EV Charging (Specifically 2013 Leaf) - better to charge high or run low for maximum range

Forums › Transport (cars, bikes and boats) › EV Charging (Specifically 2013 Leaf) - better to charge high or run low for maximum range

timbosan

2159 posts

Uber Geek

#288890 30-Jul-2021 08:20

Hey all,

So I have had my Leaf for a few months and now know its real range (around 100km) however now I am wanting to understand how best to charge it, especially for day to day commuting.

If I need to charge to on a regular basis (say every few days or more) am I better to:

a) Charge it more than 80%, say 95% (rather than right to 100%)
b) Run it low, down to 20% or less
c) Fast charge between my regular home charging to 'top-up' (to 80% or less)

Assume I charge 99% of the time at home, and I only fast charge when on long trips or when planning ir poor!

So what is best for longevity and health of the battery?

jonathan18

7413 posts

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#2752218 30-Jul-2021 08:55

We generally will not charge our 2013 Leaf to much over 80% (and earlier Leafs had the ability to set this in the charging settings) and it would normally not get much below 30% (prior to the next charge).

If you are charging above 80%, do so just prior to using the car is the advice I’ve received- eg, charge in the early morning before going to work so it’s not sitting around at that higher level.

We’re with EK so make the most of our hour of free power, charging the car every morning for that period, with the occasional longer charge if needed. That means it tends to charge to just around 80% and drop to about 55-60% (we have a caravan charger so can get more juice into it in that hour). The battery has certainly continued to degrade, but whether that’s a consequence of our charging regime or is a continuation of the side effects of how it was treated in Japan (nearly 100% fast charges) I’m not sure.

But, in the end, I’m just not going to get too anal about this; I think our family will outgrow the Leaf before the range is too low for it to be useful as an urban get-about. Like many geek-oriented Leaf owners I started out regularly monitoring the battery via LeafSpy, but found it just added an unnecessary level of stress to what is otherwise an enjoyable experience.

timbosan

2159 posts

Uber Geek

#2752248 30-Jul-2021 10:01

If you are charging above 80%, do so just prior to using the car is the advice I’ve received- eg, charge in the early morning before going to work so it’s not sitting around at that higher level.

Thanks - yeah I have done that before - set the limit to 80% wait for it to finish, then just top it up to 90% right before driving. Although I wasn't sure if this was bad for the battery, or its just leaving it sitting at > 80% of the charge that's an issue.

I have almost got over the range thing - I used to watch the range constantly, now I know what I can get out of it, I just enjoy the driving (and I do like driving it way more than a petrol car now). Only problem is that the range is not huge, so longer journeys need more planning.

afe66

3181 posts

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Lifetime subscriber

#2752362 30-Jul-2021 11:49

I've have a uk 2014 leaf for last 4 years.

I just set it to slow charge to 80% unless I think I'll need the extra range in which case its 100% charge.

If I get caught short I do a short rapid charge until its enough to achieve what I want. If I just need to get home, I might add <40% and fill up at home rather than sitting around and rapid to 80%.

I have an older leaf and from using plug share I cant actually charge at 50kw for very long so am open to using a 25kw unit.

I top up once battery gets to under 25% as I use it for pottering around town 25% still gets me more than 25km which is fine for me.

The more you use your leaf the better insight you have to range vrs charge. Excluding long trips I find I drive to the same locations on same roads. Ie same supermarket visits same friends so I am more comfortable with lower charges.

timbosan

2159 posts

Uber Geek

#2752366 30-Jul-2021 11:55

afe66: I've have a uk 2014 leaf for last 4 years.

I just set it to slow charge to 80% unless I think I'll need the extra range in which case its 100% charge.

If I get caught short I do a short rapid charge until its enough to achieve what I want. If I just need to get home, I might add <40% and fill up at home rather than sitting around and rapid to 80%.

I have an older leaf and from using plug share I cant actually charge at 50kw for very long so am open to using a 25kw unit.

I top up once battery gets to under 25% as I use it for pottering around town 25% still gets me more than 25km which is fine for me.

The more you use your leaf the better insight you have to range vrs charge. Excluding long trips I find I drive to the same locations on same roads. Ie same supermarket visits same friends so I am more comfortable with lower charges.

Thanks - my concern was range and how to run the battery on a regular basis, for example on a long daily commute. I.e. is it better to charge over 80% daily (assuming that you then drive it and not leave it sitting around), or is it better to run it down below 20% (this is when the range indicator changes to --- I think). Or both?

Or does non of this really matter, as long as I slow charge and drive the car (not leaving it sitting with a charge over 80%) and don't use fast charging (except when needed).

tripper1000

1617 posts

Uber Geek

#2752505 30-Jul-2021 16:01

Yeah, accepted wisdom is to not go too high (>80% or too low <30%) where conveniently avoidable.

The battery SoH figures seem to like being DC fast charged periodically so don't feel guilty about that. My Leafs SoH started dropping faster when I stopped fast charging.

I have a variable current charger and have the charge timer set to run between midnight and 7am. I aim to charge the car to ~80% as slow as possible. I charge off peak (better for the grid and load balancing and cheaper rates) and as slow as possible just to present a consistent load to the grid - not for any specific SoH reasons.

