this has nothing to do with it being a hybrid. Its in all cars jump start instructions. I guess the theory is that any surges might be dampened by the inductance of the heater fan motors.

 

"5. Turn the heater fan on in both vehicles to protect from any electrical
surges. Turn all other accessories off."

Thanks. I found this is the owners guide. Can't believe I've never seen this there before.

 

...wasn't ignoring you.

I was waiting for Ford to explain in detail so that I didn't enter a misleading post.

Happy to see you found the info in your manual.

Cheers,

PB
www.HybridHazards.info
Hybrid Vehicle Jump Start Towing & High Voltage Shut Down Guides

 

2006 Ford escape hybrid does not start. Scangauge II data are as follows:
- Low voltage battary = 12.5V
- Traction Battery State-of-Charge SOC = 0%
- Traction Battery Voltage TBV = 331V
It looks like HV battery died since SOC=0%. But normal Traction Battery Voltage causes me to confuse.

I tried to jump start and no success.

Any thoughts?

 

If the 12v battery does not enough juice in it to pull in the high voltage relay, the traction battery can't start the engine.

First do a charge on the 12v Battery. 12.5 volts is a bit low although I'd have thought it was enough.

I had the OEM battery short a cell after 8 years service (not bad by the way) and it was at 10.5 volts and wouldn't close the relay. So no start. Put a charger on it for a few minutes and it started.

BTW 331V should be plenty of juice.

 

Regarding protection on surges: the battery will absorb surges just fine. I've never heard, nor used, that step of running the heater fan when jump starting a car.

 

I think the issue is voltage spikes which could damage the electronics. It is indeed in the manual.

 

If you're trying to equate it to an RF choke... motor windings are not set up correctly to stop spikes. They're wired wrong to act that way. You'd need a winding in series or a capacitor in parallel.

On the other hand, if you understand how batteries and the chemistry involved works... they do just fine absorbing transient spikes.

Still never done that when jumping one car from another over many years.

 

I'd like to reiterate the point about the high voltage relay. If the 12V battery doesn't have enough juice to pull the relay in, your car won't start.

When my OEM battery had a cell fail (@ 8 years) the system voltage was about 10.5 or 11 volts. I'd have thought the relay would pull in with that remaining voltage. But it wouldn't. (BTW 10.5 volts on a 12Volt battery is indicative of a single cell shorting out.)

I put a battery charger on the 12v battery and in a few minutes it would pull in the relay and started just fine. Try this first, as the 331Volts on the Traction Battery implies to me that the Traction Battery is just fine.

 

Just a quick note on my 2009 E.H.

I was confused on which way the self-jump start feature works. I thought it was to jump the 12V from the HV battery, but the manual said it goes the other way.

I just hooked a good DVM to a weak 12V battery and pushed the button the 12V battery voltage dropped from 10.03V to 9.8?V so it takes power from the 12V battery to charge the HV one.

Carry jumper cables.