The Troubleshooting and Repair for On-board Charger (OBC) Thread

[kiev]

That is a really trashed pair of resistors, and the little one exploded!

Those parts are on the AC Input side. i would want to check all the parts on the top board in the AC input circuit also, e.g. lightning arrestor and fuses, plus the AC relay and EMI filter coils and cap. i would suggest to replace the AC relay since that may have been the culprit that caused the resistors to blow, and it's easier to do it with the waffle plate out of the way.

It looks like your blue snubber caps (on the HV DC Output side) are ok, so i would replace the 20A fuse in the Motor Control Unit as preventative maintenance.

 

[Easky15]

That is a really trashed pair of resistors, and the little one exploded!

Those parts are on the AC Input side. i would want to check all the parts on the top board in the AC input circuit also, e.g. lightning arrestor and fuses, plus the AC relay and EMI filter coils and cap. i would suggest to replace the AC relay since that may have been the culprit that caused the resistors to blow, and it's easier to do it with the waffle plate out of the way.

It looks like your blue snubber caps (on the HV DC Output side) are ok, so i would replace the 20A fuse in the Motor Control Unit as preventative maintenance.

Thanks kiev,

I have updated the google drive folder with more images including the top main board, Fuse F103 on the top AC input board tested good in circuit (do they need to be removed from the board for accurate test) Fuse F102 on the large bottom board also tested ok in circuit,

I have the datasheets here for the ac relay and resistors but where am i best getting them from? Can you please provide links to quality replacement components for all the parts you think i will need, I honestly don't mind spending the extra money here to do it right the first time, Components are relatively inexpensive so I'm happy to replace all possible failures with upgraded/better quality parts, My soldering skills are fairly good so i'd be happy enough doing it all.

Also after repair is complete with new parts fitted is there any sort of waterproofing/insulating material needed to recover soldered area? Looks to be a sort of clear coating over all factory solder joints.???

 

[Virusman]

Hi

Easky15

, just visit any web shop with electronic components for example: http://www.digikey.com/ or http://www.farnell.com.
If You want to replace relay, just by exactly the same. Gold rule: don't buy the cheapest one.

My question is: how to test charger without car and batteries? Is it possible?

 

[kiev]

Looking at the pictures, Is the Spark Arrestor (SA) okay? Is the plastic base of coil L705 on the top board melted?

i would try to find the same parts online e.g. mouser or digikey, or an electronics parts supplier in Japan if a part is not available from the online sales.

i haven't figured out a way to test an OBC without the car involved since it is CAN buss controlled and tightly integrated with the car. i have tried to publish schematics for circuits that i've traced where component values could be measured, checked and verified to be good. The relay drive circuit was traced and posted too.

For the AC input, those resistors blew because they were carrying the full AC for too long. The question is why and how this happened. Either the relay was never commanded or it opened during charging. The relay is driven by a 5V power supply on the top board created from the 12V aux battery.

Was the aux weak or did it fail during the session; did the 5V supply fail; was the CAN buss signal to start charging corrupted, etc?

 

[Easky15]

Looking at the pictures, Is the Spark Arrestor (SA) okay? Is the plastic base of coil L705 on the top board melted?

i would try to find the same parts online e.g. mouser or digikey, or an electronics parts supplier in Japan if a part is not available from the online sales.

i haven't figured out a way to test an OBC without the car involved since it is CAN buss controlled and tightly integrated with the car. i have tried to publish schematics for circuits that i've traced where component values could be measured, checked and verified to be good. The relay drive circuit was traced and posted too.

For the AC input, those resistors blew because they were carrying the full AC for too long. The question is why and how this happened. Either the relay was never commanded or it opened during charging. The relay is driven by a 5V power supply on the top board created from the 12V aux battery.

Was the aux weak or did it fail during the session; did the 5V supply fail; was the CAN buss signal to start charging corrupted, etc?

Sadly yes it does look like L705 got too hot and melted and also L706 maybe too, Here is some pics

https://drive.google.com/open?id=1JT1VzVlgU3DUhCUbd-bUZNRUoFwD0wDN

Also how do i test the spark arrestor?? Is it just like testing a fuse? Continuity check? If so it failed that..

Do i need to car to properly diagnose this?

Could this fault be cause by a timer plug cutting AC power every morning before charging is complete?

Or could a weak 12v battery mean 5v supply wasnt able to be generated?


Would an aftermarket charger be an easier option here?
Just need to get power into the batteries...

