Traction battery charging slows as it "fills up".

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Trex

Well-known member
Joined
Feb 26, 2015
Messages
921
Location
Near Port Macquarie Australia
Hi again folks,

Now I wrote this in another topic I stated:
Trex said:
Ok just noticed this in the topic I started and will say that on my PHEVs at 110 kph GPS approx 115kph dash I can charge the drive battery from empty on the gauge to approx 50% in roughly 1/2 hour. This has always been my rule ie 1/2 a charge in 1/2 hour. BUT the remaining approx 35% that my PHEV charges to and then stops charging ie approx 85% takes roughly another 1/2 hour because as we know the charging rate slows down as we fill the drive battery.

and ThudnBlundr replied. I hope ThudnBlundr does not mind me quoting him here:

ThudnBlundr said:
I've noticed that it does seem to take a while to charge with the ACC set at 70mph, but I hadn't noticed the decline above 50%. I'm not disagreeing - I've just not seen it ;)

To which I replied:

Trex said:
Hi ThudnBlundr, BTW love that name. :cool:

There are a few tests I have done where that decline above 50% shows up. Will try to start another topic here later to show them and put them in the one thread.

Regards Trex.

So those tests I have done I wish to show in the one thread here.

Lets start with my first on Wed Mar 04, 2015 under the title "It takes 3.2lts of petrol to charge the battery in my Phev.":

Trex said:
Hi,

Big storm about 7pm last night here in Australia and ran around turning everything electronic off, TV, computer etc. I also unplugged the Phev even though it was not charging (starts charging on offpeak at midnight). Forgot to plug back in so empty drive battery this morning. :oops: :lol:

Always wanted to confirm know how much petrol it takes to charge, Mitsubishi Australia say about 3lts, so here was my chance. This was done while parked doing a brim to brim petrol test.

With 1 bar showing (out of 16) on the MMCS drive battery display ( I ran the AC till the petrol motor started and then pressed the Charge button) I commenced the test:
7.31am-1 bar after pressing Charge button
7.37 -2 bars approx 6 min from 1 to 2 bars
7.42 -3 bars approx 5 min from 2 to 3 bars
7.45 -4 bars approx 3 min from 3 to 4 bars
7.48 -5 bars approx 3 min from 4 to 5 bars
7.52 -6 bars approx 4 min from 5 to 6 bars
7:55 -7 bars approx 3 min from 6 to 7 bars
7.59 -8 bars approx 4 min from 7 to 8 bars
8.02 -9 bars approx 3 min from 8 to 9 bars
8.06 -10 bars approx 4 min from 9 to 10 bars
8.10 -11 bars approx 4 min from 10 to 11 bars
8.14 -12 bars approx 4 min from 11 to 12 bars
8.19 -13 bars approx 5 min from 12 to 13 bars
8.28 -14 bars approx 9 min from 13 to 14 bars and petrol motor idled down here
8.34 -14 bars approx 6 min here and petrol motor stops and Charge mode still showing on display

My Phev used 3.2 lts.

Regards Trex

Now for the above test I later wrote in the thread "The only regret I have is not noting the seconds on my readings. Why? Look at the time intervals between the lighting of the hv battery bars."

I did edit that post above to show the approx min between each bar eg the wording "approx 5 min from 2 to 3 bars".

Now below is another test showing generator output some of which goes to charge the drive battery and some (approx 4.8 kW I think) goes to freewheeling or stopping the drag of the front and back electric motors. This was done at in Parallel mode at highway speed:

Trex said:
15 bars (out of 16) showing on the MMCS battery gauge Generator Power 6.1 kW approx. on EVBatmon. Take away approx 4.8 kW gives 1.3 kW Pressed Save right at the start for this one.
14 bars (out of 16) showing on the MMCS battery gauge Generator Power 7.7 kW approx. on EVBatmon. Take away approx 4.8 kW gives 2.9 kW
13 bars (out of 16) showing on the MMCS battery gauge Generator Power 8.1 kW approx. on EVBatmon. Take away approx 4.8 kW gives 3.3 kW
12 bars (out of 16) showing on the MMCS battery gauge Generator Power 9.6 kW approx. on EVBatmon. Take away approx 4.8 kW gives 4.8 kW
10 bars (out of 16) showing on the MMCS battery gauge Generator Power 10.8 kW approx. on EVBatmon. Take away approx 4.8 kW gives 6.0 kW
8 bars (out of 16) showing on the MMCS battery gauge Generator Power 14.0 kW approx. on EVBatmon. Take away approx 4.8 kW gives 9.2 kW
6 bars (out of 16) showing on the MMCS battery gauge Generator Power 16.9 kW approx. on EVBatmon. Take away approx 4.8 kW gives 12.1 kW

Now I stopped there as my wife wanted the car soon and I wanted to leave her some battery showing her I am such a nice guy. ;) :lol:

Anyhow, I think, it shows that the car is more efficient with a lower battery SOC just like my previous test.

Regards Trex.

Edit For the above post I subtracted the approx 4.8 KW I think needed to freewheel or stopping the drag of the front and back electric motors to show the amount left for drive battery charging on the far right eg The wording "Take away approx 4.8 kW gives 2.9 kW" ie 2.9 kW left for battery charging.

