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Kia Soul 30Kwh, 2018
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Discussion Starter · #1 ·
Thought I'd have a go at trying to work out if my 2 year old Kia Soul (30Kwh) battery is charging to stated capacity. I've ordered an OBD2 dongle and will check it when it arrives from China in about 3 months but in the meantime thought I'd try some maths - Boy do I seem to have lost my maths skills since I left school 40 odd years ago (very odd years).
Can those that know please try and follow my logic here and tell me where I'm going wrong?

The battery is 30Kwh (I've read actually 33Kwh but last 3Kwh aren't charged to preserve damaging battery??)
Car stated charge at 85%, meaning 15% charge would take it to 100%
15% of 30 is 4.5, so looking for charger to state that 4.5Kwh charged.
Charger states it delivered 6.38Kwh
6.38 is 15% of 42.49......??
I have no idea what happened there but have I got a 'special' Kia Soul with a 42.49Kwh battery?? (probably not)

I'm having another go tonight with a 40% charge - I suspect this will only confuse me more...

:oops::rolleyes::eek:HELP!! - please....
 

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40kW Leaf Tekna & 22kW Zoë Q210 dynamique intens
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Thought I'd have a go at trying to work out if my 2 year old Kia Soul (30Kwh) battery is charging to stated capacity. I've ordered an OBD2 dongle and will check it when it arrives from China in about 3 months but in the meantime thought I'd try some maths - Boy do I seem to have lost my maths skills since I left school 40 odd years ago (very odd years).
Can those that know please try and follow my logic here and tell me where I'm going wrong?

The battery is 30Kwh (I've read actually 33Kwh but last 3Kwh aren't charged to preserve damaging battery??)
Car stated charge at 85%, meaning 15% charge would take it to 100%
15% of 30 is 4.5, so looking for charger to state that 4.5Kwh charged.
Charger states it delivered 6.38Kwh
6.38 is 15% of 42.49......??
I have no idea what happened there but have I got a 'special' Kia Soul with a 42.49Kwh battery?? (probably not)

I'm having another go tonight with a 40% charge - I suspect this will only confuse me more...

:oops::rolleyes::eek:HELP!! - please....
Hi

Your not going mad the on board charger is not 100% efficient so it will always use more Kwh than actually ends up in the battery.

I don’t really know much about the Kia Soul being brutally honest but it’s also possible that if you plugged it when the battery was stone cold that the car heated the battery to charge it?

I’m sure someone much more in the know than me will correct me immediately but EV’s swallow more juice than ends up in the battery.
 

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Nissan LEAF30
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You need to take into account the losses in the charging process, both at the inverter and the battery. But that doesn't explain such a big difference. At close to 100% the battery balances by adding resistance into the circuit for cells that are high relative to the others so that they can charge further and come into balance.
I also expect some errors in the readings of charge.
 

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Charging efficiency of OBC in 30 kWh Soul varies from 90% at 27A to 75% at 10A. What EVSE are You using?
Also I've noticed when charging small amount of energy (like 15% in Your example) there is some energy unaccounted for. Like initial loss of charging process.
Discharge the car to 5%, charge it fully and then give us the reading together with charging current. Then we might be able to figure out what happening.
When you'll have Your dongle Torque pro will tell You Total Energy Charged (in the lifetime of the car), comparing value before and after charging session you'll be able to see battery capacity.
 

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Kia Soul 30Kwh, 2018
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Discussion Starter · #6 ·
Thanks one and all for responses - good to know I haven't totally lost the plot, yet.
TomIRL - sorry, so new to this not sure of acronyms yet. I'm assuming OBC is on-board charging, no idea about EVSE (Electric Vehicle...? )
Discharge the car to 5% - gotta be honest, still getting used to EV mind-set and anything less than 40% gets me a bit nervy. I will give it a go though, over the next week. How do I identify the charging current? and when you say reading, which one?
 

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Nissan LEAF30
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EVSE - Electric Vehicle Supply Equipment or charge point.

The idea of running the charge over as wide a range as possible is good but stick to below 95% to avoid battery balancing. As @TomIRL says the on-board charger is most efficient at close to its maximum rated output and the efficiency drops off dramatically at lower currents (partly why charging on "granny" chargers isn't recommended as a long term solution).
 

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Discharge the car to 5% - gotta be honest, still getting used to EV mind-set and anything less than 40% gets me a bit nervy.
Yeah, less than 40% I put mine on charge.
Just do it from 40 to 90 - that's 50% of capacity and will give a more reliable reading than 85 to 100, which as well as only being 15% has some uncertainties around what the system does near 100%.
 

