in the ballpark.

 

[brahmon]

ok thx. just wanted to know what that data was. if i face one of the panels toward the sun in the morning or afternoon, the numbers spike higher.

it's running the and fans which is all that matters! ???

 

[brahmon]

weird.  i put a smiley face and a shaka and instead got "???"

 

[brahmon]

what does the 20.4v under battery icon mean

 

[tx2sturgis]

That's not battery voltage, it's PV voltage... the voltage the controller is 'seeing' at the panels (PV=photo-voltaic).

If the panel is rated 40v, and you see 26v, the mppt controller is loading down the panel to 'maximum power point'.... 

Hence the name, MPPT, maximum power point tracking.

 

[brahmon]

thx man!

 

[brahmon]

please explain the attached display!   i don't understand.

 

[highdesertranger]

did you tell us what we are looking at? or did I miss it? brand, model, etc?

in the first pic panel voltage is 27.5volts, battery is at 63%(moderately low), the 22.8 amps under the battery symbol I don't know if that means in or out of your battery you need to read the directions for that. then under the load symbol it says 13.8 which would be normal.

second pic shows 12.1 amps coming from the panels. 25° Celsius is the battery temp. 13.8 is battery voltage and no load.

I have no idea what the evening, interval, or dawn is for. need to read the instructions

PV off is way to high. what battery do you have? if it's an AGM or Gel you are frying it. load off is 11.7 I would set it higher 12.3 or even higher. load on is fine 12.6.

highdesertranger

 

[brahmon]

thx hdr

what should i set the pv off to? 14.5? i have a battery bank of walmart everstart maxx rv batteries.

do you multiply the 27.5v panel voltage to the 22.8 amps battery voltage to get total input voltage?

i got this cheap chinese mppt off amazon and can't understand the instructions with poor translation.

appreciate your help!

https://www.amazon.com/OOYCYOO-Cont...538397619&psc=1&ref=&adgrpid=69024256077&th=1

 

[jonyjoe303]

check the voltage at battery terminals, if it never gets to 14.4 volts, you might need to set your bulk setting even higher then the 14.9 volts showed on the LCD screen. The difference between the voltage on controller lcd screen and the voltage on battery terminals is your voltage drop. You need to compensate by adjusting the bulk voltage up/down to get the battery terminals to the correct bulk voltage. 

Voltage drop from controller to the battery is a real issue, I got over a .5 volt difference. I have my controller bulk voltage set to 15.5 volts (the max the controllers goes to) and i'm barely getting the battery to 14.6 volts at the terminals (which is my goal). Any voltage at your terminals less then 14 volts while charging and your lead acid won't last long from chronic undercharging. Lead acid need to spend most of the day at 14.4 volts to fully absorb a full charge.

A good idea is to put a bright LED meter on the battery terminals so you can read the actual battery voltage in realtime, the voltage on the controller LCD is unreliable because of voltage drop. If you set it to 14.5 volts and you have a .5 voltage voltage drop, your battery terminals will read 14 volts, and the controller will think its fully charge and switch to float charge and the terminals will read even less maybe even 13 volts, thats very bad for lead acid.

For your lead acid, your goal is 14.4 volts at battery terminals, I use lifepo4 its why my goal is 14.6 volts.

 

[highdesertranger]

is the battery a Sealed Lead Acid? or an AGM? or a GEL, or a flooded? the battery should have charging specs it's best to follow their specs. the sealed, AGM, or GEL should not exceed 14.2 or whatever the manufacturer calls for. the flooded can take 14'6-14.8 depending on the battery. it is better to error on the low side.

"do you multiply the 27.5v panel voltage to the 22.8 amps battery voltage to get total input voltage?"

not sure I follow this. input to what? the 27.5 should be the voltage coming from the panels. I am guessing on this but the 22.8 amps(seems high) should be the amps going to the battery but it would not be 27.5 it would be at 14.9 were the controller was set at.

"i got this cheap chinese mppt off amazon and can't understand the instructions with poor translation."

I hear you there I read some of the Q&A and it was very hard to understand, but I got blessed a lot. LOL

highdesertranger

 

[tx2sturgis]

In the first picture you show 27.5 panel voltage. 

In the second picture you show 12.1 panel amps.

Multiply those for incoming total wattage being produced by the panels at that moment in time. 

Rounded off, 333 watts.

 

[brahmon]

thx for the great info guys! jonyjoe you were right about the voltage drop so i recalibrated the mppt to up the voltage.