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Thanks. The initial post in the thread appears to indicate that the chargers are most efficient at 40 amps. I did see the link one poster put later in the thread to his testing (Ideal Charge Rate??) but that appears to be based on using the UMC vice a HPWC and his biggest concerns are the heat of the UMC cable running at 40 amps and leading to cable breakdown or early UMC failure. Even with is numbers, the difference in efficiency is about 1% meaning almost negligible for an almost 50% decrease in charging speed.
Guess I'm missing something...or is this all about charging with the UMC and trying to balance out the heat issue?
Guess I'm missing something...or is this all about charging with the UMC and trying to balance out the heat issue?
hacer
Active Member
My link was to a specific post of mine in that thread, which itself linked to a plot and explanation, as well as the raw data. Since you didn't follow the second link, here it is only one click away: Ideal Charge Rate?? in summary, the new chargers (48A/72A) are more efficient overall and, from data that I've gathered, have a peak efficiency at 25A (almost as good at 35A too). The charger is ~1% more efficient at 25A compared to 40A, and ~1.2% better compared to 48A. Since this charges the battery at a lower current, presumably the (unknown) efficiency of the battery is also greater. Finally, there should be less stress on all of the components in the system, so if you have the time, why not? I think, but have not proven, that in very hot weather the lower charge rate is also less likely to provoke operation of the cooling system. My car has the new charger so this applies to me, but it is different for people with older cars.
hacer
Active Member
My link was to a specific post of mine in that thread, which itself linked to a plot and explanation, as well as the raw data. Since you didn't follow the second link, here it is only one click away: Ideal Charge Rate?? which that specific post is not about the UMC at all, it is about the internal charger in the refreshed cars. In summary, the new chargers (48A/72A) are more efficient overall and, from data that I've gathered, have a peak efficiency at 25A (almost as good at 35A too). The charger is ~1% more efficient at 25A compared to 40A, and ~1.2% better compared to 48A. Since this charges the battery at a lower current, presumably the (unknown) efficiency of the battery is also greater. Finally, there should be less stress on all of the components in the system, so if you have the time, why not? I think, but have not proven, that in very hot weather the lower charge rate is also less likely to provoke operation of the cooling system. My car has the new charger so this applies to me, but it is different for people with older cars.
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I actually followed the link to your post and referenced it, just didn't realize it was yours (to be honest I didn't loo). My reference was
My point remains the same. Your data only shows a 1% increase in charging efficiency for an almost 50% decrease in charging rate. Why would you do this? To save money on your electric bill or something else (heat concerns). That's what I don't understand.
My point remains the same. Your data only shows a 1% increase in charging efficiency for an almost 50% decrease in charging rate. Why would you do this? To save money on your electric bill or something else (heat concerns). That's what I don't understand.
hacer
Active Member
Your original question was:
which I took to mean how is it more energy efficient, but I can see that you might consider time efficiency. So now I understand your question.drklain said:
I don't do that much daily driving (~35 miles average), so even at 25A (~18mi/hr) I can easily charge overnight. Given that, why not save 1% (for me that's like $8 per year!)? It also theoretically has less stress on everything: connector, charger, battery. For those that drive a lot more (say 150 mi/day), you can still fully replenish that in 8.3 hours at 25A which is enough time for most people. Is it a big deal? No. But for me there is no penalty, and a tiny benefit, so why not? There are (rare) occasions where I want to charge faster, and then I just turn it up.
That makes perfect sense. Thanks for the explanation.
All goes to definitions and "efficient" is certainly a word that can be defined a number of ways when talking about charging.
I appreciate your taking the time to engage with me and educate me. It's awfully nice to engage in a rationale discussion/debate...there are so many places on the internet these days where you just can't do that!
I see you're in Clarksville. I'm in Fairfax, VA (when I'm not on the road). Perhaps we'll meet sometime and hoist a barley-based alcoholic beverage together in Tesla fellowship....
All goes to definitions and "efficient" is certainly a word that can be defined a number of ways when talking about charging.
I appreciate your taking the time to engage with me and educate me. It's awfully nice to engage in a rationale discussion/debate...there are so many places on the internet these days where you just can't do that!
I see you're in Clarksville. I'm in Fairfax, VA (when I'm not on the road). Perhaps we'll meet sometime and hoist a barley-based alcoholic beverage together in Tesla fellowship....
dhcp
Member
Bought a second UMC - one stays in the trunk 24/7 because I know I'll easily forget it on a trip or not pack it thinking "I shouldn't need it" which is always bad planning.
I picked up a second UMC because it wasn't priced much different than a perm install and I figure it gives me more flexibility than a permanently wired charger and if I ever decide I don't need it, they are pretty easy to sell quickly on the used market.
I picked up a second UMC because it wasn't priced much different than a perm install and I figure it gives me more flexibility than a permanently wired charger and if I ever decide I don't need it, they are pretty easy to sell quickly on the used market.
