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Discussion Starter · #1 ·
I made a video about the energy wasted by charging to full:


Regardless of the implications for battery health, in my MG5 at least there is a definite overhead of wasted energy (lost to heat in the battery balancing and friction braking while regen is limited) every time you charge to full.

I'm curious how much it differs from vehicle to vehicle so it would be interesting if anyone feels like repeating the test.
 

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Can you set the maximum SOC on the MG? On the Ioniq Id just leave it to 80% unless I need the full range of the car. A lot of people will just plug in and leave it to 100%, even if they are mostly just pottering around town.

I'd say there is a greater efficiency loss from ICE style driving than charging to 100%, especially once the car has driven a few miles. For example stomping on the accelerator when pulling off traffic lights, or in your example joining the A11 and going for the immediate overtake(11:06) , then braking hard from 70 to slow down for the ketteringham exit(11:11). Closing gaps, then braking hard to match speed of the car in front are traits of ICE drivers that reduce efficiency.

Try the experiment again, this time driving like Miss Daisy (but not holding up traffic). I don't think the regen factor would come much into play as high levels of regen/friction brakes would not be required.
 

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I'm curious how much it differs from vehicle to vehicle so it would be interesting if anyone feels like repeating the test.
The BMW i3 has a large top margin. It is possible to get full regen even when the battery shows 100% SOC.

Very different than my previous LEAF which had little or no regen at 100%.
 

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LEAF N-TEC 62KW
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My 62kw Leaf won't do much regening above 95% SOC and the full 35kw regen is only available from below about 85%.

So I agree, no point in doing a 100% charge unless you want to let the BMS balance the cells (once per month is often enough) or need every % of range for a long journey.
 

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Discussion Starter · #6 ·
The BMW i3 has a large top margin. It is possible to get full regen even when the battery shows 100% SOC.

Very different than my previous LEAF which had little or no regen at 100%.
That's really interesting. So you could potentially tap into that top buffer by starting a journey at the top of a mountain and use regen to charge above '100%'. It really does seem like the i3 has a totally different battery management paradigm.
 

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Discussion Starter · #7 ·
Can you set the maximum SOC on the MG? On the Ioniq Id just leave it to 80% unless I need the full range of the car. A lot of people will just plug in and leave it to 100%, even if they are mostly just pottering around town.

I'd say there is a greater efficiency loss from ICE style driving than charging to 100%, especially once the car has driven a few miles. For example stomping on the accelerator when pulling off traffic lights, or in your example joining the A11 and going for the immediate overtake(11:06) , then braking hard from 70 to slow down for the ketteringham exit(11:11). Closing gaps, then braking hard to match speed of the car in front are traits of ICE drivers that reduce efficiency.

Try the experiment again, this time driving like Miss Daisy (but not holding up traffic). I don't think the regen factor would come much into play as high levels of regen/friction brakes would not be required.
I normally drive quite efficiently but I wanted the test to be a more 'normal' style of driving with a burst up to 70mph. As the road was clear on my first part of the test, I did the overtake to attempt to replicate the same conditions.

I agree that it's possible to mitigate some of the lower regen. I actually rambled on about that very point (amongst other things) but decided to edit most of it out because the original video was nearly double the length.

Unfortunately the MG5 doesn't have a maximum SOC setting, but the Zappi can easily achieve a similar outcome.
 

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I will reconstruct your twin tests in my classic Ioniq but will then need to do that complete comparison test twice. Once to duplicate your own driving parameters and then again driving in my own preferred style. I tend to fully use the Ioniq's ability to tailor regen to the circumstances, using the paddles, and coast quite a lot. I rarely need to use the physical brake pedal and instead control deceleration by increasing/decreasing the 'clicks' as required. Then cancel regen completely once the desired speed is reached and coast again as long as possible. I don't hold up traffic but also don't burn rubber. Chilled progress and defensive driving is my style. I haven't really studied the lack of strong regen from 100% and that part will be interesting. Report to follow.
 

