HVB Life Span

[Vlad Soare]

Hello,

 

Ford claims the HVB does not require any maintenance and will last for the entire lifetime of the vehicle. OK, fine. But what exactly does that mean? Five years? Eight years? Ten years? Properly maintained cars can live for decades, and I'm sure no battery in the world will last that long.

In Europe the hybrid is pretty new; we can only take the manufacturer's word for it. But in the US Ford has been selling hybrids for quite some time now, so we should be able to get some real life data already.

What's the oldest hybrid Fusion you know of, which still has the original HV battery? Has any of you had his or her Fusion long enough to need to replace the HV battery?

How do you know when it's time to replace it? What are the symptoms?

 

Thank you.

 

[murphy]

If the HVB was totally dead you would not be able to start the engine. The engine does not have a starter motor or an alternator for that matter. The engine is started by one of the high voltage motors.

[lolder]

Ford has been selling Escape hybrids since the 2004 model. You could look at one of those forums but I know some have been used as taxis and have gone 400 k miles. The HVBs appear to last longer than the engines. A US Dept. of Energy unit showed the 2010 FFH HVB lost 8% of it's capacity after 160 k miles. The loss of capacity with a hybrid HVB is unimportant so long as it doesn't fail. Failures have been rare. Early Prii had 60% capacity losses with no effect on normal car performance.

In short, it is not an issue. Aftermarket HVB re-conditioners have had little business.

[Vlad Soare]

Thanks, that's reassuring.

I do wonder, though, whether time might have a more damaging effect than the number of miles.

[murphy]

Thanks, that's reassuring.

I do wonder, though, whether time might have a more damaging effect than the number of miles.

My Energi has a build date of April 1, 2013. I got it on April 15, 2013. I use it for local driving. It has made two trips to a destination that is 270 miles away. It just rolled over 8000 miles. The battery charged to 25 miles after a 23.9 mile trip yesterday. Battery degradation is usually correlated with the number of charge/discharge cycles. If you are a long trip, more than 25 miles, driver then there will be a lot of miles with few charge cycles. With my short trip driving there is a charge cycle for each trip.

[lolder]

Depth of discharge, charge/discharge cycles, temperature, and time all affect battery life. One of the most important is to never let the battery go dead.

[murphy]

Depth of discharge, charge/discharge cycles, temperature, and time all affect battery life. One of the most important is to never let the battery go dead.

It is not possible for an Energi battery to go dead. There is only one battery. 1.5 kWh? at the low end is dedicated to hybrid operation. When the EV portion of the battery reads 0 miles the full hybrid portion is still available. In hybrid mode the computer tries to keep the hybrid portion at 50%, the same as the regular hybrid. If it gets below the 50% point, by whatever the programmed amount is, the ICE will start to charge it until it is above 50%. If the entire battery went dead the car would be unusable because the high voltage battery is used to start the ICE. An Energi would be recoverable by the user since it can be plugged in to charge the battery. A hybrid would have to be towed to a dealer since there is no user available method to charge the battery once it is too low to start the ICE. The computer will prevent that from ever happening.

[Vlad Soare]

The computer will prevent it as far as possible, provided the car is driven regularly. I suppose you can end up with a dead battery if you leave the car unused for too long a time. How long? I don't know. Ford say one month, but I suspect they're just being cautious. A modern lithium battery pack should stand more than that.

[murphy]

When the car is off the HVB is completely disconnected from the car. It should maintain a charge for a very long time.

The one month number is for the 12 volt battery. Mine would never last that long. If the car is going to sit for a week I connect a battery tender to it.

[Vlad Soare]

Indeed, I looked in the owner's manual again, and I think you're right. When I first read it it seemed to me they were talking about the HVB, but now I realize I had got it wrong. The manual states that if the vehicle remains unused for more than 31 days you may need to jumpstart it. So, it must be about the 12-volt battery, because jumpstarting a car with a dead HVB would be impossible at home. :doh:

[Waldo]

Ford is very, very conservative when it comes to battery management. They have put double and triple protections in the systems to make sure the batteries last "the life of the car". Bottom line is don't even think about battery life as part of the total ownership experience. There's really nothing to worry about.

