Connecting charge controller and inverter to 24 v battery bank

Mbosser61

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Oct 14, 2019
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Hi I'm new to the forum and I'm trying to connect my charge controller and inverter to a 24v battery bank. I had inverter and charge controller connected on same posts but charge controller didn't charge batteries. If I connect charge controller to opposite terminals (where I have the POS to neg connection) there's no voltage reading. What am I missing ?
 

Brassburnz

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Jun 28, 2021
Messages
26
I have a 24v system with a Renogy 40 amp MPPT, two 12v Battery/Evo's in series and24v PSW inverter. Pics of your ser-up would help.
 

Mbosser61

New Member
Joined
Oct 14, 2019
Messages
8
I have a 24v system with a Renogy 40 amp MPPT, two 12v Battery/Evo's in series and24v PSW inverter. Pics of your ser-up would help.
Here's a pic of my battery bank with inverter connected. If I connect charge controller to the same 2 terminals the inverter readings fluctuate, and at end of day it seems it didn't charge at all.
 

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Brassburnz

New Member
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Jun 28, 2021
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Here's a pic of my battery bank with inverter connected. If I connect charge controller to the same 2 terminals the inverter readings fluctuate, and at end of day it seems it didn't charge at all.
What is the state of charge (SOC) for the batteries? If they are already full, they won't take much more of a charge. That's what I've discovered thanks to the collective knowledge of this group.
 

MichaelK

Photon Sorcerer
Joined
Mar 21, 2020
Messages
1,333
What you haven't documented yet is what your solar input is? How many panels/watts are you feeding into the controller? Also, how exactly are you measuring the state of charge? By voltage?

If you have an inverter connected to the system, there is power draw from the inverter even if there is no AC power being produced. Depending on the size of the inverter, you might be consuming 500-1000Wh of power just leaving the inverter turned on.

Let's say your inverter consumption is 500Wh per day, and you only have two 100W panels charging the batteries. The two panels might not be able to replace the amount of power the inverter draws in less than ideal conditions.

Do those batteries have snap-caps? You get a far more accurate reading of the state of charge using a battery hydrometer rather than reading the voltage.

What's the voltage and amperage ratings of your panels? You have them wired in series? With an MPPT controller, you'd need >36V or so to properly charge a 24V battery. The battery will want to charge at up to ~29.6V, and the MPPT controller needs several volts of headroom to function properly. It will be helpful to also know the charging parameters that are set in your controller?

A better pic of your battery setup that shows the positive and negative connections clearly will be more helpful.

Until we troubleshoot what's going on, the first thing I would recommend is to turn off the inverter, to at least eliminate the constant parasitic draw.
 
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