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Fred111 avatar image

MPPT 75/15 absorption time. FW v1.50

hello, maybe some one can help me how to set a fixed absorption time. I’m trying to set a fixed absorption time of 1 hour, but at the same moment bulk charge reaches absorption voltage it goes directly to float. Do I miss some setting?

Thanks, Fred



MPPT - Solar Charge Controller
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2 Answers
Mark avatar image

Yes the settings you currently have should/will result in 1h of fixed absorption time- but it will only do this once per day.

The MPPT determines a new day when the PV voltage is below battery voltage for a few hours, if the MPPT thinks it's still the same day and it's already provided 1h of absorption then it won't do it a 2nd time (and will go direct from bulk to float).

Have you properly tested it in after a new day has started?

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Alexandra avatar image

@Fred111 if you read the manual

https://www.victronenergy.com/live/victronconnect:mppt-solarchargers?utm_source=offline&utm_medium=qr&utm_campaign=qr%20code%20products?utm_source=offline&utm_medium=qr&utm_campaign=qr%20code%20products#battery_settings

Tail current

Set the current threshold that will be used to finish absorption phase before the maximum absorption time expires. When the battery current gets below the tail current for one minute, the absorption phase will end. This setting can be disabled by setting it to zero.

In your settings you have disabled tail current. This is mainly done for LifePO4 type batteries. If this is the battery type you have is there a reason why you would like there to be an absorption phase?

You also have set an equalization voltage - which then would suggest that you do not have a LifePO4? As they are not usually equalized.


The easiest way to set the charge controller, is to pick a preset that closely matches your battery type then tweak the required voltages to suit your battery manufacturer recommendation.

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