jasleinstein
Posts: 63
Joined: Mon Sep 01, 2014 12:03 pm

maximum charging rate for 120V?

Fri Sep 12, 2014 9:50 pm

Has anyone actually measured maximum 120v charging rate? Has anyone verified a rate of 1.9 kW? Due to the charging issue of the KLE I may be forced to charge on 110v as my other EV and the BMW need to share charge time, and they can't both get done on 220v in my charge window time. I need every kw possible to use 120v.

I was on the phone today with Clipper Creek wanting to order the HCS-20 charger. They told me they thought the i3 would only charge at 1.4 kW on 120v. I have a 25 amp dedicated circuit but don't want to waste money of the car won't charge at the higher rate. I hear BMW say the car "might" charge at a higher rate, but frankly after the KLE software setback and incorrect statements " In some cases the charging rate may be reduced by up to 30%" when in fact it all charging is capped at 5kW, I am a bit gun shy.

Has anyone actually measured maximum charging rate on 120V?

thanks

This text was used as a response in another thread, so I apologize.

KurtEndress
Posts: 52
Joined: Mon Jul 28, 2014 12:01 pm
Location: Beltsville, Maryland

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 6:30 am

I'll repeat some of what I said in the other thread.

Last night I recharged my i3 REx from 58% in 8.5 hours. That works out to about 5% per hour or 930 watts into the battery.

The L1 high setting is 12A, so it can draw about 1440 watts from the wall, but that's not what makes it into the battery.
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mindmachine
Posts: 502
Joined: Sat Mar 15, 2014 2:08 pm
Location: Ohio, USA

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 8:02 am

KurtEndress wrote:I'll repeat some of what I said in the other thread.

Last night I recharged my i3 REx from 58% in 8.5 hours. That works out to about 5% per hour or 930 watts into the battery.

The L1 high setting is 12A, so it can draw about 1440 watts from the wall, but that's not what makes it into the battery.
I have both the i3 and a 2014 Prius plugin and while I don't use 120 volt charging on the i3 I do on the Prius. I am not 100% sure weather the Prius EVSE should provide 10 or 12 amps, but the Prius reports how many kwh it is drawing and it only draws 900 watts. 920/1.2 kwh input assuming 10 amp capability would be 77% efficiency.

KurtEndress
Posts: 52
Joined: Mon Jul 28, 2014 12:01 pm
Location: Beltsville, Maryland

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 11:51 am

mindmachine wrote:I have both the i3 and a 2014 Prius plugin and while I don't use 120 volt charging on the i3 I do on the Prius. I am not 100% sure weather the Prius EVSE should provide 10 or 12 amps, but the Prius reports how many kwh it is drawing and it only draws 900 watts. 920/1.2 kwh input assuming 10 amp capability would be 77% efficiency.
Your Prius drawing 900 watts is different from 900 watts going into the battery. There are losses at various stages, but converting AC from the wall to DC for the battery is probably the biggest. What is the Prius reporting? Making assumptions about how much it draws from the wall makes the 77% efficiency figure a pure guess.

My I3 reported I drove 37.3 miles at 4.7 mi/kWh consumption. That works out to 7.94 kWh used. It said the SOC was 58% which means 7.90 kWh missing from the battery. So the car is consistent within the two digit precision of the figures.

I have a TED monitor that showed about 1400 watts extra flowing through my electrical panel for 8.5 hours (plus or minus 5 or 10 minutes). From that I calculate about 66% efficiency for the combined wiring loss, charger loss and battery loss. That's close to a wall to wheels figure except that it also includes the 120V wiring to the garage and a heavy duty extension cord. I only have a 15A circuit in the garage so that may use just 14 gauge wire which will definitely add to the loss with a 1400 watt draw. The 25 ft 12 gauge extension cord is less of a problem than the house wiring.

I'm currently working out the scheduling to have an electrician install a 40A 240V L2 EVSE for me. That will be a faster and more efficient way to charge. Though a 20% more efficient charge isn't going to pay off the L2 EVSE anytime soon since EV's are so inexpensive to run anyway.
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mindmachine
Posts: 502
Joined: Sat Mar 15, 2014 2:08 pm
Location: Ohio, USA

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 1:33 pm

KurtEndress wrote:
mindmachine wrote:I have both the i3 and a 2014 Prius plugin and while I don't use 120 volt charging on the i3 I do on the Prius. I am not 100% sure weather the Prius EVSE should provide 10 or 12 amps, but the Prius reports how many kwh it is drawing and it only draws 900 watts. 920/1.2 kwh input assuming 10 amp capability would be 77% efficiency.
Your Prius drawing 900 watts is different from 900 watts going into the battery. There are losses at various stages, but converting AC from the wall to DC for the battery is probably the biggest. What is the Prius reporting? Making assumptions about how much it draws from the wall makes the 77% efficiency figure a pure guess.

My I3 reported I drove 37.3 miles at 4.7 mi/kWh consumption. That works out to 7.94 kWh used. It said the SOC was 58% which means 7.90 kWh missing from the battery. So the car is consistent within the two digit precision of the figures.

I have a TED monitor that showed about 1400 watts extra flowing through my electrical panel for 8.5 hours (plus or minus 5 or 10 minutes). From that I calculate about 66% efficiency for the combined wiring loss, charger loss and battery loss. That's close to a wall to wheels figure except that it also includes the 120V wiring to the garage and a heavy duty extension cord. I only have a 15A circuit in the garage so that may use just 14 gauge wire which will definitely add to the loss with a 1400 watt draw. The 25 ft 12 gauge extension cord is less of a problem than the house wiring.

