Home Charging / Tracking Sessions for Business Expenses

I've seen a number of questions about chargers on the forum. I don't recall any that discuss using a home charger that lets you manage or track charging sessions remotely. Tracking individual session expenses for a home business or just to track usage is also possible.

I installed a Coulomb CT500 in 2012. It is a 240V, 30A level 2 charger with a single port capable of delivering up to 7.2kW. It is connected to the Chargepoint network. Therefore, I can use a mobile application to monitor a session (or any Chargepoint network charger) as well as view/download individual session data should I need to itemize or just want to track usage.

The unit has functioned mostly trouble-free. Once in a while, I will get GFI Fault indication and have to reset it by cycling power to it. A CTRL-ALT-DEL type function and continue. I think this may have happened twice while charging overnight in the 2+ years I have had it leaving me with a partial charge in the morning. The unit also sends out SMS and e-mail messages for things like low power draw, stop charging, cord disconnected, etc.

Anyway, I thought the group may be interested in this sort of charger when individual charge session data might be needed. I don't know if the unit is still sold but a call to Chargepoint should answer that question if you are really interested.

• CT500 Charger: https://docs.google.com/file/d/0B5LVemnP3B4sakJYOHB1MjNDcTQ/edit?usp=docslist_api

• CT500 Specs: https://drive.google.com/file/d/0B5LVemnP3B4sSEJEbG5NeDVLYnM/edit?usp=sharing

• Chargepoint Usage: https://docs.google.com/file/d/0B5LVemnP3B4sMUZ1T0NZeFE5QTg/edit?usp=docslist_api

• Chargepoint App: https://docs.google.com/file/d/0B5LVemnP3B4sQjEzSGdRY3Jpc1U/edit?usp=docslist_api

• OnStar Remote Link Mobile App: https://docs.google.com/file/d/0B5LVemnP3B4sZ0k4S01oN0xFUW8/edit?usp=docslist_api

Best,
Lou

I am new to EV driving and I need a way to tell how much I am spending on charging each night. I want to be able to pay back my housemate for the amount of electricity I use. Is there a way to track such a thing?

An electrician can install a meter, but maybe easier if they're willing is to just use your average mile/kw, and just base it on that. The community's average is 4.1miles/Kw, and if you have the app, it will show your average as well.

SImple example: you drive 1,000 miles and your miles/kw is 4, you'd have required 250KwHrs. Throw in say about a 10-15% inefficiency factor (adding 25-37kwhr), and maybe a bit more if you precondition and or set a departure time and you'd be really close.

OK I think I got it but let me ask. I'm currently just charging using the standard 120 household outlet. Our rate plan is 12.5 cents per kwh. So where do I go get my miles/Kw in the app? Sorry for all the trouble but I need to keep track of this before the first electric bill shows up. Thanks so much.

If you are using the 120vac occasional use cable, pick yourself up a 'Kill A Watt' device like this http://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_1?ie=UTF8&qid=1438134999&sr=8-1&keywords=killawatt&pebp=1438135008903&perid=0TEGJW2WVT57ASWQZKJ3

In the app, swipe right and tap the upper right-hand bar graph symbol. At least on the Android version...

One of those plug in meters should work ok.

If you're in the market for a higher current EVSE then I suggest looking at the JuiceBox Pro40, as it has an online record of charging. (Needs wireless internet connection), and isn't expensive for its capabilities.

http://emotorwerks.com/products/online-store/product/show/202-juicebox-pro-40

Thank you everyone for the great answers. I just ordered the kill a watt and when I get the 240 installed I will get the juicebox pro 40. This is a great forum.

now if only I could get power for 12.5c/kWh here!

Don't forget to put your location in your profile. It does help for some questions.

mikejrexec said:

I just ordered the kill a watt and when I get the 240 installed I will get the juicebox pro 40.

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Be careful if you use your Kill A Watt at the OUC's full power of 12 amps. The Kill A Watt is rated at 15 amps max, so 12 amps would probably be its maximum continuous current. I have read reports of a Kill A Watt becoming very warm at 12 amps continuous.

Thank Art. Is there a way to limit the OCU to less than 12 amps?

mikejrexec said:

Is there a way to limit the OCU to less than 12 amps?

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Yes. In the charging section of iDrive are charging speed settings for both L1 (120 v.) and L2 (208-240 v.) charging. Maximum L1 is 12 amps. The other 2 settings are less (10 and 8?? - not sure).

Perfect, maybe I won't burn down the house now. LOL You have been very helpful.

Those settings in idrive are so that you don't overload the circuit the EVSE is plugged into, the car can easily handle maximum. The idea is if it's on a shared circuit, you don't keep tripping the circuit breaker or blowing a fuse in the panel.

