Eliminating Mitsu's Onboard Charger/DC-DC Converter

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Jun 10, 2016
My 2012 imiev recently had its OBC fail in the middle of a charge cycle. (35K miles) The aux battery was in good condition and the car was charging in a cool garage. I live far from a Mitsubishi dealer (Upper Peninsula of Michigan) so I decided to try and fix the problem myself. The car was back on the road in 9 days.

Here is what I did:

1) Removed the entire assembly that houses OBC. Covered all open connectors with shrink wrap covers.
2) Rerouted the cooling hoses to account for the dcdc converter charger box being gone.
3) Replaced fuse in the inverter box with a 400vdc 4amp fuse
4) Used the carsoft i909 to clear the error codes on the ev ecu.
5) Plasma cut an 1/8 aluminum plate to mount the coolant tank and a brand new HLG-600H-15A from Meanwell. This power supply is meant to drive LED lights, it has adjustable voltage and current pots built in with a remote and 5V output line, and has a 431 VDC input limit.
6) Wired up the high voltage DC from the inverter box to the input of the mean well power supply, put an arduino micro controller on the 5v line to trigger the remote line a second after the supply gets input voltage. (otherwise the car will trip an error code during start up) The output of the power supply is set to 14 volts (after the diode) and routed though a high power diode which is affixed to the aluminum plate with thermal paste.
7) The expensive part (but worthwhile, I can charge the miev at 7.2 kw now) I bought a chademo charger from evseadapters.com, I use that since I no longer have an on board charger. Takes about an hour to go from 20% to 80%.

A couple notes: with the high beams on and the hvac fan on high, when the brake booster pump kicks on I can draw more current than the power supply can manage, so my voltage will dip into the 12.7 range for a few seconds. So far it has not been an issue, I just use a voltmeter in the 12v power jack to keep an eye on things. The red battery indicator light will stay lit on the dash since the car thinks it has no DC DC converter- I took apart the dash and put electrical tape over the back side of the overlay.

3700$ total into this endeavor, but I got the car 4 years ago for 5900 and its been a real treat to drive so it was not hard to justify. Link to the charger:

Here are some pictures of the fix and the fancy new charger:

Response to some very good questions about this mod:

1) The setec charger takes the car to 80%, you need to restart the charger manually to charge to 95% (See comment 6)

2) Cell balancing does appear to be taking place, I have 4.10 volts across the board according to canion when I charge to 95%

3) I also bought the J1772 EVSE to nema 14-50 outlet from evseadapters.com to use at public charging stations, though I mainly charge at home. I can route the cables through the rear window so the charger stays inside the car if its rainy or snowing.

4) The meanwell power supply is completely sealed except for the access ports for the pots only have a rubber plug in them.

5) I thought about using the Elcon PFC2500 Charger, and at less than 800 bucks that would have been cheaper. I still think I would have gone this route if I had more time and skill.

6) The charger does cut off at 5 amps, or about 95% SOC. All cells appear to be balanced, will update if this is no longer the case in a few years.
charliejuliett said:
I live far from any Mitsubishi dealer (Upper Peninsula of Michigan) so I decided to try and fix the problem myself. The car was back on the road in 9 days.
Hot Damn- you fixed the problem for less than a dealer would've charged, and successfully doubled charging speed while retaining CHAdeMO ability! The main downside I see for that Meanwell power supply will be salty water intrusion in your environment. Could be a good time to add a belly pan.

Thank you CJ- this is the sort of hacking that will be of increasing importance to keep these cars on the road in future years!
Charliejuliett, thank you!! I'm still digesting the details of your mod, but this is exactly what I had in mind when the charger/dc-dc problems started getting serious. The bonus is that you have a higher-power charging capability that is also portable. As jray3 pointed out - at less than the cost of a replacement Mitsubishi part!

I created a new topic and moved your post in here so as not to dilute the excellent thread that kiev and his astute team have in pursuing and repairing the i-MiEV's onboard charger/dc-dc.

Edit: Now that my excitement has died down, I have a number of questions -

1. When using public J1772 EVSE you would simply use an adapter such as one from http://www.tucsonev.com/? Oh, I see that evseadapters.com has one also.

