I Just Noticed That The Ammeter Moves When The Heater Is Turned ON

[veimi]

While defrosting the windshield on my car in my driveway with the heater and fan turned on max I noticed that the ammeter increased to a maximum point half way between the start of the green and the word ECO.

You could also see it decreasing as it cycled on and off.

I was wondering if anyone had information on how much maximum current that this ammeter reading indicated?

[kiev]

i think the power scale is marked with 50A divisions with full scale at 150. The center of C in ECO is halfway to 50, so i would call that 25.

Split that distance to get 12.5A.

In the FSM, the heater capacity is rated 4,200 Watts.

Full heater power at full pack voltage would be about 12 Amps, so the needle would go to halfway between the green and the C in ECO.

[veimi]

Full heater power at full pack voltage would be about 12 Amps, so the needle would go to halfway between the green and the C in ECO.

Thanks for the information.

For fun while driving home today I was curious at what speed on flat ground would result in the same current.

Only a rough estimate but I estimated 35 kilometers per hour (21 mph).

If the full charge RR were 105 km. that would imply that the car could be driven for approximately 3 hours with a 12 A current drain and a 105 km. (63 mi.) range.

With the heater on max in an extremely cold environment so that the heater did not cycle off the total current would be 24 A and the drive time time at 35 kph (21 mph) would be cut to 1.5 hours and a 52.5 km. (31.5 mi.) range.

[Don]

If the full charge RR were 105 km. that would imply that the car could be driven for approximately 3 hours with a 12 A current drain and a 105 km. (63 mi.) range.

The ammeter shows every bit of current coming from the traction battery, not just that of the motor and the heater. Most other draws from the battery are just to small to be easily seen. The DC to DC converter can supply roughly 1 kw (1/4 of what the heater uses on max) and the A/C a bit more than that - Technically, turning the radio on and off should show a difference on the ammeter, but you can't see it

The 105 km full charge RR is indicative of what you did on the last charge and not what you might get on this next full charge. In actuality, driving slowly on flat ground the car can go roughly 100 miles (160 km) on a good day, assuming no A/C or heater use

Don

[veimi]

Thanks.

My estimated calculations were based on a curiosity to get some idea of the impact on driving with the heater on in an extremely cold environment especially city driving where the heater would be a larger percentage of the total energy used. In driving for an hour with the heater fully on regardless of the speed the heater could use a max of 4.2 kwh or about 25% of the fully charged new battery capacity.

I have been reluctant to use my heater and although the RR does change with the heater on giving some indication I wanted to get a better feel for its effects on range.

By a quick estimated measurement, the heater at max draws approximately the same current as driving 35 kph on flat ground which means with the heater fully on if you drive for one hour at 35 km per hour that is 35 km of total range that you are never going to see. Sitting in your driveway for an hour with the heater at max will also result in a 35 km reduction of the total range that would have been achieved at 35 kph.

If you drive for 2 hours at 35 km per hour with the heater on at max you would have used your entire battery capacity and your total range would be half that would be expected without using the heater at max.

[Don]

The heater cuts into your max range by about 25 to 35%, depending on how cold it is. Once the car warms up a bit, it uses far less current, just switching on and off to keep the inside temp comfortable. The A/C uses about half as much, 15 to 20% depending

If you live in a cold climate where you'll need the heater several months each year, a small diesel heater might be a wise investment. The car is already set up to make installation and use of a tiny fuel burning heater relatively simple, since our heater uses water and a heater core inside the car and one of the popular heaters is a water heating model. Several threads here on the forum about the installation and use of the little Webasto's and also the cheaper Chinese knock-offs

Don

[DBMandrake]

i think the power scale is marked with 50A divisions with full scale at 150. The center of C in ECO is halfway to 50, so i would call that 25.

The power meter on the dashboard measures power, not current as far as I know. Where did you get the information that it measures current ?

Split that distance to get 12.5A.

In the FSM, the heater capacity is rated 4,200 Watts.

Interesting, because going by the voltage and current reported by Canion it peaks at 5.5kW.

Full heater power at full pack voltage would be about 12 Amps, so the needle would go to halfway between the green and the C in ECO.

I've looked at the power reading when the heater is on full and it simply doesn't line up with the 5.5kW the heater can use when on full.

