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ksmith avatar image
ksmith asked

MPPT 100/30 float issue

Hi all,

I've had a look through the masses of previous questions and unfortunately couldn't find any that were quite the same as mine.

Recently I have noticed that my SmartSolar 100/30 completes it's bulk and absorption stages and enters float mode. When in float it will match any current draw from the battery for roughly an hour and then will suddenly no longer keep matching the battery and it will then start dropping down from 100%.
It says it is in float mode, there is plenty of sunlight and panel voltage present, however it doesn't output any charge to the battery. No other chargers connected to the battery.

I have the float voltage set to 15.8V and even when the loads connected to the battery increases it does not kick it back into bulk.

I then have to reset the controller by disconnecting the solar, then battery and reconnecting, which it will then it go back into bulk mode, absorption mode and then eventually into float again.

Has anyone else experienced this issue? Is it potentially a firmware issue?

Thanksvictron-smartsolar-100-30-float-stuck.pngimage0.pngimage2.pngimage1.png

MPPT Controllersfloat
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13 Answers
marc-de-montreal avatar image
marc-de-montreal answered ·

hi, the idea that come automatically to me is have you upgraded the firmware? ..what kind of 12v battery you have for this high voltage setting? ..have you found something since your question?

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ksmith avatar image ksmith commented ·

Hi Marc,

Yes, I update the firmware at each release. It has improved, but is still occasionally getting stuck in Float when there is only a small load.

I am using Lithium NMC LG Chem N2.1 battery cells in a 4S configuration. Max charge is 4.2V per cell but I limit it to 3.95V for safety/longevity.
Unfortunately I have not found any further information on this issue since asking this question. However as it only seems to occur when there is a low load and after the sun has gone down overnight it seems to reset and will work correctly the next day until reaches float mode again. When a larger load is running then it appears to function correctly.

Thanks, Kieren

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marc-de-montreal avatar image
marc-de-montreal answered ·

your wiring is good confirmed?

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ksmith avatar image ksmith commented ·

b918f71f-edcd-4278-a031-9bdacf04e051.pngConfirmed. The issue is only apparent when the MPPT enters float mode.8ed191b3-4b77-4c62-a8f5-a59dd7cd02d2.png

This is a snapshot from VRM of yesterday’s SOC vs Battery voltage.
You can see that the state of charge is dropping throughout the day until 18:00 when it suddenly releases itself from being stuck and tries to begin charging again but there is minimal sun at this time of day.
There is sufficient sun throughout the day here (Perth, Western Australia) and the panel is in full sun throughout the day.

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marc-de-montreal avatar image
marc-de-montreal answered ·

hi, i has tried the simulation for my lithium batteries bank with lithium selected for the type of battery and the floating stage was disabled automatically.. have you selected, in your setting type of batt, the lithium?

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ksmith avatar image ksmith commented ·

These are my current settings.

I will look to try as you said and see if that makes a difference.
Thank you for the suggestion.

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daveychristie avatar image
daveychristie answered ·

I am trouble-shooting the same or similar issue. I have a Battleboard 100A battery, and an MPPT100/30 set to Battleborn's settings, with current firmware. I found recently that my battery was not recharging, and due to occasional loads, had dropped to ~80%. The charger was in float, and per BBs settings, float was 13.6V, less than the 13.8V in the battery, so no charging was happening. I pushed the float setting to 14.6V, which I confirmed with BB was okay, since the battery will be able to "rest" at night, and it's charging again. But I haven't gotten a good answer yet on how it gets into this state, and why BB's recommended settings seem to work for at least most of their customers, but not for me.

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alham avatar image
alham answered ·

Have you resolved your issue? If not, your float and absorption voltages are set at the same, when for most systems float is a few V lower.

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farnja avatar image
farnja answered ·

Hi @KSmith - I am having the same issue. Did you resolve this ever?


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kevin-b avatar image
kevin-b answered ·

did all this start after the update/

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farnja avatar image farnja commented ·
I believe I was having the same issue, maybe to a lesser extent, previously.
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patrickvanneck avatar image
patrickvanneck answered ·

Hi, I have exactly the same problem with my 100/20 charger very annoying and no solution.

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linuxhiker avatar image
linuxhiker answered ·

I too have this issue with a 100/50.


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jcallin1 avatar image
jcallin1 answered ·

I have this as well with the 100/30. Only way to fix for me is to completely reset the mppt by disconnecting both the PV and the battery :\

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river-rg avatar image
river-rg answered ·

I had this problem, it charged to 38% and then stopped charging and went into FLOAT. I figured out it was actually an error on the capacity indicator. It was actually at 100% but displaying 38%. This can be reset by holding down A/Ah (middle button) and then % (right button) for 3 seconds. It should reset to 100% which is a true reading (hence it’s in float).

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martyh42 avatar image
martyh42 answered ·

I too was having issues with the 100/30 mppt, lol to the point I even fitted another solar panel, yesterday I decided to sort it, got on the roof of my swift caravan and started disconnecting my solar panels one by one and checking the voltage, all seemed fine? went to my controller which said it was putting out 13.9 odd volts tested it and it was, tested my bus bar down under my seat and it was saying 13.4v, so I turned up the absorption voltage in my app in the end to 14.5 which the controller was indeed putting out, but down at my bar it was now only 13.5v?? so clearly the wiring already installed to my caravan was not fit for this setup. routed a new wire direct from mppt to the bus bar plugged everything back in and omg this mppt controller (I've had for nearly a year) is a beast! now have little to no voltage drop reset back to factory lipo setting and now when my batteries are 100% and I turn on a load like my fridge and some lights, the controller almost instantly matches that load by allowing in as much solar as it needs to run the load but not put any more charge in the batteries (obviously this is only done when there is enough sun) but you can see that if there is enough of a v drop between the mppt and the battery the mppt controller will not work as it should.

long winded sorry but check the voltage coming out of the controller then at your battery.

Big fat wires! voltage drop is your enemy

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armyatcdude avatar image
armyatcdude answered ·

Yeah, this happens to me too. I have to reset the MPPT. Hopefully I notice when it's going on so I can have power for the night. I paid a premium for Victron and have been EXTREMELY DISAPPOINTED with all the issues. All my cablling is to spec and this sort of thing should not be happening.

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klim8skeptic avatar image klim8skeptic ♦ commented ·
@armyatcdude your post lacks any details describing your problem.

Perhaps open a new post with details re battery, solar panels, and some screenshots from the mppt.


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