2. Does the i-MiEV shut off at 80% or can you force it past that?

3. Does cell balancing take place?

Once again, the CHAdeMO charger that you are using is -


Yet another edit: More questions -

4. I recall that one of the problems with the way CHAdeMO was implemented on the i-MiEV (unlike the Leaf) is that CHAdeMO supposedly shuts off below 5A dc input current. Have you seen this?

5. Had you considered a conventional EV charger?

One more Edit:

Here are the specifications for the HLG-600H-15A power supply -


It is rated for 36A and the "A" part number suffix means the output voltage is adjustable
NOTE: I just noticed that charliejuliett edited his original post and answered our questions there. My bad in doing those edits first, as we should keep these threads as ongoing conversations instead of going back and changing our posts (other than to correct errors that we should subsequently also note).
It seems my forum etiquette is lacking by going back and editing my original post without notice, I will do my best to conform and follow the rules from now on. :oops: I have been a longtime lurker on this site and a big thanks to those who post- there is tons of good information. I credit finding the 2 inch hitch and gas heater add-ons to the site, and they make the car a whole lot more useful.

I wanted to try and fix the charger on my car like others on this site are doing, but I realized pretty quickly that it would be well outside my comfort zone. Its a shame these things fail as early as they do and I really wish mitsu would send out a recall as the failure rate seems high.

So if you don't have a degree in electrical engineering- my caveman/brute force approach may be worth considering. I know the 36 amp output is nowhere near the original 90 amp unit its replacing, but it is possible to put these things in parallel if you find your DC demands are too high, but so far so good with just one. A benefit I forgot to add, the car lost about 30 lbs! I should note that it gains it all back and more if the setec charger is in the back.

charliejuliett, no worries about the forum etiquette - I've been a worse transgressor in the past. Glad I found your post update by accident.

1. The 36A output should be fine for most applications and I might add not to run more than one window motor at a time.

2. I'm interested in some details of your Arduino time delay, as I haven't dabbled in that world.
This is a wonderful initiative. My only concern is that you might need some protection against excessive current in the input stage of the Meanwell, due to rapid pack voltage changes. For example see this:


I hope that your old charger can be used as parts to repair other people's chargers, and/or help reverse engineer them for repair. I think your solution, elegant as it is, won't be ideal for everyone.
Finally put together a wiring diagram of how to connect the off the shelf dc dc converter, which I should mention is less than 200$. As coulomb mentioned above, this solution is not for everyone, but it is quick if you have only one car to rely on as I did. The arduino code is a simple variation of the "blink" example, about as simple as it gets:

void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
digitalWrite(13, LOW);

void loop() {
digitalWrite(13, HIGH);

I hope to someday find a imiev with a busted charger/dcdc converter for cheap and use this fix and my new 7kw charger to give it a second lease on life!

A link to the wiring diagram here:
charliejuliett said:
Finally put together a wiring diagram of how to connect the off the shelf dc dc converter,
That diagram's a beaut! What program did you use to draw it? I've gotta put down the crayons sooner or later...
I like Paint, too. Simply awesome.

I second the question above. What did you do with the old charger/DC-DC converter? Might be handy to KiEV and others working on finding the culprit to the failures.

I like your replacements for the OEM unit. Keeps the car happy with no major loss of functionality (other than having to carry around an off-board charger, though the faster charge makes it worth it).
Sadly I did not keep any part of the old dcdc converter. There were witness marks from quite a bit of arcing inside it so I assumed nothing was worth keeping.

Also, I was worried I would attempt to fix the thing and end up hurting myself, so I tossed everything from inside it. I did save the aluminum housing just in case I wanted to mount something in it.

Do we have an idea on the total number of these dcdc failures? My car alone represents .05% of the 1998 imievs sold in north america. Is our electrical grid not clean enough or something along those lines?
Great stuff! Good to see it got you back on the road. I can understand the motivation to find a solution - I'm really keen to get our miev going again as I love driving it. I'm a little less keen on paying an exorbitant amount for a replacement charger when the previous one lasted less than 2 years.

We need to charge to more than 80% daily, so I'd need to rig up a timer to restart the charge at 4am or something.

