Power to Fully Charge?

[Graham]

Now that Chargevision have told me to disconnect the cable rather then use the key to "end" a charge i am getting realistic timings on the online analysis.

However from Chargevision the last full charge says it used 11.8 kwh, the car, based on cost per Kwh, only 8.8 Kwh. I have read elsewhere that the 12kwh battery can only drop to 20% capacity so can someone explain in simple language which is likely to be correct, Chargevision or the car?

I try and calculate the true MPG by including electricity used, but if the car is underestimating by nearly a third then I may be need to use Chargevision's figures.

 

[maby]

Well, charging is not going to be 100% efficient, so I can believe that putting 8.8 kwh into a battery is going to draw more than 11 kwh from the mains.

 

[user 258]

Hi,
Based upon other car batteries it sounds like (at best) 8.8KWh is the usable amount of the battery and "about" 12KWh seems to be an average amount needed to charge from empty to full. That is quite a bit more than typical charging losses. Until we get more definitive information it sounds like either Mitsubishi get more usable capacity of of the battery than anyone else does or their charging system is especially inefficient.
Kind regards,
Mark

 

[gwatpe]

I use the LiIon [LYP] chemistry battery in my house power system and of a similar capacity and type as the PHEV. I have found that the battery in my house has an efficiency of approx 93% at power levels of around 2kW and approx 96% efficiency at the 1kW level.

Lead acid battery chemistry is close to 88% efficient across a full charge. Bulk charging only is close to 90% and absorb phase drops to around 85%. efficiency is also dependent on the power levels and reduces at increased power levels.

What you have described is efficiency below Lead chemistry. Possible measurement problems somewhere.

 

[jaapv]

The nominal capacity for use is 9.7 KWh.
As the car can drop slightly below 20%, down to 13% as the rock bottom, you may have some more "space".
The car displays are rather inaccurate.

 

[ian4x4]

Most high capacity battery systems, especially Li-ion, need quite a sophisticated cooling system.

This excess heat is your charge / discharge loss. Also they do not charge linearly, so simple measurements are hard to take.

Wiki has a good write up

http://en.wikipedia.org/wiki/Lithium-ion_battery

If you want to get technical try

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

Interestingly it concludes;

Simple Guidelines for Charging Lithium-based Batteries
• A portable device should be turned off while charging. This allows the battery to reach the threshold voltage unhindered and reflects the correct saturation current responsible to terminate the charge. A parasitic load confuses the charger.

• Charge at a moderate temperature. Do not charge below freezing.

• Lithium-ion does not need to be fully charged; a partial charge is better.

• Chargers use different methods for “ready” indication. The light signal may not always indicate a full charge.

• Discontinue using charger and/or battery if the battery gets excessively warm.

• Before prolonged storage, apply some charge to bring the pack to about half charge.

• Over-discharged batteries can be “boosted” to life again. Discard pack if the voltage does not rise to a normal level within a minute while on boost.

 

[jaapv]

The Battery University is basically about small laptop, camera etc. batteries.
Car batteries are constructed to a different level, having cooling, heating, more robust inner constructions and membranes etc.
The car electronics take care of the proper charging cycles, so in total the lifespan is optimized.I expect to get up to 10 years out of the PHEV batteries.
The only thing that will cause them to wear down sooner is frequent fast charging.

 

[maby]

I use the LiIon [LYP] chemistry battery in my house power system and of a similar capacity and type as the PHEV. I have found that the battery in my house has an efficiency of approx 93% at power levels of around 2kW and approx 96% efficiency at the 1kW level.

Lead acid battery chemistry is close to 88% efficient across a full charge. Bulk charging only is close to 90% and absorb phase drops to around 85%. efficiency is also dependent on the power levels and reduces at increased power levels.

What you have described is efficiency below Lead chemistry. Possible measurement problems somewhere.

How are you measuring that? There are two aspects to efficiency here - one is the ratio of the power you push into the battery vs. the power you can draw out of it and the other is the ratio of the power you draw from the mains to the power you can ultimately draw out of the battery. All the components in the overall system are going to waste some power - the battery will warm up both while it is charging and while it is discharging - that represents losses in each case. The charger will also warm up - that is power that is lost before it gets anywhere near the battery. I would assume that any published efficiency figures for rechargeable batteries do not include losses in the charger - the manufacturers of the battery have no way of knowing how efficient the charger that is used with their product will be.

 

[Phever]

The Battery University is basically about small laptop, camera etc. batteries.
Car batteries are constructed to a different level, having cooling, heating, more robust inner constructions and membranes etc.
The car electronics take care of the proper charging cycles, so in total the lifespan is optimized.I expect to get up to 10 years out of the PHEV batteries.
The only thing that will cause them to wear down sooner is frequent fast charging.

by 'fast charging', presumably you mean 50kW chademo charging, not hooking up to the 16/32a chargers like the home chargemaster type?

 

[maby]

The Battery University is basically about small laptop, camera etc. batteries.
Car batteries are constructed to a different level, having cooling, heating, more robust inner constructions and membranes etc.
The car electronics take care of the proper charging cycles, so in total the lifespan is optimized.I expect to get up to 10 years out of the PHEV batteries.
The only thing that will cause them to wear down sooner is frequent fast charging.

by 'fast charging', presumably you mean 50kW chademo charging, not hooking up to the 16/32a chargers like the home chargemaster type?

