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the dark side of cobalt

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Siwastaja:

--- Quote from: tom66 on July 12, 2023, 04:33:33 pm ---The neat thing about bidirectional inverters is the capability usually comes for free once you replace the input diode bridge with a synchronous rectifier.  The power stage is usually a full bridge topology, with a synchronous output rectifier, and the PFC will often have a synchronous switch too.  All of these devices are used to improve efficiency and reduce cooling requirements.  At 7kW it makes a real difference.

This is what the MG4 charger does: it's a fully synchronous design, so it can charge the car at 7kW and discharge at 7kW too.

--- End quote ---

Yeah. There is extra work from anti-islanding and safety considerations, but those can be borrowed from PV inverter designs. PV inverters took a lot of time to become truly affordable, but that happened eventually.

nctnico:

--- Quote from: mikeselectricstuff on July 12, 2023, 12:21:33 pm ---
--- Quote from: nctnico on July 11, 2023, 08:39:42 am ---Secondly using a car's battery as storage means using a battery in a way that it hasn't been designed for and you'll be wearing the most expensive part of the car without getting the monetary value for that wear. The idea is similary stupid as using solar roadways to heat roads in the winter. The power companies love it though because it means a free lunch. No, it is making money with a lunch on top for them.

--- End quote ---
That has been debunked by trials in the UK - the charge rates and levels were shown to have no negative impact on battery lifetime, and in some cases actually improved things by keeping the battery in its most healthy SoC range for more of the time.

--- End quote ---
That is not possible. Just check the warranty specs on any Li-ion battery. It will tell you a maximum amount of stored energy that is guaranteed not to degrade the battery to a certain percentage. Ofcourse you can get lucky and have a battery that performs better than advertised but you can also be unlucky. With ever improving manufacturing technologies, battery manufacturers will become better and better at making their battery as worse as they can and still meet the specifications. And if you think about it logically, it makes perfect sense. Otherwise the ever lasting Li-ion cell would have been invented a long time ago. IOW: the trial data is anecdotal evidence at best but not something to rely on.

Siwastaja:
Car manufacturers work with li-ion cell manufacturers and get their own warranties, as manufacturers know their products better than the simple public datasheet says. Rest assured, we understand what we are doing even if you don't.

mikeselectricstuff:

--- Quote from: nctnico on July 12, 2023, 05:23:33 pm ---
--- Quote from: mikeselectricstuff on July 12, 2023, 12:21:33 pm ---
--- Quote from: nctnico on July 11, 2023, 08:39:42 am ---Secondly using a car's battery as storage means using a battery in a way that it hasn't been designed for and you'll be wearing the most expensive part of the car without getting the monetary value for that wear. The idea is similary stupid as using solar roadways to heat roads in the winter. The power companies love it though because it means a free lunch. No, it is making money with a lunch on top for them.

--- End quote ---
That has been debunked by trials in the UK - the charge rates and levels were shown to have no negative impact on battery lifetime, and in some cases actually improved things by keeping the battery in its most healthy SoC range for more of the time.

--- End quote ---
That is not possible. Just check the warranty specs on any Li-ion battery. It will tell you a maximum amount of stored energy that is guaranteed not to degrade the battery to a certain percentage. Ofcourse you can get lucky and have a battery that performs better than advertised but you can also be unlucky. With ever improving manufacturing technologies, battery manufacturers will become better and better at making their battery as worse as they can and still meet the specifications. And if you think about it logically, it makes perfect sense. Otherwise the ever lasting Li-ion cell would have been invented a long time ago. IOW: the trial data is anecdotal evidence at best but not something to rely on.

--- End quote ---
It has to be way more complex than simply Wh charge/discharge, e.g. rates, tempeartures and avarage SoC

https://www.current-news.co.uk/v2g-found-to-improve-the-lifetime-of-electric-vehicle-batteries/

nctnico:

--- Quote from: Siwastaja on July 12, 2023, 05:43:10 pm ---Car manufacturers work with li-ion cell manufacturers and get their own warranties, as manufacturers know their products better than the simple public datasheet says. Rest assured, we understand what we are doing even if you don't.

--- End quote ---
Ofcourse, and every car manufacturer will try to make a product that just lasts long enough for the customer to be happy under normal usage circumstances. V2G is like having your ICE car run stationary to power your home from the alternator. It will cause wear on the engine. Maybe less because the engine runs at a sort of constant, low load but nevertheless you'll be reducing the remaining distance you can travel with the car without having the do repairs on the engine and surrounding systems. And it could be benificial in some cases to run the engine really warm when a car is used mostly for short trips but in the end wear is wear. Or maybe I should compare it with licking a lolly. A single lick doesn't seem to reduce the size but after enough licks, the lolly will be gone. Again, the ever lasting Li-ion has not been invented yet (AFAIK) so don't pretend it exists. You know better!

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