 

[kiev]

The SA should normally measure open circuit, like a capacitor; it is designed to provide a path to ground in the event of a HV lightning pulse.

Since the damage was to the ceramic resistors on the AC input side, then it could be that abruptly cutting the AC power with a timer could be the culprit.

To test if the charger is working properly, it would likely need to be put into a car.

A weak or worn out 12V aux battery will cause a multitude of problems in an EV; since the 5V coil driver power is derived from the 12V battery, then the 12V aux is a suspect culprit.

If you have a benchtop power supply you could follow some of the testing that skylogger Larry did to verify the low voltage supplies of the top board (see pages 8-9 of this thread). also check the fuse on the bottom layer of the top board.

 

[Easky15]

The SA should normally measure open circuit, like a capacitor; it is designed to provide a path to ground in the event of a HV lightning pulse.

Since the damage was to the ceramic resistors on the AC input side, then it could be that abruptly cutting the AC power with a timer could be the culprit.

To test if the charger is working properly, it would likely need to be put into a car.

A weak or worn out 12V aux battery will cause a multitude of problems in an EV; since the 5V coil driver power is derived from the 12V battery, then the 12V aux is a suspect culprit.

If you have a benchtop power supply you could follow some of the testing that skylogger Larry did to verify the low voltage supplies of the top board (see pages 8-9 of this thread). also check the fuse on the bottom layer of the top board.

Ok i will test 12v battery when next at the car, I have power supplies yes so will try these tests,

Also the fuse F701 on the bottom side of the top board is open so that will need replaced too,

Does this even seem repairable or am i safer trying an alternative charger? Is there too much damaged here?

Would really hate to replace everything then plug it all in for it to all go bang again....

 

[Easky15]

I also have a Peak Atlas DCA55 Semiconductor Component Analyser here if theres anything else you think i should test?

 

[kiev]

...
Also the fuse F701 on the bottom side of the top board is open so that will need replaced too,

Does this even seem repairable or am i safer trying an alternative charger? Is there too much damaged here?

Would really hate to replace everything then plug it all in for it to all go bang again....

That is quite interesting and points to an issue on the low voltage power supplies of the top board. F701 is on the switched 12V (aka IGCG?) into the OBC on connector C101 pin 12. From there is goes to a 3.3V regulator, IC718, likely the power supply for the microcontroller on the bottom layer.

The other 12V input is hot all the time on pin 7, and runs thru a ferrite bead FB729, which is a zero ohm resistor that might act as a fuse also, so check it too. It feeds a 5V regulator, IC710, marked M050, and this is the drive supply for the AC relay.

Capacitors C703, 705, 706, 840 are all on the 5V supply of the top board, and this supply is used to energize the AC relay on the bottom board in the potted region in which the ceramic resistors failed. These should be checked if possible.

So this may all be related to a LV power supply component on the top board and may be a simple repair to replace the components, e.g. a voltage regulator chip. i will look thru my notebook if there are additional circuit schematics that might apply.

 

[Easky15]

...
Also the fuse F701 on the bottom side of the top board is open so that will need replaced too,

Does this even seem repairable or am i safer trying an alternative charger? Is there too much damaged here?

Would really hate to replace everything then plug it all in for it to all go bang again....

That is quite interesting and points to an issue on the low voltage power supplies of the top board.

Capacitors C703, 705, 706, 840 are all on the 5V supply of the top board, and this supply is used to energize the AC relay on the bottom board in the potted region in which the ceramic resistors failed. These should be checked if possible.

So this may all be related to a LV power supply component on the top board and may be a simple repair to replace the components, e.g. a voltage regulator chip. i will look thru my notebook if there are additional circuit schematics that might apply.

Thanks kiev, ill remove those caps and test then post back results..

 

[kiev]

i think the F701 fuse blew and shut down the 3.3V supply and the IC701 microcontroller. This turned off the base or gate drive for some transistor on the top board that controls the 5V drive for the AC relay coil in the doghouse on the bottom board. This caused the AC path to run only thru the ceramic resistors and caused them to blow. Coil L702 is in the path of this switched 12V that is on that fuse circuit.

If you see any resistor looking components marked FBxxx, be sure to check if they have blown open.

[edit]
So it turns out that i had traced the 5V supply for the AC Relay and posted a description in discussions on page 8 and 9 of this thread, but i had not traced the path for the transistor drive from the microcontroller.

The CN1 flat ribbon cable has chassis ground on pins 1-4,16,18,20,31,33,40,47-50.

 

[DBMandrake]

The obvious two culprits.

