Thought: Apteras and RV parks

[KarenRei]

Here's a great idea, IMHO, for Aptera: In addition to being able to handle a 120V/15A outlet (standard home wiring), let it be able to connect to an RV power receptacle (240V, 50A). Think of it:

* 1 hour for a complete charge (i.e., you can spend almost twice as much time driving as you spend charging)
* Aptera batteries, since they're not LiCoO2/graphite, should easily be able to handle a charge that fast.
* RV parks are everywhere, even in remote locations

Net result: cross-country drives in an Aptera Typ-1e become feasible with our present infrastructure! Come on, who's with me? :) Heck, if they don't do it on their own, I may well just have to do it aftermarket.

[Matthijs]

Well I hope they will make it work for allot of different outlets. Where I live the standard is 220V/16A. I know that the acpropulsion has a system with variable outputs so it can handle allot of different ones. You can just plug in everywhere you go.

[Aptera#965]

Great idea!

I can see a conversion unit offered as an "accessory" item, for $XXX additional.

[LQUAN]

First of all, where is the Aptera charger is located - on-board or off-board. From the look of the photos I've seen so far, the charger is likely to be on board. If we are using an on-board charger that come with the Aptera, then we are pretty much stuck with that (110V/15A). Most of us are stuck because the charger is likely to hook up to the vehicle main computer. But if you are an engineer who is handy with electronics, the problem can be circumvent. I don't know about you guys, but I will make my Aptera able to accept charge from both manufacturer's on-board charger and my own charger at home. On board space is the real limitation for the size of charger - the more current (or charging speed) you want, the bigger the charger has to be. Being able to charge your car at RV park is a good idea worth looking into.

[KarenRei]

That's a good point, LQUAN. I hope that they use an offboard charger and just have you feed in DC at a given voltage (after all, that's what the batteries need). It'd greatly simplify a lot of things, as well as make the vehicle lighter (you have the option of taking the charger with you or not, depending on whether you need it), and all you'd have to change on the vehicle itself to allow for more current, if you had to change anything at all, would be the gauge of the wiring. And you're right, it currently looks like it's an onboard charger:

http://www.greencars.za.net/uploads/Aptera-3.jpg

Hopefully that will change or at least be an option. And you know, if they were to remove it from the vehicle, that'd free space up front for perhaps another kWh of batteries, boosting the range by 10% or so.

I'd certainly pay the $1-1.5k extra it would cost to boost the range and be able to charge in RV parks. Heck, I'd pay more than that.

[Apteratude]

What is the estimated cost of the batteries for the Aptera (somebody have a good guesstimate?) Maybe making the size of the battery pack variable or easy to add on to would be a great way to offer the car at a lower cost for those who only have a short commute/access to opportunity charging and don't need the 120 mile range. Maybe half that @ 60 or maybe 80 miles. If the batteries are several thosand dollars, maybe offering a segmented battery pack that can be easily linked to a second pack would be a great way to get the car to market for less $$$ and if it satisfies the driving/mileage needs of some drivers for less money, it could widen the overall appeal of the car.

[palmer_md]

Scaling the battery pack is not as easy as it sounds. I've built an EV and I can tell you that there are many tradeoffs to pack design and once you have selected the pack size, your committed to it.

For example if each cell were 2vdc and you were using 100 cells for a 200vdc battery pack. It might seem simple to just add 20 more cells to get 20% more capacity from the pack. But 20 more cells takes the pack from 200volts to 220volts. This requires changes to the motor controller as well as the charger and the battery managment system. All of these are expensive changes to the design, and so it is not easy to just scale the pack up and down.

This is just a simplified example, but it should serve to show that battery pack design is not as simple as it might sound if you want a reliable and efficient pack.

As far as charging the pack with an external charger, I would not recommend it. I am sure Aptera has chosen a charger that includes a sophisticated battery managment system. The pack needs to keep all the cells balanced with the same charge and needs to charge in a way that does not overheat any of the cells. A good battery managment system will track all the cells and charge at the fastest rate possible without exceeding any of the predetermined limits for voltage, current or temperature. By using an external charger that you carry around in the trunk, you will also bypass all of these safety features and this will shorten the life of the battery pack. Most external chargers that you could carry in the trunk and can plug into a 240v outlet are designed for quick charging of a golf cart. These chargers just dump current into the pack without any concern for the condition of the batteries. This is also an expensive and quite heavy charger. I'm not sure you would really want to purchase one of these if you saw what you were getting into.

[KarenRei]

I'm assuming something like the A123, and assuming prices a little under $1/W when produced in large format in low volumes. But there's no telling until they're more specific than just stating that they're looking at two lithium phosphate battery suppliers.

I don't see why a reduced battery pack would be unreasonable. Sure, it should save you several thousand dollars.

