Weird charging beha...
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Weird charging behaviour - keeps charging past 100% and SOC red frame does not disappear

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Posts: 27
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Hello Matthew,

I'd like to repost the photos that didn't make it into your previous message to clearly illustrate this exchange.
First of all, I'd like to point out that it's crucial, both for safety reasons and for maintenance purposes, that you have a properly documented installation (diagrams, configuration documents, etc.).
Please understand that without electrical diagrams, we have only a partial view of your installation, which complicates any analysis and makes any search for associated problems more uncertain.
Please note that we are not marine electricians. While we can provide you with an insight into your installation, we have no prescriptive role in this field.

In addition to the absence of a diagram, I'd like to point out several important points concerning your configuration documentation.

On the triggers worksheet :

  • Relay 3 (main battery) is set to NO and is not activated by default. This means that it is open in the normal state and that your battery is disconnected from your system by default
  • Relay 4 (alternator) is NC and activated by default, which means it is open by default. It is therefore impossible to charge with the alternator under normal circumstances.
  • Relays 5 and 6 are activated by default. As these relays don't seem to be used, there's no need to activate them by default. This only consumes energy for nothing.

Comparison with the screenshot of your BMS settings shows that :

  • On the triggers worksheet, relays 1, 2 and 3 are not activated by default, and relays 4, 5 and 6 are activated by default. Your configuration, on the other hand, seems to indicate that only relay 3 is activated by default (you may have changed it since then).
  • On the triggers worksheet, trigger 1 changes the status of relays 1, 2 and 3, whereas on your BMS configuration it also intervenes on relay 4 (if your relay 4 is indeed configured as NC and activated by default, this means that you close it when trigger 1 is activated).
  • On the triggers worksheet, trigger 2 changes the state of relays 1 and 2, whereas on your BMS configuration it also intervenes on relay 4 (if your relay 4 is indeed configured as NC and activated by default, this means that you close it when trigger 1 is activated).

You'll understand that it's difficult for us to produce a relevant a based on these documents, especially in the absence of any electrical diagrams.

For your safety and comfort, both now and in the future, we encourage you to contact the electrician in charge of your installation, so that he can provide you with precise documentation of your system and its configuration.

Posted : 10/11/2023 10:45 am
Posts: 348
Member Admin

The following exchange / comments were i the wrong topic and are copied here:

On 10/11/2023 @balance said:
"But we're still having the same problem, the High voltage alarm comes on when we run the engine. At that point the SOC is now showing 92.6% and voltage 14.24. 
The BMS isn't recognizing a full state of charge and isn't engaging relay 4 which should stop the alternator charge. 
We can't run our engine now without getting an H1 alarm. 
The cells have been balanced. We've been on the phone with Matt P the installer, he's not sure what's going on. The electrician in Opua who installs BMS's has run out ideas."

Response by @philtao on 10/11/2023:

Hi Matt,

It sounds like the alternator regulator is set to charge at a voltage much higher than the voltage set in the BMS to detect a full state and it is still charging with high current when the high voltage warning is triggered.

My understanding based on information you communicated us:

  • The BMS SOC parameters to detect full battery state are:
    • battery voltage > 13.80V
    • and current  < 10A
    • and stability timer = 30 seconds
  • The Alternator is set to charge at a voltage at or above 14.24 V (3.56 V per cell in average) - What is the bulk voltage set for the alternator regulator?
  • BMS cell high voltage warning (led H1) is set at 3.55V  

At 14.24V It is normal that the cell high voltage warning is triggered as cell voltage is above 3.55V

When the charge voltage reaches 14.24V the battery is not yet in absorption stage = the current is above 10A (please confirm).  Therefore the BMS will not detect the battery as being full

If that is the case you need to reduce the bulk / absorption voltage of the alternator regulator to be slightly above the BMS full battery state voltage (in your case 13.85V or 13.90V should do).  When the charge voltage reaches the bulk voltage (13.90V) it remains at that level to give time for the battery to finish charging (absorption) and for the current to go down until it gets below 10A. At that point the BMS recognises the battery as full. 

If that is not the problem, please send us the BMS configuration file (the one you have loaded in the BMS) and the measure history file (Maintenance > export historical data) so that we can analyse.

Posted : 11/11/2023 11:02 pm
Posts: 348
Member Admin

on 11/11/2023 @balance said (on a thread that was not related to this topic):

"Thanks Phillippe / Francois,
OK we dropped the voltage on the regulator which was set too high. Ran the alternator and reached float, red square gone and things seemed to be working, finally. 
However, now we have the charge profile set to Default 80-30 and under solar we charging at 84% when it should be dropping. We changed charge profile to storage 40-30 and still it's charging.
Any ideas why the BMS won't cut out the solar and follow the charge profile? The config is set up to energize relays 1 and 2, that doesn't seem to be happening. The red square is gone so the BMS doesn't need reseting."

I understand that you have updated the BMS firmware to latest version (v1.36).  Have you also updated the Monitor firmware to the latest as explained on the "Monitor and BMS firmware updates" thread.  If not already done I suggest you subscribe to that thread so that you are aware of evolutions.

Have you looked at the events log?  Is there an event to stop the charge and events to activate relay outputs for solar A, solar B, and Alternator?  something like:

Based on what you said it looks like charge management is not configured to activate output #4 (Alternator)

(note: I just reconfigured the BMS outputs on my installation and I realise now that I forgot to rename inverter output to match the output usage - of course in my case the three outputs that are activated to stop the charge are Alternator, Multiplus charger and solar charger) 

Posted : 11/11/2023 11:33 pm
Posts: 1
Member Admin


Posted : 23/01/2024 3:42 pm
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