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Forum Index : Microcontroller and PC projects : Solar charger ok for 15V mains unit?

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PeterB
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Joined: 05/02/2015
Location: Australia
Posts: 655
Posted: 10:45pm 27 Jan 2019
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G'Day lizby (& HankR)

Something like this was talked about in another thread but I can't find it.
A solar panel has a knee. The voltage remains, more or less, constant up to a certain point and then it changes to, more or less, constant current and your controller needs that knee in order to function. The controller (should) work out where that knee is so that it can calculate the optimum conditions. Optimum conditions mean maximum charging current for the existing environment.
So, I used this as an excuse to buy a 30v 5A power supply. I've been thinking about it for years. The power supply simulates the solar panel knee and it all seems to work.
An 18 volt laptop power supply would probably work if it had the above knee.
If you load it up gradually and note what happens you might be in luck or you might just have a burnt up power supply. It would depend on how it goes into over-load.
I don't know how much current you need but you can probably get a 5A power supply for 30USD. The problem we have is our mains are 230V +5% which means 242V and if the solar panels are working, it can probably get higher so a 220V supply is a bit risky.

Good luck, Peter
 
PeterB
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Joined: 05/02/2015
Location: Australia
Posts: 655
Posted: 01:14pm 06 Feb 2019
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Just another thought
I did a Google search for 5A constant current supply.
Every man and his dog makes them for $3 (AUD).
They have a voltage adjust and a current adjust so with your 18V power supply, one of these and your solar controller you have a $13 smart charger.

I'll go back to bed now.

Peter
 
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