Electric cars again

[Bob Eager]

[ARWadsworth]

:-)

[John Rumm]

Its a common problem with lots of modern battery technologies - they must never be left to go flat, and have high auto discharge rates.

[Bob Eager]

I think the point of the article is:

a) the high cost b) no way of insuring the loss c) the 'secret' tracking by Tesla

[Andy Bartlett]

If you want to see what a liability owning one of these beasts is, have a look at the roadster manual:-

[Martin Brown]

I think it is the batteries own self discharge rate in the pack that is the problem here and not the permanently on power subsystems. They just deliver the coup de grace at the end taking it into unrechargable brick state. In other words the no self destruct protection is activated.

Some of my camera batteries have about the same lifetime ~11 weeks on the shelf if left unused too. It is faintly annoying but they are cheaper to replace if they get wrecked. Most of my portable PCs batteries die a horrible death in 3-5 years of near continuous use.

What might be an issue is that most sensible standby electronics switches off when the battery gets too close to its death zone.

In the case of the Tesla it should probably sound an alarm or send a "Charge Me" text to the owner or something when the battery is close to becoming a brick. The only sensor needed is a low battery alarm!

I cannot see how the addition of 100ft extension cable that was not running hot could decrease the charge rate to a point where the car could die whilst being on charge. The pack is nominally 375v and 50kWh so delivering 3A for an hour would put 1kWh into it and 1A would be more than enough to hold it. I suppose it is possible that the charger is too clever by half and sees even a small resistive load in the cable as nearly charged battery. You do have to be very careful with Li-ion cells as their tendency to self immolate if overcharged is notorious.

Here is Telsas own more flattering description of their battery:

reckon it is far more likely that the idiot user unplugged it!

[Bob Eager]

I think there is one. The issue is if the car is parked unattended, and discharge is faster than expected. The example given was an airport car park and an extended trip away.

[Tim Watts]

charged, the Battery?s charge level can drop as much as 7% a day and 50% within the first week. When the Battery?s charge level falls below 50%, the rate of decline slows down to approximately 5% per week "

Bloody hell. That's one hell of a leaky system.

[Andy Bartlett]

Still, should keep the frost out of the garage during the winter months!

Andy

[Andy Bartlett]

OOOPs!

"Operating temperature Driving: -1°F to 122°F (-17°C to 50°C) Charging: 32°F to 113°F (0°C to 45°C)"

If it goes below 0°C and the battery needs charging - your fu$%ed!

[Dave Liquorice]

I thought the "extension cable" was between the mains supply and the car which contained the charger. Thus thuis being the US and 110v the volt drop on the cable when (trying to) pull a decent current was to great perhaps causing the charger to drop out due to low supply volts.

[Martin Brown]

High current devices like aircons and I would expect electric car battery chargers in countries like the USA are usually run on 220v across the antiphase pair rather than off a single phase domestic mains.

[Tim Streater]

Yes, ludicrous, eh? The Yanks have this joke about a plethora of different plugs in the UK - in fact since the 50s we have, domestically, just the one.

When I lived in California in the 80s, I had:

2-pin 2-pin polarised 3-pin some other job for the 240 V to run the washer/dryer.

[Dave Liquorice]

True that halves the current demand for the same power but does the Tesla live off 110v (easyly available) or 220? Is 220 kit plugable or hardwired? As you say it's only heavy load fixed kit that lives on

220 so it doesn't need to be plugable.

Even at 110v a 30m extension cable isn't that long, I'd almost need that to get from a convient socket to where the cars park...

[Dave Plowman (News)]

A 110v 15 amp supply wouldn't be of much use to a car which runs solely off electricity. Unless you charged it for a week and used it for an afternoon. ;-)

[The Natural Philosopher]

Not quite that bad. charged for 24 hours, used for 20 minutes..

[ARWadsworth]