question

rithym1964 avatar image
rithym1964 Suspended asked

How to Calibrate MPPT 450/100 Amps reading

Is there a way to calibrate the mppt 450/100 amps by firmware perhaps?

Mine shows very confusing output numbers in VC for example as a snapshot

6213W Total by #1 & #2

Current going to battery 95.8A

Battery Voltage 57.6V

So, 6213 / 57.6 = 107.86A not 95.8A as shown. I aslo put a quality clamp meter on the 450 output cable and it shows 108A going to battery. It's no big deal and I'm happy that the unit is over performing but I don't understand how it can calculate the amps so far out, it's just simple math but it's 12% out of calibration. If my GX device is using that figure to calculate total amps produced it's a long way out every day.

I tried to post screen image of the above snapshot but I just keep getting parse failure.

rs450
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
nickdb avatar image
nickdb answered ·

VRM is showing PV voltage and current, not battery current.

VC should separately show the readings for solar (PV) side and battery.

6 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

rithym1964 avatar image rithym1964 commented ·

I never mentioned VRM at all. I am referring to VC which shows me total Watts being produced by the controller and on the rh side bar it shows me battery voltage & amps flowing to battery. Seeing that Watts = Volts x Amps then a snapshot at any time should equate those figures by the above formula, but it doesn't. eg 6000W at a battery voltage of 60V should mean the current is 100A. The example I gave initially - 6213W divided by 57.6V should equal just under 108A, but it shows 95.8A in VC which is incorrect and putting a clamp meter on the controller output cable actually shows 108A going to the battery.


I am wondering how VC is so far out of calibration in it's maths I'm sure it must be a coding error my other controllers are spot on...

I still can't upload the snapshot just getting Error 'parsing response failed'


0 Likes 0 ·
kevgermany avatar image kevgermany ♦♦ rithym1964 commented ·
I think you're assuming constant voltage throughout the charge. At start of charge, output voltage will be low, with high current. As the batteries charge, voltage rises and current will drop. The MPPT accounts for this in its calcs.
0 Likes 0 ·
rithym1964 avatar image rithym1964 kevgermany ♦♦ commented ·
I'm not assuming anything i'm perfectly aware how a charge cycle works. At any given time during the charge cycle Watts is ALWAYS equal to Amps x Volts, as the Volts rise (assuming the Watts remain the same) the Amps will go down, it's called Ohm's Law. So, if my controller is producing 6000W & the battery is 60V then the Amps MUST equal 100A... it matters not at what point of the charge cycle we are at, this correlation between Watts, Amps & Voltage is always true.

So, to repeat my initial point if I now take a look at VC... the controller is showing 4700W with a battery voltage 55.50V so the power at that point must be 84.68A but it is showing as 74.10A so the controller is over 10 Amps out of calibration. I have 3 other Victron controllers and they all show the correct correlation as stated above, it is only the 450V controller that is way out.

0 Likes 0 ·
kevgermany avatar image kevgermany ♦♦ rithym1964 commented ·
Sorry, missed your reply. It would really help if you were able to post a screen shot of VC for the MPPT.
0 Likes 0 ·
rithym1964 avatar image rithym1964 kevgermany ♦♦ commented ·

Still can't upload any images I have dumped the screenshots of VRM & VC on my onedrive server

https://1drv.ms/u/s!Airt5ZiWTGNGlBVw0rijQ2PnVEyu?e=FnGaGV

Let me know if the link above is not accessible

0 Likes 0 ·
rithym1964 avatar image rithym1964 rithym1964 commented ·

Seeing that VRM has been mentioned I have been looking at that this week and that also gives very misleading figures. The PV Charger figure should total the individual controllers production and for my situation this morning I have 1055 + 674 + 4004 + 3999 = 9,732W. But the PV Total shown at this point is 8,873W which is 859 Watts lower than it should be. Over a period of a sunny day that is 8 - 10KW under reported by the GX device, that is thousands of KWH over an annual period. What is the point of having all this information if it's completely wrong ??


I hope someone at Victron will look at this there must be thousands of these 450V controllers out in the field all reporting incorrectly.



0 Likes 0 ·

Related Resources

Additional resources still need to be added for this topic