Hi,
I purchased 2007 Ford Escape Hybrid in late August from Sacramento City auction with almost 150K on the odometer. I need a car in my last college year but have tight budget. Seems to be well maintained- body in good shape and recently changed brakes. First two months worked fine, then battery fans needed replacement. Replaced them myself using video instructions from youtube. Recently it developed a intermittent starting problem. So I'm looking for guidance or help from the community to figure out what needs to be fixed. I guess something is about to die and I'm trying to figure out what it can be. Since it's intermittent - it's difficult to troubleshoot and shops wanted hefty fee for the diagnostic.
Problem description:
Sometimes in the morning it would start, run for 2-3 seconds and then stall. Recycling a key solved the problem. First time it happened a week ago on a bit colder night (no freezing - just below 45F). Once started - engine worked well for next two days. Then again in the morning - same start and stall. Recycling key first time did not help. But second time did.
Two trouble codes popped up P0A1F-20 and P0A7D-20. But battery itself was fine. After start-up car drives as usual using electric mode.
Next morning I've connected Forscan and cuptured some waveform. Some video suggested it might be fuel pump and I do see a bit unusual fuel pressure change on the "failed" start. But not sure is it bad enough to cause the problem. Also MAF is a bit lower and LONGTRIM is quite 8.95 and steady when "failed" start. Any suggestions - what to look at? Any other parameters to capture in order to get a hint? (See pictures below. Also have zip file with Forscan live streaming log files for these in attachment

First recorded FAILED start

Good start after cycling the key (first)

Second recorded FAILED start

Good start after cycling the key (second)

Third recorded FAILED start

After recycling FAILED again

Second key recycling - good start. Pressed acceleration pedal a bit during the start

One more key recycle - good start.
.

 

PRIOR to start, key on, engine off, open the BCM, list items in Table tab and provide a screenshot of the values.

 

Here are the screenshots. It took a while to grab and save the pictures (5-10minutes with key ON, engine OFF). After capturing these I tried starting the engine and it was without any problem.


BCM parameters - first half

BCM parameters - second half

 

You can omit the "No Fault" parameters, and readability is improved if you use the table tab as I suggested.

DEL_MOD_V of 0.56 = failing battery pack. Hence why the only codes you're getting are from the BCM.

A healthy back is typically < 0.19 and more often fluctuates between 0.05 and 0.16.

What this means is that the ~25 or so places the battery is monitored, the difference between the highest and lowest value is 0.56V. This is pretty bad, especially since the battery is at a reasonably high voltage with zero current in or out. If this was under a heavy load or charge or at a very low voltage/SoC, then it would be less of a concern, but this is essentially a guarantee that your HV battery is failing. If it had been sitting for months, and you had just resurrected the battery with the HV jump starter, then it wouldn't be an automatic flag, but since this is a daily or near daily driver, it shouldn't be this high.

It's likely because ONE cell out of 250 is about 0.3-0.4V below the others. When a 1.2V cell is 0.4V, it's dang near dead.

Recommend you run the BCM RMODE_BALANCE function in the Service functions.

Recommend you start recording this value, BSoC, V_pack and TRAK_M_AMP.

 

Thank you for guidance. Last two days there were no faults during the start, but I recorded suggested values on the start-up.
Sorry for keeping unnecessary parameters on the screen. I do not which one are important or not so.
Regarding voltage difference. You mentioned that voltage is monitored in 25 places. So if we divide 330V by 25 - it gives 13.2V per battery. Having 0.38V difference on 13.2V is not that great but should not be so bad unless in that battery (10 cells) only one is the guilty one. I do not know what failure mechanism is - is it single battery fails or in the battery pack few or all batteries are generating lower voltages.

I also can't find BCM RMODE_BALANCE function in my FORSCAN 2.2.8. I have only one test for BCM - and it only turns on FANs inside of the battery.
Also I've noticed tha TRAC_M_AMP is negative when motor is not working and Key is only ON. But is fluctuating from -10A to +2A when engine is working. So I guess it's OK.

BCM parameters when engine is working(battery is charging)


BCM parameters before engine start

BCM parameters during startup

 

More like 24 of the voltages are the same, and ONE of them is 0.4V lower AND it's all in one CELL.

All 250 cells are in series. If one fails, the battery is done.

Other parameters of concern are the charge discharge limits. I don't remember the exact numbers, but the maximums are above 20,000. When these are below the maximums, the BCM is limiting charge/discharge in response to some control parameter. Most common are the battery temperature and SoC during normal operation. The fact that these are less than their maximum limit with no other obvious cause is a concern:



Given that the delta value never drops to the typical <0.2V range, all signs point to failing cell in the battery.

IIRC, the R_MODE_BALANCE ( or similarly named) function is on the wrench tab.

 

Ok. Thanks for the explanations.
I'll try to capture battery parameters during the failure just to proof that battery is the one to blame. Will also try to find used battery for a replacement.
Last two days car started without any issue so I guess I might be able to drive for a few days (unless it's temperature sensitive, because colder nights are coming).

 

Were you able to find the RMODE function?

 

Yes. I've updated Forscan to latest version and found it.
Performed calibration but voltage difference still 0.31-0.38V (with Trac_M_AMP ~ -1A)
Engine started without an issue today as well. Will keep an eye on it for next few days.

 

If you have more time than money, you might try to recover your pack with a charge to TRUE full.

https://electricvehicleforums.com/fo...ry-jump-31056/

The above describes a means of using a cheap LED driver to charge your battery to full. It was intended for 2009+ that don't have the jump starter, but the jump starter won't work for a full charge. You would need to provide cooling with a box fan laying on the open pack blowing into it for the entire charge period.

You would need to charge it for the sooner of 25 hours or until you feel ~100°F air below the cells. If doing this in extreme cold, it might take longer.

In some cases, a full charge like that may restore cell balance and improve performance; however, even if it works, it's likely something you have to continue doing periodically.