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Re: Turtle at Half Charge Under Load?!?!?!

Posted: Sun Oct 06, 2019 12:25 pm
by Style
Having same issue. OP-What was the resolution to the issue ?

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Mon Oct 07, 2019 2:18 am
by Gary12345
Style wrote:Having same issue. OP-What was the resolution to the issue ?

This is generally caused by a battery cell going bad. Turtle is triggered by low voltage on a battery so even though the car has plenty of charge, one cell's voltage drops when it is used.

What country are you located?


Re: Turtle at Half Charge Under Load?!?!?!

Posted: Mon Oct 07, 2019 11:46 am
by Style
Las Vegas, NV, USA

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Tue Oct 08, 2019 6:58 am
by 1kaspars
RTFM - "turtle light" means "Power down warning light". Illumination of the power down warning light does not
indicate a malfunction.

This warning light will illuminate;
*When the energy level in the main drive lithium-
ion battery is near empty.
*When temperature of the electric motor unit
or the main drive lithium-ion battery is too
high or too low.
*When voltage of the main drive lithium-ion
battery becomes low.

According to HobDrive app and my expirience - internal resistance of cells are between 0,0015 when normal temperature and 0,0028 Ohms @ 41F. so this means colder battery / higher internal resistance. (see LEV50 datasheet Voltage vs Discharge capacity / Ah @ -25 -10 0 25 Celsius)

So do the math - 0.0028 x 185 Amps (full acceleration) -> 0.518 V voltage drop on cell. At ~50% SoC this means 3,8V maybe. So to protect cells, car limits amps. And older battery, lower temperatures, full acceleration - whay do You expect? Voltage becomes low -> power down light "on".

Days ago tested I-miev with 34Ah capacity with Canion app - this voltage drop (on all cells) can be observed directly.

So, I don't bet on DC-DC converter fail or replacing 12V battery or one cell in the pack gone bad. It is normal case - cold weather, high load.

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Tue Oct 08, 2019 10:43 am
by JoeS
1kaspars, thank you for your detailed analysis and explanation.

Style, since your battery is probably still under warranty, I would be inclined to demonstrate this to the Mitsubishi dealer.

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Tue Oct 08, 2019 12:28 pm
by DBMandrake
A bit late to this thread, but.....There are two triggers for the turtle mode light.

The normal one seen is that if the estimated state of charge goes below about 10-12% (as reported by Canion) the turtle light will come on and not go out again until the car is charged back up above the SoC threshold. The load on the battery doesn't matter for this trigger it's purely SoC.

The second trigger is the turtle light will come on if any individual cell goes below 3.0 volts, even momentarily. Normally this will never be hit in practice because even under full load at 10% SoC the cell voltage will not drop as low as 3.0 volts, as the open circuit voltage will still be about 3.6 volts.

However if you have a faulty cell that has high internal resistance the voltage of the cell may drop below 3.0 volts under full load even at a relatively high SoC. In this case the turtle light will come on when accelerating and then go out as soon as you ease off the accelerator.

So if this is happening with a reported 50% SoC the issue is almost certainly a faulty cell or cells with high internal resistance, and this would be easily confirmed by monitoring the individual cell voltages with Canion while the car is driven under load, as one or more cells will drop well below the voltage of other cells, and below 3.0 volts if the turtle light is coming on, something that should never normally happen.

One other thing that could cause it is if the BMS's estimation of Ah capacity of the battery is grossly out - for example if the battery is really 32Ah but it thinks it is 45Ah it will keep driving the car well past the point where the SoC turtle threshold would normally kick in, as a result you will eventually get to the point where cells start droping below 3.0 volts under load as the cells are OK but just over discharged.

This happened to me when I did a BMS reset causing the BMS to go back to the default 45.8Ah while my pack was really around 33Ah - it kept driving the car well past where it normally should until the low voltage shutdown started triggering under load.

Unless someone has accidentally done a BMS reset, it seems unlikely that this is the cause, more likely there is an individual high resistance cell.

Diagnosing this problem should be relatively easy with Canion - first check the reported Ah capacity to make sure it is not unusually high for a car of the age/milage (to rule out the erroneous BMS reset scenario above) and assuming not, monitor cell voltages under load when the turtle light is flashing on to identify the faulty cell(s).

