Battery Longevity

[Volleyguy]

We have the 120v charger that came with the Fusion. We are looking at a 240v charger. I know it is much faster the question I have always wondered is which is "better" in terms of the battery lasting?

[larryh]

The following paper "http://electricvehiclewiki.com/images/b/b0/Capacityfade_jpspaper2.pdf" details a study in which they try to determine the optimal charge rate for a lithium-ion cell which minimizes capacity degradation.  They determined the optimal charge rate to be 0.5C, where C is the cell capacity in Ah.  The capacity of the HVB is about 23.5 Ah.  The 120 V charger charges at a rate of about 3.28 amps or 3.28/23.5 = 0.14C.  The 240 charger charges at a rate of about 10 amps or 10/23.5 = 0.4C.  According to the paper, the 240 V charger is better.  But I'm not sure how applicable that paper really is to the Energi's HVB.

 

The 240 V Charger will generate more heat, but for a shorter period of time.  The 120 V charger generates less heat, but over a longer period of time.  Neither one heats up the HVB much, maybe at most 4 F.

 

I think the other factors that affect battery degradation will overwhelm any difference you could observe between the 120 V and 240 V chargers.  I doubt that it makes much difference which one you use. 

 

I would base my decision on whether to use the 240 V charger on other factors such as the ability to precondition the car in cold weather, faster charging times, etc. 

Edited September 6, 2014 at 08:53 PM by larryh

[Volleyguy]

Thanks Larry!

 

Yes I know all the benefits of 240v but always wondered which was strictly better for the battery. Also what was too fast for optimum life.

 

I hear our batteries are $9,000 currently so life is a BIG concern! I assume this will come down much in price?

[larryh]

According to the paper, capacity was reduced after 800 charge/discharge cycles by 17.1% for 0.25C charging (120 V charger) and by 15.4% for 0.5C charging (240 V charger).   See this post for factors that have a much greater affect on HVB capacity:

 

http://www.fordfusionenergiforum.com/topic/2491-charging-the-high-voltage-battery-in-energi/?p=16005

[shaggy314]

Also keep in mind the 240 is more EFFICIENT at charging than the 110, so you are also saving electricity when you do so.

 

I've had mine for about 1.25 years and am approaching that number on a mixed number of each kind. I live 20 miles from work, so each workday I do 2 full discharges... You'd think Ford would want a nice look at my battery info. Nearly 19k miles and 90%+ of it on EV. Counting the dealer tank, I've gassed up 7 times so far... Fuelly.com doesn't like that I got OVER 4,000 on one tank.  :happy feet:

Edited September 7, 2014 at 04:23 PM by shaggy314

[Volleyguy]

Shaggy yes of course on the less heat loss on 240v. We are getting 240v but when charging at night why do it in 2 if 6 is easier on the battery we are sleeping anyway.

 

The battery though is far more important long term cost than electricity. I have yet to read all the paper posted here from Larry but did I not see 800 charges you should see some effect? I assume you are not seeing affect?

[murphy]

Ford designed the battery to last the life of the car.  The computer will protect the battery.  They do not expect the battery to ever be changed.

 

It's more than heat loss.  The battery is over 300 volts DC.  Generating that much voltage from a 120 volt AC source is very inefficient.  240 volts AC times the square root of 2 is higher (339 volts) than the battery voltage so developing the charge voltage is more efficient.

[Volleyguy]

So Murphy you are saying 240v is easier on the battery? We are going to have both but when the car is down for the night 2 hours or 6 is no big deal a little electricity loss is not really a big deal the $9k battery is a big deal "if" one or the other 120 or 240 was easier.

 

I know in talking to Tesla they do not recommend SC all the time and to use the easier 240v. What is the easiest on our MUCH smaller batteries? By the way I have not seen any huge increase in electricity use beyond the stated use on the car energy use gauge. i.e. I am not noticing a huge heat loss? Are you?

[murphy]

Yes.  I have a power meter in the feed line to the charger.  The power used to charge the battery is always more than the car reports to MFM. 

