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Post by Telemachus on Dec 10, 2019 18:59:43 GMT
Solar controllers will draw a tiny bit of power from the batteries at night, to keep the memory alive. that's news to me - why is that different from installing the controller when it is new - or is it just about remembering the 12v battery voltage setting? Obviously not all controllers are the same, but as I understand it (having limited practical experience of these things) they need to “sniff” the battery voltage to decide whether to set up for 12v, 24v battery etc. And a diode would screw that up. Also I don’t think they would like a gradual increase in panel voltage over a long period at dawn, possibly coming and going a bit. However other settings are probably “remembered” in non-volatile memory. But of course it can be nice to look at the controller display in the evening to see the battery voltage etc. Not possible with a diode. Anyway the bottom line is that I’ve never seen a solar controller manual that suggests a diode and so I’m pretty confident it would be a Very Bad Thing, not least because it drops voltage and wastes power.
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Post by JohnV on Dec 11, 2019 7:56:55 GMT
my (MPPT) solar controller draws around 10mA during "off" times to run the controller itself and the display panel.
To prevent damage to the controller it must have the battery voltage applied before solar panel voltage. This is normal as far as I am aware.
It is completely unworried about the voltage being supplied by the panels ...... if there is sufficient for it to charge it will .... if there isn't it won't.
(If the voltage is above it's design input ..... the magic smoke escapes)
so yes, diodes between the controller and the batteries is a strict no no.
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Post by bodger on Dec 11, 2019 8:03:19 GMT
that's news to me - why is that different from installing the controller when it is new - or is it just about remembering the 12v battery voltage setting? Obviously not all controllers are the same, but as I understand it (having limited practical experience of these things) they need to “sniff” the battery voltage to decide whether to set up for 12v, 24v battery etc. And a diode would screw that up. Also I don’t think they would like a gradual increase in panel voltage over a long period at dawn, possibly coming and going a bit. However other settings are probably “remembered” in non-volatile memory. But of course it can be nice to look at the controller display in the evening to see the battery voltage etc. Not possible with a diode. Anyway the bottom line is that I’ve never seen a solar controller manual that suggests a diode and so I’m pretty confident it would be a Very Bad Thing, not least because it drops voltage and wastes power. thanks. no diodes in my circuit, so I'm 'cooking on gas'
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