CitiGo part 6: "Thermos with electrons"
The battery pack of the “VW triplets”, must be pretty well insulated. It really doesn’t exchange much thermal energy with the surroundings. I finally got myself an ODB2 dongle, to examine further:
(16:49 to 17:49: +5 C battery pack temperature rise)
Some will say that "a few degrees more or less in the battery doesn't matter. Well, if your car has sat in a hot environment for a couple of days, it's warm already in the battery. Driving for a few hours, just adds to that, and so does CCS charging. "Up to" 40kW in the brochure became 8kW in reality, even at 56% SoC, so it's not without an effect. Not much of an issue if you charge at home and do shorter trips. Or if it's colder where you live. But just 3 hours of highway driving, with a 1 hour CCS charging break in the middle, and the battery could be in the order of 50 C inside. That not only slows the CCS charging to AC levels of charging, it also degrades the battery capacity faster. So don't do this too often.
With the ODB2, I found plenty of temperature data that way, as well as State-of-Charge, and much more. I should have gotten this dongle before our trip. Too late now. But after the trip, I did plenty of research, while charging, driving and also how the battery pack cooled off overnight. So we must do a long distance road trip again some time soon ...
I wish I had gotten an ODB2 dongle from the beginning! It would have been interesting to know what the battery temperature was when we only got 8kW at 56% SoC.
This is how I found that the batteries are really like a thermos with electrons. The ignition must be on for the ODB2 to work, so I couldn’t have it sitting overnight. But after plugging the car in to charge, the ignition key could be re-inserted, and measurements ongoing throughout the charging process. I also noted how the battery temperature changed when the car was parked. This is how I found that the battery was so well insulated: The higher temperature after a longer trip would take days to cool off. Literally. The insulation also means that the movement of air while driving doesn't cool your battery much at all!
The insulation of the battery isn’t always a bad thing. Although I haven’t yet tried this car in temperatures below around 15 C, I know that it will suffer a bit in the winter. Planning the charging using the scheduler, the battery will be warm enough from the charging itself. Even with “only” 7.5kW AC at home. And this is where the insulation will shine: The battery won’t be bleeding off its thermal energy too quickly. Because you don't want it to become too cold either.
But not only that: When the temperature at night is cold enough, the battery will balance itself towards some average temperature. While the car is sitting in the sun on a hot day, it can become quite hot inside the cabin. Btu this won’t affect the battery too much either - again, because the insulation works both ways (obviously). If the temperature remains high at night, like in certain tropical climates, then it would start becoming an issue. This car is definitely NOT for Hong Kong in the summer (unless you park it in a cooler garage most of the time)
This image is from the e-UP. And possibly from the first generation (-2018). The battery is well protected, but also well insulated. Read more about the Skoda CitiGo e iV on the other blog posts in this series.
Next: CitiGo part 7: More lessons learned (a few tricks and hints)
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