I have a circuit which connects two 6v 10ah batteries in parallel to two motors which together draw ~2A. This circuit has a DPDT switch which I would like to replace with a DPDT relay and have the Raspberry Pi drive the switching.
When doing my research, I came across different types of relays with various terminologies and different ways of using them.
What are the different types of relays ? (SSR, DPDT, SPDT, Mechanical, Electromagnetic etc.)
Do relays and switches always correspond to each other ? e.g. if there is a DPDT switch, then there is a corresponding DPDT relay ?
What is a difference between a Signal relay and Power relay ?
What is coil voltage/current vs contact voltage/current ? e.g. if a contact voltage is listed as "120VAC/0.5A, 24VDC/1A" can I still use it to drive motors which draw ~2A with a 6v 10ah battery ? Are there standard ratings that relays always come in ?
When do we need to use a transistor instead or along with a relay ?
Note : I have been through quite a few questions on this community and others. I am open to modify the question iteratively to refine if required.