question

zman4500 avatar image
zman4500 asked

SmartSolar 75/15 MPPT High Output Voltage

Occasionally, my MPPT registers output/ battery voltage higher (15-17V) than the absorption set point of 14.4V. I also noticed just now that the stored data is different from the day it happened to now. This charger is connected to my camper roof 200W panel, to 2x100Ah lithium batteries. My BVM712 is saying the same thing, but they are connected via VE bluetooth.

This charger is labeled “Roof Solar” in the photos. First photo is a screen shot from yesterday, second is of same point in time of data, but from today.

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If anyone has any insight to why this high voltage may be happening or why the stored data is “updated” after the fact, I would greatly appreciate the help!


Thank you


MPPT SmartSolar
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img-9674.png (113.8 KiB)
img-9658.png (104.9 KiB)
img-9659.png (105.5 KiB)
img-9675.png (113.5 KiB)
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1 Answer
pwfarnell avatar image
pwfarnell answered ·

Most likely you have drop in batteries that do not control the charge and the BMS is disconnecting the charge and the MPPT is not expecting this so it takes a couple of seconds for it to regulate the voltage. You need to check your BMS, perhaps one of your cells is out of balance causing the BMS to shut down or perhaps the battery is full before the MPPT goes to float. Reduce your absorption voltage to say 14.2V and see what happens.

The older the data the more it is averaged to reduce the amount of storage, so short term peaks get smoothed out.

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zman4500 avatar image zman4500 commented ·

PW, thank you for your quick response. I have adjusted the absorption to 14.2 and switched back to adaptive absorption. Battery manufacturer indicates charge at 14.4 +/- .2V. I will update with how it goes.


Do you believe that also adjusting the tail current could possibly assist this over voltage issue?


Thank you

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zman4500 avatar image zman4500 zman4500 commented ·
To follow up, the change from 14.4 to 14.2V absorption set point fixed the problem and now chargers/ monitor log 14.23V as the max.


Thank you PW!

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