TimiSchor
Posts: 1
Joined: Mon Dec 17, 2018 10:26 am

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

Mon Dec 17, 2018 10:52 am

Hello...opening and reconnecting a wiring connector will renew the contact surface and break up corrosion, but a cleaning spray like DeOx-it could only help.
It appears that the 20 amp 400 VDC fuse I blew is both the charging output and the DCDC input, would you agree? That makes me suspect only one of those two actually failed.

online percentage calculator

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

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

Sat Jan 05, 2019 6:04 pm

KIEV:
I am tending to give more weight to your theory that majority of OBC Failures are being caused by a sick 12v aux battery.
At first, I thought these failures were due to mains power surges, but now I see more evidence towards the aux battery
being the lead contributor to these failures. Here in WA Australia, we are see the strange co-incident of a lot of OBC Failurs just this last year when there were not that many fauilures previouly. This is on 2010 model IMIEVs. I think one reason we are seeing a lot of cars failing at around the same time is due to the typical life span of the 12v batteries. Most of these cars in WA are using the same brand of low maintenance batteries, and since they do not require periodic topping up with water, most people run them till they drop. In two of the three cases of OBC'S That I fixed, The 12v battery seemed to be ok, showing a 12.xV reading when not being charged, and a 14.xV reading when the DC-DC was charging, but when the batteries were put under load test, they both failed. This means the 12v batteries were only working good enough to keep things alive when the car was shut down, but the DC-DC Converter was doing most of the heavy work while the car was running. I also had one case where I fixed the blown snubber caps in the OBC, replaced the 20amp MCU Fuse, and all was working, but then two weeks later, the car's 12v battery failed. even though it was a low maintance battery, you could smell the battery giving off the sulferic acid smell, and it was only showing 11v and would not start the car. Once we replaced that, all has been good now for several months. I am starting to believe that if you have a faulty 12v battery that is causing a high current load trying to be charged, and the Traction battery is also low at the same time, and you try and charge the traction battery from AC at the same time, The combination of both heavy loads and maybe a few other loads in the car added together become enough to blow the 20amp fuse. Once this blows, there is a domino effect of a inductive spike that blows the snubber caps in the OBC. For preventing this problem, it's not enough just to check that the 12v battery is going up to 14v when being charged, you have to use a load tester to see that the 12v battery is actually healthy and not causing extra current load from being in poor health.

DBMandrake
Posts: 135
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

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

Sun Jan 06, 2019 3:11 am

skylogger wrote:KIEV:
I am tending to give more weight to your theory that majority of OBC Failures are being caused by a sick 12v aux battery.
At first, I thought these failures were due to mains power surges, but now I see more evidence towards the aux battery
being the lead contributor to these failures. Here in WA Australia, we are see the strange co-incident of a lot of OBC Failurs just this last year when there were not that many fauilures previouly. This is on 2010 model IMIEVs. I think one reason we are seeing a lot of cars failing at around the same time is due to the typical life span of the 12v batteries. Most of these cars in WA are using the same brand of low maintenance batteries, and since they do not require periodic topping up with water, most people run them till they drop. In two of the three cases of OBC'S That I fixed, The 12v battery seemed to be ok, showing a 12.xV reading when not being charged, and a 14.xV reading when the DC-DC was charging, but when the batteries were put under load test, they both failed. This means the 12v batteries were only working good enough to keep things alive when the car was shut down, but the DC-DC Converter was doing most of the heavy work while the car was running.

Interesting theory that a sick 12v battery may be implicated as a trigger to these failures. For reference I have just replaced the 12v battery in my 2011 Ion a couple of weeks ago.

Here in the UK the original factory fit type is not low maintenance but actually has the old fashioned screw caps on the top. You can see both the original (very hard to find) type and a replacement type in the following article:

https://www.gogreenautos.co.uk/how-tos/ ... ry-battery

Unlike some EV's which use deep cycle or AGM types these cars seem to use regular "starter" batteries that are not designed for deep discharge.

My 2011 Ion has now done 48k miles and I've owned it for coming up on 2 years in March. The battery seemed "OK" when I first got the car, (although it was never load tested) and in the time I've had the car it has only had one deep discharge where the key was left on acc for a few hours with 3rd party heated seat covers turned on about a year ago. (About 3 amps each) This resulted in a flat battery that was unable to power the ECU's enough to either start or charge. At the time I was at home so I used a 12v charger to "jump" start a normal charging session, the 12v battery was charged up again and everything seemed fine. It was the only time the car let me down and was unable to enter ready mode.

As it's now winter again and I spend up to half an hour a day sitting in the car waiting to pick my other half up after work I run one heated seat cover rather than the main heater as I don't have enough range to just sit with the heater on for that period of time... and I recently had an experience where the heated seat cover was only on for 8 minutes until the radio faded out and both radio and my dashcam turned off. Whoops!

