Charging at 120V daily, max current for circuit breaker.

[mikeaz]

Hello everyone,

I am thinking of buying a Ford Focus electric in the next weeks.
But In my garage, there is currently only a 120V, 15A circuit breaker outlet installed (I live in US). There is no room for another 220V breaker without major update.
Is this 15A sufficient for the included 120V trickle charging cable or does it demands more current (if so, how many amps)?

I also would be interested to learn whether a 3 times a week overnight charging at 120V might affect the battery life.
My commute is only 4 miles, so it might be possible to charge it only 1 or 2 time a week.
I would be happy if someone could help me with this details.

Thank you,
Mike

 

[triangles]

In case you aren't aware of the lingo; L1 (Level 1) charging means 120VAC, L2 means 240VAC, and L3 is high voltage DC charging (basically bypasses the onboard charger). L3 is only an option on the 2017+ model years. The charger built into the FFE will only charge at the following currents:
L1: 120V, 0-12A (up to 1.44kW)
L2: 240V, 0-27.5A (up to 6.6kW)

If I remember correctly the battery has 900W of heaters (3x300W). If you live somewhere where it gets cold L1 charging could be problematic and your FFE may struggle to keep your battery warm. Charging a lithium battery that is colder than 32F will damage it. I do not know if Ford was smart enough to heat the battery before charging it or not, especially on L1. Also the battery TMS (thermal management system) only functions when the car is on or plugged in. I don't know from personal experience but some have reported that it doesn't function or doesn't function well when plugged into L1. Also if you want to pre-condition (GO times) the car's cabin heater pulls 5+kW. Since the charger can only provide 1.44kW you will either not have a very warm car or a partially drained battery to start out with. I never L1 charge so I don't know what happens.

The convenience cord that came with your FFE is set at 12A so no matter what you give it, it will use no more than 12A. NEC rules for continuous loads says that you can only put a load that is 80% of what the circuit is rated for. So A 15A circuit * 0.8 = 12A. A 15A circuit is sufficient for you 120V charging needs. I have seen several 12V EVSE's with burned up plugs. Be sure to keep the prongs on the plug clean and if your receptacle is old, replacing it with a new one is cheap insurance against burning up the EVSE's plug. There is a temp sensor in the plug on the newer ford EVSE's. If you end up burning up the plug you can't simply cut it off and put a new plug on as you'll be cutting off the temp sensor as well which I imagine would prevent the EVSE from functioning. I don't know what the temp sensor does on the newer OEM EVSEs. I imagine it would either fault and stop charging if it gets too hot or it may just throttle back on the current in which case you'd never know something was wrong except that your FFE is charging even more painfully slow.

Also as a FYI. I believe L1 charging only adds 3-4 miles of range per hour of charging. So conservatively if you charge over night that will give you about 30 miles of range (10hrs X 3mi./hr = 30mi.).

I don't know what the electrical code says but I'd imagine it would be able to put in some sort of transfer switch so that your L2 EVSE could "share" a circuit with either a stove or clothes dryer. Just remember the 80% rule. If you only have a 30A circuit, your L2 EVSE should be set at no more than 24A. In other words Don't install a 30A EVSE on a 30A circuit. Note: some EVSEs current rating are fixed and other's can be configured.

 

[racker]

So far my FFE has been entirely happy with 120V 15A charging (25 mile roundtrip commute). Nothing burned up yet! Make sure your outlet is wired really well though. I live in the Bay Area though, so it almost never drops below 32F. If you live in a cold area, wouldn't recommend 120V charging.

(also maybe your garage is insulated and stays warm even at night?)

 

[EVA]

Triangles got the details exactly right. 120V at 12A (what the cord will pull) gets you 4 miles per hour of charging. Yes you can get a lot of miles overnight. With a 4 mile commute, you should plug the car in at night - it will keep the car happy. And you'll never run out of charge.

If you live where it is warm, you'll be in great shape forever.

We live in the Chicago area. The first year we had the FFE, we used 120V exclusively. With a 20 mile round trip commute, we had no trouble, even in the winter. The car would charge more than enough overnight.

Here's what happens - if you tried to charge the car when completely cold soaked - the battery is down below 40 degrees - 120 Volts at 12 Amps isn't enough to heat the battery and add charge. So it will take a long time for the battery to get warm enough, then it will start charging. Driving the car solves that problem. Plugging it in as soon as you get home prevents that from happening - the battery is warm from driving, and it will start charging right away, and charging will keep the battery warm.

I would suggest you always plug the car in. Don't just plug it in every other day - keep the battery topped off.

120V charging will not hurt the car battery at all.

Some day you may save enough money to add the 240V circuit (don't monkey with sharing a circuit - it really isn't worth it) and a level 2 EVSE. The car will be happier, you can use Go times (meaning the car will be cooled off or heated up at a scheduled time), and it will charge a lot faster.

And if you ever find yourself getting behind somehow charging with 120V, just go visit a Level 2 charger in the area. Plugshare is your friend for that.

 

[Guest]

That would explain why my car always warned me to plug the car in when it was cold. It makes perfect sense.

 

[triangles]

Thanks EVA. I had wondered how the FFE dealt with 120V charging and cold weather. I agree with not monkeying with trying to share a circuit. I just threw that out as a last resort option.

On a side note, this was my 4th winter with the FFE and just this winter I noticed that when I plug in when it is really cold the FFE makes what's best described as a "distant leaf blower" sound. I haven't confirmed it but I believe it is some sort of battery heating. It only does this on L2 charging. I switched to L1 and the car was silent. Seems to only happen when it's really cold and car is cold soaked or near cold soaked. I wonder if the noise might be Ford operating the onboard charging inverter in an inefficient manner to generate additional heat?

 

[jmueller065]

Thanks EVA. I had wondered how the FFE dealt with 120V charging and cold weather. I agree with not monkeying with trying to share a circuit. I just threw that out as a last resort option.

On a side note, this was my 4th winter with the FFE and just this winter I noticed that when I plug in when it is really cold the FFE makes what's best described as a "distant leaf blower" sound. I haven't confirmed it but I believe it is some sort of battery heating. It only does this on L2 charging. I switched to L1 and the car was silent. Seems to only happen when it's really cold and car is cold soaked or near cold soaked. I wonder if the noise might be Ford operating the onboard charging inverter in an inefficient manner to generate additional heat?

When it was "super" cold out my FFE (on Level 2) would charge a little (like 10% - 20%) before waiting for the value charge.

My C-Max does it too: It will charge to about 50% when its cold and then wait until the value charge time.

 

[Jon_h]

Level 1 charging does NOT engage the battery heaters. You can observe this yourself using forscan.

It is OK to charge lithium batteries at below freezing temperatures so long as the current is sufficiently low. Level 1 charging is very low, like C/30 for a 2017 FFE.

Level 2 charging does engage the battery heaters. This is a great advantage as your battery will be warm after a level 2 charge and as a result IR is lower and your range / performance will be better.

As to the original question: a 15 amp circuit is fine. The level 1 EVSE is as 12 amp load.

I expect that you will only have to charge once a week with a 4 mile commute!