Phximiev
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Location: Phoenix

Re: Care and Feeding of the OBC/dc-dc

Fri Mar 08, 2019 11:24 am

JoeS wrote:Coulomb, thank you very much for your detailed explanation with the schematic - I should have reviewed the J1772 interface myself before posting. The concept of the J1772 switch triggering the vehicle controller to first ramp down the charging power had escaped me.
. . . As a result, we're now going to become far more proactive in using the Remote for the timing of our charging and I'll eliminate use of the mechanical timers completely. . .


"Hear, Hear" on the kudos and explanation. In fact, I went out and checked the portable chargers that we have and use (Mitsu, Volt, and Turbocord) and "tested" the Volt (wife ran off with the Mitsu!). Pressing the button alone without withdrawing the J1772 Turbocord caused the Volt to shut off charging and noticeably turned the charging light on the dash off. I would imagine that that such voltage drop is measurable on Canion or other programs?

So on the other side of the argument, is it fair to say that if one simply plugs in the J1772 in without engaging the button, that the charging process will not start?

Does this perhaps explain our experience why on occasion when out at a public charger where the button doesn't engage, that charging fails to start? (see Plugshare activity feed for a number of other, similar, examples)
2012 iMIEV ES
2014 Chevy Volt

PV1
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Location: Pittsburgh, PA
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Re: Care and Feeding of the OBC/dc-dc

Fri Mar 08, 2019 12:55 pm

Phximiev wrote:So on the other side of the argument, is it fair to say that if one simply plugs in the J1772 in without engaging the button, that the charging process will not start?

Does this perhaps explain our experience why on occasion when out at a public charger where the button doesn't engage, that charging fails to start? (see Plugshare activity feed for a number of other, similar, examples)

Yes, if that button doesn't release (connector latch clicking into place), the EVSE will read a car connected but not ready to charge, and therefore won't start charging. Make sure that J1772 connector is all the way in and the lock fully engaged. On some charging stations, pushing the connector straight in until it stops and then lifting it slightly is required to latch the connector.

Given that the latch button sends the shutdown signal, does anyone have the capacity to measure charge current reduction during the disconnect process? What I mean is, can we measure if the charger ramps down when the latch button is pressed or does it simply hard stop charging? With my Bolt, pressing the button causes the EVSE contactor to drop out almost immediately, seemingly just under half a second. I'm curious if that is enough time for a graceful shutdown of the OBC or if using the remote to stop charging would be kinder to the hardware as that is totally controlled by the car.
:idea: :idea: :idea: :!: :!:

Dropbox maintenance in progress. If any of my links aren't working after November 17, please PM me and let me know which one isn't working.

Thanks.

coulomb
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Re: Care and Feeding of the OBC/dc-dc

Fri Mar 08, 2019 6:23 pm

Phximiev wrote: Pressing the button alone without withdrawing the J1772 Turbocord caused the Volt to shut off charging and noticeably turned the charging light on the dash off.

Did you hear the contactor in the EVSE drop out as well? Was there a short but discernible (less than a second) delay between pressing the button and the contactor dropping out?

JoeS
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Re: Care and Feeding of the OBC/dc-dc

Sat Mar 09, 2019 4:24 am

Depressing the button on the J1772 connector while its plugged into the car results in a seemingly-instantaneous relay click in the EVSE. The resolution of my power monitor isn't good enough - need a scope.

Edit: Update.

This morning I paid attention and I could swear that the sequence was (the car still had not run out of its Remote-set time):

Buttonpush --> click in car --> click in EVSE (Mitsu EVSE 120vac)

Just went out to confirm this, but this time I have the car plugged into my eMotorWerks EVSE (240vac) as I'm about to go on a longer trip and am topping up -

Buttonpush --> click in EVSE --> multiple clicks in car

Anyone else?

In any case, the time delays are noticeable. Will pay attention each time I unplug and will update if I notice anything different.
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
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ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

Phximiev
Posts: 1210
Joined: Thu Jan 15, 2015 7:25 pm
Location: Phoenix

Re: Care and Feeding of the OBC/dc-dc

Sat Mar 09, 2019 9:51 am

coulomb wrote:
Phximiev wrote: Pressing the button alone without withdrawing the J1772 Turbocord caused the Volt to shut off charging and noticeably turned the charging light on the dash off.

Did you hear the contactor in the EVSE drop out as well? Was there a short but discernible (less than a second) delay between pressing the button and the contactor dropping out?


I don’t recall hearing anything but I will check again later as well as the time lapse.
2012 iMIEV ES
2014 Chevy Volt

Phximiev
Posts: 1210
Joined: Thu Jan 15, 2015 7:25 pm
Location: Phoenix

Re: Care and Feeding of the OBC/dc-dc

Sat Mar 09, 2019 1:22 pm

Phximiev wrote:
coulomb wrote:
Phximiev wrote: Pressing the button alone without withdrawing the J1772 Turbocord caused the Volt to shut off charging and noticeably turned the charging light on the dash off.

Did you hear the contactor in the EVSE drop out as well? Was there a short but discernible (less than a second) delay between pressing the button and the contactor dropping out?


I don’t recall hearing anything but I will check again later as well as the time lapse.