5kW is enough to drive at a constant 30mph, and the needle will be much higher when driving at 30mph with the heater off than with the car stationary and the heater on full. (and before warmup) The needle hardly moves out of the gap on mine with the heater on full.

I've always assumed that the power meter tries to subtract the power drawn by the heater and does it inaccurately, or that the meter reading is non-linear. If you compare the meter reading to the power drawn reported by Canion it does seem to be quite non-linear however it's difficult to plot it accurately while driving...

[veimi]

The power meter on the dashboard measures power, not current as far as I know. Where did you get the information that it measures current ?

5kW is enough to drive at a constant 30mph, and the needle will be much higher when driving at 30mph with the heater off than with the car stationary and the heater on full. (and before warmup) The needle hardly moves out of the gap on mine with the heater on full.

I've always assumed that the power meter tries to subtract the power drawn by the heater and does it inaccurately, or that the meter reading is non-linear. If you compare the meter reading to the power drawn reported by Canion it does seem to be quite non-linear however it's difficult to plot it accurately while driving...

Just some comments and my observations.

If one can assume that the battery voltage is relatively constant wouldn't that mean that there would be little difference between measuring current or power?

Sitting in my driveway in a cold environment with the heater and fan turned on max, the needle on my car is halfway between the start of the green and the start of the letter E in ECO.

This position of the needle corresponds approximately to its position when the car is being driven at 35 kph (21 mph) on level ground with the heater and fan off.

[DBMandrake]

The power meter on the dashboard measures power, not current as far as I know. Where did you get the information that it measures current ?

5kW is enough to drive at a constant 30mph, and the needle will be much higher when driving at 30mph with the heater off than with the car stationary and the heater on full. (and before warmup) The needle hardly moves out of the gap on mine with the heater on full.

I've always assumed that the power meter tries to subtract the power drawn by the heater and does it inaccurately, or that the meter reading is non-linear. If you compare the meter reading to the power drawn reported by Canion it does seem to be quite non-linear however it's difficult to plot it accurately while driving...

Just some comments and my observations.

If one can assume that the battery voltage is relatively constant wouldn't that mean that there would be little difference between measuring current or power?

If the battery voltage were constant yes, but it isn't. It varies a lot with changes in load and regeneration. It's pretty normal for the voltage to drop 20 even 30 volts under full acceleration vs coasting and to rise at least 10 volts during regeneration, so there are large swings in response to current out/in of the battery, and therefore an ammeter would be misleading.

Also we have no reason to assume it isn't Power - it even says "Power" right on the meter... Ultimately it's power that gives your acceleration (or generates heat in the heater) so that's what matters.

Sitting in my driveway in a cold environment with the heater and fan turned on max, the needle on my car is halfway between the start of the green and the start of the letter E in ECO.

This position of the needle corresponds approximately to its position when the car is being driven at 35 kph (21 mph) on level ground with the heater and fan off.

Mine barely goes into the green - this was taken with the heater on full blast and Canion reporting a consumption of about 5kW from the heater:



If I drive at 30mph with the heater off Canion also reports about 5kW of consumption, but now the meter is somewhere within the word Eco.

So at least on my car the heater usage is dramatically under reported by the power meter on the dashboard. Not sure why and whether that's on purpose or accidental. It's something I noticed soon after I started using Canion but didn't think much of it.

Another thing that's a bit suspicious about the power/regen meter is that judging by the presented scale, maximum regeneration is only 1/3rd of maximum acceleration in terms of power, but that's not true. Maximum power (before motor losses etc) is around 55kW while maximum regeneration is around 25-30kW so about half of maximum acceleration.

So either the meter is non-linear or the regen side of the scale cuts off prematurely when more regen is still available. (Probably the latter)

I wouldn't treat the power/regen meter on the dashboard as gospel, I think it takes some liberties in its presentation and should only be considered a relative meter.

[veimi]

It's pretty normal for the voltage to drop 20 even 30 volts under full acceleration vs coasting and to rise at least 10 volts during regeneration, so there are large swings in response to current out/in of the battery, and therefore an ammeter would be misleading.

I am not disputing your observations, but it is my understanding that the nominal battery voltage is 330 Volts which would suggest that even with a 30 Volt drop under load the difference between an ammeter and power meter indication would be less than 10 % which would occur only at the highest acceleration or speed.