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Comment by mrgzg1 | Hacker News Reader

Having used one of these used LifePo4 batteries for my van build, https://www.techdirectclub.com/lifepo4-lfp-battery-24-volts-... I'm pretty impressed how much bang for buck I can get compared to traditional lead acid batteries. In future build's I'll resort to just using singular Nissan Leaf battery cells, give more configurability + easy to replace just a dysfunctional cell.

I see a lot of useful tools on van and boat sites, around managing non traditional batteries and interfacing them with solar panels + engine alternators. Off to a cleaner and decoupled from grid future! Micro grids everywhere.

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Careful with Leaf batteries, they used air for cooling instead of water which means that most cells show significant capacity loss after a few years.

Climate and usage dependent.

And it's not even a matter of air vs water, is between being actively thermal managed or not.

This is why the first/second generation Leaf batteries sell for REALLY cheap from used battery dealers. They're generally in poor condition. As compared to harvesting used 18650 cells in the 2500mAh range capacity from other 'used' sources, and building a DIY powerwall that way.

Indeed! More than getting ripped off on capacity, I'm super scared of using large capacity lithium batteries in general. Having seen small samsung phones blow up, I'm a little scared and have a lot of fuses and cut off switches.

To be fair, there is no real contest between a good LiFePO4 cell and some Samsung battery as thermal runaway on the former is near impossible in normal conditions.

IIRC, this is highly dependent on the climate in which they were operated. A battery used in Phoenix may have much bigger problems than one from Pacifica.

LFP is rumored to be part of Tesla battery investor day, where the LFP will be used for cheap / standard range cars at $80/kwhr at PACK level, and NMC for higher performance / longer range.

And allegedly LFP is improving density further based on some chinese rumors about CATL's advances in LFP for next year's batteries.

But there's so many rumors...

That is my guess. If you treat a LFP battery well you can probably get 4000 cycles out of it. If one cycle is 250 mi then there's your 1M.

Downsides are lower energy density and higher internal resistance, so it's probably not the battery they would want in one of those super fast Roadsters with the huge range.

Just took a look at the battery listing you provided. I have not seen someone use an actual tape measure showing the HxWxD of the product rather than just listing them. I think I prefer it.

I'd rather see the listing. Is the height 9", 10", 11"? Hard to tell because of the angle.

Agreed that having it listed is better, they do have exact dimensions in the listing as well. I was definitely shocked by how big this actually was when I picked it up in person. Not to mention that its 73Kgs! A good chunk of my van's weight budget.

May I see your van ?

I'll dig up a photo of the battery / electronics and post it here soon. To give you an overview of it: - 300W of flexible solar panels (~$90/pop, tend to get about 1.5kWh on great sunny days, enough to power my fan + fridge without having to run the van) - Victron MPPT charge controller (pretty impressed by their quality, and their app that talks to the controller over bluetooth, nothing comes close to them in simplicity of setup) - Victron battery to battery charger without ground isolation (gets triggered by engine hot signal, so I don't drain the van battery) - 2000W cheap inverter for running instantpot / magicbullet. I prefer to have DC appliances, but hard to find DC pressure cooker / mixers - couple of 12v regulators for 12vdc devices - ofc the BYD Lifepo battery, I haven't deep cycled this a ton, but my suspicion is that it's around 3.5kWH usable capacity.

I plan to add a cheap 360 camera system from aliexpress and run it off the aux battery mainly for security monitoring around the vehicle, the standard backup cams on any 2017+ vans are decent. If I get to it, it'd be interesting to get a Pi in there with OBD breakout to read in car data / gimmick.

I have a very similar system! What fridge do you have? I have an ARB.

where did you get 300W panels for $90?

I think he meant 300W total. He didn't say how powerful each $90 panel is.

There's so many different directions for jokes on this comment, but yes, I too would be interested in seeing the mods.

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