question

thtruck avatar image
thtruck asked

MPPT output voltage too high


I have 2 mppt's, a 100/30 and a 100/50 both smartsolar. I have set them up with the usual parameters for a 24 volt AGM battery. 28,8 absorption and 27,6 float. But every time the mppts absorp at 29,14 and float 27.9 which i don't want.

I changed the floatvoltage to 27 volts but then the mppts float at 27,3.

I have reset both mppts but nothing seem to change this behaviour. What can be wrong?

In a couple of months i will change my batteries to LiFePo4 so i dont want my mppt's too charge higher then i want to.

The mppts were in a network but i removed that. Nothing changed.

screenshot-20230412-161549.jpg

screenshot-20230412-161644.jpg


screenshot-20230412-161652.jpg

vrm-voltage-absorption.png

vrm-voltage-float.png

MPPT SmartSolar
screenshot-20230412-161549.jpg (300.6 KiB)
screenshot-20230412-161644.jpg (289.0 KiB)
screenshot-20230412-161652.jpg (308.4 KiB)
vrm-voltage-absorption.png (336.3 KiB)
vrm-voltage-float.png (332.9 KiB)
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1 Answer
nickdb avatar image
nickdb answered ·

Sounds like it is the temperature compensation adjusting the voltages.

32.4mV/C above/below 25C. At 15C (as per screenshots) that would equate to 0.32V, give or take.

As long as the compensation specs match the battery specs, compensating for temp is perfectly ok.

Else, disable it.

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thtruck avatar image thtruck commented ·
But can i switch the temp adjusting off or modify it so the mppts will charge exactly to the volts i want them to charge? I've used the AGM standard user preset and then changed the floatvoltage only.
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nickdb avatar image nickdb ♦♦ thtruck commented ·

Yes, just select the limit, it will provide an option to disable it.

You will need to change to “user defined” settings and expert mode first.

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thtruck avatar image thtruck nickdb ♦♦ commented ·
Ok i will try that. Thanks.
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