Quote:
Originally Posted by jadnashuanh
At least in the USA, DC fast charging capability is an option when ordering the vehicle. This brings up at least a couple of questions in my mind.
1. With some batteries, their overall life is shortened when fast charging is done. Is that an issue with this vehicle?
2. Why do they list the 80% in 20-minutes, and in the fine print 100% in 30-minutes? Is it because continuing to charge that last 20% isn't all that good for the thing on a fast charge (or, maybe it's the perception thing about time)? Admittedly, you probably wouldn't want to regularly get the batteries down to zero (or close), so 80% may be more the norm, but I wonder...
3. Since in most places, at least for now, there aren't that many DC fast chargers out there, and the cost and infrastructure to install one in a residence is not a likely situation, if you bought the vehicle without the DC fast charge option, is it something that could be retrofitted later when they did (if ever) become a common feature on the landscape? At what cost, if possible at all?
Any thoughts?
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1) The fast charging it self isn't the problem, it's the heat created while your dumping so much power into the pack so quickly. This is where a good thermal management system can really help prolong the life of the cells. BMW developed a sophisticated thermal management system (TMS) for the battery to keep the cells from overheating and to warm them if needed. During DC Quick charging the cells are monitored to assure a safe temperature is maintained. That being said, I wouldn't recommend using DC quick charge all the time. A few times a month though when you need to drive long distances won't have any measurable negative effect.
2) To protect the cells from overcharging, DC quick charge usually will only charge the car to 80% full. AT that point (depending on the car) the charger will either shut off or it will slow down to a safe rate which is usually what the car charges at on 240V (or 230V in Europe) when charging on standard L2. That's why you see manufacturers say (20 minutes to 80% on DC quick charge) I'm not sure about the 30 minutes to 100% - that is wrong, the car will not finish the last 20% in 10 minutes, in fact the final 20% will likely take 35 or 40 minutes since the charge rate slows dramatically once it's over 95%.
3) No. If you don't get it with the original purchase you will not be able to add it later. I'm not saying it would be impossible, but it would be prohibitively expensive. It's not just a new connector for the charge port. As I said the thermal management system has to be programmed to accept DC quick charge and be robust enough to accommodate it. I'm not sure the whole TMS or at least parts of it aren't more heavy duty on cars with the DC quick charge option.