I've noticed that the three things that keep coming up on the forum as highly desirable are options on batteries, on charging, and vehicle upgradeability. Perhaps we could formalize this and send it to Aptera in the form of a unified request by multiple customers for them to take into consideration? Something along the lines of:

* Option: Reduced battery pack to save money/weight
* Option or standard: heavy enough gauge internal wiring for fast charging
* Standard: external charger instead of internal, optimally which can handle multiple voltages and significant amperage, ideally which could handle as much amperage as the batteries can.
* Standard: Upgradeability for when tech advances (so one could later, for example, remove the battery pack and put in a higher energy density or higher power one, and if necessary replace other components to work with the new power source)
* Standard: Open design specs when released

[KarenRei]

But 20 more cells takes the pack from 200volts to 220volts

Only if connected in series. Anyways, we're not talking about an aftermarket mod here, but something designed in.

[palmer_md]

Only if connected in series. Anyways, we're not talking about an aftermarket mod here, but something designed in.


Like I said it was a simple example....how do you connect 20 volts in parallel with 200 volts?

You could double the pack and have two 200volt packs, but then there are complications with parallel packs that need to be addressed. I know someone is going to say have many parallel packs so that small increments are available. This is where cost becomes and issue. Most motor controllers and chargers have been designed around 200-300 volt range in order to keep the amperage at a reasonable level for the motor. To get enough cells to get into that range it is expensive. To install a parallel pack it is double expensive.

Anyhow it does not make sense to try and discuss this topic in generalities. Suffice it to say that I've run the numbers several ways in trying to get my EV to have more range and no matter how you look at it is becomes very expensive to add range.

[KarenRei]

I'd have to run Kirchoff's laws on the circuit -- it's been too long ;) But really, there are easy cases. For example: If you had four parallel banks of three batteries in series each:

B-B-B
B-B-B
B-B-B
B-B-B

Assuming that the batteries have sufficient of power density (which, as lithium phosphate, they certainly should), you could reduce it to:

B-B-B
B-B-B
B-B-B

or

B-B-B
B-B-B

or

B-B-B

Let's look at the specific example of the Tesla (since the Typ-1e's battery configuration hasn't been announced). It uses cells that are 3.6V and 2.2A-h, so we're looking at about 8 Wh per cell. The Typ-1e has 10kWh, and assuming similar stats for the cells, that's 1,263 cells. Assuming 220V for the Aptera, you'd need about 21 cells per series to achieve the desired voltage, so you'd have sixty series in parallel.

AFAIK, at least. But yes, adding range is expensive, and I doubt there's any room for adding range unless they remove something anyways. But removing range seems reasonable if one wanted to save money.

[palmer_md]

You are correct, however you missed my point. I could be wrong because Aptera has not made any announcement about the details regarding the battery pack, but almost all the EV battery packs I have seen are a single series of batteries. Most chemistrys give about 2volts/cell and by the time you string together 200-300 volts worth you have enough capacity to run a car about 80-100 miles depending on the vehicle. The Aptera goes 120 miles and that is due to the light weight and the aerodynamic shape. You cannot remove any of the batteries in a string without changing the voltage, and since there are no parallel strings you cannot change that either.

I'm not trying to be argumentative, but I just did not explain myself very well in the first post. I hope you do not take this the wrong way, but I am just trying to provide you with some insight as to my experience with EV battery packs.

Again, I could be completely off base and the battery design for the Aptera is fully capable of scaling up and down, but this is not likely to be the case due to the nature of most battery designs.

Regarding the Tesla example....They are the only ones I know of that are using these small batteries in multiple parallel strings. If Aptera goes this same route you would be correct. They have an unsual pack, but they get a lot of press so people know what they have and assume it is how it is normally done. They way they did it is very labor intensive and the controls package for the battery managment system would be a nightmare. This is probably why the car costs 5 times what the Aptera is going to cost.

[c0mp13x]

Regarding the original issue of multiple charging inputs on an EV, the Mitsubishi MiEV takes this approach:

...The car can be recharged using normal household current at 100 volts (taking approximately 14 hours to recharge), 200 volts (7 hr recharge time) and 3-phase 200 volt. In the latter case, it would take only 30 minutes to recharge the vehicle to 80 percent SOC (state-of-charge) using a Quick-charge system. The charger is built into the vehicle, the 100 volt female plug on the right rear, the 200 volt receptacle on the left rear...
At the bottom of the full article there is a picture of the 200V charge port if you scan through the photos: EV World MiEV Article (http://www.evworld.com/article.cfm?storyid=1352#)

http://www.megawattmotorworks.com/articles/images/miev.jpg

[Yanquetino]

You've gotta hand it to Mitsubishi. :D That's definitely the way the go: take full advantage of the electrical infrastructure already in place: at home, work, airports, Costco, even RV parks. Aptera, Miles, Subaru, Zenn, et. al., should follow suit.

I especially like the look of the iMiEV Sport. It even has a photovoltaic roof like the Aptera that keeps the car cooler when parked.

http://surmonte.files.wordpress.com/2008/01/90709070101m.jpg

[KarenRei]

Just a thought: Aptera hasn't officially picked a battery manufacturer yet. It seems to me that the charger they use would likely depend on the batteries that they use (for example, what voltage the cells like to charge at). So, I would wager that they haven't finalized on a charger yet.

