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MN3548DIY battery current

Started by ewilhelm, January 13, 2022, 08:26:19 PM

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boB


Well, it is good that there might be at least a little bit of sanity in these measurements !   :)

You are absolutely correct in that understanding what is going on is important.  Maybe I don't understand what I think I understand about how the PV and battery side are connected together ?

Maybe the 5A that is showing is actually coming from the PV and into the inverter input to power the inverter ?

40 watts of idle would only be around 1.5 amps or so though.

Must ponder some more.  I'm not up there right now so I cannot measure. 

Someone needs to verify these numbers etc.


K7IQ 🌛  He/She/Me

ewilhelm

Here's more: 100 - 200 W flowing out of the MN3548DIY as measured by an AC power meter. Same power flowing out of the batteries as reported by their BMS. Sun is just coming up, so solar is active but weak. MN3548DIY's LEDs are flashing reporting both that the inverter is operating (it is) and that the battery is charging (definitely not charging).




boB


What was the battery voltage at that time ?

K7IQ 🌛  He/She/Me


boB


I wonder if the DIY had finished a charge and their message is just wrong ?

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ewilhelm

I think it's related to the overall issue of incorrect measurement of current on the PV, as described from different angles in this thread. When the sun is down, the numbers make sense: AC charger, battery in/out, and inverter. When the PV is doing anything, there appears to be a phantom 200 W that typically shows up as higher battery input current than seen on the BMS or an ammeter. When the real PV power is below 200 W, this results in weird scenarios where the MN3548DIY reports battery input current while the batteries are actually outputting current. When the real PV power is above 200 W, it looks like a measurement error or offset, but now the signs of current flow are at least correct.

Regardless of this problem, my overall system does appear to be operating within its design range. PV, batteries, and loads are all about matched given the time of year.

If you're not getting similar reports from others, perhaps I simply have a bad unit?

boB


I think that I have heard of another instance of incorrect current measurement reporting.
Unless maybe you have reported other than just here ?

We are talking with SRNE about this.  I need to try and  round up all other reports of this.

Thank you !

boB
K7IQ 🌛  He/She/Me

ewilhelm

I've only reported here. Thank you for your help!

boB

K7IQ 🌛  He/She/Me

FNG

Quote from: ewilhelm on February 25, 2022, 08:51:35 PM
I've only reported here. Thank you for your help!

Can you email me ryan@midnitesolar.com I would like to replace this unit and see if the issue stays or goes