MPPT 100/20 turning load on/off every second

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tomvacek asked Oct 26, '20

MPPT 100/20 turning load on/off every second

Good afternoon,

after the firmware update few days ago, the solar MPPT controller now turns load on/off every second. It happens most often in voltage scenarios around 11.5V or lower. My Custom minimum voltage is set to 11.0V so before it used to keep load on until Voltage dropped below 11.0V for about 1-2 minutes.

The connected load is light with only some LED light bulbs about 10W. After the MPPT turns load off, the voltage goes up a bit (for example from 11.5 to 11.6V) and the MMPT turns load on again one second later which causes Voltage to drop a bit and the MPPT turns load off again. This repeats every 1-2 seconds. Even turning Load Output to "Always On" continues this repeating cycle.

firmware update

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Alexandra ♦ commented · Oct 26, 2020 at 05:43 PM

@tomvacek

It sounds like your battery is not doing well at all, as the voltage is dropiing under low load. How high does the voltage go during the day when it is charging? Have you been reaching absorption and float stages?

What battery do you have?

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tomvacek Alexandra ♦ commented · Oct 26, 2020 at 07:54 PM

Thank you for the response. It is 100Ah new this year so shouldn't be bad especially with a light load 10W (about 1A). I can reach float and absorption on sunny days no problem.

The issue newly emerged this weekend after the MPPT firmware upgrade. I have the minimum voltage to turn off load set to 11V. So why is Victron MPPT now turning off already at 11.5V and then one second later turning back on. Then one second later turning off again then turning back on. It's never done this before the firmware upgrade.

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Answer 1 · 2020-10-26T22:53:57Z

freesurfer answered · Oct 26, 2020 at 10:53 PM

What is your low voltage load disconnect, and your low voltage load reconnect options set to?

From what I can tell the defaults for your controller are to disconnect at 11.1V, and reconnect at 13.1V. If the reconnect is set lower it could cause an oscillating effect like that. Check the settings and if you have any custom algorithm set up, try re-applying them. See this link for more info:

https://www.victronenergy.com/live/victronconnect:mppt-solarchargers#load_output

Also check that the cable connections to the battery are good and not causing a voltage drop when the load switches on.

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tomvacek commented · Oct 27, 2020 at 04:49 PM

I tried today to put Load Output back to the Conv. Algorithm 1 with the disconnect at 11.1V and reconnect at 13.1V.

However, the MPPT continues to turn off load already at 11.5V (not 11.1V as set). Then one second later it turns it back on again. Then one second back off. Then one second back on. Etc. Etc. The Voltage oscillates around 11.5-11.6V while turning on/off under load of about 1-2A.

This all started happening few days ago when I updated to the new firmware. Before, it would turn off load correctly at the voltage disconnect value.

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boxerbob tomvacek commented · Oct 31, 2020 at 10:39 AM

Hi tomvacek. Thanks for linking in from my earlier comment. I only started using the system, so the firmware update was immediate, I didn't use anything older. As yet I have not changed any settings. Where would I be able to compare your settings to mine? Interesting that I do not get the oscillating on/off as you do, mine goes off once and back on. The lights do not trigger it, nor does the electric step, even when it pulls 8A at end stop. Only the roof fans and the compressor fridge. Regards. Bob

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Answer 2 · 2020-10-31T22:40:06Z

ddickov answered · Oct 31, 2020 at 10:40 PM

Hi there could you advise what battery you are using in the system is if flood led acid, AGM, lithium.

Thanks david

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Answer 3 · 2020-10-31T22:41:32Z

ddickov answered · Oct 31, 2020 at 10:41 PM

Double check the charge voltages as per the battery manufacturer float, bulk, absorption.

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