Jump to content
Thank you for the great forum, Safe Driving over the weekend. Sincerely Jason
Sign in to follow this  
Sandro

Requesting assistance with dropping voltage

Recommended Posts

Good day to anyone reading.

I have had my solar setup since April 2019 and have had no issues untill the 3 days ago where my system would charge up to full during the day and sit spiffy at 56.4v and 100% charge and then suddenly 5pm rolls around, the sun goes down slowly and I am at 50% charge and 50+/-v. 

I have load tested the batteries and they are still healthy. 

My setup:

5kva axpert inverter. 4x 200ah 12v gel batteries in series at 48v. 6x275w american solar panels. 

My max load is around 1.8kw when I sometimes turn my borehole on during the day. Otherwise it is sitting around 220w - 380w depending if my PC is on or not. 

Batteries are sitting at around 28 degrees in the hottest parts of the day and the inverter is set up by the suppliers of the goods. 

I hope I have provided sufficient information for any help, otherwise feel free to ask and I will respond to the best of my knowledge.

Thank you for reading,

Sandro

 

Share this post


Link to post
Share on other sites
8 hours ago, Sandro said:

Good day to anyone reading.

Welcome to the forum.

8 hours ago, Sandro said:

3 days ago where my system would charge up to full during the day and sit spiffy at 56.4v and 100% charge and then suddenly 5pm rolls around, the sun goes down slowly and I am at 50% charge and 50+/-v. 

Who says 50% SOC? The inverter, or a BMV or similar device?

Does your battery last as long as it does during the night or on rainy days?

The SOC meter on an Axpert inverter is a rough guide at best, and almost totally useless if you happen to have an LFP battery (you don't). Around 50 V battery means around 12.5 V per 12 V module, which at 5pm when you might have some loads is not too bad. But if you have no significant loads when the battery voltage drops to ~50 V, then you might have a problem.

8 hours ago, Sandro said:

I have load tested the batteries and they are still healthy. 

But they are possibly being chronically undercharged due to a combination of 1) your panels are quite light on, you could do with another string of them, and 2) the charge bugs in the Axpert inverter-chargers.

You could check if your inverter is eligible for patched firmware, which will fix the charge bugs. Otherwise, if you have equalisation facilities, use that to equalise about 60-120 minutes every day at the bulk charge voltage (56.4 V). It's not perfect, but better than nothing.

8 hours ago, Sandro said:

5kva axpert inverter.

There are many models fitting that description. It helps to give the exact model.

Share this post


Link to post
Share on other sites

Coulomb,

thank you for replying,

the inverter is reading 50% (2/4 bars), at the moment there is no clouds and I have not had a rainy day (unfortunately).
The voltage drops to 48.5 +/- throughout the night, whereas previously I could wake up with 75% charge and 52v on the batteries.

I am not sure on the model number, it was the Mecer axpert 5kva MKS II from www.easypower.co.za.

My panels take all of the load during the day whilst charging the batteries, usually pulling around 1.2 -.1.6kw.

What I cannot get my head around is the sudden drop in charge when my load in the evenings is 340w max, as nothing has changed in my rig and my house in the past few days.

I am a solar newbie, any advice on how I can update my firmware? can I run ethernet straight to the inverter into my router?

Thank you.

Share this post


Link to post
Share on other sites
21 hours ago, Sandro said:

The voltage drops to 48.5 +/- throughout the night, whereas previously I could wake up with 75% charge and 52v on the batteries.

Well, I believe that the terminal voltage of lead acid batteries reduces as the temperature increases, but likely not to that degree. It's usually around -3 mV/°C/cell, so -72 mV/°C for a nominally 48 V battery. Suppose it's gotten 10°C hotter lately, that would account for some 0.72 V lower voltage. You are seeing 52.0 - 48.5 = 3.5 V, almost 5x as much.

21 hours ago, Sandro said:

What I cannot get my head around is the sudden drop in charge when my load in the evenings is 340w max, as nothing has changed in my rig and my house in the past few days.

My guess is that the battery isn't getting fully charged.

21 hours ago, Sandro said:

I am a solar newbie, any advice on how I can update my firmware? can I run ethernet straight to the inverter into my router?

No. The connector on the inverter that looks like it's an Ethernet port (because they use an RJ-45 socket) is actually the RS-232 port. You need to use the provided RJ-45 to D9 cable, then a USB to serial adapter to allow your computer to talk to the inverter. You can only update firmware through that setup as well. (You can use the USB port for monitoring, if your inverter has one, but not for firmware updating, unless the USB port is the only port (there is no RS-232 port)).

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

Topics

Contact Us - Power Forum South Africa

×
×
  • Create New...