Now the below post shows the effect of that "filling" of the battery and how it affects fuel consumption and Regen:
Trex said:
Hi folks,

This will be the last test I will do for awhile. I hope it helps everyone. :)

I picked the flattest area around here ( and it is very flat across the river valley here) on the dual lane freeway (in each direction) that runs past our "town". It is made up of approx. 12kms of 100kph zone and 10km of 110kph zone. I picked that stretch for its easy turn around at each end as well as being flat.

So the test consisted of driving in one direction then the other followed by a quick turnaround at each end. Traffic was light. I sat on 105kph . I used cruise control the whole time except at each end when I was turning around.

Now this is the same as I did the other night but more scientifically ie I ran both directions fully before taking measurements to allow for any wind or elevation changes. I have not, I repeat not done that before. :oops:

Here are the results.

Press Save button straight at start with full battery. 15 bars showing (out 16 ) on MMCS when finished test. 7.8L/100k Petrol motor never stopped. B5 15kw
Press Save at 13 bars. 14 bars showing (out 16 ) on MMCS when finished test. 7.8L/100k Petrol motor never stopped. B5 25kw
Press Save at 11 bars. 12 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times B5 37kw
Press Save at 8 bars. 9 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times. B5 37kw
Press Save at 7 bars. 8 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times. B5 37kw
Press Save at 6 bars. 7 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times. B5 37kw
Press Save at 4 bars. 5 bars showing (out 16 ) on MMCS when finished test. 7.2L/100k Petrol motor stopped like a proper hybrid IMO. B5 37kw
At 1 bars (normal mode). 1 bars showing (out 16 ) on MMCS when finished test. 7.2L/100k Petrol motor stopped like a proper hybrid IMO. B5 37kw

Note No AC or heater on.
Note The B5 amounts are Regen that I could get at the end of the runs with the paddles set to B5 when turning around.
Note Where I said the petrol motor never stopped it only stopped at each end of the run where I turned around.
Note Where the Petrol motor stopped I read it at the same point of the hybrid cycle.
Note There are no more notes. :lol:
Regards Trex.

Now that decline above 50% I was writing about does actually show up before 50% to some extent but it is more noticeable above it. Hope you know what I mean.

It should also be noted these are all dash SOC readings.

So I hope you can understand these tests and what they show . But please ask those questions if you do not. :)

Regards Trex.
 
Now in this test from above:
Trex said:
Hi,

Big storm about 7pm last night here in Australia and ran around turning everything electronic off, TV, computer etc. I also unplugged the Phev even though it was not charging (starts charging on offpeak at midnight). Forgot to plug back in so empty drive battery this morning. :oops: :lol:

Always wanted to confirm know how much petrol it takes to charge, Mitsubishi Australia say about 3lts, so here was my chance. This was done while parked doing a brim to brim petrol test.

With 1 bar showing (out of 16) on the MMCS drive battery display ( I ran the AC till the petrol motor started and then pressed the Charge button) I commenced the test:
7.31am-1 bar after pressing Charge button
7.37 -2 bars approx 6 min from 1 to 2 bars
7.42 -3 bars approx 5 min from 2 to 3 bars
7.45 -4 bars approx 3 min from 3 to 4 bars
7.48 -5 bars approx 3 min from 4 to 5 bars
7.52 -6 bars approx 4 min from 5 to 6 bars
7:55 -7 bars approx 3 min from 6 to 7 bars
7.59 -8 bars approx 4 min from 7 to 8 bars
8.02 -9 bars approx 3 min from 8 to 9 bars
8.06 -10 bars approx 4 min from 9 to 10 bars
8.10 -11 bars approx 4 min from 10 to 11 bars
8.14 -12 bars approx 4 min from 11 to 12 bars
8.19 -13 bars approx 5 min from 12 to 13 bars
8.28 -14 bars approx 9 min from 13 to 14 bars and petrol motor idled down here
8.34 -14 bars approx 6 min here and petrol motor stops and Charge mode still showing on display

My Phev used 3.2 lts.

Regards Trex

I do not know whether others have noticed that it took 6 mins to light bar 2 then 5 mins to light bar 3 then a lot of 3 and 4 mins, which if I had noted the seconds could have evened out to something roughly the same IMO. Well that 6 min and 5 min I think might be explained by what is called the chemical hysteresis effect ie I was discharging the traction battery using the High Voltage Air Conditioner to make the petrol motor start (and to properly "empty" the traction battery) then begin charging with the generator driven by the petrol motor.

Now Electropaedia (https://www.mpoweruk.com/) states :

"During charging the chemical reaction lags behind the application of the charging voltage and similarly, when a load is applied to the battery to discharge it, there is a delay before the full current can be delivered through the load. As with magnetic hysteresis, energy is lost during the charge discharge cycle due to the chemical hysteresis effect."

That effect ie chemical hysteresis, or lag or delay, has always made me wonder whether we should charge longer than the PHEV does during its normal hybrid cycle. But hills and such probably make that point mute. But I still think it is something worth contemplating sometimes. :)

Or it could be just the battery bars are just not totally in "sync" with the % increases in voltage from charging I suppose. I might test it one day. ;)
 
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