There is a voltage drop penalty for using solid state relays.  According to the data sheet it is .64 V.   If the load on the device is 10 amps that’s 6.4 watts being dissipated as heat.  Since it appears that the voltage drop remains constant regardless of the load, then the more current you pull through the device, the more power is wasted.

I like the mechanical contactor because there is only the wiring losses that have to be dealt with.  When you have an alternator go out, having the battery heat up your solid state relay starts to feel like a waste.

Kevin

I am doing the wiring of my Legacy and would like the group's advice on the use of Solid State Relays like SSRDC50V80A Relay Datasheet    

or a traditional mechanical contractor like a Cole Hershee 24115.

They are about the same cost, and handle the same load but are there other reasons why I haven't  seen the SSRs used. I am using the Vertical Power VP-X which makes extensive use of Solid State Relays so I wonder if their time has come and I should design the power distribution with SSRs?

Stan Fields

L2K - 201

Austin