A Forum run by Enthusiasts of MidNite Solar

Charge Controllers and Clippers => The "Classic" charge controller => Topic started by: binkino on April 16, 2016, 12:01:50 PM

Title: Relais on AUX1: Add a diode? a cap?
Post by: binkino on April 16, 2016, 12:01:50 PM
ref. the manual, AUX1 can support 12V 200mA outrput

actually I switch a small 12V relais, that switches a big 230V relais, so I can switch on/off the Westech 3000 Combo inverter in its AC line (grid fallback if battery is low)
(can not adjust the low-bat point and at wich voltage the inverter has to go back to batterie instead of grid.)


Now I want to replace this provisional now finally by a better solution.
Found this: http://www.ebay.de/itm/111222002690

coil volts: 12V DC/AC (9,6-13,2V)
energy for coil: at 12V DC/AC = 165mA

165mA is below 200mA max., so that looks okay.


The AUX1 switching this 2 times per day



Is it recommended to add to the coil a "reverse diode" or/and a cap in parallel to the AUX1 connector, to protect the Classic?

Or does the Classic allready have this or a similar protection?

Title: Re: Relais on AUX1: Add a diode? a cap?
Post by: australsolarier on April 16, 2016, 09:37:41 PM
i always put a diode to a relay. i use  1N4007, 1000V/1A.  they are very cheap.

there is a lot of information on googles about it.
Title: Re: Relais on AUX1: Add a diode? a cap?
Post by: TomW on April 17, 2016, 11:16:13 AM
Pretty good info here:

https://en.wikipedia.org/wiki/Flyback_diode (https://en.wikipedia.org/wiki/Flyback_diode)
Title: Re: Relais on AUX1: Add a diode? a cap?
Post by: TomW on April 17, 2016, 11:19:15 AM
Boils down to this:


(http://www.douglaskrantz.com/files/ElecFlybackDiode/Diodeconductpolarity.jpg)
Title: Re: Relais on AUX1: Add a diode? a cap?
Post by: binkino on April 17, 2016, 01:29:31 PM
Quote from: TomW on April 17, 2016, 11:19:15 AM
Boils down to this:


(http://www.douglaskrantz.com/files/ElecFlybackDiode/Diodeconductpolarity.jpg)

ehm if I connect the diode like in your schematic, it will blow - itselfe or the classic (short circuit, and no Johnny will come around haha)
positive will flow thru the anode to the negative pole

the doide must be connected reverse.
anode to negative and kathode to positive of soucre power
so if the coil "unloads" (just don't know in english) after release the power for the coil, the energy will be "catched" by the diode



thanks for all links ;)

I know about that, thanks ;)

only interesing, if the Classic needs it.

But will add it, safe is safe ;)

Title: Re: Relais on AUX1: Add a diode? a cap?
Post by: TomW on April 17, 2016, 01:58:33 PM
Mea Culpa.

I just grabbed the wrong picture.

It depicts the polarity of the collapsing field. (Those arrows pointing in towards the coil) When you remove power it induces a current in the coil in reverse from the original energizing field.

Sorry but this is why giving advice is so hard in this field.

You never know the ability of the person(s) who will use it and it is hard to find a balance between not enough and too much info.

Tom
Title: Re: Relais on AUX1: Add a diode? a cap?
Post by: binkino on April 17, 2016, 02:44:17 PM
all ok :)