They can charge what they like because you cannot shop around to get it done more cheaply, so they do.
probably would have been a fraction of that price if they were still nationalised, but then you might have had to wait for 6 years for them to do it.
Andrew
I could be - I live in Manchester, my sister lives in Carlisle. She currently has cancer and is undergoing chemo. It is quite possible that I may go there and back two days on the run. Even without the cancer, it is possible that I go there to do some DIY for her, then go back the next day with extra items/tools that I have found I need.
They typically seem to recommend 80% from what I have seen, with 100% possible for longer journeys. I think that recommendation is for high-speed DC charging though and at least partly to free up the charger, as the last 20% will charge much more slowly.
The recommendation is also for lower speed (domestic) charging. Apparently (allegedly?) the battery life is longer if you limit it to
80% most of the time.
That’s 80% battery charge, not a speed of charging. Not saying that high speed charging isn’t worse for you battery but the recommendations for home AC charging are based of charge level rather than speed.
Tim
Just rereading, I see we’re probably in agreement. Feel free to ignore my post. ;-)
Tim
A couple of weeks ago, I charged my battery to 100% at home. The last 15% or so happened very slowly. I assume to minimise battery heating,
If you find the BatteryUniversity article for lithium ion charging, the Phase1 of charging is CC, and the Phase2 is CV. Constant Voltage of 4.2V per cell, is used from 80% fill to 100% fill. The charger chip measures the current flow during this time. When the charging current falls to 3% of the Phase1 current flow, the battery is considered "full". Phase2 is the "topping charge" phase. And the reason it is "slow", is because the bias on the battery is not allowed to rise over 4.2V. If it went to 4.3V or 4.4V, the battery would likely catch fire. This is why "precision chargers" is the name of the game, with lithium. You cannot make mistakes while charging.
So what the charger is doing during Phase2, is it is taking the battery to absolute max voltage, and the declining current flow value is a way of the battery saying "geez, I'm full".
If you take the bias (the charging) off the battery, the cells relax on their own to 3.7V. This is their "nominal voltage", "not being force-fed" value. For as long as the battery is held (unnaturally) at 4.2V, that "hurts" the battery. Owwy.
the battery also has a preferred temperature range. Batteries can go into thermal runaway, but there is usually some additional factor about the design ("Bad" quality cells, lithium metallic particles), that contributes to a fire. While you could cool a battery and stop that, you'd need a ton of liquid nitrogen or liquid helium to calm the cells down. And not a lot of materials like to be "shocked" by being hit with cryogenics. When there is a fire, the fire department may dump water on the materials, but this is to reduce the level of conflagration, rather than completely stop thermal runaway.
Some cars have a heat pump, and at around 20-30%, the heat pump comes on and cools the battery to 35-40C or so. Before charging starts, the heat pump is reversed and is run at a heater, to bring the pack up to room temperature (higher than outdoor winter temps). A good car design, thermo-regulates during charging.
When you own a BEV, some thought should go into where it is parked... And this is DOUBLY the case, if there is a recall notice, where the manufacturer intended to change out every stinking battery pack, because of a fabrication defect. When that happens, you park AWAY from the house :-) You even have to be careful about adjacent trees. I have a tree, if a fire started next to it, it would turn into a towering inferno. And potentially ignite my neighbours house.
I would expect a good car design, when you're setting the level on the LCD screen, the "help" information should be explaining the way to get the best life from the battery pack. Initially, the manufacturer cares, because of the "battery warranty", but after that, the owner cares about battery life (like, if it affected resale value).
Fast charging with high power DC chargers, seems to have some stress component to it. At least one car, the computer actually "denies" fast charging, if you do it too many times in a row. I would expect any normal car driver, to be "incensed" when this happens. The Porche Taycan, apparently does not do this. So they are "eating" the battery life penalty and battery warranty, because of the elevated sticker price of the car. But on econo-boxes, I would expect the charging scheme to be "pretty tame" so the battery warranty claims will be reduced. Your 7kW charger at home, is beneficial from several points of view. Nice.
And the thing is, Lithium is a damn fine chemistry. These "rough edges" it has got, are nothing compared to the runners-up in the battery chemistry contest. There are battery choices that would downright suck, by comparison. For example, the silver batteries they are experimenting with, right now are only good for 1000 charge cycles. Which isn't enough for a car. And they will not ship those, until that number can be improved.
Paul
No. It isnt like that. You were doing well up to that [point.
3.7V is the AVERAGE voltage on a cell. It starts at 4.2V and gradually drops to around 3.3v when its fully discharged and any more will damage it. At highre loads the voltage my go lower due to internal cell resistance.
Just bung a nail in there in place of the fuse and save all the expense. Can't go wrong.That's a dodge I learned back in the old days before all this 'elf n' safe tea nonsense came in. ;->
The info on the site varies a bit. The time scale here is deceptive.
This is medium term. This shows you're right. 7mv/day apparent self-discharge by the looks of it. This is in the enhanced self-discharge article.
"Lithium-ion 5% in 24h, then 1–2% per month (plus 3% for safety circuit)"
So by that declaration, it is 95% full after 24 hours.
*******This one uses a different statement.
Is the -7mv slope the relaxation, or is it self-discharge ? Maybe the drop from 4.2V (CC phase) to 4.153V is the previous paragraph "relaxing" thing.
From BU-409
"Estimating SoC by reading the voltage of a charging battery is impractical; measuring the open circuit voltage (OCV) after the battery has rested for a few hours is a better indicator."
But then using their table of values, the cell is no longer at 100% at that point.
So then, the marketing voltage of 3.6V per cell ("a 14.4V pack") is actually a half full or less cell. And not really a nominal voltage.
It would have been less confusing if the nominal was 4.153V, as it'll just keep self-discharging if left to itself. Leaving the chemistry with no characteristic voltage.
Paul
I have been using - and abusing LIPO cells for nearly 20 years in model planes.
There is a sort of surface charge - you get about 15 seconds of peak power then it settles back to a long slow degradation of voltage before falling off a cliff at the end of the discharge.
Self discharge is pretty negligible. I think it would be rare to see a pack lose half its charge even after a year in the drawer.
What is more true is that they lose capacity after only a few cycles at the sort of power levels we use.
People who ran then dry in 3 minutes in ducted fan planes, would dump the pack after a year at best.
But 30 weekends of maybe 15 charges per weekend is 450 charge discharge cycles.
Car seem similar, at say 100 miles per charge 450 charges nets you around 45,000 miles.
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