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Discussion Starter #1
So out of curiosity, I've discharged the vehicle to what is 0% on the guess-o-meter and charged it to a 100%.

Here are my observations at 0 percent:

1) When you reach 0 percent on the guess-o-meter, the heaters shut off (seat and cabin). Cabin fan and rear window defroster still works.
2) The car is still drivable at reduced power mode. I did maybe 200 meters, didn't experiment more.
3) 12V battery is still being charged from HV battery, power windows and power steering seem to work fine.
4) 1-2 hours with everything on (cabin fan at full speed, high beams, rear window defroster) didn't seem to change anything. The voltage at 12V battery was still 14.5-14.6V (which indicates it being charged).

With a 32A Level 2 EVSE, I've achieved the "full" (100% guess-o-meter) charge at around 3.5 hours. It took 23.41 kWh. If we assume that the charging efficiency is approximately 90%, the battery accepted around 21.1 kWh.
 

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2013 FIAT 500e
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Thank you for the detailed report, & please report back with any driving range changes, or if you have OBD please tell us its % readings compared to the car's gauge.

Your odometer's 43.8k km is 27.2k mi, at which point 21kWh usable capacity seems pretty good, but I wouldn't be surprised if the charger isn't that efficient, since it puts out so much heat.

The "137km" shown on the charger is 85 miles total range, but probably as inaccurate as the car's mile gauge.

Since rear defrost stayed on, I wonder if cabin heat would stay on for safety reasons in defrost mode, to help you get to the 12V warning level. Maybe even get some use out of the humidity sensor by temporarily re-plugging it & spraying some mist on it :devilish:

fyi, this time it was still perfectly clear, but for future reference, "guess-o-meter" (GOM) is generally used to refer to the wildly-inaccurate mile gauge, not the somewhat-less-inaccurate % gauge.
 

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Discussion Starter #3
By the way, speaking about the EVSE, there was no noticeable heat emission from it - I was checking the enclosure and the cables. Mine is rated for 80A, so the wires are pretty fat.

Before this one I had a 16A L2 (dryer plug version), which sucked (the cable would heat noticeably) and the factory L1 which would also get pretty warm.

I got the efficiency percentage from here: A comparison of electric vehicle Level 1 and Level 2 charging efficiency - IEEE Conference Publication

I'll see how it behaves with range.
 

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Thanks, & if you have AlfaOBD please compare its % to the car's, at full charge & when it gets low. If you don't have OBD, I'm curious if you observed something else that prompted you to try the re-calibration.


I didn't mean EVSE heat, but rather the quite considerable amount wasted in our onboard charger. Maybe the efficiency study accounted for that, although I can't access it to check.

On L1 mine is pretty hot & on L2 I can barely touch it. That still might waste a bit less heat per kWh, since it's heating about 1/5 as long.

I haven't felt a Leaf or Bolt (like the study used), but the eGolf doesn't get anywhere near as hot. It came out a couple years after ours, so maybe it has a newer, more efficient unit.
 

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Just a quick thought on draining. From the report, and my own experience, the 500e will disable the HVAC at 0% and trying to get the car to completely drain the HV battery. But the 12V DC/DC charger is still activated. I think that could be exploited.

If you connect a 2000 watt continuous inverter to the battery and then load the inverter, with a electric resistance space heater for example, it would force the DC/DC to operate at maximum power trying to keep the battery at 14.2V. IIRC that DC/DC maxes out at 1.6 kW. That would speed up the process of draining the HV battery. Also that unit would offer decent backup power from the 500e in the event of a power outage too.

ga2500ev
 

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That would mean pulling 145 Amps continuously from the 12 V battery charging module if we are not to drain the 12 V battery. Can the on board 12 V charger handle that?
 

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That would mean pulling 145 Amps continuously from the 12 V battery charging module if we are not to drain the 12 V battery. Can the on board 12 V charger handle that?
Not sure. I thought I heard 1.6 kW quoted for the DC/DC. But it may have been for a Chevy Bolt.

I'm not sure it matters anyway, as the 12V battery itself can easily handle a 145 amp continuous load. They don't list car starting batteries with 650-700 Cold Cranking Amps for nothing. The DC/DC from the HV battery should simply current limit at maximum capacity trying to get the voltage of the 12V battery back above 14V where it normally charges. However, it would be important to monitor the actual voltage of the 12V system to ensure that it doesn't fall off a cliff. Best would be using an inverter with a low voltage alarm/cutoff so that you'd get a warning when the battery drops below a safe voltage.

The point is that since the DC/DC is active even when the 500e has cut off other power drains at 0%, it can be used to drain the HV battery faster. And since the car is on, the HV contactors will cut out once the HV battery gets too low to power the car.

