EV Discussion thread

QrizB

1961Nick said:

ICE vehicles also have vampire drain but you're unlikely to notice because there's no convenient way of seeing the battery SOC. Obviously using an ICE to power the alternator to replenish the battery is pretty inefficient compared charging using mains electricity.

I'm still catching up with this thread so please excuse me quoting a month-old post!

A typical 12 volt car battery will hold one kilowatt-hour of energy.

During spring 2020, when our cars were rarely used, both Mrs QrizB's Qubo had a flat battery (flat enough that the central locking wouldn't unlock) after about a month of negligible use. This suggests an average vampire load for a small and unsophisticated ICE of less than two watts.

((After that we made regular use of a mains charger to keep our vehicle batteries topped up.)

A while ago I estimated (based on appropriations of the various losses, and in the context of motor caravanning) that generating a kilowatt-hour from a moving ICE might require an extra litre of fuel.

paul991

not only that ,as  i have just found out leaving a battery not being recharged for a few months will damage it so will need to be replaced

QrizB

paul991 said:

not only that ,as  i have just found out leaving a battery not being recharged for a few months will damage it so will need to be replaced

Mrs QrizB's car battery lasted until this year, so another three years after going flat during lockdown.

Maybe we were lucky!

(Apologies for the digression from EV discussion, although I think EVs also have 12v batteries for the majority of their support systems so it might still be relevant )

EricMears

The instance I just don't understand is the chargers at Leicester MSA.   They have a pair of Gridserve machines at each side and they worked OK for years but the now have a sign attached claiming that the site doesn't have enough power to run them.  I suppose it's just possible that the new improved chargers draw more than the older ones but surely not twice as much so why couldn't they just use one and cover the other until first breaks down ?

Magnitio

QrizB said:

A while ago I estimated (based on appropriations of the various losses, and in the context of motor caravanning) that generating a kilowatt-hour from a moving ICE might require an extra litre of fuel.

Some ICE cars over the past 10 years or so will engage the alternator to charge the battery when slowing down and disengage it when accelerating or at steady speeds when the battery has sufficient charge. In effect, a very mild form of regenerative braking which does save some fuel.

JKenH

This article appeared in Autocar about Nio who have an innovative way of generating brand loyalty. Sorry, but the only link I can provide is via Readly.

The only way is Nio

The Chinese EV maker is building its brand by using a wide-reaching, innovative approach that goes far, far beyond cars. James Attwood asks if it will catch on here

Tesla’s Elon Musk may have bought up Twitter, but Nio has essentially started its own social media network – and it’s apparently working. Nio’s car sales are currently numbered in the hundreds of thousands, but the brand claims that its app has 2.3 million registered users, with around 240,000 active each day. In total, they have shared 20 million posts.

Effectively, Nio uses its app to help guide and direct the efforts of the sort of fan clubs that most car brands have. Shen claims there are now more than 500 Nio user clubs, who organise a combined 1400 events per week. There’s also a partner programme, where Nio enthusiasts are encouraged to offer discounts to other app users.

Nio products? Oh yes: the firm has a whole Nio Life brand of merch developed in collaboration with around 500 designers and other companies. Spanning eight categories, there are hundreds of thousands of different items, ranging from homeware to fashion, and waffles to wine.

Suggestion about Autocar 5th July 2023 page 40
https://go.readly.com/magazines/5321d063abb90f06c300001c/64a3d4dad95db9001f630186/40

JKenH

QrizB said:

1961Nick said:

ICE vehicles also have vampire drain but you're unlikely to notice because there's no convenient way of seeing the battery SOC. Obviously using an ICE to power the alternator to replenish the battery is pretty inefficient compared charging using mains electricity.

I'm still catching up with this thread so please excuse me quoting a month-old post!

A typical 12 volt car battery will hold one kilowatt-hour of energy.

During spring 2020, when our cars were rarely used, both Mrs QrizB's Qubo had a flat battery (flat enough that the central locking wouldn't unlock) after about a month of negligible use. This suggests an average vampire load for a small and unsophisticated ICE of less than two watts.

((After that we made regular use of a mains charger to keep our vehicle batteries topped up.)

A while ago I estimated (based on appropriations of the various losses, and in the context of motor caravanning) that generating a kilowatt-hour from a moving ICE might require an extra litre of fuel.

That got me thinking about just how much energy there might be in a 12v car battery. Sizes vary, with some only 60 Ah which would suggest a capacity of 0.72kWh but what does that mean in real terms? In theory, the battery can discharge at 1 amp for 60 hours or 2 amps for 30 hours, but do we ever completely discharge the battery or after a month or so might it be capable of say lighting up a 2w bulb? Is the battery rating just a nominal useable capacity and not its actual capacity? An6 battery experts on here?

