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dhyland asked

VE.Bus System [288] Automatic monitoring Low battery

Hi, I have been getting increasing momentaneous low battery warnings that last a few seconds My system components are: - VICTRON Multiplus 48/300/35-16 - NARADA Gel batteries, 4 x 200 Ah in series - SOLARMAX 2000s solar inverter, with 2010 Wp of panels (connected to the Multiplus via a VICTRON current sensor) - VENUS OS running on a Raspberry PI - Currently configured for ESS 80% I suspect my batteries may be are nearing their End Of Life, that would explain the alarms @ night when they reach 80% SOC. But today I got an alarm at 10 AM, after a -22,58 A spike that triggered a 48.97 voltage drop. This was when the batteries were being charged. Why did this spike occur, when on mains voltage + solar output? Did the inverter go into boost mode for an instant? How can a reliably test the health of my batteries? Maybe I have one or two bad cells? NOTE: I would like to attach photos and/or screenshots, but can't figure out how

MultiPlus Quattro Inverter ChargerESSVenus OS48v batterylow battery warning
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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

NOTE: I would like to attach photos and/or screenshots, but can't figure out how

Click on Insert Image, which opens a browser to your image files or simply drag & drop the image into the browser window:

bildschirmfoto-2023-03-08-um-184253.png

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1 Answer
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Mike Dorsett answered ·

There would be 2 causes for a sudden drop in battery voltage, the first is if the batteries are sulphated, near end of life or other internal resistance problem. The second would be corrosion or lose terminals - this one you can do something about.

To test the batteries, you would need to fully charge them, then let them float for an hour or so. Being gel batteries, you can't test the density of the electrolyte, so you would need to place the battery on a heavy load - boil a full electric kettle - with all charging sources disconnected. Check the volt drop on the battery terminals and cable drops while on load, and again on low load afterwards. Any connection warming or getting hot points to a corrosion problem, battery voltages under load will be lower, but look for any one or two batteries going lower than 10.8V. with the AGM batteries you have, you won't be able to get at the individual cell voltages.

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Related Resources

Additional resources still need to be added for this topic

Victron Venus OS Open Source intro page

Venus OS GitHub (please do not post to this)

What is ESS training video

ESS Quick Installation Guide

ESS design and installation manual