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r2d2wat avatar image
r2d2wat asked

Smartsolar 100/50 going into absorption, then float too early

SmartSolar 100/50 error?


The 100/50 controls 2 x 300watt panels, in parallel, 12v (1000ah) AGM batteries.

It starts the morning working perfectly, then gets in absorption mode early, then stays in float mode. A Smartsolar 100/30, Bluetooth linked, is working perfectly. I checked all the connections, even though that doesn’t make sense. A reset made no difference.

Recent problems included tripping of 50, then 60 amp DC circuit breakers (the cheap ones were all I could get). This has not happened since finding a good quality, 100 amp circuit breaker.


The 100/50 is compared to my SmartSolar 100/30 with 2 x 270watt panels, parallel. (New 100/50 has been ordered to replace it, since it often manages more than 30 amps.) The 300w and the 270w panels have similar sun and shading, and this unit is working great.

The surface temperature if both controllers is similar, about 110 deg F.

About a month ago I installed a smart voltage sense. Both controllers connect to it and the charge parameters are identical, per the battery manufacturer. Both controllers attach to the same power posts.


Photo 1. 100/30 in absorption

Photo 2. 100/50 in float - same time, same sun on larger panels.


Not sure, but the problem might have started after a recent firmware update. Is there a way to update again? Any other suggestions please. Defective?

battery charging
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3 Answers
JohnC avatar image
JohnC answered ·

Hi. Take a closer look at the unit that's showing Absorption at 13.70V.

Something wrong there for AGM batts, maybe in the settings?

Of course, your units aren't 'synced', and can only decide individually how to charge. This shouldn't normally be of concern, as they should be roughly the same in function. But that 13.70V, hey??

The sync functionality is likely to arrive in future firmware, but I doubt firmware is your issue..

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r2d2wat avatar image
r2d2wat answered ·

Thanks John. I hadn’t even looked at voltages! Float voltage is set to 13.80, absorption to 14.25.

So it could be that the 100/30 is staying in bulk, then absorption too long, before going into float? It is the unit I would expect problems since it is at its limits.

I will need to compare with my third controller, a Blue Sky 3024i, managing 4x 130w panels in parallel. But I got spoiled with the Bluetooth on the Victron units.

Any other suggestions please, now that I am even more confused?

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JohnC avatar image JohnC ♦ commented ·

Don't worry about either unit being at it's limits, this is tough kit and will self-regulate. Each mppt will determine what to do itself from Vbat, and of course that will be influenced by what the other mppt is doing.

Why one is showing Absorb at 13.70V I'd be seeking out first.

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r2d2wat avatar image
r2d2wat answered ·

Yes, the problem seems to be with the 100/30 staying in absorption too long. My Blue Sky controller is also in float mode.

I guess I got used to, and happy seeing all that power, so I overlooked seeing too much power.

Worried that the 100/30 in absorption too long could damage the batteries, I tried shutting it down in the afternoon sun. Interestingly, the 100/50 markedly increased its output to match what the 100/30 had been doing.

Then I tried resetting the float voltage from 13.8 to 13.75 volts on the 100/30 - still stays in absorption.

Then 13.7, 13.65 volts for several minutes at each step. Stays in absorption.

Is it likely that the 100/30 being stuck in absorption too long could be a firmware issue, or a defective item? It seems to be keeping up with the load I have in the daytime, but I don’t know if there is risk of overcharging.

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JohnC avatar image JohnC ♦ commented ·

Yeh, I think I'm getting confused by your confusion.. :)

You *must* look at your V's, and don't worry about what state the mppt's say they're in. ~13.7 is a typical Float V, and won't hurt your batts.

What hasn't been mentioned is your Absorb V settings, and for your AGM's would typically be ~14.4. Do you have something like that set, or ever see it?

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r2d2wat avatar image r2d2wat JohnC ♦ commented ·

The absorption voltage settings are are 14.25.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

Hi r2d2wat,

"Then I tried resetting the float voltage from 13.8 to 13.75 volts on the 100/30 - still stays in absorption...Then 13.7, 13.65 volts for several minutes at each step. Stays in absorption. "

With the firmware v1.42/3 the absorption timer continues to count time when the batts are below the absorb voltage. This dead time is added to the absorb set time.

This will make the recorded absorption time look longer than what has been set.

Also if you have 2 different mppt/array's, 1 mppt may take over the absorb current, while the second mppt will drop down to zero current, but #2 absorb timer will still run. Then when #1 mppt goes into float, #2 mppt will start absorption again to finish its programmed absorb time cycle (adding time that the batts are actually held at the absorb voltage).

I was seeing this ^ with my 75/50 and 100/50. The 75/50 would get lazy and not contribute to the absorb phase, until the 100/50 had gone to float.

https://www.victronenergy.com/blog/2019/09/11/victronconnect-5-9-solar-charger-improvements-and-much-more/ A quick overview about the firmware changes and VictronConnect 5.9. A good read.


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r2d2wat avatar image r2d2wat klim8skeptic ♦ commented ·

klim8skeptic. Thanks. So it sounds like the absorption phase is based on time, not so much on voltage until the time is done. And one of the controllers takes over.

All good news, nothing to fix.

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