They do need to be slowly charged to 100% occasionally just to help with cell balancing, but the occasions/journeys when I need to take it to 100% seem to be enough to keep mine in balance without doing any special charges.

gzt

17105 posts

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#2752628 30-Jul-2021 18:47

jonathan18: If you are charging above 80%, do so just prior to using the car is the advice I’ve received- eg, charge in the early morning before going to work so it’s not sitting around at that higher level.

This sounds odd to me. Given the choice I'd do that in the evening to allow the battery to cool down overnight. Let the battery mysticism commence ; ).

zenourn

271 posts

Ultimate Geek

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#2752636 30-Jul-2021 19:04

I now have more longitudinal SoH data than I can model. Are slowly working on updating https://www.preprints.org/manuscript/201803.0122/v1 to a full paper with updated results.

- Cell balancing with the Leaf happens whenever the car is on, charging to 100% has no effect. Is why you always see the red/blue colours in Leafspy. Needs to be continuous given the extremely low rate (~30 mA) that it can balance cells at.

- In low/moderate temps (i.e., ~ =< 20'C) a high SoC doesn't have much effect of battery degeneration. I have our 2015 Leaf set on an 100% charge end-timer for 6 am. In the hot parts of summer I set it to 80%.

- Charging to 100% is better than taking down to a low SoC. When taking down to a low SoC you stress weaker cells to a greater degree, which causes them to get even weaker.

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timbosan

2159 posts

Uber Geek

#2752682 30-Jul-2021 21:58

zenourn:

I now have more longitudinal SoH data than I can model. Are slowly working on updating https://www.preprints.org/manuscript/201803.0122/v1 to a full paper with updated results.

- Cell balancing with the Leaf happens whenever the car is on, charging to 100% has no effect. Is why you always see the red/blue colours in Leafspy. Needs to be continuous given the extremely low rate (~30 mA) that it can balance cells at.

- In low/moderate temps (i.e., ~ =< 20'C) a high SoC doesn't have much effect of battery degeneration. I have our 2015 Leaf set on an 100% charge end-timer for 6 am. In the hot parts of summer I set it to 80%.

- Charging to 100% is better than taking down to a low SoC. When taking down to a low SoC you stress weaker cells to a greater degree, which causes them to get even weaker.

This is exactly what I was after! I like the following ideas:

"I have our 2015 Leaf set on an 100% charge end-timer for 6 am" - I assume this is to help with making sure the battery doesn't get too hot? I.e. cooler overnight = cooler battery when fully charged?

"When taking down to a low SoC you stress weaker cells to a greater degree, which causes them to get even weaker." - Not something that I thought of, but in hindsight is obvious!

zenourn

271 posts

Ultimate Geek

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#2752687 30-Jul-2021 22:20

timbosan:

"I have our 2015 Leaf set on an 100% charge end-timer for 6 am" - I assume this is to help with making sure the battery doesn't get too hot? I.e. cooler overnight = cooler battery when fully charged?

Yes, three benefits:

- Usually is the time of coldest battery temps. AC charging itself doesn't increase the temp of the battery much at all.

- Reduces the time spent at 100%

- Also kindest on the electricity networks (and usually means will be from 100% renewable sources).

timbosan

2159 posts

Uber Geek

#2753167 1-Aug-2021 12:15

Great information so far, thanks so much all!

However I have been thinking about getting an outdoor powerpoint installed, and wondered if slow charging is only the 8 amps you get from the standard powerpoint, or if a 16amp caravan socket also counts as 'slow'?

@tripper1000 I noticed you specifically do this but for grid / other purposes, not for battery health, but are you doing 8 amps or 16amps?

Cheers!

zenourn

271 posts

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#2753175 1-Aug-2021 12:30

16 amp caravan socket is also slow charging (L2) and is currently what I use to charge my Leaf.

However, when I installed it I put in 32A 3-phase wiring and am now changing it to a 22 kW T2 socket EVSE as I now have two EVs, one with T1 and the other with T2.

At a minimum I'd install 32 A cabling for future use. You can get 7.2/22kW EVSEs for $1k. A 16A caravan socket charger is ~$500 so doesn't cost much to future proof.

RunningMan

8953 posts

Uber Geek

#2753176 1-Aug-2021 12:31

@timbosan Any AC charging is considered slow, DC charging is considered fast (rapid).

tripper1000

1617 posts

Uber Geek

#2753789 2-Aug-2021 15:31

@timbosan

When I said slow charging I did mean slow for AC as you assumed.

I have a 16amp caravan outlet, however my EVSE is adjustable and can select any current between 6amps and 16 amps (in 1 amp increments).

I adjust the current to achieve ~80% in the allotted time (usually midnight to 6 or 7am). So if the car is at 40% SoC I would select 6 or 7 amps and it if is down to 20% SoC I might set it to 8 or 9 amps.

The beauty of a 16amps outlet and adjustable EVSE is that if I get caught short I can still give it a "fast" charge at 16amps. This reduces the temptation/necessity to charge beyond 80% "just in case".

I still have a portable 8 amp, 3pin type EVSE for when charging away from home (bach's etc).