With the recent launch of Furuno XL and the new charting options available I decided to add a Lenovo Tiny PC. Going to run Nobeltec Timezero to one of my Furuno TZT3 displays. Doing a integrated computer is new to me so need some advice on sizing power. The Lenovo has AC power supply and the input voltage is 20V. While I always have generator running I would like to keep my navigation and electronics independent and not have a hiccup if offshore and generator is turned off. So I plan to run a Victron 24-24 converter which has the ability to be set to output 20V. What I am needing advice on is how to determine what size to install. The power supply that came with the computer indicates 90W so based trying to determine what size converter to size correctly. I get a 24/24 -17 400w or 24/24-12 rated at 280w or 24/24-5 rated at 120w. When I tune the output voltage to 20v I assume some power is reduced. If oversized could that hurt Lenovo computer? Would appreciate any input on sizing correctly.
20 volts at 90 watts is not much, around 4.5 amps. As you adjust the voltage up down, the amps available will change. I don't think that lil computer will draw more than a couple of amps so the small unit would work. My next concern would be heat dissipation and ruggedness. As Mfg's build things to supply more power (watts) they improve the gizmos cooling. I would consider a larger unit for these thoughts.
Your approach sounds fine and should almost work. From those options I'd choose the 24/24-12 which will supply up to 240W @20V. These converters are current limited so max power is dependent on input/output voltage. There is no need for an isolated version in this application. It's not really oversized as the load will only take the current it requires. I said almost because the issue has always been those square tips they've been using on thinkpads for years now. The only way to get one AFAIK is to cut one off a perfectly good ac-dc power supply. I'm still running mine through inverters
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