A bit of voltage monitoring and I realised that the battery was so sick that it was only able to power a 3 amp heated seat cover for 8 minutes, (about 0.4Ah usable) when a 36Ah battery should be able to power it for well over 10 hours... Yikes. I also discovered that the radio doesn't shut off until it gets down to 9 volts. Amazingly, after this happened I was still able to put the car into ready mode so ECU's and contactors seem to be rated to still function as low as 9 volts.

So a couple of weeks ago I replaced the battery with a Yuasa YBX5054 and all is well again - it easily runs the heated seat covers for a long time without any significant sag.

I did some cycle testing of the old battery (it's stuffed anyway so why not) and at a discharge rate of 0.4 amps it had only 1.4Ah usable capacity left from 36Ah. There was nothing wrong with the electrolyte levels - despite me not checking them in the two years I've had the car the levels were perfect. Looking at the battery I'm reasonably sure that it's the original 8 year old factory battery, and that doesn't surprise me because ICE car tradition is that you don't replace a 12v battery until it lets you down. Nobody replaces them preemptively.

The lesson I learnt from this is that the demands on the 12v battery in this car are exceptionally low, allowing the battery to deteriorate dramatically without any symptoms, and by then it is too late. That battery would have failed to start an ICE years ago and been replaced. When parked it only needs to be able to supply a few of the ECU's in standby mode, such as the central locking ECU, and to start the car or commence traction battery charging as long as it can stay above 9 volts for a couple of seconds while the BMU ECU is trying to sequence the contactors then the DC/DC converter will take over and supply all the 12v system loads including the heavy loads like the brake vacuum pump and power steering which are both hundreds of watts peak.

If a failing 12v battery is implicated in these OBC charger failures then as you say we are going to see a lot more OBC failures soon as the 12v batteries on the old cars start giving up, and I'm glad I've replaced mine!
I also had one case where I fixed the blown snubber caps in the OBC, replaced the 20amp MCU Fuse, and all was working, but then two weeks later, the car's 12v battery failed. even though it was a low maintance battery, you could smell the battery giving off the sulferic acid smell, and it was only showing 11v and would not start the car. Once we replaced that, all has been good now for several months. I am starting to believe that if you have a faulty 12v battery that is causing a high current load trying to be charged, and the Traction battery is also low at the same time, and you try and charge the traction battery from AC at the same time, The combination of both heavy loads and maybe a few other loads in the car added together become enough to blow the 20amp fuse. Once this blows, there is a domino effect of a inductive spike that blows the snubber caps in the OBC. For preventing this problem, it's not enough just to check that the 12v battery is going up to 14v when being charged, you have to use a load tester to see that the 12v battery is actually healthy and not causing extra current load from being in poor health.

Can you describe what is on either side of this 20 amp fuse and which direction the flow is in depending on operating mode and conditions ? I haven't seen the circuit diagrams you guys are referring to.

I'm a little bit skeptical however that a weak and failing 12v battery will cause issues directly as a result of placing a higher load on the DC/DC converter that is trying to charge it. On the contrary a weak battery that has lost 90% of it's capacity as mine had will provide an "easy" load to charge, because it will have both high internal resistance and a very small capacity to charge.

Mine only required 1.4Ah to fully charge it, and the internal resistance was high enough that my 6 amp charger had to throttle back to about 2.5 amps within seconds of starting the charge to keep the voltage from going over 14.4 volts. In other words it literally couldn't be charged at a rate any higher than about 2.5 amps or 36 watts even from dead flat!! Hardly a difficult load for the charger which I believe is designed to be able to supply at least 80 amps to the 12v systems.

No, if a failing 12v battery is responsible I think the mechanism will be different, it will be a loss of proper contactor control and sequencing or a low voltage induced malfunction of one or more ECU's.

Let me paint one possible failure scenario - not for this exact fault you're referring to but the kind of thing that could happen. Contactors are just big relays so like relays they have both a pull in current and a hold current.

For example it may take 1 amp to pull in a contactor, but only 0.3 amps to hold it. (1/3rd of the pull in current is typical with relays)

During the power up sequence of the battery pack for either charging or entering ready mode there is a pre-charge contactor that connects the pre-charge resistor on the positive side for a fraction of a second before the main positive side contactor is closed. Normally it would expect the voltage to charge up in a very short time. If it does, it then closes the main contactor, if it doesn't, it opens all the contactors and aborts assuming there is a fault such as a short on the output or a faulty pre-charge resistor.

However what happens if the battery is very weak and only just able to supply one or two contactors ? The negative contactor and pre-charge contactors are closed and start to charge up the output. At this point a couple of things could happen.

