[quote=“svdv”]Thanks danf, I understand.
But I’ve got a 15V PSU 320W already (MeanWell RSP-320-15 with rated current 21,4A). I understand I need 346W so my PSU is 26W to weak, but what will happen if I use this only for the heatbed? And with the Power Expander (or even 2 in parallel)? And with the use of 14AWG silicone wiring.
Or should I go for 24V anyhow to make it safe and solid without risk of overheating the PE?
The smell of a burned PE is disgusting and stay’s around the printer for several weeks. Got it twice and I don’t want a third one
So, I am looking forward to your answer and than it’s time to decide what to do…[/quote]
The RSP-320-15 is adjustable between 13.5 and 18 V. If you’re only using it for the heat-bed, then lower the voltage to its lowest. Verify using a volt meter. Your max current draw will then be 13.5/.65 = 21 A consuming 280 W (it will drop as the bed heats up). This is over the power expander continuous rating, but you might get away with it. Have air blowing over it, like Jansinger in this thread. Might be wise to check with reprap.me. I wouldn’t use the screw terminals however, but solder directly like the fourth picture on http://reprap.me/power-expander.html.
Your previous power expander cards, how did they fail/burn more specifically? Concentrated to any specific component?