That’s actually an ingenious idea I hadn’t thought about. How much cheaper are these batteries once they’ve been retired? Would this be a viable option for someone running solar at home, and wanting to store the power for later use, or is a home battery still the better option?
this post was submitted on 20 Nov 2023
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A 50 KWh or more battery pack will be overkill for most homes. But those will likely be available for cheap soon so it might still be a good option. Putting a pack that weighs several hundred kilos in your basement might be difficult, though.
Yea, with a car you can't really use them once the range gets low enough
With this, a bunch of batteries can work together for much longer. You also don't need to worry about weight since they're in one place
A Tesla Model 3, for example, has a battery capacity of 50 to 82 kWh. Let's assume the lowest capacity of 50 kWh. A car battery is basically unusable long before it has lost around half its capacity. So 25 kWh. American households on average consume 10.6 MWh annually or about 29 kWh per day.
So an old Tesla battery still provides enough electricity to power an American household for nearly an entire day.
Really puts into perspective what a monumental waste of energy individual traffic, also with electric cars, is as well.
Well, sort of, it's just that any sort of locomotion requires a lot more energy than you might think.
Yeah sure. But there's a difference between moving a 2 ton vehicle per person or a bike.
I'm assuming that doing full charge/discharge cycles on them daily will put more wear on them than every day driving would?
But if your buying them at scrap value and the. Still selling them as scrap after a few more years I guess it works out.
The way lithium batteries work, they wear out less if you only discharge and charge them slightly. So a battery that is charged to 60%, discharged to 40%, and repeated like that will keep most of its capacity even after years of prolonged use. On the other hand, charging a battery quickly, until it is full, or discharging it until it is nearly empty will reduce its capacity over time.
A Tesla Model 3 has a battery capacity of at least 50 kWh. Even if it has lost half of its capacity, the 20% capacity difference between 60% and 40% charge, or more realistically, the 50% difference between 75% and 25%, still represents 12.5 kWh of capacity. Suppose you had an array of 1,000 such batteries. That would represent 12.5 MWh of storage capacity, enough to power ten thousand homes (at 1.2 kW each) for an hour. Certainly nothing to sneeze at.
This flies in the face of everything I thought I knew about charging my phone & laptop
If you have an android there should be a "protect battery" mode that literally caps the charge at 85%
I honestly thought once it got to 100% it stayed mains powered until unplugged to stop overcharging. Never realised 85% was optimal.
The voltage of a Lipo corresponds to it's charge level. So a Lipo at 4.2V (or in case of high voltage Lipos 4.35V) is full.
Up to ~80% of the charge, the lipo is charged by current limiting (basically, the voltage of the charging circuit raises so that it stays so much above the cell battery that it's charging at a set current). This is the fast charging part of the charging process.
After the charging voltage reaches the maximum allowed cell voltage (4.2V/4.35V), the charging circuit cannot go above that voltage because it would risk overcharging and blowing up the cell. So the carging circuit holds the voltage at maximum level until the cell voltage catches up. Since the voltage difference shrinks with every bit of charge on the cell, so does the charging speed.
That's why you only see "Charges the phone from 0-80% in X minutes" in the ads, and not 0-100%.
This means, that the charger in incapable of overcharging the phone.
But keeping the charger running even though it doesn't charge the phone anymore wastes energy, so what they do once you reach 100% is that it will disable the charger until the voltage is down to 95%, when it will resume charging. That's why it's quite likely if you unplug the phone after charging overnight, that the battery is not at 100%, but slightly below.
The old rules applied to nickel batteries or whatever the last gen was called.
NiCd was the one with the bad memory effect that required full charging cycles. They where also really toxic which is why they are illegal in many countries now.
NiMh hardly had any memory effect left, but would degrade comparatively quickly.
Li-Ion/Li-Po is what we currently have. They don't like to be full or empty for long times and like shallow charging cycles.