Loading after a short drive

[Trescator]

Dear friends.
Is it recommended to charge the battery even after a short drive?
Thinking about using one of 1000 cycles....

 

[Sprinty]

I'm also interested in this, my drive to work is 19 miles, so should I charge even night when I get home or every other night? I'm getting a Rex so don't mind dipping in to the tiny bit of fuel it may require on the second nights drive home.

Also what do you mean 1 of the 1000 cycles?

 

[MikeS]

Handbook p152 states - charge when below 30km otherwise performance of the electric drive will appreciably deteriorate.

 

[agj]

Also what do you mean 1 of the 1000 cycles?

I am not a specialist, but "cycle" means "complete charging". Any battery has a life span of X "cycles" before it starts to deteriorate. Just like any camera has a number of shutter releases before it needs servicing.

A short charging is not computed as a "cycle" but as a "partial cycle" and does not account for the 1000 complete cycles. Hope that was clear :shock:

Maybe someone who REALLY knows can confirm.

 

[Sprinty]

Handbook p52 states - charge when below 30km otherwise performance of the electric drive will appreciably deteriorate.

So charge every other night, not what I would of done!

Hopefully 80 miles on the charge is realistic then so back and forth to work two times then a charge

 

[Sprinty]

Also what do you mean 1 of the 1000 cycles?

I am not a specialist, but "cycle" means "complete charging". Any battery has a life span of X "cycles" before it starts to deteriorate. Just like any camera has a number of shutter releases before it needs servicing.

A short charging is not computed as a "cycle" but as a "partial cycle" and does not account for the 1000 complete cycles. Hope that was clear :shock:

Maybe someone who REALLY knows can confirm.

So if I were to drive it every day for 3 years that would be the battery done? Doesn't tie up with the 100'000 mile warranty does it? Or maybe that was the limit bmw came up with, hope new battery's become available one day!

 

[BrianStanier]

Those of us who have had a Leaf for 3 years at the end of this month see little or no difference in battery degradation whether 20,000 miles (for me) or over 50,000 for a few others. Cycles does not seem to be ant where as significant as time. We all seem to be at about 90% capacity, some of which is just the lower winter temperatures. The i3 chemistry may not be the same, but I would expect similar performance.

 

[ultraturtle]

There is no carved in stone "1,000" cycle limit on the life of a lithium ion battery pack. There is, however, a relationship between depth of discharge (DOD) and charging cycles. From a big picture perspective, regenerative braking alone would use up thousands of charging cycles in a matter of months for a city driver. Consider this graph of cycle life vs depth of discharge for a lithium ion battery used in a different application:

The question of whether to discharge deeply and charge less frequently in order to minimize cycles, or charge at every opportunity in order to minimize depth of discharge becomes more of a wash. All of the data I've been able to gather points to minimizing DOD as the best way to preserve the life of your battery pack, so I charge my EV at every possible opportunity.

BMW's guidance to "charge when below 30km otherwise performance of the electric drive will appreciably deteriorate" may be interpreted incorrectly, causing some confusion. The life of a lithium ion battery pack drops drastically when repeatedly discharged deeply. In my opinion, they do not mean to encourage the owner to discharge below 30km range remaining, but are advising them against doing so unnecessarily.

 

[Alessandro]

There is no carved in stone "1,000" cycle limit on the life of a lithium ion battery pack. There is, however, a relationship between depth of discharge (DOD) and charging cycles

Just curious, but what about after those x cycles of charging ? I mean, is there a linear degradation or a more drastic, i.e. exponential loss ? And on the charging side, will it take more kWh to charge it with aging ?

 

[ultraturtle]

Just curious, but what about after those x cycles of charging ? I mean, is there a linear degradation or a more drastic, i.e. exponential loss ?

I think it was General MacArthur who once said "an old lithium ion battery never dies, it just fades away" There is a growing industry repurposing EV battery packs for stationary power backup and load leveling applications after their capacity has dropped to a level that is no longer practical for motive energy.

And on the charging side, will it take more kWh to charge it with aging ?

As it ages, the battery pack will maintain roughly the same charging efficiency (ratio of kWh out to kWh in). Only the total kWh capacity drops.

 

[RJSATLBA]

It's interesting to see the view that deep discharge is really bad for battery life because Apple's advice for the iPad would lead users to do a deep discharge regularly (Google 'iPad battery care').

