Date: Friday, September 7 2007 04:02 pm From: Bill Dube To: aeroelectric-list@matronics.com Reply-To: aeroelectric-list@matronics.com Subject: Re: AeroElectric-List: A123 Systems Nano-phosphate technology and aircraft (was: KillaCycle on Dish Net Tonight) Attachment: Part 1: noname (TEXT/PLAIN 7bit 5177 bytes) --> AeroElectric-List message posted by: Bill Dube Whomever is designing the electronics doesn't have real experience with A123 Systems cells. They think they are dealing with conventional Li-Ion cells, and they are wrong. A123 Systems nano-phosphate cells are quite different than other Li-Ion cells. They will take a LOT of abuse. About the same amount as an AGM. It is straightforward to make a drop-in replacement for a 12 volt (or 24 volt) lead-acid battery using A123 Systems cells. The existing charging system will work just fine. (It must have the voltage set somewhere between 13.5 and 14.8 volts.) In an airplane, you would want a warning that alerted the pilot that the system was going over 14.8 volts and would make noise if the system was going over 15 volts. It would also be useful to know if the battery temperature was going over 80 Celsius. (You can go up to about 100 C without damage, but no higher or you risk venting the cells and damaging the plastic separator.) >>> Case study <<<< I have had a 3.5 lb A123 Systems battery running in my completely unmodified GMC van for the past 7 months. It snaps the engine over much better than the original 35 lb lead-acid battery. Let's talk about abuse. My wife left my van door unlocked and someone rifled my glove box and left it open with the light on. This killed the battery and it sat at ZERO VOLTS for over a week. I thought, "So much for THAT battery." I then decided to do what the typical consumer would do and I connected up the 3.5 lb completely dead battery to a fully-charged car battery with jumper cables. Hundreds of amps flowed and slightly warmed the cables. I waited a couple of minutes for the 3.5 lb battery voltage to come up, disconnected the jumper cables (the worst thing you could do) and cranked up the van. It started instantly. The alternator then gave the 3.5 lb battery ~100 amps until it came up to 13.4 volts and then tapered off. The BMS showed that all the cells were still in balance! This was five months ago. I haven't capacity-tested the battery, but I can't tell the difference in cranking performance. It was just as if nothing had happened. I even left it parked for 5 weeks while I was out of town and it cranked right up without a problem. If you were to torture a conventional Li-Ion battery like this, it would have burst into flames, or at least it would have just burst. I tell this story to folks with years of experience with conventional Li-Ion cells and they cringe when I get to the part about the jumper cables. :-) The A123 Systems cells will, indeed, "take the abuse". I have a very simplistic charge-balancing electronics (BMS) on my GMC van battery. Nothing fancy is needed. If you overcharge them grossly, they will vent a small amount of flammable vapor (like paint thinner.) If there is an ignition source, this vapor could catch fire. The cells can also burst if overcharged severely. That is the extent of the hazard this technology presents. Bill Dube' Robert L. Nuckolls, III wrote: > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > > At 04:32 PM 9/5/2007 -0600, you wrote: > >> You can do a fantastic electric motor glider, but nothing long range. >> Imagine if gasoline weighed about 100 lbs per gallon and you will >> understand the range issue. >> >> These "Nano-Phosphate" type cells will make a big dent in the weight >> of airplanes soon. As you can see, they put out a huge amount of >> power for their weight, so they will be perfect starting batteries >> for airplanes. This specific type of battery has none of the safety >> issues that other high-power batteries have. > > > One of my principles is working with the A123 > products with an eye toward a certified replacement > of SVLA/NiCAD batteries on T/C aircraft. So far, > they've reporting nothing that suggests that the > the task is impractical but successful integration > of Li-Ion technology into aircraft WILL require > a battery-friendly charging system (read new smart > regulator for existing aircraft) or a drop-in form-fit- > function device that includes battery management > capabilities. The Li-Ion's are not drop-in replacments > for SVLA . . . they won't take the "abuse". > > Bob . . . > > > > > > _-============================================================ _-= - The AeroElectric-List Email Forum - _-= Use the Matronics List Features Navigator to browse _-= the many List utilities such as the Subscriptions page, _-= Archive Search & Download, 7-Day Browse, Chat, FAQ, _-= Photoshare, and much much more: _-= --> http://www.matronics.com/Navigator?AeroElectric-List _-============================================================ _-= - NEW MATRONICS WEB FORUMS - _-= Same great content now also available via the Web Forums! _-= --> http://forums.matronics.com _-============================================================