Battery Powered use for a modified compact Mac?

[iantm]

I started thinking about modern battery tech (e.g. EcoFlow or Jackery power stations) and how it might feasibly drive a compact Mac for some appreciable amount of time. Hopefully hours, not minutes, and definitely not days. For focused writing sessions.

How long would a 245Wh battery be able to run a Mac that's not primarily designed to be portable? I assume it could run a laptop for some time, but as absurd as it sounds I wanted to consider using a compact Mac for writing in a remote place. Think "cabin in the woods" more than "backpacking". Definitely not roughing it, but wanting to bring that experience with me. There's electricity in the intended use case, but I want a bit of freedom to be on the back porch.

What would be some of the better ways to optimize power use? I have a @zigzagjoe LCD mod for SE/30. I imagine that has a much lower power draw and consumption than a CRT. Currently (pun not intended) it's using the original (recapped) power supply. How much of a difference will it make a difference if I were to use a modern power supply?

Not talking about heavy gaming use. Really just writing. Yes, I recognize I could use my modern laptop, a vintage laptop, iPad, FreeWrite, or ReMarkable. But the point is more experiential than practicality.

 

[zigzagjoe]

I started thinking about modern battery tech (e.g. EcoFlow or Jackery power stations) and how it might feasibly drive a compact Mac for some appreciable amount of time. Hopefully hours, not minutes, and definitely not days. For focused writing sessions.

How long would a 245Wh battery be able to run a Mac that's not primarily designed to be portable? I assume it could run a laptop for some time, but as absurd as it sounds I wanted to consider using a compact Mac for writing in a remote place. Think "cabin in the woods" more than "backpacking". Definitely not roughing it, but wanting to bring that experience with me. There's electricity in the intended use case, but I want a bit of freedom to be on the back porch.

What would be some of the better ways to optimize power use? I have a @zigzagjoe LCD mod for SE/30. I imagine that has a much lower power draw and consumption than a CRT. Currently (pun not intended) it's using the original (recapped) power supply. How much of a difference will it make a difference if I were to use a modern power supply?

Not talking about heavy gaming use. Really just writing. Yes, I recognize I could use my modern laptop, a vintage laptop, iPad, FreeWrite, or ReMarkable. But the point is more experiential than practicality.

An unmodified machine isn't super power hungry, I measured one around 35w (@AC) without HDD. Adding accelerators and PDS cards will change this, especially if they're vintage boards, though the booster and 30video cards are very economical and only end up adding about a watt each. I never did measure the delta on the LCD panel vs the original CRT, but with some guesswork off the datasheet I come up with about 6 watts draw on the panel+backlight if brightness is all the way up. The logic board itself (+CPU, RAM, ROM) only draws around 10 watts as I recall.

Your bigger problem is conversion losses as the original PSUs are inefficient - around 60%. Retrofits are better but 80% is still pretty bad. If you wanted to improve on this, you'd want to go DC-DC so you're taking a regulated 12v out of the Jackery and feed it into a PicoPSU or similar to avoid losses from going from DC->AC->DC. I'm not a fan of PicoPSUs in vintage equipment but for your particular use case it might make sense. Note: only buy the official "mini-box" branded PicoPSUs, the knockoffs are terrible quality and you should avoid them like the plague!

All that said you should ask how much runtime you actually need, though. A portable battery usually manages around 80% efficiency especially if you're going to AC, so your 245wh becomes ~ 200wh usable. At 35w on an unmodified machine you'd get 5-6 hours of use. Might be enough?