The contractor clicked and there was a delay, probably no more than a second.

Also with the Volt 120v charger, I toggled the switch several times with the same result: (1) button off, contactor clicked, Volt lights off, (2) button on, contactor clicked, Volt lights on.
2012 iMIEV ES
2014 Chevy Volt

Aerowhatt
Gold Member
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Re: Care and Feeding of the OBC/dc-dc

Sat Mar 09, 2019 5:29 pm

Mitsu tested things for the way that they suggest they be used. So as long as one is starting and stopping charging in the ways supplied and suggested in the manual, then things should be alright. There are externals like line surges and spikes, power outages, etc., that the system must absorb rarely as well. It's very good idea to have a surge suppressor tied into your main breaker panel. If one charges with 120V only, then a good quality plug in line surge suppressor would be advisable. The kind one would run power through to protect a desktop computer for instance. Most of these will still provide power after the surge suppression section has sacrificed itself clamping a big surge, or spike. I prefer one that will no longer provide power after the surge suppression has been defeated. That way it's obvious that in needs replaced.

The one thing Mitsu and the charger manufacturer did not coordinate well on (IMO) is the mounting location of the OBC and how well (or poorly) it could convection cool the case while functioning. It does heat up less running on 120V, but it also runs a lot longer too. So, I think there, we may be trading heat stress for MTBF (Mean Time Between Failure) component issues. I'm making sure that the chargers on our cars get plenty of active ventilation while charging at 240V. Charging is (has been) always stopped automatically by the cars systems, or by using the push button on the EVSE nozzle as recommended in the manual. I was toying with the idea of offering up kits for actively cooling the OBC but there wasn't sufficient interest to make it worthwhile last summer when the failures started showing up.

For the 12 volt battery. I have found that regular testing is essential for all uses. Not just cranking amps but the longer, more difficult to do capacity testing. IMO a 12 volt car battery that has less than 75% of its new reserve capacity should be replaced especially on an IMiev. Shorted cells, etc., almost always occur on batteries that would test below this threshold. My 2014 has had a new battery in it for about a year now since the original failed its biannual test. At the time, that battery was only a bit over 3 years old :( . Another chemistry is tempting and there are some affordable options out there. I'm not sure though, that an alternate chemistry ameliorates the problem. Any battery chemistry can have a sudden weakness, or cell failure. At least we know lead acid and it's proclivities well.

Aerowhatt
(July) 2014 cool silver ES, acquired new 4/2015 (40.9ah at ~34K miles)
(Aug) 2014 Labrador Black Pearl ES, acquired new 3/2016 (39.7ah at ~20k miles)

kiev
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EVSE relay and Main Contactor sequence observation

Sun Mar 10, 2019 10:11 am

Recently i made an effort to notice the J 1772 push-button sequence on my Bllink Level 2 (240 vac) EV SE.

It occurs almost instantly, but after a very brief delay the EV SE relay opens first, then about 1 second or less later, the contactors in the car can be heard to open.

[edit]
i repeated the observation using the OEM level 1 (120 vac) EV SE, and this time the delays were in the same sequence but were noticeably longer.
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bradleydavidgood777
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Location: Media, PA

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Apr 09, 2019 11:47 am

I've been trying to follow this thread but haven't kept up to it all, and much of it is over my head so I get tired of reading.

I am mostly trying to understand the current theories for failures and if what can be done to hopefully avoid this issue.

This is what I understand...and please, correct me or add to this.

1. Do not let your 12V battery get low or old.
2. Do not cut power to your EVSE while charging. Wait until the charge is finished. Then remove the plug from the car first. If you can't wait for the charge to finish, remove the plug from the car while charging first, instead of cutting power from the EVSE or utility power side.

Let me know if I missed anything.

Questions:

Should I make it routine maintenance to have my 12V battery checked at inspection time? And if so, what kind of reading should I be looking for to justify replacing it?

Should I consider adding some kind of protection before this failure point? If someone here knew what to do and how to do it, I would gladly get in line for this upgrade. I'm pretty handy so I think I could probably remove parts if it is not that difficult and does not require special equipment. Then could ship parts to someone and they could do the upgrade and send them back. Has anyone considered this? Could be a good way to make some extra cash and would also be a great contribution to this group. Think about how great it would be to tell a new owner that they could avoid this issue by getting the upgrade.

Thanks
2017 I-Miev

Don
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Tue Apr 09, 2019 2:02 pm

I believe it's been determined that the primary cause of the On Board Charger failures (the $4K unit that charges the high voltage traction battery) is that it overheats. It's water cooled, but the cooling system doesn't remove much heat and on a warm day, it gets really hot inside. Kiev took many temperature readings which pretty much proved Mitsu's cooling system has major flaws

Several of us tried using fans on hot days to carry away some of the excess heat. Since the way we use our two cars never requires fast charging, I quit using 240 Volt L2 charging completely. In fact, 90% of the time for the past 8 months or so I've been using the stock 8 amp, 120 volt Panasonic EVSE for nearly all my charging. The other times I've been using my modified 12 amp 120 volt EVSE. The OBC doesn't get nearly as hot charging on L1 as it does using L2

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2017 Chevy Volt Premier
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1979 Honda CBX six into six

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