I have a Victron temp probe connected to the negative on a battery and tbe temp side of the cerbo. I’m told the 12v 100 watt heaters are too much for the cerbo relay #2.
The goal is to have the cerbo turn on/off the heaters at certain temperatures.
Any suggestions fir the best way to do this?
Thanks
Use an additional 12V relay, that can handle the current, powered by the Cerbo’s relay to drive the heater.
For example a 12V / 25A relay or any similar or bigger automotive relay.
As @alexpescaru said, but make sure the relay has flyback protection otherwise surge current switching the relay may damage the Cerbo relay.
Thank you for this info. All makes sense.
I put battery heaters from UltraHeat.com on my 48v battery. Four heating pads total. Two heating pads on each of the two 8s column of cells. The current draw from the heaters would have been a little too close to what the Cerbo GX relays were rated for. So I put in two relays that are rated for 60v in and 60v out. I already had a DIN rail breaker box and the relays were added to that with a bit of tweaking (the relays are taller than standard DIN rail breakers).
Phoenix Contact makes a variety of relays for different voltages. Here’s a link to the one I used.
FWIW, when I added a warming system to my 12v DIY LiFePO4 batteries in my prior system, each heating pad was rated for 1 amp. One pad on each of the long sides of the battery. When it comes to warming the batteries, low and slow is better than hot and fast.
The same wisdom applies to BBQ 
Each of the numbered items on the relay are a terminal that a wire gets connected to. What the diagram doesn’t show is the negative feed to your device. The negative is not switched, only the positive.
So no, the yellow/blue wires do not connect to each other externally (outside the relay). The relay connects them internally when you turn on the switch.
Be sure you know if the relay is Normally Open (NO) or Normally Closed (NC). It matters.
I believe that Normally Closed is typical and doesn’t change anything.
Thanks Jim
If I understand correctly., I don’t connect the yellow wire to anything. The rest I understand where they go.
Based on the diagram and my experience with 12 volt relays, there isn’t a yellow wire to do anything with. It’s inside the relay. The drawing at the bottom of your screenshot may be less confusing as it simply shows the connections to be made to the terminals. The numbers on both diagrams would be the same.
