New device boosts road time for Leaf by 50%

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

yontyont

Member
Joined
Mar 11, 2016
Messages
5
Battery-switching device promises more road time for Leaf drivers.
Nissan Leafs, which go about 107 miles on a charge, sometimes end up relegated to commuter cars due to battery-life worries.

They could work about 50 percent longer with a device provisionally patented by Vanderbilt University’s Ken Pence, professor of the practice of engineering management, and Tim Potteiger, a Ph.D. student in electrical engineering. It reconfigures modules in electric car battery packs to be online or offline—depending on whether they’re going to pull down the other modules.


“We know there are some battery cells that run out of juice earlier than others, and when they do, the others run less efficiently,” Potteiger said. “We make sure they all run out of energy at the same time, and there’s none left over.” That means they commonly show empty with 10 percent or more power left, Potteiger said. Their device also can connect to electric cars’ software for a more accurate read that allows drivers to get the most out of a charge.

https://news.vanderbilt.edu/2017/11/20/battery-device-tesla-leaf/
 
Why the dupe post?

OP already posted the same link at http://www.mynissanleaf.com/viewtopic.php?f=17&t=24951.

Mod Note: Deleted other thread.
 
More details for ignorant:
Nissan Leafs, which go about 107 miles on a charge, sometimes end up relegated to commuter cars due to battery-range worries. The mass-market, standard Tesla Model 3 can go double that but still can be disconcerting on long road trips.

Both batteries could work up to 50 percent longer with a device provisionally patented by Vanderbilt University's Ken Pence, professor of the practice of engineering management, and Tim Potteiger, a Ph.D. student in electrical engineering. It reconfigures modules -- clusters of battery cells -- in electric cars to be online or offline depending on whether they're going to pull down the other modules.

The two used the open-source Tesla high-density, lithium-ion battery to model their method of improving durability and increasing range, adding a controller to each of the battery's cells.

"We know there are some battery cells that run out of juice earlier than others, and when they do, the others run less efficiently," Potteiger said. "We make sure they all run out of energy at the same time, and there's none left over."

With both the Tesla and Nissan battery packs' current configuration, gauges give a worst-case scenario on the amount of power left so that users don't get stranded. That means they commonly show empty with 10 percent or more power left, Potteiger said. Their device also can connect to electric cars' software for a more accurate read that allows drivers to get the most range out of a charge.

The older the batteries are, the more likely they are to experience problems making them less efficient, and the more useful the team's device becomes, Pence said. "They'll have a longer useful service life," Pence said. "Drivers won't see the 50 percent return immediately, but they will later on in the life of the battery."

Instead, the duo ended up with the battery switcher and are working with the Vanderbilt Center for Technology Transfer and Commercialization to get it to market.
 
Only thing I can think of is that perhaps all that shunting of electricity between the cells causes excessive degradation of the battery. If you avoid the shunting, you avoid increased battery degradation.

But that's just a SWAG.

Any battery engineers out there?

https://news.vanderbilt.edu/2017/11/20/battery-device-tesla-leaf/
 
The 50% numbers aren't for a new Leaf. The posts that say they 100% charge and then only get 15-20 miles range because they have a bad cell, this would increase their range. When a module is dead, it basically switches it out connecting the module before the dead cell to the module after. If you have battery modules A-B-C and B is bad, it would switch it out so that B is floating and A connects to C directly. Lowering the pack voltage but keeping the car from shutting down to the lowest cell in the pack. And it just keeps doing that until there is not enough series voltage.

That's what I gather from reading the page. I could see in an extreme case of a single very bad cell in the pack of otherwise good cells, you could approach the 50% number.
 
We get the idea, actually. It would typically add very little range, and occasionally add about 10 miles, rarely somewhat more. The title is pure hyperbole, like a 140 mile 2011 Leaf.
 
I believe the article says that battery pack lifetime will be extended by 50% due to a more efficient way of managing the battery balance and/or discharge.

So instead of a 5 to 8 year battery, you have a 7.5 to 12 year battery.

You will get 10% more range from the bottom end of the battery pack and maybe even the top end. That is use the full 24kw pack instead of 22.5kw.

The math works out. 24kw - 10% = 22.6wk, so about 10% more range.

Any engineers out there want to take a SWAG at it?
 
Not that I want to feed the "arrogant" OP! who could have just said the article was about extending battery life not distance.....but that makes more sense, 50% increase in battery life and maybe 10% increase in battery capacity. I thought our Leafs had something similar, isn't that what the battery shunt graph is for on LeafSpy, showing which batteries were active and which ones were currently being shunted?
 
Sounds vaguely like dynamic balancing. I heard about it years ago, not new.

The usual way battery packs in BEVs are balanced is "top balancing". While charging all the cells to the same voltage by using bypass resistors to "balance" the pack by switching in the resistors to discharge the cells that have higher voltages. While discharging, the pack takes the exact same current out of each cell, when the cell with the smallest capacity and thus the lowest voltage hits a lower limit the pack is empty. Notice that the cell with the smallest capacity sets the limit for the pack, and the cell with the smallest capacity is working the hardest and thus will have the most cycling wear.

Dynamic battery balancing, by one of several methods, keeps the voltage in the cells the same as they are discharged. This levels the cycling wear on the pack, and reduces wasted energy in balancing resistors, and slows wear and provides more usable capacity, especially as the battery pack ages.
 
Let's see ...

In a NEW battery,
wire in parallel
add a controller to each cell
add programming

All to solve a problem begat by poor QC and inadequate thermal control.
 
SageBrush said:
Let's see ...

In a NEW battery,
wire in parallel
add a controller to each cell
add programming

All to solve a problem begat by poor QC and inadequate thermal control.

Exactly, an unreliable and labor intensive solution for a questionable savings and likely other issues. Classic "lab theory" project that is not grounded in real-world applications, If it were easy to embed this and practical then OEMs would do it without the extra hardware. Will make for pages of useless posts here however. Patented, that's the best part :lol:
 
SageBrush said:
Let's see ...

In a NEW battery,
wire in parallel
add a controller to each cell
add programming

All to solve a problem begat by poor QC and inadequate thermal control.

There already is a "controller" for each cell (or groups of cells), complete with programming. With a top balanced battery, the controller just measured the voltage and switches in a resistor when needed to balance the cell relative to the rest of the pack.

Regardless of how good of QC or thermal control, battery cells are not identical. By spreading rather than concentrating the wear, longer life can be achieved.
 
DIY builders have been achieving essentially the same result for years in terms of the cells running out at the same time. It’s called “bottom-balancing”. Doesn’t require a truckload of relays. In fact no BMS at all.
 
I believe the article says that battery pack lifetime will be extended by 50% due to a more efficient way of managing the battery balance and/or discharge.

So instead of a 5 to 8 year battery, you have a 7.5 to 12 year battery.

The 'Canary pack' degrades rapidly over time unless kept very cool. Unless this device can slow time, I don't see a big increase in longevity for pre 4/2013 Leafs.
 
Back
Top