I believe this situation is what the U69 recall campaign is all about IIRC.

ga2500ev
 

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A couple of follow-ups on the continuous dscharge of a 12V battery. In RCGroups, there is a post stating the maximum continuous discharge of an automotive battery is 10C, where C is the amp-hour rating of the battery. Car batteries are not rated in amp-hours, but in reserve capacity, which is the number of minutes it can be drawn upon at 25 amps. The conversion factor between reserve minutes and amp hours is 0.417 according to this article in Sciencing. H5 batteries in the 500e are listed with 100 minutes of reserve capacity, giving a 41.7 AH C rating. Given the 10C continuous draw ability, one can draw 410 amps from the battery.

As with all lead acid batteries, the faster you draw, the less actual capacity is available. So while in theory one should get 6 minutes of operation at 10C, since C is the 1 hour current draw until empty, it would actually be less time in a real situation.

ga2500ev
 

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A car battery can draw ~1.5 kW comfortably. I hooked up a 2000W inverter to my car battery and ran 2 vacuum cleaners simultaneously, drawing a constant 1.5 kW and it didn't even flinch.
 

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At 0% I'd still bet that in defrost mode the onboard heater would still work, for driving-safety reasons, much like the rear defrost & power steering. Also for driving-safety, most likely the A/C compressor would still be activated by the humidity sensor. Either of those provide much more drain than fan & lights (which drain more on LOW beam, with fogs on)
 

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Discussion Starter #11 (Edited)
At 0% I'd still bet that in defrost mode the onboard heater would still work, for driving-safety reasons, much like the rear defrost & power steering. Also for driving-safety, most likely the A/C compressor would still be activated by the humidity sensor. Either of those provide much more drain than fan & lights (which drain more on LOW beam, with fogs on)
I've tried to play with temperatures (edit: and modes, including defrosting), and the cabin heater nor the A/C did not work - the fan was just blowing air from outside. Cabin heating shut off exactly at the moment when the charge gauge hit 0% and could not be enabled again. Which kind of makes sense, as in terms of safety, it's more important to have juice to move out of the traffic or get on the flatbed, or keep hazard lights on rather than to have A/C or heating.

Edit: I think the reason behind what works and what does not is simple: HV cuts off everything except 12V charging and the drivetrain. And if the 12V is charging, all the 12V equipment works (hence the rear defroster, which seems to be just a coincidence as it's a legacy from other 500s).
 

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Discussion Starter #13
Right. I don't suppose you remember if you tried defrost for long enough to feel if heat came back on. Windshield defrost (to move out of traffic or drive onto a flatbed) is at least as critical as rear window defrost*, so both should still work. The compressor should also come on to safely clear the windshield, since that's the only purpose for adding the humidity sensor.

*pretty sure my '67 Bronco didn't even have one, but it definitely had windshield defrost, even though you could easily reach it to wipe when the engine was still cold.
I kept the defog/defrost mode on for about 15 minutes. No heating nor cooling in the airflow.
 

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I've tried to play with temperatures (edit: and modes, including defrosting), and the cabin heater nor the A/C did not work - the fan was just blowing air from outside. Cabin heating shut off exactly at the moment when the charge gauge hit 0% and could not be enabled again. Which kind of makes sense, as in terms of safety, it's more important to have juice to move out of the traffic or get on the flatbed, or keep hazard lights on rather than to have A/C or heating.

Edit: I think the reason behind what works and what does not is simple: HV cuts off everything except 12V charging and the drivetrain. And if the 12V is charging, all the 12V equipment works (hence the rear defroster, which seems to be just a coincidence as it's a legacy from other 500s).
Yes, your findings coincide with what I have experienced also.
 

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It took 23.41 kWh. If we assume that the charging efficiency is approximately 90%, the battery accepted around 21.1 kWh.
I am sorry to disappoint you, but you are wrong here.
Read further.

I joined this forum merely to respond to this post. I mean, seriously.

I had 2014 500e. Orange. Awesome car, amazing driving experience. Bolt is boring comparing to 500e.
The torque steer, the raw power, the peppiness, and this quiet ride (of course after disconnecting the pedestrian warning speaker)
I put on it about 8-9k miles during 11 months ownership. We had great summer and we wen through cold winter.
Initially he was charged through L1 on 120 V, but within days it was setup at 240 V.
When Consumers Energy offered a rebate for L2 charger - I got one. ChargePoint WiFi, 25 ft. Net cost (self install) was maybe less than a 100.

All right. What is wrong here?
The temperature.
You thermometer shows +8 deg C. The battery likes temp of about 18 deg C. If it is not this warm, it will warm up when being charged.

Some say it is risky, but I have done it dozens of times.
Connect to ECU via OBD using AlfaOBD app.
In battery section (this one does NOT require any special wiring - but do NOT for whatever reason attempt to connect to other sections especially if you get a warning special connector is required) you can view (I think... it has been a while) battery current.
Battery voltage is between 330 V and 400 V (empty to fully charged). The current should be about 16-18 A at all the time if connected to L2 charger (6.6 kW). Only drop takes place at 98% or above. More or less there. If you see less than that at, say, 45%, it means that the rest of the current is being drawn to warm up the battery.
I found that with the ignition OFF, the heater takes about 2 kW.
However, if ignition is ON, depending how cold the battery is - it may take more than 6 kW. Yes, I saw current being drawn from the battery for several minutes. The heating loop on the battery would reach temps of nearly 120 F (that is nearly 50 deg C). Then it would tone down and finally turn off once the battery pack reaches 66 F (19 C).

