Series mode efficiency

[kakish]

Hi,

Today I was observing Watchdog measurement during urban trip. I noticed heavy difference between Series and Parallel mode in terms of fuel consumption.
60kph in Series mode was showing approx. 15-20l/100km whilst 80kph in Parallel drops to 7-8l/100km.
Is Series mode so inefficient? It seems like 1/3 of power from ICE vanish in Series mode (comparing ICE power to Generator power).
Moreover in Parallel mode power demand is wisely splitted between ICE and battery (charging when ICE has surplus and draining to keep ICE in sweet spot), in series mode greater demand increasing rpm's (and fuel consumption), no support from battery is acquired.

Is that normal behaviour?
Should the gap between generated energy and ICE power so high?

I'm a bit worried about some generator issue, as I cannot reach on highways fuel economy as mentioned on forum (like generator generate less energy and allows shorter EV segments )

greetings,
Kuba

 

[karl]

The batteries are charged also in series mode, probably at a higher rate than in parallel mode at slow speed.

What you are seeing is the momentary fuel consumption.

If you go for a while, the ICE will shut down. At lower speeds, I think the ICE will be active for 1/3 of the distance or less, so you have to multiply the consumption with that percentage...

 

[kakish]

The batteries are charged also in series mode, probably at a higher rate than in parallel mode at slow speed.

The PHEV Watchdog energy meter shows no flow into or out fo battery, so no charging or discharging,
Meeter shows approx 30kW on ICE provides 20kW on motors without charging battery.

On parallel we have three situations:
ICE power < power demand == battery discharge
ICE power = power demand == no energy flow
ICE power > power demand == battery charge
It is connected with fact that ICE rpm is aligned with speed

On series ICE power & rpm is modulated to cover power demand but still 1/3 of ICE power vanish.
In the moment of switching from Series to Parallel I observe high fuel consumption improve.

 

[jaapv]

I am starting to trust these Watchdog readings less and less... :roll:

 

[kakish]

I am starting to trust these Watchdog readings less and less... :roll:

That's why it would be nice, when someone do check on second hand, how their Mitsubishi behave.

 

[karl]

... If you drive the car in "series" speed for a while, it clearly alternates between long periods on electric and short periods using the ICE. It would give that it alternates between charging and discharged the battery too.

Maybe the parameter used by the dog is not exactly what the developer interpreted it to represent, and is only relevant in parallel mode for some reason.

 

[kakish]

I managed to do more research in watchdog logs,
it seems that mine Mitsu doesnot recharge battery in series mode when generator puts energy in motors.
When motors has no torque applied, approx. 22A goes into battery, but when they are working no more than 4A.

Does anybody has logfile of series mode to do comparison with mine behaviour?

greetings,
Kuba

 

[kushan]

As per below mitsi spec parallel hybrid mode has 2% losses while the series hybrid mode has 15% losses.

 

[roussir]

Wow. In fact, 15% on top of 15%, for a total loss of 27%. I had no idea it is so much more inefficient in series mode. The total loss in parallel is more like 3%, due to the loss from 2.8 to 2 kW.

 

[kushan]

Yes, series mode has heavy losses though it may not be consistent. We should not forget about, all these values are instantaneous. In reality, there is a cyclic behavior that repeats (starting the petrol engine and charging the hv battery and then stopping petrol engine and going into ev mode, and then repeating). On top of that there will be regeneration also resulting in increasing efficiency. Overall I think efficiency would be averaging around 15% to 20% most of the time.