Charging rate

[Technicks]

How or where can we see the active charge rate? I'd like to see if my level 2 charging actually delivers what it's supposed to.

I have a 2014 model with rex.

Thanks in advance.

 

[jadnashuanh]

Borrow or buy a clamp on inductive ammeter. Or, install one in-line permanently, or, chuck the EVSE you have and buy one that has a display that shows the power used, or just wing it. If you have a plug-in verses wired, you might find a plug-in device that would give you that information.

The max power the i3 can use is something that provides 7400W. Now, power (watts)=volts * amps. If you know your voltage applied and the size of the EVSE you have, you can see how close to that magic 7400W you can be using. For a fully discharged i3 battery pack, and a maximum sized EVSE, it should take somewhere between 3.5-4 hours to reach full charge depending on the temperature of both the car and the environment.

In my case, I have a 30A EVSE and my supply voltage typically is in the range of 247VAC, so 30*247=7410W, or more than the i3 can use. IF my supply voltage was say 208vac (a more typical value at a commercial location), that same EVSE could only supply 208*30=6240W, or only about 84% of what the i3 could use and this is with exactly the same EVSE in the same car just by the difference in input voltage. In Europe, where their nominal voltage might only be 220vac, a 30A EVSE would only provide 220*30=6600W, which is why many of them supply more amps (often 32A), which still isn't the max the i3 can use, but better.

Did I confuse you yet?

The i3's on-board charging circuits are not perfect - there is some conversion loss from the ACV going in to the monster DCV power supply needed to charge the batteries. Plus, while charging the main batteries, it is also recharging the 12vdc battery, keeping the computer running, and the sensors and potentially the heating or cooling circuits of the battery pack. The charging rate is not linear...IOW, it won't be max the whole time...it might start out slower, ramp up, then as the battery gets fuller, slow down again, all depending on the temperature and the logic that's trying to maximize its life.

 

[Technicks]

I'm so sorry, I should have been a bit more clear. As a Power Electrical Engineer I'm more than familiar with power measurements and conversions. I was only interested in knowing if the car itself can display this information. From your message I assume it does not.

However, the info you provided is very good and I'm sure many other users will find it helpful!

 

[spinball]

The car does not display this. I have an OpenEVSE which displays amps and the highest I've seen is 31.8A draw at full power. There is a certain percentage of error on this reading but that number should be pretty close.

 

[jadnashuanh]

The only thing the on-board electronics in the i3 will tell you about the charging is the TOD of when it thinks it will be finished, not the actual input power being used.

 

[jasleinstein]

To not show the actual charging rate on an EV is silly and stressful for the owner. The unreliable range calculation and lack of this function have been big issues for us since we bought the car. Now that BMW has the KLE issue resolved they should be open to display the actual charging rate. I suggest those of us who think it is a good idea, make suggestions in the proper portion of the forum.

 

[jadnashuanh]

Personally, I don't really see the advantage. They do show you when the car will be fully recharged, and that's what most people really care about. Many commercial units do show the rate, and you can buy one if it's really that important to you. Now, could it be added, probably. The sensors are probably there, or they could infer it from those that exist if not measure it directly. For most people, it's an irrelevant data point...when the car will be recharged is much more useful. I don't see the big deal about adding the numeric SOC, either. How many cars have you ever driven that showed how many digital gallons were left in the tank? Very few. If it were a big deal, it would show up on all of them as the first ones with it occurred decades ago.

EV's are relatively new...people are unfamiliar with them, but I do not think this is a critical item or a must have in the scheme of things.

It can't hurt to ask...I just wouldn't hold my breath.

The actual charging rate will vary considerably based on the EVSE's input voltage, the battery's temperature, and how close to full it is...most people are not educated enough, and would likely declare it is defective unless it showed the 'max'. Probably cause more service requests for nothing that is wrong.