Trying to work out best option for switching 48v loads. id like to be able to trigger loads via vrm.
Loads I’m trying to connect are:
Heating Pad (dump load, attached to hot water vessel): 48v 300w 7a
Hot Water unit: 48v 1500w 32a
Under floor heating 48v 100w 2a
Looking at specs on CerboGX and I/O extender (i currently do not own the extender, but will purchase if needed), but all these loads exceed the maximum current/amperage of the internal relays.
So, my current idea is to use the internal relays to trigger an external relay,(possibly with an external switch triggering digital i/o then triggering cerbo relay, but that’s a whole different question). this seems clunky and i am wondering if there’s a more streamlined way to achieve this? can the digital i/o on the cerbo trigger a relay? is there a aftermarket accessory that switches 48v loads? i.e shelly or SmartSwitch DC4(cannot switch 48v loads unfortunately,)
You can have a look at the battery protect. They have a remote input that you can control with the Cerbo. I use them for switching loads around the boat on a 12V system and use them for protection against high voltage from solar panels, etc. I did break one switching a 900W 12V to 24V booster. Resistive loads should be ok.
Having suitably sized external relays is the traditional method of boosting (plc) relay capacity. This also applies to Cerbo, Gx and other similar products. The alternative is to low or high side switch using power mosfets, also driven by the relays or possibly the digital outputs. Relays do give more isolation in case of faults.