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Discussion Starter · #1 ·
I’ve had Leafs for a few years and moved to an i3 fairly recently - I was anticipating using and charging it in a similar manner (i.e. keeping it between approx 20 and 80% most of the time).

I joined the i3 FaceBook group and was thus a bit surprised that ABC is heavily promoted there (Always Be Charging).

I’m a bit wary of that, seeing as the recommendation with pretty much every other EV is to go to 80/90% unless you need the range.

I know that it’s got a reasonably sized buffer, decent BMS, is actively cooled etc but why should it be different from other EV’s?

I’ve read that cell balancing happens above 80/85% so you probably do want it charged up here fairly regularly, but not sure why you’d go above that all the time? (apart from making it simpler for the end user)

Thanks! Dan
 

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2020 BMW i3S 120Ah BEV
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People like to tinker, and in an EV it's all new, and the tinkerers will tinker like mad. I remember being told not to run the petrol tank too low (sludge), or too high (air locks), and frankly ignored it completely and had no issues. I think that the real difference in battery SOH lifetime between "ABC" and careful control over battery charge state will be so minimal it may not even be worth it in 10 years time, let alone during the first three years, or the 7 years of battery warranty.
Not that I'd claim there was NO difference either. Just that it probably wasn't worth any additional time spent on the task..!
 

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I charge mine when I find free charging, if it runs out I have the rex so its either to the nearest free charger or home, as I posted on another thread we are playing a game to see how many miles we can do before we pay for the first charge :). The only problem I have is I have access to rapid free charging but have to pay to park, does this still count as free:unsure:? It does for me if I have to go shopping there but not sure it will break the rules of the game
 

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We always charge to 100%, but that only happens once a week, most weeks. We use it 'til its lower than our next likely journey, then charge it up overnight (ie 'til full) and repeat. Simples. But then I just drive it in comfort mode too...I'm not doing all kinds of antics to max the range, and if its cold I have the heater on and if its hot I have the aircon on. I guess I treat it like a car really. Seems to be fine, but only 30 months and 10k miles in so far.
 

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I had a gen 1 i3 for 5 years.
I had a 46 mile commute, so a minimum 92 miles a day so would take it from 100% to 3% every day.

After 5 years and over 100k miles on the clock i could still get 90+ miles on a full charge (in summer), so from that anecdotal evidence i'd say the car can handle charging to 100%.
 

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I came home the other day and had 1 mile range left I new it was going to be tight.
I plug in around every 5 days fully charge then run it down to around 10 miles miles and charge again. I’ve never really thought about if this is wrong or not, I suppose as I had th3 car from new and will only keep it a couple of years it doesn’t really matte.
Thanks
 

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2020 i3
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I just charge when I need to. Occasionally I'll put it on a slow charge to 100% to do the cell balancing.
The ABC thing is to help those with range anxiety mainly I think.
The only thing you do need to avoid is leaving the battery in a very low state of charge for a prolonged time. The BMS will take care of the rest.
 

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I have the Rex version but the battery part is the same. From what I have read, and there are some interesting engineering articles on the BMW, but "Samsung SDI" made i3 battery, when it first came out, is that it is not only liquid cooled but "buffered" both at the top and bottom ends of the battery. Which means that even if it says you have charged to 100% you have in fact not. Same at the bottom end. With the Rex version, the engine kicks in when you have 6.5% battery remaining. Stopping it filling to "max 100%", and emptying it to 0% helps to protect the battery and maintains the health of the battery.
Ours is now almost 4 years old and completed 55,000+ miles. I have not noticed any reduction in its range in winter or summer compared to previous years (less range in the winter obviously), and we charge ours generally to 100% most of the time once or twice a week over those 4 years.
 

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but "buffered" both at the top and bottom ends of the battery.
All BEVs have a safety margins at 0% and 100% indicated.

Nissan have a very small top margin. Letting a LEAF 24 or 30 sit at 100% is not good for the battery. Worse, there is an issue with the on board charger that Nissan never fixed. Plugging the car in when it is already at or above 98% will overcharge the battery and damage the pack.

The i3 has a larger top margin. Plugging an i3 in at 100% will not damage the pack. In fact, BMW recommend leaving the car plugged in so that the 12V battery doesn't run down.
 

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Agree that there is no evidence to suggest that charging to 100% reduces battery life. That apart, there is no way of setting the charge limit in the car so if you charge overnight at cheap rate you have no option unless you have a programmer in the wall box (which I don’t).

