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Just a reminder to everyone during this lock down... most of us are not using our cars much so try to keep your EV around 50% when not in regular use. Keeping an EV at high or low charge is not good for the battery. Whatever you do, don't keep it above 80% or before 30% for long if you can help it. This is general advice but particularly relevant right now when cars are not getting regular use.
 

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Just a reminder to everyone during this lock down... most of us are not using our cars much so try to keep your EV around 50% when not in regular use. Keeping an EV at high or low charge is not good for the battery. Whatever you do, don't keep it above 80% or before 30% for long if you can help it. This is general advice but particularly relevant right now when cars are not getting regular use.
We have just taken delivery of a brand new MG SV EV which is sitting in the garage with about 50% charge in main battery and a bit more in 12v battery. Because my wife is in the extremely vulnerable category, we are not likely to be driving it anytime soon (like 6-12 weeks). What's your advise? Is it OK just to leave it, or do we need to top up the battery? does turning on the "engine" but not going anywhere do any good?
 

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I'm not sure how to reconcile this advice with what I read in the manual of my BMW i3. For those who have this car, on page 203 it reads:

"Do not allow the vehicle to sit idle for extended periods with a low charging state.

Before storing the vehicle for an extended period, check the battery charge indicator to ensure that the high-voltage battery is fully charged. For longer idle times, park the vehicle with a charging plug plugged into a suitable power source. Regularly check charging state. Otherwise, the high-voltage battery can be damaged when there is excessive discharge.

For idle phases that last several weeks, park the vehicle with a fully charged battery if possible."

This suggests that the i3 wants to be in a full state of charge when it's not in regular use. I've written to BMW asking for clarification, I'll post here if I hear back from them.
 

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Well, they put it in the manual for a reason. Probably because there’s a large top buffer.
 

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I am sure that I cannot be the only one with this predicament. I suppose most EV owners can go out at least once per week for essential shopping but I can't. I am worried that if I take the car out just for a "spin", the police will regard this as unnecessary travel. These things are sent to try us!
 

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I am sure that I cannot be the only one with this predicament. I suppose most EV owners can go out at least once per week for essential shopping but I can't. I am worried that if I take the car out just for a "spin", the police will regard this as unnecessary travel. These things are sent to try us!
I'm also in the Extremely Vulnerable category and was thinking if I need to drive around for a bit to condition the 12v battery, keep the brakes clear etc. that would be Essential being as I may need the car for emergency travel to the hospital/Doctors?
 

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Regarding the i3 advice in the manual... I suppose you should follow the manufactures advice if that is what it says. As has been suggested... we don't know what the top buffer is. If that is quite large, as it is with the Ampera for example, then 100% charge puts the car at maximum charge state but at that 100% the battery isn't full. However, it is generally accepted that keeping any Li Ion battery at high or low state of charge is not good. You just have to make your own call.

IMO I would aim to keep mine at between 50% and 70% if not using for any appreciable period. With any top buffer that is likely to be a genuine 40-60% but you decide :)
 

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I'm also in the Extremely Vulnerable category and was thinking if I need to drive around for a bit to condition the 12v battery, keep the brakes clear etc. that would be Essential being as I may need the car for emergency travel to the hospital/Doctors?
The LEAF appears to top up the 12v battery from time to time even if you aren't driving it. The only sign of this happening is that the right hand blue light flashes for a bit.

This activity is unlikely to have much effect on the charge state of the traction battery.
 

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The LEAF appears to top up the 12v battery from time to time even if you aren't driving it. The only sign of this happening is that the right hand blue light flashes for a bit.

This activity is unlikely to have much effect on the charge state of the traction battery.
Never had a problem with my 30kWh Leaf but my e-Niro 12v has gone flat twice now. It was due into my local dealer to check what the problem was but they are shut now..
 

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@David M - discharging 12v battery in eNiro / Kona seems to be quite common.
I have Kona and it started doing this sporadically then increased to almost daily problem (after driving).
The guy who installed my dashcams has eNiro and the same thing is happening.
I also know or heard about 2 dozen people with the same problem.

Anyway, after 5-6 visits to dealership Hyundai decided to replace 12v battery (even though it passed load tests and they have tested lots of components: proximity to keys, calibration sensor, etc... and never found a problem). After replacement the issue disappeared and for last 4-5 weeks never had that problem.
 

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The LEAF appears to top up the 12v battery from time to time even if you aren't driving it. The only sign of this happening is that the right hand blue light flashes for a bit.
After a long drive on 20th Mar, set to charge up to nominal 80% (usually 79%) overnight from 24% and unplugged in the morning of 21st. Did not check %SOC on unplugging as it usually was reliably 79% except when warming was programmed when it sometimew was in the low 80's

On switching on to get end of month mileage on 31st, noted SOC was at 69%. Today when moving the car so I could mow round its parking area noted the brakes sounded a bit rusty, so drove up and down drive with brakes lightly applied to clear rust - not forgetting the parking brake!, and when finished %SOC was 68%. Don't know if the drop from presumed 79% to 69% SOC was due to topping up the 12v battery - seems a bit much as nominal 12v battery capacity is about 500Wh and mine, being a 2013 manufactured original, would probably be a lot less.
 

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I have always subscribed to the middle range charge level as Paul originally posted. It was not until I had my first EV (2014 Leaf) that I appreciated this but I have applied it to all other Lithium battery devices. It was only last year that I saw the advice in respect of something other than a car. I bought a new laptop and this has a battery saver mode which limits the charge to 80%.

For cars there is a key difference with those fortunate to have newer cars with larger capacity batteries. With the old 24KWh leaf a 60% battery was a limitation if you needed to make a trip in an emergency. The rapid charging network was pretty flaky back then. I always kept it at no less than 80%. Now I am lucky to be able to let the Kona sit on the drive at 50%. For those with the smaller batteries then you will need to make a prudent judgement of balancing a safe reserve for journeys against the battery life.

The Kona seems to be more temperamental over its 12v supply if not used. I also worry about disc corrosion living on the coast. I therefore did the same as Hilltop Dave and ran it up and down the drive yesterday against the brakes. My drive is less than twice the length of the car but I can get a full wheel revolution.
 

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My Leaf 24 was charged to 48% and left for 2 week, somehow dropped down to 42%.

This time, I charged the car to 62%, Leafspy read 3.92-3.94 v for each cell. Accounting for self drain over long period, it should be okay to sit like that for at least 2 months.

I also pumped up all tyres to 45 PSI to prevent flat spot. Maximum is 50 PSI, accounting for possibly 10% reading inaccuracy on the cheap pump.

I also used a 12v charger on the 12v battery to make sure it's fully charged.
 
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