[FUSION665TANK]

let me see if I have this straight. Health of battery equals the capacity to hold charge. ex. , brand new battery is able to charge back to 100% capacity. Over time the health of battery will degrade causing it to only hold 95% of 100%...85% of 100%. So, at some point your fuel mileage will drop because the EV motor will drain the battery quicker causing less miles to be gained due to health degradation of batteries overall capacity to hold charge. So, in a Fusion hybrid, someone who drives 200 miles a day would see a quicker degradation than someone who drives 50 miles a day...????

Edited October 20, 2017 by FUSION665TANK

[mwr]

let me see if I have this straight. Health of battery equals the capacity to hold charge. ex. , brand new battery is able to charge back to 100% capacity. Over time the health of battery will degrade causing it to only hold 95% of 100%...85% of 100%. So, at some point your fuel mileage will drop because the EV motor will drain the battery quicker causing less miles to be gained due to health degradation of batteries overall capacity to hold charge. So, in a Fusion hybrid, someone who drives 200 miles a day would see a quicker degradation than someone who drives 50 miles a day...????

I don't now that that less battery capacity would result in less MPG, at least during the normal life of the car.

[lolder]

The HVB degradation in a non-plug-in hybrid does not affect it's mileage. It would only affect the one minute full throttle speed. Some years ago, a US DOE agency did tests on a first generation 2002 Prius that only had 40% capacity left and the mpg was unaffected: avt.inel.gov/pdf/hev/end_of_life_test_1.pdf

It is only important that the HVB does not fail open-circuit. Then the car coasts to the side of the road as the ICE cannot move the car without an HVB. Open-circuit failures are almost un-heard of.

Edited October 20, 2017 by lolder

[billford]

Would not worry about high voltage batteries. Friend works at a dealer and has never replaced one yet due to failure. Although there was a recall on the Escape hybrid batteries that had an internal jumper harness replacement. That battery is completely different from the Fusion/Cmax.

 

Not related, but around here, there are fleets of Prius taxis. The only reason they change high voltage batteries is due to vehicle collisions. The cars will wear out before the batteries.

[FUSION665TANK]

That was one of my concerns with hybrids and high mileage. I just bought the FFH in August and now have 11297 miles already. I average 200 miles a day just for work then you tack on personal use. I can easily push 1500 miles a week up to 2000 miles. On occasions I have driven 520 for work in one day(rare).

 

So, being an I.T. Field engineer I see day in and out the issues with lithium -ion batteries. Especially their degradation of their Health and recharge back to 100% capacity.

[billford]

They are neither fully charged or discharged.

I use a scangauge and monitor the high voltage battery. It stays between about 38% (engine turns on) on the low side to about 65% (regen braking stops) on the high side. This keeps the battery in the midrange for long life. Normally stays in the low to mid 40% range

Don't have to worry about overcharge.

[mwr]

They are neither fully charged or discharged.

I use a scangauge and monitor the high voltage battery. It stays between about 38% (engine turns on) on the low side to about 65% (regen braking stops) on the high side. This keeps the battery in the midrange for long life. Normally stays in the low to mid 40% range

Don't have to worry about overcharge.

Do you mean that when the car's vertical state-of-charge indicator shows full (green all the way to the top), that the actual charge is only about 65%?

[billford]

Do you mean that when the car's vertical state-of-charge indicator shows full (green all the way to the top), that the actual charge is only about 65%?

 

Yes

[murphy]

It has been stated many times that the battery was designed to last for the life of the car. It can never go anywhere near actual 0 since that would mean there is no way to start the engine. There is no traditional starter motor. The engine is started by one of the high voltage motors.