I only do short trips and charge at 75%. One day there will be a panic and I will have to do an unplanned long journey so it would be daft to have to sit and wait whilst the car charges up before I can set off.
 

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I just want to point out that there's nothing unique about the battery cells BMW uses that would make them immune from generic best practices for caring for any other Li-Ion batteries. Yet at the same time, "generic best practices" can be light on evidence, and are certainly not written in stone.

The i3's top-end buffer is only about 5%, depending on which size pack the car has. So at 100% SOC displayed, that's still in the range of 95%.

Limiting charge to 80% probably isn't going to have a marked difference in battery health vs. choosing 85%. Who is to say a 75% cap isn't preferable? (Some battery manufacturers quote 70% as an ideal storage SOC -- which implies a lot).

There's nothing absolute in these numbers. In general, lower % charging cut-offs are better for longevity than higher. Lower charging current is better for longevity than higher. Lower internal temperatures (within reason) are better for longevity than higher. But if that leaves you with a car that you can't use because it's never charged and won't go the distance on a half-charge, then that's not "better" either. Each owner has got to do what's right for their needs.

My own situation sees about 20% of battery use on a normal day light day and 50% on a normal heavy day. I can recoup 40% charging for 8 hours at work. If I'm above 60% when I reach work, I generally don't charge because I have no need or desire to reach 100% -- unless I know I'll be needing extra range. I rarely charge at home, but when I do, some days I charge L1 if I just need a small bump, and other days I plug in to Level 2 at 16A, which feeds my i3 at 10% per hour. I have a 40A L2 unit that I haven't bothered to install yet because I just haven't needed it. I'll get to it soon, but I know 32A charging will deteriorate my battery more than charging at the 16A rate, if only by a little. I don't hesitate to stop off at a DC fast charger if I need it, but those days are few and far between.

In summary: do what's right to serve your needs, but be mindful of the battery's long term well being, particularly if the car is a keeper.
 

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The suppliers of the Lithium battery for my golf trolley recommend keeping it at 50% charge if storing long term. How on earth do you charge to 50% and what happens when you want to play and forget that it isn’t charged? Anyway, my golf pro says they last forever. In practice, they will outlive the life of the trolley and if you try to transfer them to a new trolley they won’t match.
So, a totally different application but the common sense solution to charge and forget is the same. I read anecdotal evidence that an i3 battery is good for 300,000 miles or more.
 

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I have a full electric boat, 2 lifePo4 battery banks one for drive 36 kwhs [36 volt batteries] and the domestic bank is about 9 kwhs [12 volt batteries]. The drive bank is currently asleep at about 60 % charged, all of the solar is currently directed to the domestic bank which lives at between 60% and 80 % charged. both these banks are from EVs the drive bank buses from NI and the domestic Smiths electric vans. The bus bank had a hard life they were cooled and heated but each pack when broken open had a large number of replacement batteries, which was good for me, but not for valence, the van banks had done less than 100 cycles because the vans were a bit naff because of design errors.
I fully expect these battery banks to last me out as they arnt stressed in use or charging, I have a generator to charge things in winter if we go for a cruise but on the whole we prefer to cruise when the weather is nice and rivers arnt flowing like raging torrents!!
What I am saying here is if you are keeping your car for a long time charge properly rapid charging like the NI buses had kills batteries and if you dont need to dont overcharge batteries as it will reduce their life
 

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It's a car.
It will depreciate over time.
Being an EV there will be some battery degradation.
For some it will be more, for others less.
Life's too short to worry about what a few "know it all" know.
 

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Discussion Starter · #15 · (Edited)
Thanks for all the replies, as has been mentioned by @gofer I think the ABC is just to maximise available range (so people are less likely to get caught out) and I think to keep it simple, whereas I like to complicate matters ;-) I'll thus continue to use the timer to put in a few hours on economy 7 as required, usually to 80/ 85% or even 100% on occasion to keep the BMS on it's toes and to get some cell balancing in there.

As @eNate mentioned I don't see why the i3 cells/ pack/ BMS are vastly different to most other EV's. IIRC eTron can be charged to 100% with impunity as it has a very big top buffer and Tesla (currently) advise always charging the LFP Model 3 to 100% (but that's for other reasons I suspect - i.e. to work out how to manage the battery better).

I'm also only charging with 3.6kW as I have a Rolec charger that's bound to catch fire if I go for the full 7kW, so as per @peterboat 's boat the cells should be getting an easy life.

Will probably make little difference, but I'll feel as though I tried and it doesn't affect my usage or enjoyment of the car.
 
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