FWIW, each EVSE outputs a signal to the vehicle that announces how much power it has available...the car then decides how much, up to that limit, it wishes to use, so the car would never overload the EVSE, but the EVSE could overload the circuit it is attached to.

Thank you Jim.

I just wanted to give an update. Thehome charging with the OUC is working perfectly for me. I mounted it to the wall next to the outlet and plug in through a Kill A Watt meter. I did set the charging rate on the vehicle to "reduced" to protect the meter but have not noticed any significant increase in charging time. For my driving needs this system works perfectly. Thanks everyone for all the help.

FWIW, the meter is rated at 15A, and even at the 80% rule for continuous use, the max the OUC can pull is 12A, which, by no coincidence, is exactly at the 80% point of max load. IOW, it should work fine at the full charging rate of the i3 using the USA supplied OUC. But, if you can recharge within the timeframe desired, it should be fine.

Note, if you set preconditioning and/or a departure time, the car will use all of that 12A and pull any extra from the batteries, so you might not have a full battery if you precondition, but it still should be better than just driving off in an unconditioned vehicle.

mikejrexec said:

Thehome charging with the OUC is working perfectly for me. I mounted it to the wall next to the outlet and plug in through a Kill A Watt meter. I did set the charging rate on the vehicle to "reduced" to protect the meter but have not noticed any significant increase in charging time. For my driving needs this system works perfectly. Thanks everyone for all the help.

Click to expand...

If you do need to charge faster at some point and you haven't noticed your Kill A Watt getting warm at the Reduced charging speed setting, you could increase the charging speed to Maximum and monitor the temperature of your Kill A Watt. As Jim stated, it should be capable of passing 12 amps safely, but if the outlet that it's plugged into or its outlet might have a high-resistance connection, the higher amperage could overheat your Kill A Watt. The reports I read of an overheated Kill A Watt did not explain why this had happened.

Even if I measured my i3's electrical consumption I would still have a devil of a time calculating it's cost without installing a dedicated meter. My latest PG&E bill has 12 different rates, covering 4 tiers of consumption and 3 times-of-use, ranging from about 15¢ to almost 50¢/kWh, not to mention different seasonal rates, junk fees & taxes, and then the annual true-up for my solar panels! Mind you I am on the E6 plan, and switching to any of the E1 or E7 or EVA or EVB plans would be ........... well I don't know if any would be better or worse as I don't have a supercomputer and a PHD in maths.
Far simpler is to estimate consumption and allocate the costs to the highest-tier off-peak rates. For example, I have a 10,000 miles/year lease, so I limit my i3 self to 833 miles/month before firing up my 15-year-old Honda Insight. OK, 833 miles at my 4.5 miles/kWh average, less 10% for conversion losses and such, call it 4.0 miles/kWh, divide that by 833 and round off to 200 kWh/month consumed by the i3. So (from my latest bill) 125 kWh at 24¢ plus 75 kWh at 30¢ comes to $52.83 (before taxes & junk fees), or about 6¢/mile for electricity, not bad.
Compare that to the Insight's 60 mpg at $3.50/gallon for gas, comes out to, well whaddayouknow, 6¢/mile for gas, not bad.

Wow i3an that is some range of prices. Here we don't get that many choices. Probably a good thing in my case. Houston is still new to the EV game. Most of the chargers I visit at grocery stores and such still charge for free. I wonder how long that is going to last?

I think free level 2 at grocery stores, malls, maybe movie theatres will be around for a while. They can be considered a marketing expense, used to attract new customers. They don't really cost that much to put in, probably well under $10K, and the electricity that is consumed is measured in single digit dollars per day. The business gets far more in retail sales than the unit costs/consumes.

I think that free DCFC is going to come to a crashing halt next year once the NRG settlement with CA expires. Those units are expensive to buy and install (typically > $30K, maybe even $50K).

In general, making something free reduces its value (its free, how much can it actually be worth?). The result tends to be abuse of the free resource (people plugging into a DCFC and walking away for hours, people using a DCFC to "top off" when they are at 75% already, certain individuals hogging a DCFC as if its their own personal machine, etc.) Putting some cost on a DCFC puts the model more in line. If its worth it to you, you'll use it. If not, you'll stay away. I did a quick poll on Facebook (not even remotely scientific) to see what people thought was a fair price for DCFC. It seemed centered around $5-$7. I suspect in practice that $7.50 to $10 will be more like it.

If you get ~75 miles from a 30 minute charging session for $10 (for example), that's 13.3 cents/mile. More than at home, most likely, but still reasonable. A gas car (25 mpg, $3.50/gallon) is about the same price per mile and nobody blinks at that.