One is the load of those two contactors may pull the battery voltage low enough to cause the BMU to crash/malfunction whilst still allowing the contactors to remain closed. This would almost certainly burn out the pre-charge resistor if there is any active load on the HV system as it's only designed to handle that load for a fraction of a second.

Another possibility is that the ECU continues to function and tries to close the main positive contactor but the voltage is too low so the contactor can't actually pull in, but the two that are already closed have enough power to keep them closed. So the ECU thinks it has closed the main contactor but it actually hasn't and the load is still being supplied by the pre-charge resistor. This will almost certainly result in the pre-charge resistor burning out in a very short time as well.

Once that resistor is toast the car even with a healthy 12v battery will no longer start or charge.

If you think about the interactions between contactor sequencing, contactor loads on the 12v battery and the variations in battery voltage that may cause with a faulty battery and the effects that may have on ECU and contactor functioning it's easy to envisage scenarios where the normal high voltage sequencing systems fail with catastrophic results.

It may be prudent than any car which has a failure with the OBC has its 12v battery tested and replaced before it is put back into service if there is any doubts about the condition of the battery. It's a small price to pay to avoid another failure if it is a contributing factor!
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

mikedufty
Posts: 32
Joined: Tue Apr 05, 2016 1:04 am
Location: Western Australia

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

Sun Jan 06, 2019 3:35 am

Hard to know if the battery was a factor on ours. Never had any trouble with it except going flat once when we left it for a few weeks (coped with the same thing OK later so I suspect an interior light may have been on). It was not the original battery. Mitsubishi did replace it with the charger but I don't know if it failed testing or it was just a good thing to rule out.

coulomb
Posts: 167
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

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

Sun Jan 06, 2019 4:08 am

DBMandrake wrote: Can you describe what is on either side of this 20 amp fuse and which direction the flow is in depending on operating mode and conditions ? I haven't seen the circuit diagrams you guys are referring to.


It's basically bare battery positive, after the main positive contactor; see the schematics on the first page of this topic.

Image

I'm a little bit skeptical however that a weak and failing 12v battery will cause issues directly as a result of placing a higher load on the DC/DC converter that is trying to charge it. On the contrary a weak battery that has lost 90% of it's capacity as mine had will provide an "easy" load to charge, because it will have both high internal resistance and a very small capacity to charge.

That's true. But it might blow the fuse in the first second or so if the battery voltge is really low, possibly confusing the DC-DC into sending too much current. It's a long shot, I agree.

Mine only required 1.4Ah to fully charge it, and the internal resistance was high enough that my 6 amp charger had to throttle back to about 2.5 amps within seconds of starting the charge to keep the voltage from going over 14.4 volts.

Right. So it would have to be in the first second or two.

Let me paint one possible failure scenario - not for this exact fault you're referring to but the kind of thing that could happen. ...
This will almost certainly result in the pre-charge resistor burning out in a very short time as well.

Nice theory, and we've seen at least one pre-charge resistor blow, but most of the time, it seems that they don't.

Once that resistor is toast the car even with a healthy 12v battery will no longer start or charge.

It could explain a lot of the "won't go to ready" problems. [ Edit: In other words, perhaps a lot of the unexplained "won't go to ready" problems are due to undiagnosed pre-charge resistor failures. ] I like your second scenario better, where the auxiliary battery doesn't have the voltage to power the third contactor. Maybe one of the ECUs (perhaps the EVCU) will notice the lack of battery voltage when there is a HV load, and drops all the contactors out and record a trouble code, but dropping the contactors at that time might cause some inductor(s) to send voltage spikes about, often killing those tiny capacitors in the charrger.

Edit 2: Your first scenario, where the ECU crashes due to undervoltage on the auxiliary battery, seems less likely. The processor and most of the circuitry operates at 5 V or 3.3 V or even less, so there would be a voltage regulator of some kind there. It seems unlikely that this regualtor would fail to run the processor, even if the auxiliary battery voltage dropped to 6 volts. I suppose a sudden auxiliary battery voltage collapse could send a glitch through, but it seems unlikely.

kiev
Posts: 924
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

You can't judge a book by looking at the cover, and

Sun Jan 06, 2019 6:50 am

You can't judge a battery by looking at the water.

Thanks to Larry and Simon for sharing your excellent notes, that's very interesting and helpful. The resting voltage and electrolyte levels are not sufficient to determine if an Aux is good or bad--it can appear to be OK, but it's just an illusion. A load test and capacity measurements are required to know the true state, and Simon's testing is a perfect example.

i've collected some FSM links related to trouble codes and problems related to the Aux Battery, and added these in the second post of this topic thread. i'll post them here also as it's related to the present discussion.

