Speak EV - Electric Car Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
Got a basic question on EV design. Background: I want an EV but do not want to pay $90K+ for a Tesla or have to charge a Leaf every 70-80 miles. Now, Nissan says the Leaf uses a 48 cell battery to power it. My question - why not 144 cells, configured as 3 batteries that can be charged in parallel (same time will be required for charging) and perhaps a selector switch on the dash for which battery I want to use while driving (1, 2 or 3). The range immediately goes up to around 225 miles. Seems like we already have the technology and engineering capability to do this. Higher weight should help pull the CG lower, too. Any idea what is stopping the manufacturers to get a 200+ mile range using this technique? Can this be done as an after-market upgrade? Has anyone done this? With 6 batteries the range could go over 450 miles, comparable to gasoline cars. What is the trade-off point?
 

·
Registered
Joined
·
3,308 Posts
You have a good point, and the tech can sustain this already. However I suspect cost to produce and ongoing repair/support cost is the main downside. The manufacturers have all got the cost of after sales screwed down to the lowest possible point. Adding a level of complexity runs the risk of increasing that cost for them....
 

·
Super Moderator
Joined
·
7,529 Posts
There's already 192 cells in there, with four in each of the 48 modules.

In the module, two cells are connected in parallel, and those two are connected to another two in series. This is a 2s2p configuration.

So there is kind of "two" batteries in there already, but splitting them up to charge would offer no advantage. In parallel they can accept a 125 amp charge, but split in half they could only take a 62.5 amp charge.


A battery twice the size as now would be nice though, as for why no one but tesla has done it, the answer is somewhere between lack of desire, fear of competing against conventional fuelled products, perceived lack of demand, influence from the oil lobby and cost to develop a platform actually designed for that much battery. But, tesla has proven the demand and will take the whole market for themselves unless the others decide to compete. I hope they do!
 

·
Registered
Joined
·
1,956 Posts
Given the same battery chemistry, more cells will take more space and more weight. Bigger, heavier vehicle takes more power to move it, so increasing the battery capacity by twice will not double the range, which means that the cost to charge for a given range is more.

The CG on the Leaf (as with most EVs) is already very low compared to ICE vehicles, because the battery pack is under the floor.

It also takes more power to charge completely, so a 30 minute trip to a CHAdeMO charger will become a 60 minute trip (or hope that someone provides higher power rapid chargers - 100kW CHAdeMO does exist, but chargers are very rare)
Tesla have done it, but their cars are BIG, and cost double.

At the end of the day, it's all possible, but it's all about compromise. You could design a car that could go 2000 miles on one charge, it would be huge and ugly, impractical and expensive. You could sell precisely zero vehicles because that's not what the market needs.
 

·
Registered
Joined
·
1,119 Posts
So in a Leaf sized car, where are the extra batteries going to fit?
They could do it more easily in something the size and shape of a van, though.....
 

·
Super Moderator
Joined
·
7,529 Posts
So in a Leaf sized car, where are the extra batteries going to fit?
They could do it more easily in something the size and shape of a van, though.....
Where there's a will there's a way!
 

·
Registered
Joined
·
5,443 Posts
Got a basic question on EV design. Background: I want an EV but do not want to pay $90K+ for a Tesla or have to charge a Leaf every 70-80 miles. Now, Nissan says the Leaf uses a 48 cell battery to power it. My question - why not 144 cells, configured as 3 batteries that can be charged in parallel (same time will be required for charging) and perhaps a selector switch on the dash for which battery I want to use while driving (1, 2 or 3). The range immediately goes up to around 225 miles. Seems like we already have the technology and engineering capability to do this. Higher weight should help pull the CG lower, too. Any idea what is stopping the manufacturers to get a 200+ mile range using this technique? Can this be done as an after-market upgrade? Has anyone done this? With 6 batteries the range could go over 450 miles, comparable to gasoline cars. What is the trade-off point?
Cost. I don't think Nissan think there's a market for a £45k Leaf. They're probably right.
 
1 - 7 of 7 Posts
Top