Going back to practical matters, I have left sports cars parked up for 6 months (SORNed) and gone back to them and they have started and with my MR2 I did that for several years in succession. I didn’t charge the battery in between - I know I should have done but just never got round to it. It still started fine. 

With my Leaf I recall calculating the vampire drain was 4w, or 0.96 kWh in 24 hours. That would flatten an ordinary 12v car battery in less than a day 10 days but the Leaf 12v was continuously topped up by the traction battery - you could see this was happening by the flashing lights on top of the dashboard and the clunks coming from the car. 

Our Golf stands several days at a time when we are on holiday, as does the Picanto and over a fortnight they both still start. The Picanto battery is about 60amps so 0.72 kWh  so I guess the battery loses a lot less than 0.05 kWh per day. This is a 2022 car with touch screen, Bluetooth, sat nav and all mod cons. 

Edited: correction - thanks @Magnitio for pointing out the error.

QrizB

JKenH said:

QrizB said:

A while ago I estimated (based on appropriations of the various losses, and in the context of motor caravanning) that generating a kilowatt-hour from a moving ICE might require an extra litre of fuel.

That got me thinking about just how much energy there might be in a 12v car battery. Sizes vary, with some only 60 Ah which would suggest a capacity of 0.72kWh but what does that mean in real terms? In theory, the battery can discharge at 1 amp for 60 hours or 2 amps for 30 hours, but do we ever completely discharge the battery or after a month or so might it be capable of say lighting up a 2w bulb? Is the battery rating just a nominal useable capacity and not its actual capacity? An6 battery experts on here?

I don't claim to be an expert but I've been messing about with lead acid batteries for 40 years or so and have read an embarrassingly large amount of info.

The quoted Ah capacity of a lead acid battery is usually a C/20 rate. That means it's based on a constant current load applied for 20 hours until the battery falls to (usually) 1.75 volts per cell (10.5V for a 6-cell 12V battery). So an 80Ah battery will maintain a 4A load for 20 hours.

Higher current loads result in lower apparent capacities. The "reserve capacity" quoted for a battery (usually in minutes) is how long it will support a 25A load until falling to the same 1.75 Vpc. The 80Ah battery might have a reserve capacity of 150 minutes, which works out as 62.5Ah at 25A.

And lower currents will give slightly higher apparent capacities. The C/100 capacity could be 90Ah.

Just to complicate matters further, different standards bodies (such as BCI, SAE, DIN and EN) sometimes have slightly different test requirements (wg. battery temperature or cell voltage) so when comparing batteries you should be aware that not all tests are equal.

Grumpy_chap

Grumpy_chap said:

I am doing my first charge tonight with my power monitor plug so will have a figure to give some assessment of the accuracy of the energy assessed by the car versus actual plug power draw.
I am doing a 140-mile round trip tomorrow so will be able to measure that as well.  It will be all mileage and no "vampire loss" energy as charging overnight today and will charge again when I return home tomorrow evening.

OK, so here goes, my non-scientific mini-data set of two, but here goes:

Full charge on the car is to 90% (as TESLA manual suggests) and the car stops the charge once the 90% is reached as measured by the car.

Saturday 22/07 = charged to full

Monday 31/07 = charged to full

• 9 days of whatever "vampire drain" occurred
• 104 miles, of which 94 were in the return journey on the Monday 31st
• Power as measured by the car 24 kWh
• Power as measured by the power monitor plug 26.29 kWh
• Power delta 10%
• 3.96 mile/kWh as measured by the plug
• 4.33 mile/kWh as measured by the car

Tuesday 01/08 = charged to full

• No days of "vampire drain"
• 143 miles
• Power as measured by the car 33 kWh
• Power as measured by the power monitor plug 37.48 kWh
• Power delta 13%
• 3.81 mile/kWh as measured by the plug
• 4.33 mile/kWh as measured by the car

On this limited review:

• I need to add 10% to the power (and costs) for those charges where I have only the car data
• "Vampire Drain" does not appear to have been significant
• If I can drive with the in car display showing 220 Wh/mile then that will mean actual 4 miles/kWh achieved.  A useful target.

Magnitio

JKenH said:

With my Leaf I recall calculating the vampire drain was 4w, or 0.96 kWh in 24 hours. That would flatten an ordinary 12v car battery in less than a day but the Leaf 12v was continuously topped up by the traction battery - you could see this was happening by the flashing lights on top of the dashboard and the clunks coming from the car. 

4W for 24 hours is .096kWh.