I'm sure that he does. However, the fact that Mitsubishi warn that frequent use of the Chademo chargers will reduce battery life expectancy probably should be taken into account by those I've seen here speculating about the possibility of an after-market mod to the PHEV to increase the charging rate to 32A. The faster you push current into a battery, the more heat it is going to dissipate - don't try to charge it faster than you actually need.

 

[Phever]

The Battery University is basically about small laptop, camera etc. batteries.
Car batteries are constructed to a different level, having cooling, heating, more robust inner constructions and membranes etc.
The car electronics take care of the proper charging cycles, so in total the lifespan is optimized.I expect to get up to 10 years out of the PHEV batteries.
The only thing that will cause them to wear down sooner is frequent fast charging.

by 'fast charging', presumably you mean 50kW chademo charging, not hooking up to the 16/32a chargers like the home chargemaster type?

I'm sure that he does. However, the fact that Mitsubishi warn that frequent use of the Chademo chargers will reduce battery life expectancy probably should be taken into account by those I've seen here speculating about the possibility of an after-market mod to the PHEV to increase the charging rate to 32A. The faster you push current into a battery, the more heat it is going to dissipate - don't try to charge it faster than you actually need.

in that case, i doubt i'll 'fast charge' more than a dozen times in my ownership. diesel for long trips, leccy for commuting and bumbling round the peak district.

 

[jdsx]

Don't put diesel in it, whatever you do... :lol:

 

[ian4x4]

If you look at the charging characteristics, you will see that the voltage and charge ramp up quite quickly.

It is in the final 20% or so that things need to be taken carefully.

Correct me if I'm wrong, but lifetime of the battery isn't so much about number of charge cycles, but damage caused by maximum voltage and heat stress, caused during this end of charge cycle.

That is why rapid charging only goes to 80% to avoid this.

Mitsubishi are willing to guarantee the battery for 5 years so they must be sure they have controlled the charging correctly.

 

[maby]

If you look at the charging characteristics, you will see that the voltage and charge ramp up quite quickly.

It is in the final 20% or so that things need to be taken carefully.

Correct me if I'm wrong, but lifetime of the battery isn't so much about number of charge cycles, but damage caused by maximum voltage and heat stress, caused during this end of charge cycle.

That is why rapid charging only goes to 80% to avoid this.

Mitsubishi are willing to guarantee the battery for 5 years so they must be sure they have controlled the charging correctly.

It's not so much the initial 5 years as what follows really, isn't it? I haven't seen a price for a replacement battery pack yet, but I seriously doubt that it is going to come in at less than £5k - I would like to keep it running as long as possible!

 

[jaapv]

5k now. But how much in 2020?

 

[greendwarf]

If you look at the charging characteristics, you will see that the voltage and charge ramp up quite quickly.

It is in the final 20% or so that things need to be taken carefully.

Correct me if I'm wrong, but lifetime of the battery isn't so much about number of charge cycles, but damage caused by maximum voltage and heat stress, caused during this end of charge cycle.

That is why rapid charging only goes to 80% to avoid this.

Mitsubishi are willing to guarantee the battery for 5 years so they must be sure they have controlled the charging correctly.

Does that also apply to home trickle charging? If I only do a few miles a day is it better to only part-charge rather than to the max?

 

[greendwarf]

5k now. But how much in 2020?

Depends on demand. I understand that at present all lead acid batteries are recycled into new ones - hence a good scrap value. Assuming the PHEV ones are also recyclable and EV has really taken off then the cost of a new one may well be mitigated by the trade in price for the old one. Of course, worst case scenario is for some new technology (fuel cells?) to make ours obsolete in the next 5 years.

 

[jaapv]

I think it is impossible to predict. Prius batteries have come down dramatically over the last decade and there are third party refurbishers. And who is to say that our cars won't be upgradable to new technology ?

 

[ian4x4]

Li ion batteries differently to most other older batteries, they do not trickle charge and it would be very detrimental to their life.

If you look at the articles on the internet Li ion batteries ramp up (less than hour?) then fill to capacity within the next few hours, then need to be isolated from charger. Overcharging would cause battery stress and possible failure.

You shouldn't need to worry as Mitsubishi will (hopefully) have designed their charging system to do this.

And to answer a previous question, if I was going to guarantee a battery for 5 years, I would design it to last (within it stated loss of capacity) at least 10 years. I would find this financially safer.

 

[greendwarf]

I think it is impossible to predict. Prius batteries have come down dramatically over the last decade and there are third party refurbishers. And who is to say that our cars won't be upgradable to new technology ?

Going off topic, this is an interesting site https://www.plughybrid.de/ Would give the PHEV the option of extended range for a loss of cargo capacity (although there is that rather useless area under the rear floor) The ability to be able to unplug and take it out of the car when you wanted would be even better. I presume we will have to wait for its US launch before somebody designs a PHEV specific version.

Have any present or past Prius users experience of these or similar?