Electric battery degradation

What's Up? What's Up?

 

where's the o/p md?

 

MIA?

 

it would seem.

 

That is incorrect. Plugging in DOES charge your AUX battery. It's as if you are in READY mode. I have verified it with a voltage meter and you can tell by watching the dome lights get brighter when you plug in.

 

Quick, send a memo to my dealer, because he's convinced it doesn't (and so am I).

My car sat in their showroom for many months, and it was plugged-in the entire time. The aux battery went dead many times, because of customers opening doors and having things demonstrated. When I looked at it, the aux battery was flat, and they had to call a technician up to boost the battery. He told us that this was "always happening" because everyone assumed that plugging in the car would charge the battery. It certainly does not (although it would be great if it did).

 

maybe they forgot to plug the other end into the wall.

 

The charging light was on. It's possible that something changed in the design since I purchased mine, but in my case, no.

 

It only charges the AUX battery when it's charging. When it's done charging, it's no longer providing any power/charge to car so, in the AUX battery will drain even if it's plugged in.

On a side note, I have used the charging power of my 12v battery to charge an 8000mah lipo battery at 8amps. There is no way that little 12v battery would have been able to complete that charge without help from the external power source.

 

that makes sense. if the car is sitting in the showroom plugged in, it's not gonna charge much, and the interior lites are probably on a lot.

 

I would think the more relevant thing to measure if battery degradation is suspected is the amount of energy required to charge from empty to full. There are lots of things that can affect how efficiently the energy in the battery is used, but battery degradation would imply to me that the storage capacity of the battery is declining over time. If the battery still takes about the same amount of energy in kWh to charge, that would seem to imply that's its capacity is still about the same. Although there will likely be some variation from charge to charge (perhaps more so at different temperatures) a 25% decrease in range should be very easy to see if it was truly caused by loss of capacity I would think?

FWIW I believe the lifetime/degradation of li-ion batteries in consumer devices is not a good analog for EV batteries. They are often using the cheapest cells possible, and even when using decent cells they tend to skimp on the charging / balancing / monitoring electronics which puts much more stress on the cells. They are also often compelled by capacity per weight / volume requirements to use a very large portion of the SOC range, which also hastens their demise.

Rob

 

Sorry to bring back to life a dead thread, I was out of PC for a while.
What you said regarding Leaf battery is interesting and coincides with what we know here in Israel on the Renault Fluence ZE developed for (now dead) Better Place.
Both use same battery and auxiliaries, which to me it is a design for battery swap strategy that may have been picked-up by Nissan in a harry for the early Leaf .
Better Place's business plan was that the short expected battery life can be factored-in to the lease price of the battery since in Israel (and Denmark, I suppose) to drive an EV mile costs 1/6 of the cost of ICE mile of an average modern ICE car (and that's with today's gas prices!) due to very heavy taxation on gasoline. Plus the fact that the battery-swap stations had the equipment needed for cell balancing etc.
Now that Better Place gone and battery swap stations closed, the poor Fluence ZE owners (about 1000) suffer from accelerated battery degradation, claim that Renault is 'walking away from the product' and are developing a 'summer anxiety'.

Not good at all for plug-ins reputation and market development in Israel

 

What other plugin cars are available in Israel now or in the near future?

 

Right now only Leaf, Prius PHV and Mitsubishi Outlander PHEV. Others are hesitating to jump in.

 

There is a way to extend your range close to its original amount, it's called REBOOTING, that is: disconnecting your 12 Volt battery cable for a few seconds and then reconnecting it. The negative side is the easiest. Generally you will go from 10 or 10.5 miles to 12, 13 or 14 miles again.

 

i'm back unto 13.7 with this method.

 

Has it changed your actual electric miles or just the estimated electric miles? Even if you think it increased your actually driven miles, I would suggest that the real cause is simply the arrival of warmer weather.

 

Maybe the best way to check battery degradation is by watching changes in energy input battery can take.
I am charging at 230 V (the1 phase grid in Israel).
In October 3013 when I have installed a permanent kWh meter in my electrical distribution box, dedicated to the charging line, I was measuring an average of 2.95 kWh per full charge starting at zero EV miles (i.e. when car just switches to HV).
These days, with similar temperatures, I am measuring 2.84 kWh on average for same span - a reduction of 3.7% over 18 months and about 22000 km (about 2/3 of them are electric).
This is encouraging, I am happy.

 

what i believe is happening is, the software suppresses battery usage over time, and resetting the computers brings back the original parameters. what do you think andy?

 

I would agree that looking at what it takes to charge to "full" from a known state of charge (like when it switches from EV to HV) at a given temperature is a reasonable measure of battery degradation. Determining your actual range on a full charge at a given temperature also works, but you have to exactly duplicate the drive. Same route, same speed (including acceleration/deceleration pattern), same number of stops at signals, etc, etc, which seems a lot harder. Looking at the estimated EV range on the display is essentially meaningless, since it is just a guesstimate based on recent driving history, which gets reset to a factory default if you disconnect the 12v battery.