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Discussion Starter · #10 ·
I will reconstruct your twin tests in my classic Ioniq but will then need to do that complete comparison test twice. Once to duplicate your own driving parameters and then again driving in my own preferred style. I tend to fully use the Ioniq's ability to tailor regen to the circumstances, using the paddles, and coast quite a lot. I rarely need to use the physical brake pedal and instead control deceleration by increasing/decreasing the 'clicks' as required. Then cancel regen completely once the desired speed is reached and coast again as long as possible. I don't hold up traffic but also don't burn rubber. Chilled progress and defensive driving is my style. I haven't really studied the lack of strong regen from 100% and that part will be interesting. Report to follow.
Excellent. I'd love to see the results.
 

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That's really interesting. So you could potentially tap into that top buffer by starting a journey at the top of a mountain and use regen to charge above '100%'. It really does seem like the i3 has a totally different battery management paradigm.
It's not just BMW. I seem to recall the old Mercedes B250e was the same too. Not only could you regen with a 'full' battery, but you could also choose to make use of the top buffer by pressing a button (Range Plus, I think it was called) and for that charge session it would override the buffer and recharge to full, meaning you could travel further if you really needed the extra range.
 

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My Soul, if I charge to 100% (which I usually do) won’t allow regen straight away “Regenerative braking not available, battery full” come soon up on the dash, but I can barely travel half a mile before it’s back (unless I was downhill I guess).

Certainly once my fuel gauge reads “99%” I have full regen back.
 

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My Soul, if I charge to 100% (which I usually do) won’t allow regen straight away “Regenerative braking not available, battery full” come soon up on the dash, but I can barely travel half a mile before it’s back (unless I was downhill I guess).

Certainly once my fuel gauge reads “99%” I have full regen back.
Are you sure it's "full" regen though. I've seen around 60-70kW in the Ioniq (ie heavy deceleration from 70mph), what is it for the Soul, I wouldn't get that if the battery was above 90%. But even at high charge % I do get some regen, maybe 5 or 6kW as soon as you try and get any more than that then a warning flashes up I think. But then I rarely charge to 100 anyway, especially since pandemic.
On another note, I'm surprised the Leaf 62 only ever gets max 35kW.
 
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Soul doesn’t read out the KW I don’t think - just shows “added miles” in a little circle on the dash - where could I see the KW?
 

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Soul doesn’t read out the KW I don’t think - just shows “added miles” in a little circle on the dash - where could I see the KW?
Not sure on the Soul, the Ioniq has a power screen on the infotainment screen, with the actual kW being used/regenerated.
Shows motor, climate and electric system usage (And battery care, but that's always 0, it's only applicable in sub zero temps I believe)
It's quite a useful screen, it's where I realised that motor power gets restricted as temperature drops below around 8°C. In decent temperatures you can pull 99kW under acceleration (motor is 100kW), I've seen around 85kW in freezing temps, it's quite noticeable, especially joining a dual carriageway from a short slip!
Assume it drops further with temperature.
 
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Charged to 100% for the first time in a while last night. I nearly went into the back of a car at the first traffic lights!
 
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Are you sure it's "full" regen though. I've seen around 60-70kW in the Ioniq (ie heavy deceleration from 70mph), what is it for the Soul, I wouldn't get that if the battery was above 90%. But even at high charge % I do get some regen, maybe 5 or 6kW as soon as you try and get any more than that then a warning flashes up I think. But then I rarely charge to 100 anyway, especially since pandemic.
On another note, I'm surprised the Leaf 62 only ever gets max 35kW.
The gauge goes from -35kw to +160. The regen braking on max is strong, just right in fact. It will slow me from 40-20mph in 20m down a 20% gradient, or from 40 to 0mph in about the same distance on the level. Any stronger would be too much.

I can see the max power dropping at high speeds, but not sure whether it's a design feature or the BMS cutting it down to stop the battery or motor overheating during sustained acceleration. (I was on my way from 50 to 100mph at the time)
 
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