Will a 24V 16A relay work?

Das_DIY · Mar 17, 2021

I have an inverter powered by a car battery that I use when 220V power goes off (see block 1 below). I use a battery charger to charge up the battery before I can re-use it (see block 2 below). Id like to connect these devices so that the battery is charged when 220V power is available. (A mains power switch is needed for the charger thats not shown here). A relay is required to switch from the "charge" position to supply the inverter when mains power is lost.

Will a 16A 24V relay work for this? These relays are typically found in vehicle applications. Or am I missing something? Any recommendations are welcome....

Rockingit · Mar 17, 2021

Unless I'm missing something here, isn't it just easier to run the battery charger 24/7 and use a relay on the 230 line side of the inverter??

Lucien Nunes · Mar 17, 2021

The 230V transfer switch is a whole different kettle of bananas. The OP hasn't mentioned it yet and I've avoided the issue. If it were me, I would leave the battery charger permanently connected and hack the inverter to give a remote standby, controlled by an opto-isolator from the mains. But can't really advise that to a DIY poster.

Actually, @DasDIY, how were you going to switch over the 230V AC side of things? If you are doing that manually, can't you switch the inverter on manually and save the complications?

One trick is to have all of the cable tripled up, etc, as well from source to load so in effect they form "load sharing" resistors.
But it only works well if the cable R values are a few times worst-case contact resistance, so longer the cable (within reason) the better

I do this with multipole connectors for my battery-powered equipment. One pole and core is adequate for the load, but by using two separate identical cores in the cable I can get reliable current sharing so that no contact ever carries more than half its rating, reducing heating and enhancing lifespan and reliability.