Insider knowledge... I will help where I can - Page 2 - Jaguar I-Pace EV400 Forum
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post #11 of 17 (permalink) Old 08-19-2019, 06:05 AM Thread Starter
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Great! Welcome! Maybe you have a thought on the shuddering issue described /videoed by gordondd in the "seized up" thread ...
Haven't read the thread but when we had prototype vehicles the difficulty was in keeping the 12v batteries charged sufficiently to enable the high-voltage contactors to operate.

In other words the 12v system did all the software/control functions including operating the high voltage/high current switch that directs current towards the drive units.

If you have insufficient charge in the 12v system (charging fault, been left sitting a while etc) then the contactors aren't able to close and the car won't drive.

On the subject of vehicle recovery - the parking brake can be released manually via the rear calipers and the vehicle can be dragged VERY slowly (less than walking pace) for a VERY short distance (ie onto a low-loader). Towing at speed with any of the wheels on the ground is a big no-no.
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post #12 of 17 (permalink) Old 08-19-2019, 12:08 PM
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Originally Posted by grogee View Post

Haven't read the thread but when we had prototype vehicles the difficulty was in keeping the 12v batteries charged sufficiently to enable the high-voltage contactors to operate.

In other words the 12v system did all the software/control functions including operating the high voltage/high current switch that directs current towards the drive units.

If you have insufficient charge in the 12v system (charging fault, been left sitting a while etc) then the contactors aren't able to close and the car won't drive.
How did they solve the problem? It seems that the 12v battery is still an issue with some owners. Thanks for the tip about towing. Hopefully I'll never need it but it could help when contacting roadside assistance to ensure only a tow vehicle with the necessary flatbed arrives.

Last edited by 2761; 08-19-2019 at 12:12 PM.
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post #13 of 17 (permalink) Old 08-19-2019, 12:27 PM
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Grogee, does the car perform some type of high voltage battery conditioning/energy consolidation during the night? Overnight, the state of charge drops 1% on occasion and lost 2% while sitting for the last 2 days. The hazard button is not illuminated so I'm wondering what SoC loss is considered normal. Dealer couldn't answer this question. Thanks.
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post #14 of 17 (permalink) Old 08-20-2019, 12:12 AM
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Towing at speed with any of the wheels on the ground is a big no-no.
Yet the vehicle allows neutral to be used at speed. Is there a difference?
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post #15 of 17 (permalink) Old 09-09-2019, 09:36 AM Thread Starter
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The charge depleting on its own does not surprise me, I don't know what the figures should be but I bet this is no different to a Tesla or Chevy Bolt etc. Left to its own devices the HV battery will 'look after' the 12v batteries and ensure their charge does not drop too low, this is done via the inverter unit where there will inevitably be some losses to heat. Together with the quiescent drain on the 12v battery systems (alarm, ECU memory retention etc) that would equate to a small drain on the HV battery.

It might be worth starting a thread to see what other i-PACE owners are getting (or losing) if they leave their cars unplugged/not charging overnight.
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post #16 of 17 (permalink) Old 09-09-2019, 09:42 AM Thread Starter
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Yes there's a difference. The 'neutral' setting is an electronic simulation of 'neutral' in a conventional car. In practice the motor, gearbox and battery are permanently connected (assuming contactors are closed - as they should be with "ignition" on).

If the vehicle is coasting in neutral, the system is directing charge around the HV network to simulate zero or near-zero load on the wheels. It's doing this in conjunction with the cooling system to ensure no part of the HV system overheats.

If the vehicle is towed on all four wheels, the cooling system is inactive, and charge builds in a switching unit (I forget its name, something like the Six Switch). This charge has nowhere to go as the motor generates a potential difference and the reason towing on four (or two) wheels is not recommended is because of the risk of arcing at/around this switch and consequent "thermal event" risk.
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post #17 of 17 (permalink) Old 09-09-2019, 11:20 AM
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The charge depleting on its own does not surprise me, I don't know what the figures should be but I bet this is no different to a Tesla or Chevy Bolt etc. Left to its own devices the HV battery will 'look after' the 12v batteries and ensure their charge does not drop too low, this is done via the inverter unit where there will inevitably be some losses to heat. Together with the quiescent drain on the 12v battery systems (alarm, ECU memory retention etc) that would equate to a small drain on the HV battery.

It might be worth starting a thread to see what other i-PACE owners are getting (or losing) if they leave their cars unplugged/not charging overnight.
My car sat outside in subfreezing temps (<20 F) for 10 days and displayed no loss of charge.
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post #18 of 17 (permalink) Old 09-09-2019, 12:33 PM
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Originally Posted by grogee View Post
Haven't read the thread but when we had prototype vehicles the difficulty was in keeping the 12v batteries charged sufficiently to enable the high-voltage contactors to operate.

In other words the 12v system did all the software/control functions including operating the high voltage/high current switch that directs current towards the drive units.

If you have insufficient charge in the 12v system (charging fault, been left sitting a while etc) then the contactors aren't able to close and the car won't drive.

On the subject of vehicle recovery - the parking brake can be released manually via the rear calipers and the vehicle can be dragged VERY slowly (less than walking pace) for a VERY short distance (ie onto a low-loader). Towing at speed with any of the wheels on the ground is a big no-no.
The "seized" thread is the one I created which can be found here:
https://www.i-paceforum.com/forum/19...ompletely.html
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