 

For example:

 

outbound trip 10.7 miles, 2.2 kWh used, 164 MPGe

inbound trip 10.4 miles, 2.3 kWh used, 153 MPGe

The battery was not empty but I used 4.5 kWh for the trip.

 

power to recharge the battery was 5.46 kWh.

 

Interesting statistic:  In 16.75 months I have put 1031 kWh into the car.

[shaggy314]

You can always us delayed charging and start at 4 AM... I might start doing that too if it is better to have the car sit overnight on an 'empty' battery than a 'full' one.

[Hybridbear]

You can always us delayed charging and start at 4 AM... I might start doing that too if it is better to have the car sit overnight on an 'empty' battery than a 'full' one.

It is generally believed that it is better to have the HVB at a full charge as little as possible. However, the impact of this behavior over the life of the HVB is unknown since 100% on MFM isn't really 100% of the HVB capacity.

[Volleyguy]

We just got the 240v charger and will have installed this week so delay until use seems the consensus for battery life. (on overnight charge)

[meyersnole]

Fuelly.com doesn't like that I got OVER 4,000 on one tank.  :happy feet:

 

I have read your post before, but just really read it this time. Wow! That is impressive.

 

My first tank I got just over 2,500 miles in 126 days before filling up. (Probably because I was challenging myself to see how far I could take it). So no trips to FL etc.

 

I have been traveling a lot more lately, so I am usually in the 900-1,200 mile range per tank... basically I get gas when I go on a trip.

 

Back to topic: I thought the battery never really fully charged (Murphy's post about computer protecting the batter) so there is no need to jump through hoops to time your charge.

 

On the cost of batteries, as long as these vehicles continue to get more popular and the resources do not become constrained I would think that the prices would continue to decline. We are protected from significant loss by the 8 year (or longer in some states) warranty. These same concerns were around back with the original Prius. Battery technology has come a long way since then. If resources are constrained than I would think alternate solutions would be researched given current growth trends.

 

If I keep this car long enough to get a battery replacement ( I doubt it, only planning 7-8 years ) then I expect I will have either a smaller battery or significantly more range as an option. Further, I do not expect it to cost $9K. Ford really has no incentive to reduce the prices yet as the insurance companies are paying them before they come out of warranty. (IMHO) 

[Volleyguy]

We just had the 240v charger installed and that is much nicer/faster!

[Dan's Energi]

I hear our batteries are $9,000 currently so life is a BIG concern! I assume this will come down much in price?

That will come down soon I'm sure.  The Leaf, which uses a MUCH larger battery, has already cut it's price - a new one will be available for $5,499!!! Granted, that's a passively cooled battery, but has ~4x the capacity.

 

Also keep in mind the 240 is more EFFICIENT at charging than the 110, so you are also saving electricity when you do so.

 

I've had mine for about 1.25 years and am approaching that number on a mixed number of each kind. I live 20 miles from work, so each workday I do 2 full discharges... You'd think Ford would want a nice look at my battery info. Nearly 19k miles and 90%+ of it on EV. Counting the dealer tank, I've gassed up 7 times so far... Fuelly.com doesn't like that I got OVER 4,000 on one tank.   :happy feet:

Are you sure that Ford isn't taking a look at your battery info?  The other manufacturers can do it through the cellular antenna (anonymously?).  Can't Ford?

 

I have read your post before, but just really read it this time. Wow! That is impressive.

 

My first tank I got just over 2,500 miles in 126 days before filling up. (Probably because I was challenging myself to see how far I could take it). So no trips to FL etc.

 

I have been traveling a lot more lately, so I am usually in the 900-1,200 mile range per tank... basically I get gas when I go on a trip. 

Our Volt has been filled up around 10-12 times and has about 36K (and a smaller gas tank too)!  We've only filled it once this year and we drive it about 40 miles/day 6/week IIRC!  City EV's are easy to keep EV.  We're not going to be able to go nearly as far with the FFE because of it's shorter range but it's worth it.

Edited September 17, 2014 at 02:43 PM by Dan's Energi