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Comment by stcredzero | Hacker News Reader

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stcredzero·

the cost of the project needs to drop by half not the cost of the batteries

Manufacture larger self-contained units the size of a standard shipping container?

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that would be awesome, but would be one heavy shipping container..

Well, given we ship around semi-trucks full (ok not completely full due to the exact weight you describe) of lead-acid car batteries for recycling, it wouldn't be unthinkable. Li-on, I believe, is roughly 200% lighter for the same battery.

IE: http://www.powertechsystems.eu/home/tech-corner/lithium-ion-...

Not sure how that carries over to larger batteries as I've only really dealt with them for ATV type use.

40kg for lead acid equals 13.6kg for lithium so that's 66% lighter.

Is 200% lighter half as heavy, or is it buoyant? Cause 100% lighter is weightless. So 200% would be a negative weight. I am just confused.

You are correct, the link to powertechsystems.eu has those erroneous percentage calculations.

The back of my envelope says that a shipping container full of Li-on batteries would weight 192.5 tons at 2.5 kg/L compared to the maximum standard load of 30.5 tons. So it would have to be mostly empty. I don't think that makes it infeasible, though.

Make it a 10ft shipping container. (1/4th size) That should be good for a full standard load of around 30 tons, with some empty space for equipment access. Maybe redox flow batteries will win for the grid scale use case, because it could become feasible to process the solution in-situ and save a bunch of shipping weight.

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