Eliminating Mitsu's Onboard Charger/DC-DC Converter

[PV1]

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).

[charliejuliett]

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?

[redcane]

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?

[charliejuliett]

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!

[coulomb]

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.

[charliejuliett]

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.


https://drive.google.com/drive/folders/ ... sp=sharing

[JoeS]

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:

http://www.evric.kestar.com.au/docs/DC- ... _Input.pdf

(the pdf image not visible on all browsers)