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Originally Posted by Chhanda Das Accuracy is indeed a concern with all electronics in all cars of all fuel types. For example, EVs' battery management systems (BMSs) need to be calibrated during every service which means that they are used for some time in a miscalibrated state as they are not serviced every day. Just like the burning of fossil fuels in ICE cars, the charging/discharging of EV batteries are chemical reactions too. So inaccuracies are a real possibility with EVs as well. Recalculations of estimates are needed for EVs too since the battery (pack) will not hold the exact same amount of charge or discharge the same amount every single time. And a difference in voltage will cause a difference in amperes delivered to the air conditioner's compressor too. A major proof of this inaccuracy in EVs is the inconsistent consumption of battery power with the same load and this is seen in mobile phones, laptop/tablet computers, etc too. In summary, just because it is an EV, we cannot assume that it is more accurate than an ICE vehicle. |
Kindly do not consider my explanation as an attempt to discredit your experiment - it's accuracy or the data extracted . It does exactly what the intent was, the real time fuel consumption of the car as a whole.
My explanation is more geared to the point that, when an ICE engine operates it powers up the entire ecosystem of belts/pulleys.
So the fuel consumption that we see in the video, is used to run everything, all the engine/transmission components and the accessories - timing belts, alternator, water pump, power steering pump, or air conditioning compressor etc. The list is quite exhaustive.
So technically the fuel consumption we saw via OBD2 output is a sum of all.
First step would be isolating it down to the AC compressor.
And then there are the losses of energy transfer from engine to the AC's compressor.
So the derivation from the liter/hour seen in the video to isolate AC compressor's consumption needs to account for all these intermediaries and then the conversion losses and that too over different ambient conditions. That was the estimation/calculation accuracy concern i meant when it came to indirect calculation for AC consumption, especially if we are looking for real time values.
In contrast the KW load shown is EV's is at the AC compressor's inverter terminal. There are no moving parts, it is almost an end point consumption.
So there is no calculation required. It's the isolated consumption of just the cooling circuit, displayed real time.
The inaccuracy of "measurement systems" was never the concern.
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Originally Posted by Chhanda Das A major proof of this inaccuracy in EVs is the inconsistent consumption of battery power with the same load and this is seen in mobile phones, laptop/tablet computers, etc too. |
Respectfully, this is the only statement i would disagree with.
Load is never same, the load variability of our driving style simply based on gradient and traffic (even in presence of a gear based transmission system), over a few minutes can be all over the chart.
Even with mobile phones, laptop/tablet computers, etc, load variability due to user screen access, background consumption of apps, networks, parasitic drains are well documented.
Same load would be a battery connected to a resistor, if that's the case then the estimate once set could remain accurate for thousands of cycles.
But these load variability discussions, would be out of scope of this topic. Hence, would not like to bring it in for the risk of digressing from this thread.
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Originally Posted by Chhanda Das In summary, just because it is an EV, we cannot assume that it is more accurate than an ICE vehicle. |
EV systems need these energy data to give range estimates, ICE's don't need it, atleast, not at the level of criticality that EV's require. So I would say that EV's need to have a more accurate onboard system for this, while an ICE vehicle can do without this altogether.
So it is upto the manufacturer to decide whether they want to show this data or try to keep the costs down in case of an ICE vehicle. But with an EV, the manufacturer does not get to overlook and choose to do without this, an accurate measurement comes as a part of the system.
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Originally Posted by Chhanda Das Accessing such information in EVs is definitely easier but it is not too hard in ICE vehicles either. All modern vehicles have OBD2 or higher version ports in them. |
No doubt about that and i completely second that.
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Originally Posted by Chhanda Das Sadly, he didn't record anything other than what you might have already seen in the video. This was because the original purpose of the video was to demonstrate the addition of a missing feature in our Creta. |
Yup, the purpose was different, the fuel consumption/hour data. Though, i would still struggle to isolate the real time AC consumption from that: not upto that challenge
I have been a follower of your interesting DIY projects, the solar exhaust was a cool one(literally
).