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russ-tanner avatar image
russ-tanner asked

Does the blinking blue LED at night indicate the charger is off?

Hi all. I need some clarification on the LED lights and how my SmartSolar MPPT 75/15 charger works.

I have two Renogy 100 watt mono panels wired in series. The bluetooth app updated the firmware, twice, and is working well. I can be 40 feet away before I lose connection.

This morning I got up early, about 4:00 AM. I live in Alaska, the predawn sky was not quite sunrise. As the SCC is new to me, I've been watching the app to learn more about how it functions, particularly in less than optimum lighting.

This morning, the CC was blinking a slow blue, one flash every couple of seconds. And I could not connect the bluetooth app. I checked my battery voltage, 12.6 volts. This is set up in an RV, and the propane sensor is always on, but I was pleased to see an almost full battery bank. I have two 70 ah Duracell AGM RV 12 volt batteries.

AS the morning progressed, the blue light stopped flashing and was now steady, indicating "Bulk" charging. But still no Bluetooth connection. The sun was not yet up.

And a little while later, voila, the Bluetooth app connects, and all is well. The sun had just cracked the skyline.

My SmartSolar 75/15 CC has three lights, blue for "Bulk", yellow for "Absorption" and green for "Float".

I looked in the Victron Toolkit, it did not have much for info, nor in the manual. I have read many posts on "blinking blue light", but I still do not have a firm answer to the questions;

"Does this unit turn itself off at night to remove parasitic draw? And does the blinking blue light indicate an off or standby condition? And is the Bluetooth turned off along with the CC, and is this normal behavior?

Thanks for your input.

MPPT Controllers
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3 Answers
rickp avatar image
rickp answered ·

The manual says this:

Note (*1): The bulk LED will blink briefly every 3 seconds when the system is powered but there is insufficient power to start charging.


The SmartSolar 250/100 I have does the same. It isn’t cutting off any parasitic load from the SCC itself, it’s just letting you know it’s operating normally and waiting on the PV for power. Normal operation.

Its in the graph at the bottom of page 7 here:

https://www.victronenergy.com/upload/documents/Manual-SmartSolar-charge-controller-MPPT-75-10-75-15-100-15-100-20-EN-NL-FR-DE-ES-SE-.pdf

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russ-tanner avatar image russ-tanner commented ·

Thanks Rick.

I'm on about day 4 with this SmartSolar 75/15 unit. My confusion was on the first day, at night and no charging (Blinking blue LED) I could not connect with the Bluetooth Android App and I still do not know why.

The next morning, at 4 am ( yea I get up early), blue LED is working, but now I can access the controller with the bluetooth. And now I can plainly see the Controller is on and understand why the Charger is off (no sun) and now things make sense. Plus, when the SCC is not charging or "off", there is a little pop up tutorial with some info that was interesting.

Having the charger off, well I think that is a fine idea. My last SCC (Renogy PWM) never turned off, and the lower morning volts were telling. And I can already see the Victron unit is keeping the battery volts up by this action. So far the unit works quite well and I am pleased with the performance.

As for turning on, in series, the unit starts charging just as the sun cracks the horizon.

And I've since watched a couple of Victron videos that have helped.

For me, an old school guy, nothing beats a well written manual, a PDF, printed and in your hands. The online PDF is somewhat lacking and some grammar correction are needed. I expect an "operational SCC" is what I would get out of the box.

The bouncing around looking at Youtube videos, an app on my phone, well things could be consolidated and rewrote. The whole translation into English can be lacking and confusing sometimes. But I got there.

But at least there is a manual. Renogy has nothing to read besides simplistic set up instructions. The move to a Victorn SCC was a good move.

Thanks again for helping to clarify things for me.

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mrseas answered ·

The "online" manual has the answers.

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russ-tanner avatar image
russ-tanner answered ·

I found my answer, sort of.

And no the answer is not quite in the online manual. I saw no reference to the bulk blue LED, but a reference to install the Victron Toolkit app.

In the app buried in there, under the 3 LED section, where it in pink says Not Charging with the blinking blue LED, push that, and a better explanation pops up. The blinking blue LED indicates that the controller is not charging. I figured that out all by myself since it was 4 am.

Scroll down and under possible causes is; Not enough sun-light. Okie dokie.

Any solar charger is not going to charge at night, that is a no brainer.

So I have to use reverse logic, in that for the charger to "start" the controller needs to see 5+volts PV over the battery volts. And no less than one volt is needed to maintain operation. Thus, if the unit is not started, I must assume it is turned off.

Or plain English, "The Controller is off until the unit sees PV 5+volts over Battery volts, and needs a minimum of PV 1 volts over Batter volts to remain ON.


Or what the manual says;

● The controller will operate only if the PV voltage exceeds battery voltage (Vbat).

● PV voltage must exceed Vbat + 5V for the controller to start. Thereafter minimum PV

voltage is Vbat + 1V.


There is no mention of the Bluetooth, but I'll just assume if the CC is "non-operational", or OFF, so is the bluetooth.

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