Tales of an Assembly


levi

Still fresh, damnit!
Joined
Oct 6, 2008
Messages
13,538
Location
Somewhere off the coast of the EU
If it is not a generic charger (cheapest option), it would be interesting to be able to set a maximum charge capacity, because batteries charged to 100% downgrade, it is bad for battery. For example good electric cars only charge to 80% (when they say "100%" and stop charging they charge only to real like 80%; the same for discharge, it is best to stop discharging at 20%, as with this battery last a lot of time; of course, hot is also bad).
Most electric cars allow you to set a limit (such as 80%) when you're fast charging. I get the impression this doesn't apply when you're home and charging on the half-dozen* kilowats that comes down your one-phase ring main, but I'm not sure how much manual intervention is required in this situation.

But I get the impression that you only need to be careful about overcharging a battery when you're using some super charging solution. When you're using plain old USB2 I'm not sure it matters so much if you go closer to full. Computer charge circuits also learn where 100% is based on use, and it's not the same as 100% of the battery's actual chemistry. You can get the Pandora's battery to go a few ticks above 100% when charging it ISTR.

* I hear talk of 7kW bandied about, but I make one 13amp 230/40 ring main to carry about 3kW so I'm not quite sure how these home boxes are connected. Maybe it's on a 30A cooker fuse? That seems about right.
 

Djoga'Ro

moonstruck
Joined
Apr 3, 2016
Messages
1,708
@levi Charging current is one aspect of battery degradation - if it causes a lot of heat, the battery ages faster.
A LiIon battery for instance is considered full, when its voltage is at 4.2V, btw. And they wear more per time the fuller they are. For this aspect charging speed or charging at all is irrelevant. That's why some charge their devices only to 80%.
 

ible

professional vim user
Joined
Mar 24, 2014
Messages
2,467
Location
Seattle, WA
Most electric cars allow you to set a limit (such as 80%) when you're fast charging. I get the impression this doesn't apply when you're home and charging on the half-dozen* kilowats that comes down your one-phase ring main, but I'm not sure how much manual intervention is required in this situation.

at least for Teslas, you set the limit ahead of time, and that's across the board (home/superchargers/anywhere). on trips you can set it at 100% if you like, but they'll remind you to set it lower for day-to-day use if you keep it there for a few days.

although, depending on if the supercharger is busy, they may set your limit back to 80% (you can manually increase it back to 100%, but i think this is active only for that charging period -- it'll go back to what you had before maybe??), which is a good default to keep the flow rate up.
 

oskda

Very Active Member
Joined
Mar 29, 2015
Messages
301
Most electric cars allow you to set a limit (such as 80%) when you're fast charging. I get the impression this doesn't apply when you're home and charging on the half-dozen* kilowats that comes down your one-phase ring main, but I'm not sure how much manual intervention is required in this situation.

But I get the impression that you only need to be careful about overcharging a battery when you're using some super charging solution. When you're using plain old USB2 I'm not sure it matters so much if you go closer to full. Computer charge circuits also learn where 100% is based on use, and it's not the same as 100% of the battery's actual chemistry. You can get the Pandora's battery to go a few ticks above 100% when charging it ISTR.

* I hear talk of 7kW bandied about, but I make one 13amp 230/40 ring main to carry about 3kW so I'm not quite sure how these home boxes are connected. Maybe it's on a 30A cooker fuse? That seems about right.

Fast charging is only fast until certain %, after that it goes down progressively.

About charging until near real 100% battery or discharge near 0% real capacity, it is an "extreme" action, bad for battery longevity, but allowed because it is best to do some more age to battery than get stranded somewhere in a road.

For example Chevrolet Volt (in EU Opel Ampera) is an EREV (or REEV), it is an electric car with a small battery, like 16 kWh total capacity, which only uses about 10 kWh (and with that small battery there are Volt with more than 400.000 km and battery is perfect, so they know how to protect/handle charge/etc). It never charges more than 80% nor discharge more than about 20%. When you see 0%, it is like real 20%, and when you see 100% it is like real 80%. The difference is that Volt, as EREV, has a gasoline generator, so it doesn't let you stranded, and it doesn't need to age battery discharging near real 0% or charging near real 100%. In a pure, only battery, EV (BEV) you don't have that chance and they let you stress/age battery in those exceptional cases, but it isn't good for battery.

Volt/Ampera battery always charge at low speed: maximum 16A (like 3600W) in a charge point. In home with a standard EU shucko (a domestic socket standard for most EU) it only charges at 10A (2300W, as voltage is usually 230v in public lines). In US it may be slower because voltage line is lower.

Tesla rely on a very big battery (a Volt has much more battery cycles on its life, if it is used mainly as EV), but charging and discharging near real 0 and real capacity is bad for battery. if you do it all times, as we do with smartphones, battery would age much much faster.

On other side Tesla and Volt has excellent battery cooling, while smartphones and Pyra don't have, so our batteries not only suffer from near 0% discharge and near 100% charge but from heat while using for battery itself (it gets heat when charging and discharging) and for heat produced by other components in device.

If you look at a Li battery advice, you will see it is better not to charge 100%, but well below, and not discharging to 0%, but well bellow, and get a proper cooling so it is at adequate temperature. Obviously Tesla and GM know about that condition.
 

Phlyra

Electric
Joined
Jul 25, 2019
Messages
487
Fast charging is only fast until certain %, after that it goes down progressively.

About charging until near real 100% battery or discharge near 0% real capacity, it is an "extreme" action, bad for battery longevity, but allowed because it is best to do some more age to battery than get stranded somewhere in a road.

For example Chevrolet Volt (in EU Opel Ampera) is an EREV (or REEV), it is an electric car with a small battery, like 16 kWh total capacity, which only uses about 10 kWh (and with that small battery there are Volt with more than 400.000 km and battery is perfect, so they know how to protect/handle charge/etc). It never charges more than 80% nor discharge more than about 20%. When you see 0%, it is like real 20%, and when you see 100% it is like real 80%. The difference is that Volt, as EREV, has a gasoline generator, so it doesn't let you stranded, and it doesn't need to age battery discharging near real 0% or charging near real 100%. In a pure, only battery, EV (BEV) you don't have that chance and they let you stress/age battery in those exceptional cases, but it isn't good for battery.

Volt/Ampera battery always charge at low speed: maximum 16A (like 3600W) in a charge point. In home with a standard EU shucko (a domestic socket standard for most EU) it only charges at 10A (2300W, as voltage is usually 230v in public lines). In US it may be slower because voltage line is lower.

Tesla rely on a very big battery (a Volt has much more battery cycles on its life, if it is used mainly as EV), but charging and discharging near real 0 and real capacity is bad for battery. if you do it all times, as we do with smartphones, battery would age much much faster.

On other side Tesla and Volt has excellent battery cooling, while smartphones and Pyra don't have, so our batteries not only suffer from near 0% discharge and near 100% charge but from heat while using for battery itself (it gets heat when charging and discharging) and for heat produced by other components in device.

If you look at a Li battery advice, you will see it is better not to charge 100%, but well below, and not discharging to 0%, but well bellow, and get a proper cooling so it is at adequate temperature. Obviously Tesla and GM know about that condition.
Do you know anyone who has better experience with a Toshiba SCIB-based EV?
 
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