fredrussell
Well-known member
True enough, but I think the thing people are finding hard to understand is that a machine that is essentially a rolling lithium battery should be dependent on a small separate lead acid battery!
Do Electric vehicles have deep cycle starter batteries or "house" batteries?
- Thread starter SvenH
- Start date
Bouba
Well-known member
That has confused mankind since EVs made a comeback
Elessar
Well-known member
What’s completely mad is that when you are using the car the 400V traction battery charges the 12V battery.
When you are not, it doesn’t and can’t.
So the 12v battery goes flat because, say, you left the interior light on and you are stuck - even though you’ve loads of charge under the floor, there is no way to access it as the car won’t “start”
No worries though you can just just start it with regular jump leads from any other car.
And an electric car can jump start any other car.
I had to show an AA man this as he tried to drag a car onto a flatbed truck whilst stuck in park.
You won’t connect to the 400V battery by mistake as they make that difficult.
Supertramp
Well-known member
I think the logic is that in the situation above you flatten a 12v replaceable battery rather than trashing thousands of pounds of lithium by total discharge. What seems silly is to not put check/replacement of the 12v battery as a routine service item (including for normal cars).
I suspect the assessment of lithium battery condition will become a significant part of ownership and used car purchase as the proportion of older cars increases and more people use them expecting 10+ years/150,000 miles of life.
coopec
N/A
Maybe this is relevant?
Research on Heat Dissipation of Electric Vehicle
Based on Safety Architecture Optimization
ShieldSquare Captcha
Elessar
Well-known member
How can a 90,000 Wh battery be flattened by a 960 Wh battery? That so called logic of yours is illogical!
Supertramp
Well-known member
The main battery will isolate to prevent excessive discharge leaving the 12v to keep the alarm, locking etc alive. Not my logic!
Elessar
Well-known member
Not the point. You can’t link them temporarily to boost the 12V if it goes flat is the point.
Supertramp
Well-known member
I understand and agree with you. There are various complex workarounds to open the car if flat (to access the battery!). Presumably it's just some kind of design oversight though they all seem to suffer from it.
I might mess with boat electrics but I'm not going near my car electrics! Unless it goes flat....
I might mess with boat electrics but I'm not going near my car electrics! Unless it goes flat....
arcot
Member
Tesla has heat pump....
arcot
Member
Tesla has jump socket in front bumper for 12 volt house battery only
dunedin
Well-known member
Presumably only in recent models, after the much publicised issues of flat Tesla 12V batteries (such as the James May one).