Does anyone know what the Battery push button switch is for? I found it when I removed what looked like a fuse panel cover on the drivers side of the vehicle under the hood lever.

Thanks

 

It is to put a jump-start charge into the HV battery from your 12V battery. In other words if your HV battery somehow is discharged to a point it can't start the engine, you can use the low voltage 12V battery to put enough charge in the HV battery to start the engine. If your 12V battery is low also, you can jump charge that like a normal jump start with another vehicle. This push button jump start was eliminated in the '09 FEH.

GaryG

 

OK, I have to ask. What happens with the 2009 and later if the HV battery goes down? Is there some other provision?

 

Don't know for sure Steve. I know the Battery Control Module (TBCM) is powered by the 12V system Key-On or Off. The only thing I can think of is the TBCM is programmed to prevent the SoC from dropping below 32% which is more than enough to start the engine. This could be an updated fail-safe system that would protect the battery even more than the old system that the battery could drain below 32% under certain conditions.

Example: When I ran out of gas in my '05 FEH, I drained the battery at speeds of 40mph till I found a place to add gas. The battery still had enough SoC to restart the engine but I know it was way below 32%. In my '09 FEH, the speed is limited to about 20mph when I run out of gas and as I get near 32% SoC the speeds drops. I made it to a gas pump at 32% SoC and my '09 FEH would go no further in EV. Filled the tank and the engine started normally.

My guess is that if the SoC in the newer FEH gets to a point it can't start the engine, the battery needs to be replaced. It could also be, the 12V jump is automatic now when the HV battery SoC is to low. This would allow another vehicle or jump start pack to assist if the 12V battery is low also.

According to the '09 manuals, there are new permanent P-code DTCs and clearing conditions that can't be cleared by a scan tool. The TBCM will now set one of these codes with a very low SoC.

GaryG

 

Gary-
The issue I see is if the FEH is left idle for a long time, which could allow the battery to drain below 32 SOC, especially if SOC was low when the vehicle was parked. It seems to me that the pre-2009 system is better in that it allows the traction battery to get enough charge for the system to start up again. Of course, it may be some kind of battery chemistry change would have problems with such a "cold charge start", although I think you mentioned that with the 2010, not the 2009.

Does the 2009 FEH owner manual have any warnings about long term parking?

 

When I first learned the '09 FEH had eliminate the manual HV battery Jump Start, I had a concern. Not anymore because I think the system is automatic now. The '09 FEH drains the 12V battery much faster than older models while sitting because it has more electronics. As soon as I turn the key to the On position, my HV battery and D/C/ to DC/DC converter recharge the 12V battery in seconds dropping the SoC fast. Every day the '09 sits without starting, I see this drop get bigger and bigger each day sitting.

The '09 FEH manual states you may need to jump start the 12V battery after 31 days of being parked. There is no mention of the HV battery jump start anymore. This is why I think the new system is automatic if the HV battery has a low SoC.

In addition, one problem of the older FEH was removing the 12V battery cables before modules could be shutdown by the PCM. This allowed the HV battery to continue to drain below 32% SoC even with the key OFF. The Power Sustain Relay was deleted in the '09 FEH and the computer was modified with a new control shutdown feature.

GaryG

 

Or perhaps they knew that (because the 12v is used for so many electronics), that the 12v would not be able to charge the traction battery.

Any way, thanks for the discussion.

 

I killed my 12 battery trying to ripp music to the Nav HDD. Killed it sooo bad i had to "jump it" so the relays would let the BIG battery start it. I wount be making that misstake again. So to me, sounds like the 12v batt will die but not the BIGN~! in my '09 that is....

 

We recently had to replace the 12v battery in our 09 (after only 1 1/2 years but let's not go there.) The wife said that both in the morning and the afternoon, when she would turn the key to start, nothing would happen. She left the key on for a minute or so, then the truck would start up.

 

I have a 2009 ford escape hybrid
I can not find this jump start button for it. Removed everything cosmetic on driver side and no button to press
Help