I'm a little bit interested in maybe going the Elcon PFC2500 route - you mentioned this seemed like more work? I suppose you need to figure out where to tap into the HV circuit, and maybe work with the existing BMS. Although I assume the existing BMS would still perform balancing if you just brought the voltage up to the max voltage?
I think the Elcon charger would work without too much fuss, the cars HV lines are easily accessible, they are the lines I tied into with the dc dc converter. You could also tap the chademo HV lines by using a jumper inside the car and a jumper at the chademo port if I remember correctly. The only hiccup I worried about was needing to wake up the battery BMS while charging- by either turning the car on to get the READY light or some other method. I am not entirely sure this is required, so someone correct me if I am wrong.

If you are able to get things going using the Elcon it would definitely be a more cost effective way to go. I don't believe its waterproof, so it may have to be mounted inside the vehicle or protected somehow. Good luck!
charliejuliett said:
I think the Elcon charger would work without too much fuss
Yes, connecting it would be straight forward. My problem with this solution is that the BMS is not controlling the charger maximum current.

Some of the older Elcons had an "enable" input that was able to set the charger output to 0-100% with I think a 2-5 VDC control signal. It's not isolated from the battery, so it's awkward to use. But a relay or two with suitable resistors could tell it to drop the current back to say a few amps, or even half an amp. So when a single cell got too high in voltage, the charger could cut back and give the bypass resistors time to let the others catch up. The problem is getting that information reliably. Also, these old models are getting hard to come by, and you have to wonder if they will last well.

If you are able to get things going using the Elcon it would definitely be a more cost effective way to go.
More cost effective than a new charger, unless Mitsubishi drop the price substantially (as may even happen; see other posts). Not cheap compared to repairing the charger, but of course not everyone is set up to do repairs, even if the information is available here.

I don't believe its waterproof, so it may have to be mounted inside the vehicle or protected somehow. Good luck!
The Elcons are waterproof and designed to work in cars. But the newer models are poorly documented, and there are some horror stories about them.
Just an update repairing the OBC on the miev by eliminating it entirely:

I've driven about 1000 miles since the repair. There have been no issues and I like how quickly the car charges. I did replace the vacuum pump, and it cut the current draw from 30A to about 16A DC when the vacuum booster pump kicks on. I can run the car at night with the bright headlamps, seat heater, diesel heater, HVAC fan on high and my system doesn't drop below 13.7 VDC. The setec charger is great, even though there is some interesting spelling on the HMI (Automic Charging, lol).

I really wish the OBC hadn't failed, but it made me realize how much I did not want to let go of the imiev. I will make sure to update this post if anything happens with this new setup.

Inasmuch as OBC/dc-dc failures are occurring worldwide at a seemingly more-rapid rate, it is now becoming more imperative to perhaps find cost-effective replacements for the failing dual-function module as a backup plan in case repairs are not successful.

charliejuliett, it's been about nine months since you performed your modification.
How is the mod working for you longer-term?
How is the Setec CHAdeMO charger performing?
Further thoughts about using an Elcon?
Perhaps a schematic/program of your Arduino time delay?

Edit: in case no one had gone there, here is the suggested dc-dc input snubber circuit referenced by coulomb:


(the pdf image not visible on all browsers)

I'm new to the forum
My 2012 I miev Onboard failed got 60.000 miles and a lot of charges
Following your advice to my best understanding I will be happy with Elcon
I found this one ELCON UHF 3.3KW CANBUS CHARGER from evsource for 894 $ seems to be plug and play but I'm not sure
Can you give any advice
mandrei said:
I found this one ELCON UHF 3.3KW CANBUS CHARGER from evsource for 894 $ seems to be plug and play
I don't know the the UHF models, but the CAN bus versions of the older ones required a CAN bus message every 10 seconds or it would stop charging, and would not start at all without a CAN message.

So you'd need something to intercept CAN bus messages from the BMS and send commands every second or so to the char ger.

I would not call that plug and play.

Repairing the original char ger, or if possible getting it replaced under warranty, seem to me to be easier options.

Edit: Many USA bought imiEVs would still (just) be eligible for a warranty replaced on-board char ger, since the warranty on the char gers was extended to 10 years in the USA.