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Kia Soul 30Kwh, 2018
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Discussion Starter · #9 ·
Charging efficiency of OBC in 30 kWh Soul varies from 90% at 27A to 75% at 10A. What EVSE are You using?
Also I've noticed when charging small amount of energy (like 15% in Your example) there is some energy unaccounted for. Like initial loss of charging process.
Discharge the car to 5%, charge it fully and then give us the reading together with charging current. Then we might be able to figure out what happening.
When you'll have Your dongle Torque pro will tell You Total Energy Charged (in the lifetime of the car), comparing value before and after charging session you'll be able to see battery capacity.
Hi TomIRL.

Ok, done some stuff and possibly not looking too bad - let me know your thoughts please.

The EVSE is a Wallbox Pulsar Plus running at 32amps and maxxed out by the limitations of the Kia Soul of 6.6Kw.
I managed to discharge the car to 7% (5 miles left) and had a strange feeling in my gut (terror!) and a nagging car demanding charging.
So, the car reckoned it needed 93% (27.9Kwh). It charged to 100% as far as the car was concerned. The charger reckoned it delivered 31.51Kwh which is 93% of 33.88 Kwh (I think).
It effectively, more or less appears to have over delivered 3.61Kwh. Going by previous comments about losses I understand that this is possibly within permitted limitations and to be expected and the greater the delivery the proportion of 'over delivered' reduces.
1.88 on 6.38, 2.61 on 14.61 and 3.61 on 31.51.

Still waiting for the dongle so would appreciate hearing your thoughts in the meantime,
cheers,
Dave.
 

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So, the car reckoned it needed 93% (27.9Kwh). It charged to 100% as far as the car was concerned. The charger reckoned it delivered 31.51Kwh which is 93% of 33.88 Kwh (I think).
Where does that 33.88 come from?

The car needed (and apparently not got) 27.9. The charge point delivered 31.51, which is 3.61 more, probably losses. So 3.61/31.51x100 = ~11.5% losses.
That's not unreasonable, though one hopes that as the technologies advance the average for new cars will gradually improve.

If you'd only charged to 80% the losses might have been a little lower as batteries tend to get warmer near full charge.
 

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Kia Soul 30Kwh, 2018
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Discussion Starter · #11 ·
Where does that 33.88 come from?

The car needed (and apparently not got) 27.9. The charge point delivered 31.51, which is 3.61 more, probably losses. So 3.61/31.51x100 = ~11.5% losses.
That's not unreasonable, though one hopes that as the technologies advance the average for new cars will gradually improve.

If you'd only charged to 80% the losses might have been a little lower as batteries tend to get warmer near full charge.
Thanks!
The 33.88 is what 100% would be if 31.51 was 93% - part of my earlier misunderstandings. i.e., if the car's asking for 93% and the charger is delivering 31.51, then what is 31.51 93% of ?.... - I know ;)
 

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Kia Soul 30Kwh, 2018
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Discussion Starter · #12 ·
....to be honest I'm not overly worried about the amount of losses cost-wise at the moment as my overall cost for EV energy during December was £11.55 - a great reduction from my previous ICE vehicle (5LV8 Merc ML500) @£90+. It's more just interest in battery efficiency after a couple of years. Checked my dongle from China progress which was quoted mid-feb to mid-March delivery and it's with Royal Mail so may very well be here tomorrow!!
 

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11.5% charging loses seem to be perfectly reasonable. It looks You have battery at perfect state of health. Your maths looks ok to me. You might actually have more than 30 kWh available(it's fairly possible in the Soul, ours is showing circa 30.5 at 29000kms). The discharge then fully charge process could help the BMS to recalibrate and operate better in the future.
If You feel not safe to drive down to 0% You can drive the car down to 5% and then park at the charger, open all the windows and crank the heater up to the max. It won't take long at current temperatures. Just pług it straight in afterwards.
 

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Kia Soul 30Kwh, 2018
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Discussion Starter · #14 ·
11.5% charging loses seem to be perfectly reasonable. It looks You have battery at perfect state of health. Your maths looks ok to me. You might actually have more than 30 kWh available(it's fairly possible in the Soul, ours is showing circa 30.5 at 29000kms). The discharge then fully charge process could help the BMS to recalibrate and operate better in the future.
If You feel not safe to drive down to 0% You can drive the car down to 5% and then park at the charger, open all the windows and crank the heater up to the max. It won't take long at current temperatures. Just pług it straight in afterwards.
Thanks very much for all that Tom, very useful.
Dongles arrived so I'll give it a go sometime in the next few days when I've got a mo' 👍
 

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Kia Soul 30Kwh, 2018
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Discussion Starter · #15 ·
Dongle and SoulSpy, he say 100%!!, so happy bunny - thanks for the input guys
 
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