I have had a 2007 Escape Hybrid since Sept 2006 - great vehicle by the way. I do think I am having a battery problem and would appreciate some techie help. Here are some symptoms. After the truck has been left unused for 4 or 5 days it now struggles to start. The scan gauge shows around 9 volts not 12. Once I had to jump it when the scan gauge read about 8.5 volts. When the Escape is up and running the voltage is a bit over 13. When you turn it off, the voltage drops to the normal 12.

Is this simply a dying 12 volt battery? If so, does one go to the local parts store and pick up an Escape compliant battery? Could it be something more sinister sucking the juice out of the battery?

 

If this was a conventional engine, I'd ask you if your battery terminals were dirty and suggest you clean them. A corroded battery connection tells the alternator that the battery is charged and doesn't try.

 

If you live in SW where it is hot, battery dont last long. i have had them die in less than 18 months. I would check terminals like was suggested and if they look good then try a auto parts that checks battery's.

 

You have to do something like this with a multimeter and



pull fuses

and see if the voltage changes in the multimeter display in an attempt to find a "drain". Something is draining your system. Try this and report back. I have more information later this week.

 

Struggles to start? you mean has trouble rolling over?

The 12V battery isn't used to roll the engine over at all. Its only used to energize the relays that isolate the HV battery from the system. If there is enough juice to close the relays it would start without any problem.

 

It is my understanding that the 12 volt battery is being charged, as needed, from the hybrid battery with a voltage down-converter anytime "drive" is enabled. The 12 volt battery is an "integral" part of the system start-up in that a low 12 volt reading will undoubtedly have an adverse effect on "starting" (definition intentionally left open).

 

I'm pretty sure the 12v does not crank the ICE directly as there is no conventional starter.

It is my understanding that all the 12v battery does is power the accessories, computer, safety systems (ABS pump for example) and high voltage relays when the system is not in "Run" mode.

I know that if I use my 12v air pump while the key is in the off position, it's rather slow. As soon as I turn the switch to position 1 (not the "crank"/go position), I hear the relays click and the pump goes into overdrive. This is before the ICE even turns on for it's warm-up.

Once the 12v is used to close the 330v relays, the system is powered by the HV battery and the only current going to the 12v should be to charge it. The HV battery is used to spin the ICE and power the wheels during the warm-up routine (unless more torque is requested than the battery/EV motors alone can handle and then the warm-up routine is ditched for a more ICE powered scenario).

 

While the system is on the HV battery or the generator is providing high voltage power to the system. There is a stepdown converter for the 12V system to power accessories when the car is running.

Starting the car causes the 12V batteries to close isolating relays on the battery (a safety feature). After that, the 12V battery is only for the accessories again. The power to roll the engine over is entirely provided by the HV battery which sends some of its 330V and current to the traction motor/generator (I forget which one is used to roll the engine over) to start the engine. You'll hear no cranking... there is no starter motor, the traction motor or the generator is used to roll the engine to start and because it has so much more power than a standard starter the "start" is accomplished in less than a second. The engine just comes on.

There is some confusion on a "jump start" procedure using the 12V battery. You can jump start from a 12V if you have a low HV battery... however what is done (look at the manual to make sure I dont get this wrong) is if your 12V is high enough there is a button on the driver side near your left leg under the dash. You hit it and wait 8 minutes.... during that time the 12V battery is upconverted electrically to 330V (or close to that) charging the HV battery from the 12V battery. When you start the vehicle the newly recharged HV battery starts the car. It can't start DIRECTLY from the 12V system. If your 12V is dead TOO... I believe you can hook up jumper cables to another 12V battery (presumably in a conventional car) and then press the button... wait 8 min... and follow the same steps.

We have no alternator and no starter motor. We have two generator/motor units. both can provide power to the wheels or recharge the HV battery... current in that HV system is used to recharge the 12V system.

If your 12V is dropping to 9V or less either the battery is bad, the stepdown system is bad, OR you've got some sort of short or something in your 12V system that is draining that battery.... do you have trailer wiring? If so I'd check those connections just to see if its something easy.

 

I have a "drain" on my system. I have had the engine compartment battery voltage as low as 8.3! And yes, the engine will not start with the engine compartment battery this low. I had to put the battery charger on this battery and boost up the voltage so it would start. I took the vehicle into my local dealer this August (2008) and they kept it overnight and I received a $200 bill for labor. The dealer could not determine what was wrong but pointed their fingers at their fingers my aftermarket Kenwood DNX7100 soundsystem. I then took the vehicle to the local audio-shop who were kind enough to recheck everything and keep it in the shop for several hours for no charge. The headunit was not causing the problem. I found out last week, my engine block heater is not working. I have an appointment this week. Will have to see what is wrong. I hook up a trickle charger to my 12V battery and plug it in when I arrive home after work.

 

12 volt Lead Acid battery lifespans vary greatly, and generally, they need to be changed every 3 to 7 years. 7 years in a car being exceptional.

Lots of rough roads, heat, cold, and a just a couple "ops" such as leaving the lights or radio on all day ( or night ) all can shorten the life to less than 3 years. This is a "consumable" product like the motor oil, and may just need to be changed more often than you'd like.

My original battery ( since Dec. 2004 ) is in my car, and I have approx. 69,000 miles on it. If I park for a week more more, the 12v battery is 11.5 volts.

A fresh, new battery is usually 12.6 to 12.8 volts just sitting there.
So mine is starting to show wear, but that's normal.
HTH,
-John