I'm currently working out the scheduling to have an electrician install a 40A 240V L2 EVSE for me. That will be a faster and more efficient way to charge. Though a 20% more efficient charge isn't going to pay off the L2 EVSE anytime soon since EV's are so inexpensive to run anyway.
You are wrong, the Prius measures what is going into the battery and that is what i stated. Based on the time to charge the Prius from empty and the usable capacity of the battery I know it is reporting the kwh rate of charge that it is actually storing. But since you apparently know so much what is your question and reason for asking the same question in two different threads anyway? :roll:

jasleinstein
Posts: 63
Joined: Mon Sep 01, 2014 12:03 pm

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 6:41 pm

We got a little off base here. So the maximum charge rate for the i3 on 120v is 1.4kW right? It will not charge at 1.8 or 1.9 kW?

thanks guys!!

KurtEndress
Posts: 52
Joined: Mon Jul 28, 2014 12:01 pm
Location: Beltsville, Maryland

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 8:53 pm

jasleinstein wrote:So the maximum charge rate for the i3 on 120v is 1.4kW right? It will not charge at 1.8 or 1.9 kW?
Yes, with the i3 120v occasional charger it will draw 12 Amp at maximum, or 1.44 kW. What goes into the battery will be less.

I don't kmnow if it is possible to do better on 120V with a differnet EVSE. From what I read the ESVE can signal over the J1772 connection that it is capable of 6, 12, 18, 24, or 30 amps. Maybe the i3 could handle 120V at 18A if the EVSE said it could do it. I seem to recall someone saying that their car was charging at 3 kW off a L2 EVSE and found that it had been installed incorrectly with only one hot lead connected; effectively just a 30A 120V circuit.
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KurtEndress
Posts: 52
Joined: Mon Jul 28, 2014 12:01 pm
Location: Beltsville, Maryland

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 9:22 pm

mindmachine wrote:You are wrong, the Prius measures what is going into the battery and that is what i stated. Based on the time to charge the Prius from empty and the usable capacity of the battery I know it is reporting the kwh rate of charge that it is actually storing. But since you apparently know so much what is your question and reason for asking the same question in two different threads anyway? :roll:
Wrong about what? I asked (once in this thread) what the Prius is reporting as I don't know much about the Prius. You clarified that the 900 watts is what is going into the battery, so question answered.

I admit I'm skeptical of an efficiency computed from one measurement and an assumption. I'd be interested in hearing what its measured draw from the wall is so its efficiency at 120V charging could be computed.
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jasleinstein
Posts: 63
Joined: Mon Sep 01, 2014 12:03 pm

Re: maximum charging rate for 120V?

Sat Sep 13, 2014 9:53 pm

KurtEndress,

Sorry I should have referred to my earlier post. I am trying to see if buying the Clipper Creek 1.9kW charger will help my charging rate.One of the folks at Clipper Creek thought the i3 would not charge at a rate over 1.4 kW on 120v, regardless of which EVSE was used. .

Has anyone measured a charging rate over 1.4 kW using 120 for their i3? If so what EVSE were you using? How did you measure it? I have both a TED 5000 and good old fashion digital Fluke ampmeter.

I just looked at my charge rate. I ran the batteries down to 15 miles. Using the EVSE that came with the car, plugged into a 20 amp 120 circuit it is scheduled to take 28 hours to charge the car. ugh.

thanks

mindmachine
Posts: 502
Joined: Sat Mar 15, 2014 2:08 pm
Location: Ohio, USA

Re: maximum charging rate for 120V?

Sun Sep 14, 2014 5:22 am

jasleinstein wrote:KurtEndress,

Sorry I should have referred to my earlier post. I am trying to see if buying the Clipper Creek 1.9kW charger will help my charging rate.One of the folks at Clipper Creek thought the i3 would not charge at a rate over 1.4 kW on 120v, regardless of which EVSE was used. .

Has anyone measured a charging rate over 1.4 kW using 120 for their i3? If so what EVSE were you using? How did you measure it? I have both a TED 5000 and good old fashion digital Fluke ampmeter.

I just looked at my charge rate. I ran the batteries down to 15 miles. Using the EVSE that came with the car, plugged into a 20 amp 120 circuit it is scheduled to take 28 hours to charge the car. ugh.

thanks
The quote below is from a email sent to me by the i genius about charging:

_____________________________________________________________________________________________________________________________________
"Finding the Charge Time for an EV
Amps * Volts = Watts (per hour)
This will be the rate of charge. Since the i3 has an 18.8 kWh battery capacity, we will then divide 18.8 by the rate of charge to get the number of hours it will take.
*Since the battery is measured in kilowatt-hours, we need to make sure we divide our answer in Watts by 1000 so we are using the same units.
So there are 3 settings for the charging rate in the car, which equate to 8 amps, 10 amps, or 12 amps. The voltage is constant at 120, and we just do the math from there.
So if the car is set to use all 12 amps for maximum charging rate, we can 120V * 12A, which equals 1440W (1.44 kW) per hour.

We know that EV charging as a whole has about 81% efficiency. So we'll multiply the watts per hour by the efficiency to get a more realistic rate of charge, which gives us 1.44 (.81) = 1.1664
The usable battery is 18.8 kWh, so 18.8 / 1.1664 = 16.12 hours to charge.

If they have their i3 set to charge at 8A, we do the same thing.
120V * 8A = 960W (.96 kW)
.96 (.81) = 0.7776
18.8 / .7776 = 24.177 hours"

Everything I have heard and found says the max draw for 120 charging is 12 amps max, but in the calculation the i genius did not take into account the slow down of the charging rate over that occurs during last 10 to 15 % to full! So the calculated 16.12 hrs will be longer! However the 28 hrs seems way too long unless something isn't working right.

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