question

I didn't want a daisy chain the wiring so I can keep the relay turned off on the temperature controller. And I'm really not interested in purchasing more stuff when I already have everything I need. To use t-sense I assume I would have to buy more equipment. And as stated earlier, the charger turns off on a multiplus fine. I just need to signal the BP to disconnect so solar power so they don't charge the batteries. Is it not possible to program aux 2 to shut off the BP when aux 1 is closed?

Alexandra.

Thank you for the response. I bought this multiplus about maybe 6 yrs ago. I don't recall it coming with a temp sense and even if it did, I couldn't tell you where it is anyway. I was running it on a tesla medel s battery module connected to an electrodacus bms but decided to go with something safer (lifepo4). I also placed a BP between the MPPTs and the battery and would still need a solution to stop charging from solar anyway. Regards.

In the manual, Appendix A is:

Terminals for: (left to right)
Voltage sense
Temperature sensor
Aux input 1
Aux input 2
GND-relay
Starter battery plus + (starter battery minus must be connected to service battery minus)
Programmable relay contacts K1
Programmable relay contacts K2

If I understand this correctly, I have 2 programmable relays, k1 & k2 and need to use one of those. So I moved the the wires to k1 nc & com as the solar should be normally charging, changed the "Programmable relay" setting to use k1 and stil will not turn off the BP.

I'm sure you're aware of this but I'll ask anyway...just to tick the box

Are you aware that the K1&2 relays are open collector style, and aren't wired like a normal relay?

Here is a pretty good description and schematics of how you would go about wiring up the k internal relays.

The load mentioned on the schematics would represent the coil of an external relay.

So even if the programming code logic you have written is correct, without the wiring correct it wont work.

Minimum you would need is an external relay, sized to your needs.

BTW....any switch can be replaced with a relay, so going by what others have shown above, you could replace the remote switch on the BP with the contacts of a switching relay, and the coil operation done by one of the k internal relays of the multi.

Any chance of seeing a schematic of your system

Screenshot_20240510_135857_Firefox.jpg

The optional on/off switch on this schematic can be replaced with a relay that you program one of the internal k relay to switch. This would then turn the BP off and isolate any dc load (read inverter or battery or both depending on what relay you use)

1. First off, yes the BP turn off function is quite acceptable to do what you want. I assume in the guts of the device is an SSR......although dont quote me on that

The two images attached show you the logic you want

The first image shows your connection from the temp controller to the aux in terminal.

When the temp reaches your setpoint, the relay on the temp controller closes. This closure connects a 5v signal to an interrupt port on a microcontroller inside the multiplus which performs the function set by the assistant. You have this wired correctly and is why it works.

The second image, while not showing exactly your situation, will explain the operation you need

The circuit shows a fan connected via K1 NO and COM, to a battery and will turn on and run when K1 is switched.

What you need is a simple switch across the BP terminals, that once closed will isolate the Input from the Output terminal resulting in a disconnection of the mppts from the battery.Screenshot_20240727_085029_Chrome.jpg