Ultracapacitors in parallel with battery

The main reason for putting the Leaf's battery in parallel with a Ultracapacitor is the possibility of extending the battery life 3 times... I am not an Electrical Engineer but I used to tinker around with my Electric RC Car when I was young! I also am not a Leaf Owner just yet but I am planning on it once I see some of my doubts get answers. I really want to discuss the pros and cons and hopefully get some answers from Nissan themselves. Here is an article about a recent advancement in ultracapacitors:
http://taintedgreen.com/green-business/imagine-a-nissan-leaf-with-a-graphene-based-supercapacitor-battery/000856/mj-6

It seems we are a long ways away from replacing batteries with ultra capacitors but I will list some information about them. "Supercapacitors/Ultracapacitors/hypercapacitors are devices that can store electricity, a bit like batteries, but their different characteristics mean that they have different pros and cons. Unlike batteries, supercapacitors don't have 'memory'. They can be charged and discharged an unlimited number of times without degradation of storage capacity, which means that you can charge and discharge them completely (batteries in hybrids and EVs are usually only cycled within a fraction of their full charge to extend their lives). They can also be charged and discharged much faster than batteries (so that very fast recharge stations for EVs would be possible). The main downside is that so far their energy density has been much lower than chemical batteries, so they store only a fraction of the power."

Here are the Leaf's battery Specs:
Type: laminated lithium-ion battery
Total capacity (kWh): 24
Power output (kW): over 90
Energy density (Wh/kg): 140
Power density (kW/kg): 2.5
Number of modules: 48

Here is a brief explanation about a battery-ultracapacitor system does:
http://www.illinoiscapacitor.com/pdf/Papers/Flat%20Supercapacitors%20evolve%20to%20meet%20needs.pdf

So what all this boils down to is can you modify your leaf in this way as a means to offset the cost of replacing the batteries plus the cost of the setup? Would Nissan consider doing this in future models? Or will tinkerers be left to answer these questions? Let me know what you think, there are other perks to adding an ultracapacitor such as a slight range increase! Also if you are a speed freak the capacitor would help in raising the juice (amps) required to move those wheels!

Www.theeestory.com

Using any kind of capacitors as energy storage is not as simple as replacing the batteries with them, and you can't simply add them in parallel.

Storage batteries have a rather flat voltage curve, which means they put out a relatively constant voltage while being discharged. Capacitors have a linear curve, so that means the voltage drops from 100% to 0% as their stored energy drops. This means you have to add in a non-trivial power supply architecture that can compensate for this steady drop and boost the voltage to a near constant level, as the PM motor needs a high voltage to maintain it's RPM. (otherwise back EMF is greater than the input voltage, and current stops flowing.)

For extremely high transient loads, adding capacitors as a "stiffener" is sometimes done, but with modern batteries this is really no longer needed, as they have rather high /C ratings.

For instance; The 6.5kWh pack of A123's I have in my Prius can handle an 840 amp continuous discharge, and a 1440 amp discharge for 10 seconds without issue. The pack can easily be recharged in 15 minutes if you have a big enough charger. These cells are now a 6 year old design, so newer designs are even better!

Once we have flourishing EV market, you will see a rapid increase in battery R&D and we will get some exciting new technology that will make today's stuff seem like garbage.

-Phil

I can't wait until battery technology follows a law like Moores Law in integrated circuits!

Ingineer said:

Once we have flourishing EV market, you will see a rapid increase in battery R&D and we will get some exciting new technology that will make today's stuff seem like garbage.
-Phil

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What will this do to our resale value in say, 5-8 years?

jlaw99 said:

What will this do to our resale value in say, 5-8 years?

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If it happens that fast, I suspect there will be an upgrade path, so I wouldn't worry about it.

-Phil

Exactly! Look at the 1990s EVs that are still on the road. The trucks filled with lead-acid used a proprietary 8V battery that hasn't been made for years. Enthusiasts have figured out how to install modern lead-acid batteries, provide management support, and satisfy the car's electronics that all's well in the battery box. Other's have found out how to remove lead-acid and NiMH and install LiFePO4 with the same effect - new battery, instant weight loss, longer range, and much better battery life.

If my VW diesel's fuel injection pump dies, I have to get it rebuilt or get a new pump from VW. If the pumps are no longer made, I'm out of luck. Worst case for the Leaf - it's 2023 and our 2011 Leaf needs a battery. Nissan no longer exists, AESC was bought by the Exxon-BP-Mobil-Koch group and are now making parts for coffee pots, and the only source of lithium on the market are for radio control airplanes. Even in that horrible alternate-future parallel universe, we can refill the Leaf battery box with existing batteries and keep the car on the road.

Check this out for a real example - this gent developed his own computerized battery management system for electric cars, and rebuilt the NiMH battery in his Gen1 Insight with a couple different flavors of lithium.
http://www.insightcentral.net/forum...l-issues/16928-a123-20ah-lithium-install.html


The 20Ah prismatic A123 cells were severely torture tested:
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=15093

Here's a look at a battery build. This is a drag-racing (very high power!) pack made from 30Ah prismatic lithium cells.
http://photos.plasmaboyracing.com/LiPol-Module


Even in a "Mad Max" environment we'll be able to keep ourself in batteries! :lol:

I agree with Andy, who knows how the value will hold up, but someone, somewhere will probably figure out a way to keep it going! =)

Here's my 6.5kWh A123 pack in my Prius:


It's got 864 cells all hand assembled with a custom BMS.

-Phil

That, Sir, is a thing of beauty!

edit...

Nothing like being late to the party. Really impressive work!

Ingineer's PHEV:
http://priuschat.com/forums/gen-ii-...-plug-in-hybrid-electric-vehicle-project.html

Ingineer's ScanGauge Replacement:
http://priuschat.com/forums/gen-ii-prius-main-forum/87174-new-alternative-scangauge.html

Ingineer said:

I agree with Andy, who knows how the value will hold up, but someone, somewhere will probably figure out a way to keep it going! =)

Here's my 6.5kWh A123 pack in my Prius:

It's got 864 cells all hand assembled with a custom BMS.

-Phil

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I want the sticker off of that battery pack!

"Not only will this kill you, it will hurt the whole time you are dying!"

Simply awesome.

Rake said:

I want the sticker off of that battery pack!

"Not only will this kill you, it will hurt the whole time you are dying!"

Simply awesome.

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Here's a copy. I made it myself, and it is copyrighted, but I allow non-commercial use provided you give credit if you use it digitally:



I'm a firm believer, that if something makes you laugh, it's much more memorable! =)

-Phil

Thank you, Sir!
I will use it only as you intend.