[Caevlist] battery recommendation

David Ullman ullman at davidullman.com
Sat Mar 3 05:55:50 PST 2018

Some of you have been to my place to see the wind tunnel work I am doing for an electric airplane.  I should have tunnel results by late summer and then start building a system for real airplane testing.  In this regard I am starting to get serious about components for the full sized airplane.   Large EDF (electric Ducted fan ) evolution for model airplanes is advancing at a rapid pace.  There are now quiet 120mm units that will produce 15 lbs of thrust for a short period and 8 lbs continuous (limit is motor heat).  Sixteen of these will make my little plane fly very well.  I plan on starting with 4-6 on the plane with the IC engine still in place to gather data before removing the IC engine altogether, a year or more away on that.  More on the project at www.davidullman.com/aeronautics <http://www.davidullman.com/aeronautics>  


The one area I have done very little is batteries.  During my test stage,  later this year, each  of the 4-6 motors needs battery power of:

*	Nominal 45 V
*	25 Ah for 30 minutes of flight testing.  The more, the better.
*	100 amp draw max, 50 amp continuous
*	Near zero fire hazard.
*	Batteries must be complete with BMS and charger.  I have no interest in making batteries another area of research.
*	Weight – as light as possible – I can go up to 200 lbs for batteries to power 4-6 motors but prefer something lighter (next gen batteries??)


It seems that I should be able to get someone to take a Leaf (or other) battery pack and help me reconfigure it this fall.  Any ideas?


David Ullman


ullman at davidullman.com



From: caevlist-bounces at rdrop.com [mailto:caevlist-bounces at rdrop.com] On Behalf Of gburket at peak.org
Sent: Friday, March 02, 2018 9:29 PM
To: Alan Batie <alan at batie.org>
Cc: caevlist <caevlist at www.rdrop.com>
Subject: [Caevlist] EV conversion affordability


On the question of EV conversion affordability, I've outlined some areas to address this issue using the Nissan Leaf as an example:


Drive System:

I just priced two used 2013 Leaf EV drive systems(DS) at a salvage yard with 40-60k miles on them. The DS includes the charger(110V/220VAC input, DC fast charge input, AC pump control, and DC to DC), motor control inverter, motor, and reduction gear/differential. The cost is $600 each. Amazingly, $250 less than one of your new Leaf headlights! These DSs look small enough to be a pretty easy drop-in in most FWD vehicles, and possibly some mid-engine cars. Rated @ 110 hp, they have much less power than the 300-400HP Teslas. This DS does take the Leaf to over 90MPH, so it's probably good enough for smaller vehicles.



A company in CA is converting the Tesla 6S (~24V) battery modules to a 12S (~48V ) configuration. 8 of these in series are close to the Leaf's stock voltage and give 44 to 50 kWh of storage capacity, almost twice that of the stock Leaf's battery . This is with a battery weight close to the Leaf's stock battery weight, giving the vehicle ~2X the stock Leaf's range. The cost of the modified modules is pretty high, ~$1600/ module, for a total of ~$13,000. The price of the Tesla unmodified modules has plateaued recently at ~$1400. I suspect the price will drop as more modules come onto the market. A  S100D complete battery pack recently sold on ebay for ~$11k. This takes the price down to ~ $700 per module-say in a group purchase. Batteries will probably always be the most expensive cost for a conversion.


Sensors, controls, BMS, general wiring, software mods, drive-line hook-up, safe battery installation: 

Could someone else with more experience jump in here to give some idea of the costs involved?


Other conversion costs, labor?


Donor vehicle cost:

Again, does someone else have more experience in this area?


Please let me know your thoughts on this, Glenn




From: "Alan Batie" <alan at batie.org <mailto:alan at batie.org> >
To: "caevlist" <caevlist at www.rdrop.com <mailto:caevlist at www.rdrop.com> >
Sent: Tuesday, February 27, 2018 11:26:18 PM
Subject: Re: [Caevlist] And the rest advance a notch


On 2/27/18 7:24 PM, gburket at peak.org <mailto:gburket at peak.org>  wrote:
> Can you wait for the Hyundai Kona crossover to come out. It looks like 
> it will have good range and relaxed seating for us flexibility deprived 
> people.

The Hyundai site doesn't say anything about it being a hybrid of any 
sort...  Oh, I see the announcement just today of the EV version, and 
wow, that does look interesting.  Another reason to go with a 1-year 
lease - there's a lot coming out in a year!

> Soon you could pick your ICE vehicle(within a practical design range), 
> and have people like Otmar, Kirk, or me convert it for you.

That's an interesting idea, but unlikely to be affordable...

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