Information needed about ev battery

rarees1

We recently bought a used ev 23 Nissan Ariya. We have a home charger (7.4kwh) and are very pleased that it's costing us between 1p and 2p per mile, depending on the drive. We are on Octopus Intelligent Go which costs 8p per kWh between 23:30 and 05:30. We also have solar panels and so can charge for free provided at least 1.4kw excess is being produced.

I read somewhere that the number of charging cycles affect the life of the battery.

a) Can someone please explain what a charging cycle is? Is it how often the car is plugged into the charger or when the solar dips and rises again so the charge pauses does each count as a charging cycle?

When researching evs at various dealerships, we were advised to plug the car in as a matter of routine when we got home each day so ensure the battery stayed charged up. Now we're not sure if that will cause the battery to degrade sooner. We aim to keep it in the 20% - 80% area and usually charge now once it goes below 40%.

b) Is it better to keep topping up every day or to charge a larger % once or twice a week as needed?

When we go on a longer journey for our holiday next month, I know that the max charge our car will accept is 132kw.

c) Is it better for the battery to be charged for longer at a lower power, e.g. 22Kwh rather than 130kwh? (We reckon we'll just need to top it up and not do a full charge)

And finally, we're still waiting for Nissan Connect to change the ownership details on their system so we are currently instructing the charger what we calculate the % to be, but when checking the car afterwards, the % charged to is always higher.

d) It's a 3 year old car. If the car says 80% charge, is that 80% of 63Kw (50.4kw) or 80% of whatever the degraded battery capacity is (e.g. 80% of 90% capacity would be only 45.36kwh) ?

Sorry to ask so many questions. We are pensioners. We don't regret buying the ev but it's been a steep learning curve. It's a huge investment of money for us and we don't want to degrade the battery because of ignorance. I have to say that the dealerships we went to when researching gave mixed messages and we don't have a huge amount of confidence that we've been advised correctly.

Thank you to anyone who actually reads this to the end!

BlueonBlue

Google can find you things…things like information on your car in forums.Could be more if you look .

https://www.ariyaforums.com/?utm_source=google&utm_medium=organic

Keep_pedalling

The worse thing you can do to degrade the battery is leave it on full or very low charge for long periods, so under normal circumstances keep the charge level between 20 & 80% if you are planning a long journey then charging to 100% the night before is going to do no harm. Likewise dropping below 20% is not really a problem as long as you put it on charge as soon as you can. Other than that don’t worry about it.

On the road I would not bother with slow chargers it is going to make no noticeable difference to battery life if you do several rapid charges just don’t charge beyond 80% at which point the charging rate will drop significantly. Without the app you should be able to set the charge limit to 80% using the infotainment system in car.

facade

If you attempt to Google these questions, you will find conflicting advice, all backed up with scientific research.

You are best to do what you say, charge to 80% when it goes below 40%, and charge slowly. Leave rapid charging for the once or twice a year events like Lands End to John o' Groats.

Never let it go below 20% unless not doing so means walking home, and only go to 100% just before a long journey (the objective being either not to ever have to public charge, of if unavoidable just put in the minimum to get home with between 10-20% left to minimise the cost and reduce degradation)

The dashboard % display will be % of current (degraded) battery capacity (otherwise it would never go to 100%…), tbh degradation isn't a huge problem, most EVs suffer terminally expensive failures of the electronics or other systems way before the batteries fail (except the early Leaf).

("Battery Health" is the current maximum capacity as a percentage of the original, degradation should be 100% minus battery health %, but people often write battery health as degradation to confuse. You can get the battery health easily via OBD as the car knows it's current and original capacities)

A charging cycle should be 100% of charge, which can be done in small increments, your solar pulsing on & off would just be a small increment and only count as a small part of a cycle.

So if the battery is rated at 1000 charge cycles then you can fully discharge & recharge it 1000 times, or charge it from 70% to 80% 10,000 times (or add 1% via solar 100,000 times). Some research (that I believe in) says that smaller 80% charges will increase the overall cycle life, whereas full 100% cycles will reduce it.

FWIW I normally charge my EV back up to 80% when it gets to 40%. I've only ever fast charged it once, and I struggled to get the cable back out, (probably took 2 years off my life trying everything possible before it eventually let go after what seemed like an hour) so never again! 😉

(If I'm about to go far enough to drop the charge below 80% I'll take it to 100% and let it sit an hour to balance the cells immediately before I set off, but mine is a lithium ferro phosphate battery (LFP) and the manufacturer recommends the 100% charge)

MattMattMattUK

Set a daily charge limit of 80% in the car, boost up to 100% if going on a long journey. Charge every day back to 80% when at home. Use fast chargers when needed, as others have said they have minimal impact on battery degradation and do you really want to sit at a services charging for five hours, not fifteen minutes?

QrizB

a) Can someone please explain what a charging cycle is

For lithium batteries, it's charging and then using (or using and then charging) 100% of the battery capacity. Here's a blog post that explains it:

https://innovativegreenpower.com/battery-charging-cycle-explained-what-counts-as-one-cycle/

And here:

https://evbattery.us/how-many-charge-cycles-does-an-ev-battery-have/

While not exactly the same as an EV, Apple say the same thing about iPhone batteries.

https://www.apple.com/batteries/why-lithium-ion/

b) Is it better to keep topping up every day or to charge a larger % once or twice a week as needed?

We plug ours in on most days (Octopus's new "streams" game encourages it) but IMHO so long as you keep you car between 20% and 80% it doesn't really matter from a battery health perspective. Charge once or twice a week if you find that's more convenient.

c) Is it better for the battery to be charged for longer at a lower power, e.g. 22Kwh rather than 130kwh?

Most cars only have a 7kW onboard charger. A 22kW AC charge point will be using your onboard charger and so you'll only get 7kW of charging. If you're trying to add 40kWh to your car using a 22kW charger it'll take almost six hours.

Instead, you'll probably want to use a DC charger. We try to match our en-route charging stops with mealtimes (usually lunch, sometimes dinner). A 50kW charger will take about 50 minutes to add that same 40 kWh, which is time to stretch your legs, visit the loo and get a coffee and a sandwich from a nearby cafe. A 100kW charger might get you done in 25 minutes; better if you're in a hurry and just need the loo and a cuppa, but not so handy if it's lunchtime.

chrisw

You are massively over thinking it and worrying unnecessarily. As said, try and keep it between 20% and 80% but top up to 100% before a long journey.
We are used to phone batteries and similar degrading quickly and needing replacement - EV batteries are very different and have complex management systems so should easily outlast the life of the car.

Bluebell1000

If you can charge for free from excess solar, then just plug in whenever you have spare electric, as you won't get all that much each day unless you have a very large system. You can still restrict it to a max charge level, though we tend just to fill to 100% if we have enough solar, and haven't noticed any issues.

MattMattMattUK

https://forums.moneysavingexpert.com/discussion/comment/82112184#Comment_82112184

As an example this seems like a good idea, but often is not. Most suppliers will pay you 12p per kWh for flat export rate and 8p per kWh for overnight EV charging, so even with charging losses you will be net better off exporting during the day and importing at night.

rarees1

https://forums.moneysavingexpert.com/discussion/comment/82111892#Comment_82111892

Thanks - that's very helpful

rsvtoddy

And one thing to consider before a long trip where you will need to use a rapid charger - try one near home so you know how it works. Plan your route and have a backup plan for a charger as occasionally they are a bit temperamental!