I think, especially now that these cars are ageing a bit, I will charge control more closely in the very hot/ very cold weather via the remote... though luckily that is quite rare here in the UK (and the climate is somewhat similar to Japan) (can't remember any charger failures here). If I lived in a hot dry climate, a well placed CPU fan cut into the charger case could also help with heat dispersion, as could (possibly) modification with an improved heatsink in the vulnerable places.

Don't get too comfy, there have been multiple on board charger failures in the UK recently.

Kes who posted this thread is located in Scotland not far from me and has had the charger go on both his cars...

He also posted over on speakev.com about his problems, (with more up to date information) and there have been other reports on speakev.com of UK charger failures recently as well.

Makes me a bit nervous about mine which is a 2011 model with over 50k miles now. On the plus side I recently replaced the very weak 12v battery so it has a good healthy 12v battery now. If that is the underlying cause of many of the failures I should be alright for a few years, touch wood.

I also use a Rolec wall charger and always end charging either by letting it finish charging itself (most days) or squeezing the trigger on the J-1772 connector - I never turn the power off at the wall first even if I was using the granny EVSE. So if that's another cause of failures I should be OK there too, especially now I'm aware not to do that.

Unfortunately I was right to be nervous - my on-board charger has now failed as well and probably taken out the 20A fuse and caps based on the symptoms. I have ordered caps and fuse preemptively but haven't had a chance to open anything up yet due to work and constant bad weather in the evenings - hopefully I will be able to look this weekend between rain showers...

I replaced my 12v battery only a year ago and it is still going strong so I would suggest that weak 12v batteries are not an underlying common cause of this common failure.

Also I never switch off the charging at the supply - I always let the car finish charging by itself (the vast majority) or press the trigger and remove the plug from the car. 99% of my AC charging is performed at home, and we do not get power cuts at home either. So I'm also sceptical about the interrupted AC theory.

Mine failed about 2 hours into a charging session at home which started at about 25% SoC and ended prematurely at 70%, so it would have still been charging at a full 13 amps (240v AC input) at the time of failure.

 

[DBMandrake]

Can anyone who has attempted this repair advise on the following:

I'm not keen on removing the entire on-board charger unit from the car if I can help it, so that I don't have to disconnect coolant lines and refill and bleed it later, but I'm also not keen on doing a close inspection of the main PCB (with the two blue caps) and repair in-situ in the car either, as the weather here is atrocious now and for the near future, with the car situated outdoors.

So I was wondering whether removing the main PCB (with the two blue caps) complete with waffle plate, and bringing that in the house for close inspection and repair and then refitting it was the best approach ?

From what I can see from this thread the PCB with waffle plate can be removed without un-soldering any pins with a little bit of force to make the heat transfer compound let go between the waffle plate and the coolant channel ? Are all the faults diagnosed so far on this one PCB ?

If I don't need to un-solder the waffle plate to effect a repair (fingers crossed - depending on what I find damaged) then can I refit it with the original thermal paste or will I need to clean up and re-apply new thermal paste ? (And if so, any recommendations of what to use ? It's a long time since I last used thermal paste...white beryllium stuff!)

I guess if I did have to remove the waffle plate then I would have to do the re-soldering of the waffle plate to the PCB after it is bolted down to the coolant channel and the PCB was bolted back into the board to ensure a perfect height match and no mechanical stress of the soldered joints...

Those that have un-soldered a waffle plate successfully, do you think a regular vacuum de-soldering station would do the job OK ? I don't have one, but I'm happy to buy one if I need it as it's something I would find useful for other electronics work. (I normally get by with a hand operated solder sucker and solder wick but sometimes wish I had something better for de-soldering...)

My current plan is to leave the charger unit in the car, remove this main PCB with waffle plate together, visually inspect the two 1000pF caps and other parts in the doghouse, replace the two caps regardless, and replace anything else visibly damaged, but also to perform the relay test to check the value of the 2x 4.7 resistors and ensure that the relay shorts them out reliably.

Even if there is no visible damage to them I'm definitely not putting the board back in until the resistors and relay have been functionally checked...

Should I be checking F701 as well ? Is that on the same board ?

 

[kiev]

Once you remove the lid screws and carefully pry it up to start breaking the sealant, you will be able to see the smaller top board with flat ribbon cable down to the bottom board. There are the AC input wires into the top board toward the rear and down to the doghouse region below on the left side.