How about this: Aptera is planning on opening up a page for us to customize our cars in the coming months. If they don't have charger options on it, perhaps we all write in requesting that?

[LQUAN]

Hey, pretty cute looking EV. It has the front end of a VW Bug and rear end of a Porches - sort of. But I opt for aerodynamic and distinguisable appearance. I'll wait for a while. If Aptera doesn't come together, then this Mitsubishi will be my second choice.

[qpham63]

I can not tell you about the battery pack but I can say that what i saw was an extension cord with a standard flat 2 prong with a 3rd ground prong so most likely it is 110V. Now I have mickey moused things in the past playing with 220V back in the mid 80s to get 220V where we needed for heating a home made oven using electric dryer elements and running 110 was not getting enough wattage. As last resort, I made up a female adapter to plug into a dryer receptacle to get 220 V through a regular 110V extension cord although I would rule out Aptera Motors Inc. They are too professional to Mickey Mouse stuff like I did in college.

So what is the big deal with charging on 110? at 120 mile range for EV only, you will fill the need of 95% of your driving. Are you serious about spending a couple of hours at RV park each time you need a charge to drive a few more hundred miles? If you have that need, the hybrid model is what you want.

Otherwise, 110 would be a better choice. Most parking lot has lamp post and some will have 110 out door out let...I have never seen 220V like that but then I have never spent time in an RV park...

I am no EE but is there a way to make the on board charger to sense the voltage it is getting and deal with it accordingly? My laptop charger does that.

[KarenRei]

Not a couple hours -- less than one hour. You forget -- the battery pack on the Typ-1e is only 10kWh. An 50A RV receptacle has two 120V circuits, so that's 12kW of power:

http://rvtravel.com/rvarticles/120-Volt_AC_Systems.shtml

From dead to full, assuming the batteries can keep up, would thus be 50 minutes (plus a little extra time to account for rectifying losses). I know the batteries can *discharge* that fast, since the Typ-1 uses an 18kW motor. Which means that that level of charging, at the very least, shouldn't blow any fuses.

Drive for 1 1/2 to 2 hours, charge for less than one in a pretty location -- why not? Sounds like a nice trip to me :)

[butter]

okay, I just have to say, irrelevantly, that iMiev Sport is ONE CUTE FRICKIN CAR.

wow. I would SO be in line for that -- barring an exorbitant price.

CUTE CUTE CAR!!

[palmer_md]

Most batteries have maximum charge rates about half of the rated discharge rate. And even then it is not recommended to charge that fast. A slower charge is easier to control and keep the batteries in balance and will also lengthen the life of the pack. If you charge too fast you will definitely have a much shorter life for the pack.

I imagine that they are installing a 120vac onboard charger that will charge at the battery manufacturers recommended rate to get the most life from the pack.

While it is possible to have an onboard charger that can accept 120 or 240volt these chargers are more expensive and the only thing it usually does is change the way the transformers work on the input side, and the DC output side is just the same. (ie 120vac with 10 amps or 240vac with 5 amps...not any faster charge rate).

Not to say they wont install a quick charge capability or offer it as an option. They could offer an offboard charger that can give a faster charge, but this would require some engineering to remove the battery management system associated with the onboard charger as well as selling a multi-thousand dollar charger to go with it. If they see a market for fast charging they may decide to do something like this, but I dont imagine the first few vehicles will have this, but I could be wrong.

This argument is going along the same lines as the Rav4EV one in that what is a really nice idea and many people would like it, but it is going to be too difficult to sell to the public at large at the prices it takes to actually pull off, so the manufacturer is not likely to pursue this as an option.

Mike

[KarenRei]

Most batteries have maximum charge rates about half of the rated discharge rate. And even then it is not recommended to charge that fast. A slower charge is easier to control and keep the batteries in balance and will also lengthen the life of the pack. If you charge too fast you will definitely have a much shorter life for the pack.

They're reportedly using lithium phosphate. Lithium phosphate can usually handle a 10-20 minute charge just fine. See the DeWalt A123 batteries for an example. You can even charge them faster, although I wouldn't trust doing that with something as expensive as car batteries.

(ie 120vac with 10 amps or 240vac with 5 amps...not any faster charge rate).

Which is why you'd need a charger capable of handling the increased wattage and significant amperage.

Not to say they wont install a quick charge capability or offer it as an option. They could offer an offboard charger that can give a faster charge, but this would require some engineering to remove the battery management system associated with the onboard charger as well as selling a multi-thousand dollar charger to go with it.

Well, ideally, it wouldn't be a "second" charger, just one charger that can handle different inputs. But even if it was, I'd gladly pay several thousand dollars more for more charging options. According to the poll, I'm not the only one concerned about limited charging options:

http://www.ballot-box.net/service/poll.results.php?poll=21206&popup=

Over 30% of Typ-1e customers who took part in the poll were "moderately" or "significantly" concerned (factoring out the people who took the Typ-1h option).