Perhaps somebody is interested to build up an overvoltage protection if the installed MPPT fails and pushes the batteryvoltage up to more than 60V.
Yes, we can buy this from Victron . But this nice piece of elektronic has a lot of other functions I dont need in my installation.
Here is my spec:
- 60 Ampere MOSFET switch between the positive MPPT output and the positive rail of my battery system
- Switch off voltage adjustable 50…65V
- self holding the switchoff state till external oder button controled reset
- external reset or shutoff control via an 10mA optocoupler interface
- signaling the switch condition via an 20mA open collector optocoupler output
My realized solution is running since some weeks, circuitboard based. Cheap and everywhere available components are used.
If somebody is interested, I will share my circuit diagram, component dimensioning, comoponent sources and Gerberfiles to order the circuit boards.
Just for explanation. My circuit is basing on a high voltage OpAmp and a standard DC SSR.
One of the OpAmp inputs is feed by a 13V reference voltage. The battery voltage is feed via an adjustable voltage devider to the other input.
The OpAmp compares the two voltages and its output controles the input of the SSR. High output of the OpAmp level is closing the SRR MOSFET switch (MPPT connected to battery), low level is opening the SSR MOSFET (MPPT disconnected from battery).
Selfholding is realized by feedback the OpAmp output to one of the inputs by which the OpAmp output is forced to go stay at low level.
With the optocoupler input you can reset the selfholding circuit or swich on/off the SSR.
The optocoupler open collectoroutput shows the state of the SSR control voltage.