8 Channel Relay Voltage Drop Issue

I have recently been working on a retro pi arcade cabinet and decided it must be home assistant controlled because why not? It’s controlled with a Wemos D1 Mini running ESPhome and a 5v, 8 channel relay board. I am only using 6 channels of the relay board, controlling a monitor and marquee light (120v ac), 2 sets of 12v LED strips, speakers (12v), and the raspberry pi running retro pi (5v). My issue is that the DC loads seem to be suffering from crazy voltage drop across the relays. The pi comes up with the lightning bolt symbol even if I disconnect the USB hard drive, which it didn’t before (2.5A power supply has always been just fine). I’m also seeing the voltage drop with the 12v loads. I have used this relay board before with only 120v loads and had no issues at all. I’m wondering if anyone has experienced similar issues or knows of a workaround. Final note-- all wires are hooked up to the relays with ferules – not sure if that would make a difference.

You haven’t posted any detail (ie: make/model) of the relay board and there are LOTS of them on the market. Sounds like you have a poorly made one of the relay resistance is high.

Put a meter across the relay contacts (at the terminals you connect to) and measure the resistance. Secondly you could try measuring the actual volt drop.

Unfortunelty it has no identifying marks other than “8 Relay Module”. Contact resistance seems to be all over the place on the different channels, ranging from 4 ohms to about 3.8megaohms. I think I’m just going to have to order a new one – do you know any reliable brands other than the cheap china junk?

Yeah those values are really bad, even the 4 ohms. 3.8 meg is essentially open circuit so there is definitely something wrong there.

What country are you in?

I’m in the US

Unfortunately I don’t know of anywhere in the US but you could likely use Amazon I guess.

Another idea I just had is to ‘wet’ the solder joints on your existing relay board as you may have dodgy connections. Use your soldering iron to simply melt the existing solder on the connections for the relays and terminal strip.

I may give that a try. Otherwise I’ll just buy new from a more reputable seller. Thanks for your help