The mounting screws and faston tabs can be removed (slide the white plastic up and it will free the faston clips) and this top board can be laid over to the right. Now the bottom board can be seen and examined for blown components and schrapnel. i have replaced the blue snubber caps without removing the bottom board, and have also removed the board with the waffle plate. And used a vacuum desoldering tool to free the waffle plate, which was a tough job even so and i damaged some of the vias of the solder holes. If i need to remove the top board, i just slide the FRC connector release on the bottom board and leave it connected at the top.

They put too much thermal paste so expect that if you remove the bottom board with waffle plate. There is no worry about solder height--the bottom board floats above the waffle plate and the hold-down bolts/studs hold the plate, not the board.

if you decide to remove the BB and WP, there are numerous faston tabs with the white plastic covers that must be removed. Slide the cover up and it will release the faston lock clip. The wires are all colored and coded to the tabs, but take a picture with phone to remember how the wires are laid and wrapped on re-assembly.

With the faston tabs removed you can use the diode function of your multimeter to check for damage in the waffle plate, hopefully you will have none.

 

[DBMandrake]

Does anyone know how many litres of coolant it takes to refill the system if I do completely remove the charger and whether regular 50/50 glycol based coolant is suitable ?

 

[DBMandrake]

Ok here's an update on progress.

I've confirmed the 20A MCU fuse has blown, no surprise there, and I can also confirm that one of the two blue caps has split, although not as violently as some other cars as there is no debris anywhere, just a clean double split of the cap:

The resistor I was also a little bit worried about at first as there is a black mark on the corner near the capacitor however on closer inspection I think it is residual potting mix or perhaps just the effects of heat build up over many years heating the potting mix causing it to wick up the side of the resistor:

It doesn't look like an actual burn mark on the resistor and there is no melting of the potting mix at the base of the resistor or the cap itself. So I will measure the resistors from the top and verify relay operation - if they both seem OK I'm not going to replace the resistors because that would require waffle plate desoldering which I am not currently equipped to do.

I presume it's not possible to do meaningful diode checks on the waffle board without desoldering it ? If so I'll just have to take the chance that there is nothing blown on it.

I've decided not to remove the whole OBC box from the car - the outsides are very corroded as are all the mounting bolts, and removal would require work outside the car (not possible with current weather) including draining and refilling the coolant - and I don't have any to hand. (And funny story, my other car, a petrol car broke down terminally last night so I have no working car at the moment making this OBC repair super urgent... :roll: )

So the plan is to remove the bottom board from the box together with attached waffle plate to take inside for repair as it looks a bit too awkward to work on the board in the recess of the box hunched over inside the car to stay out of the rain - especially the potting mix removal.

I've also checked white fuse F701 on the underneath of the top board that was reported as faulty earlier in the thread - it measures ok.

 

[kiev]

Yes you can check all the semiconductors/diodes with the WP still attached to the BB, just have to remove the wiring to the inductors first. But you will have to do that anyway to remove the BB from the box.

Remove the black plastic sleeves on the board standoffs, follow the numbered arrows at the base of the standoffs pointing out the order of removal and installation. There is a schematic with the measured voltage drops, i'll have to look to find the post.

 

[DBMandrake]

I have the board right out and ready to start working on it now, so if you can give some guidence of which pin pairs to check with a meter in diode test mode to test the waffle plate that would be great.

Did anyone find a replacement source for the four electrolytic caps on the board ? Two of the large ones and the small one have wrinkles in the plastic wrapper suggesting they may have been a bit hot, however they are not bulging at the ends.

The large ones have 4 pins and the small one 3 - a bit of an odd layout! Unlike some of the other units shown in this thread there is no heat discolouration on the inside of the lid at all. I'm desparate enough to get the car working again that I may have to leave the electrolytic caps as is...

 

[Sandrosan]

DBMandrake,
I am sorry for your troubles, you were so ansious and then it happened!
I think a voltage spike has triggered and brocken the blu snubber cap and then blowing the fuse. Is my thinking possible?

I already put 3 SPD 275V AC rated before my EVSE and I am going to put another 3 Varistors at 250V AC or even a bit less as the voltage here is 230V (one P to E, one P to N and another N to E).

I also protected the EVSE line by an A type RCD with overcurrent protection.

I would suggest you to do so too after you fix your OBC. I wish you good luck, I am very confident you will be succesfull.
Cheers

 

[Sandrosan]

Can you reach the electrolitics caps terminls? If you have a DMM with capacitor function you may at least test them.
It is not a sure test for their full integrity but much better than nothing.
I have seen many photos of such board and all of them have these capacitors well suffered the heat, but I think few have been replaced.