I have three high resistance cells in my car at 56k miles that I will be replacing soon - they're not yet bad enough to cause the symptoms described in this thread, however they are already affecting rapid charging speeds and regenerative braking.

As far as I can see DC/DC inverter is a red herring - if that wasn't working the 12v battery wouldn't charge and before long the car would stop working altogether.

The DC/DC inverter is easy to test - measure the 12v battery at the battery terminals while the car has been turned off and unplugged for an hour, it should be between about 12.2 and 12.6 volts. Then turn the car on to ready mode - if the voltage immediately goes up to 14.2 - 14.4 volts and stays there, the DC/DC inverter is working normally. You can turn high beams on for extra load and it should still stay in that range.

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Tue Oct 08, 2019 1:03 pm
by DBMandrake
Graveaxis wrote:The code is obd dtc 39 PFC output voltage fail
Or obc dtc 39 PFC output votltage fail.

kiev wrote:i would have expected to hear that they found a P-code DTC, such as P0A09 or P0A10, which are codes for something wrong in the DCDC converter.

The OBC code 39 is a very specific sub-code related to the Power Factor Control circuit located in the upper plenum of the On Board Chargger which creates the high voltage necessary to recharge the pack. It has nothing to do with the operation of the DCDC.

Error code 39 in the OBC is caused by excessively high AC mains voltage, as measured after the power factor correction circuit in the OBC. Diagbox reports error code 39 as "Fault on the power factor correction module output voltage". Please see my experience with this last year from the following thread: ... ge.104001/

In short, when the AC voltage goes above 247v the car will refuse to charge and sets temporary error code 39 in the OBC. The code is informational and the car will charge normally as soon as the AC voltage is back in range.

Although I don't know for sure low AC voltage might also set the same code, however if it can I have no idea what the low threshold might be. In the UK AC voltage is allowed to be as high as 252 volts, so this 247v limitation can be an issue for us.

So it's probably nothing to worry about and unrelated to the fault at hand - just the AC voltage being too high or too low during an attempted charging session.

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Wed Oct 09, 2019 1:21 pm
by Style
thanks for the information. I think its a cell going bad. I borrowed a OBDzero previously from my Brother. I may have to borrow it again and check it. I've made an appointment at the local Mitsubishi dealership to get it checked. my warranty on the battery goes until November 2022, so I'm covered for about 3 more years. It would be nice to get my range back to what it was like a couple of years ago.

The other thing that happens is when charging here on a chargepoint system (Chargepoint is a pay-to-use system in the US) the app will report that the battery has stopped charging. after maybe 10 minutes to a half-hour it will start charging again. see attached graph from the chargepoint app. not sure how to attach photos, so here's a link to a screenshot: ... VJLUhPY1dV

I think it happens at home when charging too, but that's usually overnight so I don't care. When I'm sitting in a parking lot waiting and every minute matters, having it stop charging for a few minutes is annoying. I also had it charging one time at 3kW, stop for 5 minutes and then continue to charge again but at 1kW, so only added like 3.3kW in 2 hours of charging. charging for 2 hours and only being able to drive 13 miles is really annoying.
Is that due to battery temperature or something?

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Wed Oct 09, 2019 1:24 pm
by DBMandrake
A pause in charging current of up to 30 minutes at a low SoC is actually a characteristic of these cars - they all do it, so it’s normal and unrelated to your problem.

Note: only the current draw drops to near zero - the pilot signals that keep the EVSE operating remain active.

Re: Turtle at Half Charge Under Load?!?!?!

Posted: Sun Dec 15, 2019 1:06 pm
by Camshaft
Greetings to all, I suffer a similar case, turtle shows up when battery is almost 50% charge under load, car is almost 60,000 miles did electric monitor and inverter temp. 25-45 C (77-110 F) cell temp was 25-35 C (77-95 F) but I did notice a Voltage variation of up to 0.6 of a Volt between the cells, could it be that the issue? are you aware of a way to replace just the weak cells?

All the best for such a great team

Ziad from Amman , Jordan.