Use Your iPad Regularly
For proper reporting of the battery’s state of charge, be sure to go through at least one charge cycle per month (charging the battery to 100% and then completely running it down).

 

[MikeS]

BMW's guidance to "charge when below 30km otherwise performance of the electric drive will appreciably deteriorate" may be interpreted incorrectly, causing some confusion. The life of a lithium ion battery pack drops drastically when repeatedly discharged deeply. In my opinion, they do not mean to encourage the owner to discharge below 30km range remaining, but are advising them against doing so unnecessarily.

I don’t know enough about these batteries to make a specific statement myself. However, I do not consider BMW’s advice in the handbook can be misinterpreted - it states ‘Charge the high-voltage battery when the range is below 30km, otherwise, the performance of the electric drive will appreciable (sic) deteriorate’.

Now it may well be that what BMW has stated is wrong, or like the grammar poorly drafted. However, i think it is clear.

 

[SanSerif]

The entire manual is grammatically and linguistically challenging. It's a rather poor translation and I would take any statement as gospel!

As for the sentence in question, even taken as a good translation, it can be read both ways: "charge ONLY when below 30% or else" or "if it falls below 30% then make sure you charge it".

It would be nice to get to the bottom of it. But, as I'll be using every day and charging every night, it's a bit academic. I imagine the design use *must* be for a similar charge pattern - having to plan a run down to 30% would be very limiting.

 

[fdl1409]

This advice does not refer to the battery life span, but to the power is can deliver. Below 30% SOC, the voltage is low and the performance of the car reduced.

For keeping the battery fresh, it is best to keep the SOC in the medium range between 30 and 80% SOC.

Frank
Germany

 

[Bunter]

below 30 km not 30 % SOC!!!!

 

[MikeS]

This advice does not refer to the battery life span, but to the power is can deliver. Below 30% SOC, the voltage is low and the performance of the car reduced.

Yes, I suspect that is the correct interpretation. The manual provided is poorly presented and poorly translated - the statement being discussed is in the manual under the CHARGING VEHICLE/RANGE section.

I wonder if someone who has a hard copy of the english version of the manual can say what p152 says in this section? Or have they left in the typos and mistakes?

 

[Alessandro]

There is a growing industry repurposing EV battery packs for stationary power backup and load leveling applications after their capacity has dropped to a level that is no longer practical for motive energy.

no longer pratical in a "pure" electric vehicle, yes, but in a serial hybrid (i.e. with REx) is a totally different story, because even those tiny 20 or 30 km of battery range remaining (say, after hundreds of thousands km or miles) make the car still perfectable usable. If it's so - i.e. almost 100% of starting range within those 1000 cycles or more and a slow degradation thereafter - then the vehicle has an almost unlimited life (not that I think this is an important target to achieve). Interesting, anyway !

And on the charging side, will it take more kWh to charge it with aging ?
As it ages, the battery pack will maintain roughly the same charging efficiency (ratio of kWh out to kWh in). Only the total kWh capacity drops.

Are you sure it doesn't increase internal resistance so the kWh need to charge it ?

 

[agj]

The entire manual is grammatically and linguistically challenging. It's a rather poor translation and I would take any statement as gospel!

This is true for all the linguistic versions I've come across (English, Dutch, French, Spanish). It seems that only the German version is accurate, but I can't read German (Scheiße! )

Hence my plea, in another thread, for an objective, interactive and exhaustive knowledge base

 

[Trescator]

I Think its best to let the car be plugged in as often as possible after Reading your answers....
Have anyone heard an approx price for changing batteries?

 

[fdl1409]

Handbook p152 states - charge when below 30km otherwise performance of the electric drive will appreciably deteriorate.


I´ve had a look at my German manual. There it says on page 154:

Bei einer Reichweite unter 30km die Hochvolt-Batterie aufladen, sonst könnte die Leistung des Elektroantriebs spürbar nachlassen.

They definitely talk about horsepower here, not about the life span of the battery. Less SOC means less voltage and subsequently less horsepower.
This will be particularely true in the lower SOC range, because there is a minimum voltage limit to protect the battery against deep discharge, and in order to avoid this power may be cut down.

Frank
Germany
i3 REx in June hopefully