kiev
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Location: The Heart o' Dixie
Contact: Website

Re: Mitsu Tech said I set car to not charge on Mondays

Mon Mar 11, 2019 2:10 pm

From an engineering standpoint, there are numerous relays and contactors throughout the vehicle that are critical for safe vehicle operation and for chargging, and some must never be switched under load due to arc-flash damage to the contacts.

The 12V aux battery is the power source for the energizing coils of these contactors, and if the aux is old, weak or worn out, then it can wreak havoc and permanent damage to relays, ECUs and the expensive Chargger Unit, Motor Controller Unit, DCDC Converter, etc., if it drops out or gets pulled too low while driving or chargging.
kiev = kenny's innovative electric vehicle

JoeS
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Re: Mitsu Tech said I set car to not charge on Mondays

Mon Mar 11, 2019 2:17 pm

logicalmethods, glad to hear the 12v battery replacement solved your car's erratic charging behavior.

1) The 12v battery is the source of most of the problems experienced by the i-MiEV, although it is normally not an issue while the car is charging (because the dc-dc is keeping the 12v at the proper level). Best thing everyone can do is replace that battery after a few years, even though it 'tests' ok. This is especially good to do if there is any history of that particular battery having been deeply discharged one or more times during its lifetime (as often happens with i-MiEVs sitting on dealers' lots).

2) The graph you posted is perfectly normal behavior:
a) The temporary dropout after you started charging is normal, and is believed to be the car's attempt to determine if there is excessive sag in the traction battery voltage when power is removed. This 'timeout' can range from about six minutes to 20 minutes, and can be infuriating if you're trying to recharge the car quickly in order to get on your way.
b) As the battery approaches full charge (fuel gauge displaying 16 bars) the input current decreases, the cells get balanced if needed, and then the input simply cuts off when the charging current drops to a certain level.

Both of these topics are fairly extensively covered in many different posts on this forum.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

logicalmethods
Posts: 8
Joined: Mon May 18, 2015 11:08 am

Re: Mitsu Tech said I set car to not charge on Mondays

Mon Mar 11, 2019 5:11 pm

I appreciate the quick response about my charging graph. I agree that it makes logical sense for the current to gradually decrease as the car approaches fully charged however that is not normal behavior for charing the car. 90+ percent of the charge graphs are pegged to the top of the chart until the battery is full and then there is a hard cut off. The gradual decrease that you see in the graph i posted above is abnormal and usually coincides with the car not getting a full charge.

In the case of the graph above. the car was short 3 bars when we disconnected it from the charger.

Any further thoughts?

kiev
Posts: 942
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: Mitsu Tech said I set car to not charge on Mondays

Mon Mar 11, 2019 5:51 pm

That session was just short of 4 hours, and the current ramp-down started after a little less than 2 hours.

It says you added 6.64 kwh, and you said that it was 3 bars short of full. So when you started the session you were at about 7 bars.

4 hours at a true level 2 will usually add about 12 bars, so it should normally have been full after 3 hours.

When a car won't reach 16 bars after a full charge it can sometimes mean a defective cell. The Canion android app along with a Scantool OBD LX dongle can read and display the voltage of all the cells, and help determine if any are worn out and holding down your pack.

Is this a home EVSE unit that you are using?

[EDIT]
Nevermind, Now i see that this is from a public chargepoint station.

Unless you have a bad cell, i would tend to think that this is an issue with the station rather than your car.

All bets are off when someone else controls your chargging session.
kiev = kenny's innovative electric vehicle

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