Aux Battery

testing:
http://mmc-manuals.ru/manuals/i-miev/on ... 701ENG.HTM

Charging:
http://mmc-manuals.ru/manuals/i-miev/on ... 101ENG.HTM

Removal and Installation (precautions for disconnecting negative terminal and extended d/c):
http://mmc-manuals.ru/manuals/i-miev/on ... 500ENG.HTM

DTCs related to aux battery:

Low supply voltage (C2005,2006 DTC for EV-ECU):
http://mmc-manuals.ru/manuals/i-miev/on ... 700ENG.HTM

High supply voltage EV-ECU, DTC C2007:
http://mmc-manuals.ru/manuals/i-miev/on ... 100ENG.HTM

EMCU low supply voltage, DTC P0562:
http://mmc-manuals.ru/manuals/i-miev/on ... 101ENG.HTM

OBC low supply voltage, OBC code 04:
http://mmc-manuals.ru/manuals/i-miev/on ... 600ENG.HTM


Other aux battery related codes:
DCDC Converter, DTC P0A09:
http://mmc-manuals.ru/manuals/i-miev/on ... 300ENG.HTM

ASC Traction controller, abnormal voltage readings (DTC):
http://mmc-manuals.ru/manuals/i-miev/on ... 101ENG.HTM
kiev = kenny's innovative electric vehicle

redcane
Posts: 35
Joined: Sat Aug 18, 2018 2:21 am

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

Sun Jan 06, 2019 1:23 pm

coulomb wrote:Nice theory, and we've seen at least one pre-charge resistor blow, but most of the time, it seems that they don't.

Once that resistor is toast the car even with a healthy 12v battery will no longer start or charge.

It could explain a lot of the "won't go to ready" problems. [ Edit: In other words, perhaps a lot of the unexplained "won't go to ready" problems are due to undiagnosed pre-charge resistor failures. ]


Firstly I'd like to clarify that the pre-charge resistor in my imiev needed replacing, but it's absolutely not to do with the original OBC fault. It was a mistake on our part in reassembling the charger. I think that in the absence of essentially a short on the high voltage circuit that resistor should be fine.

Once that resistor is toast you need to replace it to charge or get the car into ready. Although chademo charging should still be possible. I don't know that there are any other cases?

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

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

Tue Jan 15, 2019 11:30 pm

DBmandrake:
Thank you for lots of good additional info. In your case with the failed 12v battery, If battery plates get aged and coverted in sulfate,
it will loose capacity, but charging current is reduced. But, The other failure mode of these batteries is when plates collapse and short.
When plates collapse and sort, you end up with a cell bypassed by the short, so a 6 cell battery becomes a 5 cell battery, and then ends up over charging the remaining cells. This turns into a domino effect damaging the other cells also. The faulty battery we had on the last OBC that I fixed, was drawing a massive amount more current, and the outside of the battery would get hot to the touch during charging. The DC-DC Converter was able to pull the voltage across the battery up to 14v but when shut down the battery would drop down to 11v. There are probably quite a few batteries that end up with shorted cells, since there are not deep cycle batteries and the plates are closer to each other.

Barbagris
Posts: 237
Joined: Wed Feb 20, 2013 8:34 am
Location: Bilbao, Spain

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

Mon Jan 28, 2019 3:07 am

Hello everybody.

Another case more. Peugeot iOn, year 2011, 95,000 km / 60,000 mi, charged almost every day, the 12-volt battery was replaced two months ago. In the middle of a charge suddenly stopped. When trying to restart the charge, blow the fans a moment and everything stops.

Well, it seems I have a lot to read, and I do not speak English enough. Thanks, Google translate.

I have no oscilloscope or experience with SMD, only a cheap tester? multimeter?

I would appreciate all the help / ideas about how to start, what are the most common failures.

I'm reading, and thanks in advance.

Barbagris (Greybeard)
Last edited by Barbagris on Mon Jan 28, 2019 10:16 pm, edited 1 time in total.
...learning...

redcane
Posts: 35
Joined: Sat Aug 18, 2018 2:21 am

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

Mon Jan 28, 2019 3:43 am

Hola Barbagris,

I think the first place to check is the fuse for the on board charger, located in the motor inverter. This is under the cargo space in the back. This can contain hazardous voltages, but can be checked with a multimeter. Most likely the "snubber" capacitors in the charger are destroyed also. ( I would say that covers the majority of the failures.) The capacitors in the charger can be checked visually, but you need to first remove the on board charger to facilitate working on it. It might be possible to remove the top cover and check for scorch marks while it is in the car.

Buena Suerte, ojala que su coche puede conducir de nuevo.

(Creo que su ingles es mejor que mi espanol, pero yo voy a ayudar si quiere. Puede mandarme un PM.)

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