Due to this very reason I stopped top off charging as it would still warm up the battery very same way.


One would wonder how much energy would it take?
Well, depends how cold it is. :)
I found about 2 kWh was used for battery that was at about 0 C and garage was at about +10 C. Sure, car was sitting for about 8 hours before it started charging so the battery could warm up a bit.
As for cooling the battery, unless you hit very high ambient temps, anything below 25 C would only activate the radiator fan, hence the energy load is minimal.


One more thing - battery capacity.
In the app, the battery section data is LOOOOONGGGG. Somewhere there you can find Ah (yes, the regular Ah). This is the best means to compare batteries between cars.
Mine was 48.2 - 49.8. Somehow using L2 allowed me to "wake up" some of it.
Math: V * Ah = Wh, because V*A=W).
400x49.8=19960 Wh, that is 20 kWh. When completely full. If you used discharged voltage - you will get 16.5 kWh.
That is not a good comparison, it only gives you an idea how voltage can play in estimating battery capacity. Resting voltage is, if I recall correctly, 3.75 V per cell. Having 97 cells (or 96?) it should be 364 V, that means mine 50 Ah is 18.2 kWh.
Brand new should be 63 Ah, gives 22.9 kWh... you should be at 380 V to get 24 kWh. So it is a bit of a stretch by Fiat.

I wonder who has mine Orange baby...
It was a local guy (Mid Michigan), but never spotted him on any forum.


See here for the log and great info.

The log view:

and add yours info for comparison:


On a side note.
I have all the FIAT/Alfa special cables if anyone be interested. Yellow, red, violet, green...
 

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Discussion Starter #16
That's interesting. I know that warming up consumes quite a bit of energy, but I have never noticed anything significant while charging with the "ignition" off. When the heater is on at -25 or so, L2s (especially public ones throttled to less than 6 kW) quite often do not even catch up with the heaters in the system.

How did you measure 2 kWh for heating?

Li-Ion batteries warm up naturally during charging and discharging, and the +8 C does not tell much, since the car during my experiment was in direct sunlight with no wind. I highly doubt the heating would consume more than the 600W thermal / efficiency loss.
 

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How did you measure 2 kWh for heating?
Timing.
Of course that is a rough estimate and YMMV :)
When I plug it in and see current to the battery being 12 A at about say 340 V that means that the battery is being charged with 4 kW. However, my app from CP and also power meter (see below) tell me the charger pulls about 6.8 kW... means the rest goes to the battery heater system.
Taking into account that the converter would be 90% efficient, I'd conclude 4.5 kW is drawn, leaving 2.3 kW for the heating.
I would check on it from time to time and after about 30-50 minutes (depending on a day) the current would jump to 18 A, while the battery temp would be at 19-20 C (starting temp was 5 C). Again, in the garage.
Hence, overall I estimated the energy taken into the battery for heating was 2 kWh.
You can actually hear the click of the heater relay when you start charging and when you stop. Also, there is a whirring noise and it changes if the battery is being heated vs equilibrated state. There is a different pump for this purpose.
Furthermore, there is a coolant reservoir that gets warm very quickly when the battery is being heated.
Believe me - each time you plug it in - the battery will be heated.

Now, this data is based on my findings when I started using L2 charger.
L1 and the 240 V L1 - I did not look this deep yet. :)

Quite rough estimate, right?

As for battery warming up - yes, it does, but not quickly enough when it is cold. I can tell you even more.
The battery temperature is SOC dependent.
The more depleted it gets, the faster it warms up when driving.
I tested it several times. Same route, same starting conditions. On 95% or more SOC after driving the distance battery gained about 5 degrees. On 80% - similar.
But when it dropped below 40% - it would gain 10 degrees. No, it was not being heated, it was simply pulling more current due to lower voltage.
Meaning - at 80% you have say 380 V. To produce 60 kW you need then 158 A.
At 40 % and 340 V it is already 177 A.

Again, those are now from my memory, rough numbers. Do not quote me and say it is 351 V at 40% and 386 V at 80%.
It should give you only an idea, show you the concept.



As for the ignition on or off.
I think I did not present it right.
Ignition ON, all accessories are off, car is plugged in. Battery is cold. The very priority takes battery heater. It pulls all energy it can, even slightly from the battery - I noticed as much as 2 A being pulled out. That means about 7 kW. It starts heating up the battery as fast as it can. Upon heating about 50 deg C on the heater battery inlet line, power drops and the battery is being charged. Still, about 2 kW or so will go to the heater.
Same, very same scenario, but ignition OFF. Only about 2 kW is being stolen by the heater.

108607
 

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So this applies only for L2 charging then? Because you cannot afford a 2kw loss in heating circuit when you use a L1 since it doesn’t even supply that sort of current you’ll be in the negative since it tops out at 1440watts (1.4kw)
 
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