Electric IMAC Plane poll?

[Haggy]

	Quote: Originally Posted by sideways
	Well i have already ordered a 2m electric pattern plane, so i can see it happening in the near future for me. My Imac Plane will soon be the only combustion powered plane i own. (Anyone want to buy a YS160 powered Cyclone, ha ha) There's a few people flying electric in pattern now. It's alot easier to justify electric over glow, in fact i'm certain glow will fade over the next couple of years in everything up to 2m. The big cost, like always, is setup. Once you're setup the price difference on a 2m size plane and under isn' t that much difference really. And electric is alot better on equipment and airframes. Besides if it was all about saving money i'd sell my planes and take up jogging. Gas is obviously a little harder to justify being cheaper to run, but battery prices are getting better and better. Hobby City have some Zippy-H batteries that alot of people are getting good results from. The only issue is that you need a generator to charge the batteries at most places........so you still have noise.....and you still burn gas. It will happen......It's just when Apparently the hardest thing to get use to is the lack of noise......try flying with ear-muffs on.

What plane and setup are you running - or planning on running???

Cheers
Chris

[rmarsden]

As more rc flying fields are encroached upon by housing and other development and noise restrictions become increasingly onerous, the transition to electric power will appeal to more pilots and clubs. More customers will lead to lower prices for batteries and other electric power components as the number of suppliers and competition for our hobby funds increases. I predict that within two years, electric power systems with equal or better performance (power and weight) will cost less than gas power for all planes up to 40%. For pattern planes there are now a few airframes built solely for electric power - Krill and Oxai both have them.

I will likely convert my 35% Comp-Arf to electric in 12-18 months but I will probably stick with gas for the 40% ZN just to always have that WOW factor available.

[gareth.ky]

It's all about charging. The batteries are already light, powerful enough and have enough endurance.

You need 3 sets of batteries and 2 chargers to fly every 30 mins (with lipos that charge at 1C in an hour). If you are running 2 packs a flight then you need 4 chargers and so on.

So the way I see it some part of that equation needs to change. Packs need to charge much faster so you need only 1. MIT recently made a breakthrough in LiPo design that could charge one in a few seconds. So that may be taken care of in a few years.

The next problem is where do we get the juice to charge the packs? None of the fields I fly at even have electrical outlets. Running a generator to charge your packs seems to defeat the purpose of reducing noise. To charge big packs quickly we need a big source.

I can see the batteries getting here before the clubs get their act together and get power at the field.

[rmarsden]

	Quote: Originally Posted by gareth.ky
	The next problem is where do we get the juice to charge the packs? None of the fields I fly at even have electrical outlets. Running a generator to charge your packs seems to defeat the purpose of reducing noise. To charge big packs quickly we need a big source. I can see the batteries getting here before the clubs get their act together and get power at the field.

Thre solution on a personal level is quite simple. Eighteen months ago I acquired (for free, Thanks John!!!) a slightly used 210 A-Hr 12V Caterpillar Industrial battery (part no. 153-5720). This battery theoretically has 2510 W-Hrs of available energy for recharging LiPos and a cold cranking capacity of a whopping 1500 Amps. I think It would power pretty much any charger out there designed for 12V input power My 10S packs typicaslly use about 3.5A-Hrs of intergrated current draw for each 8-10 minute IMAC practice round with my 25% Extreme Flight Yak-54. Assuming an average voltage of 37 volts for the 10S packs, then I need 129.5 W-Hrs of energy to recharge each pack. Ideally, I could do 19 recharges of my 10S pack each day. But, the big battery doesn't hold 12 volts throughout its discharge cycle, and the charger/balancer wastes some energy as well. So I could probably do 8-10 recharges with no problem. I have done five 10S pack recharges in a single day and let other pilots charge their smaller packs as well with no problems. This big battery stays permanently in the back of my SUV and would cost only $300 to replace and is easily recharged overnight with a standard 10-12A automobile battery charger. It is much cheaper, lighter, quieter, and smaller than a generator. Well, maybe not lighter - the brute weighs 120 lbs which is why I leave it in the back of the car but it deosn't take up nearly as much space as a generator. With long jumper cables, I can top it off in 15-20 minutes using the SUV's alternator if I ever need to. It has also come in handy for giving jumps to others who car batteries went dead or for running inverters to power laptops etc. when away from AC power.

Sice the power requirements scale pretty well with the weight of the plane, for a 35% IMAC plane I'll need about 120% more energy per flight so instead of 8-10 recharge cycles, I could get 3-5 without needing to recharge the big battery. For a 40% IMAC plane I could get 1-3 recharge cycles - so for a 40%er I would need to top off the big battery from the car's electrical system. Still not a big deal.

Why is it the club's responsibility to supply your energy? Do they supply you with gas or nitro for your other planes?? Should you not also be responsible for supplying your own kilowatts??

[Judge]

A few thoughts on big lipos. I've been running some larger fast electric boats (44-inch / 18 pounds / 80 mph range). These boats use the BIG Neu 2230 (700 to 1000 Kv) motors running on 10S2P 10,000 to 12,000 mAh capacity packs.

We do the packs usually with four 5S packs, two in series and those two set in parallel. I run two Hyperion DUO chargers at races to recharge them between heats. Two packs per charger at 5 amp rate. Usually takes about 45 minutes to top them off. This is because first, you should NEVER drain a big lipo below 20% remaining capacity, and less if you can. So 75% recharge at 1C takes about 45 minutes. A bit longer in truth due to the way the rate drops off as it nears capacity.

I can get maybe 2 charge cycles out of a 55 amp-hour Optima deep cycle marine battery before the chargers pull the battery down below the minimum input voltage, usually around 11 volts for my chargers.

So the solution is a generator and power supply. The Honda and Yamaha 1 to 2 Kw generators are nearly quiet enough to run in your living room without bothering you, but they are pricey. I just found a new source for smaller, quiet generators:

http://www.kipor.com/prouducts_detail.asp?info_id=83

The 1 Kw is around $550 and the 2 Kw is around $800. The Honda and Yamaha can be over $1,300, so these are good prices.

Next you need a good power supply. The Bulldog brand are very popular with the hard core electric boat racers

http://www.rivergatedist.com/PowerSupply.htm

I have the 75 amp version. This runs both Hyperions and gives me enough juice for a heating pad and such if I need it, We warm up our packs to a target temp of 110 degrees for optimal performance.

This is a race proven set up that many of us use for boat racing big boats. I plan to use the same set up with my electric pattern plane, which will be a snap since I only need to charge 2 packs at a time!


Here's the chargers that I use along with many, many electric boat racers. Solid chargers taht have proven to be able to take the punishment of our uses:

http://media.hyperion.hk/dn/eos/

I use the EOS0610i DUO2. Great charger.

[nate540]

I don't know how many of you have trailers but what I did was mount 2 225 amp hour deep cycle batteries in a tongue box and then wire them into the trailer. I also have a 3000 watt inverter for ac power and I made up a retactable 30' cord with bannana plugs on the end to pull out to our picnic tables and everyone just plugs in there chargers. We run all day and have never drained the batts. Once I go home I just plug in the battery tender and it's ready next time. When I goto Joe Nall we run all week charging reciever pack on the gas planes all week with no problems.

[rmarsden]

	Quote: Originally Posted by nate540
	I don't know how many of you have trailers but what I did was mount 2 225 amp hour deep cycle batteries in a tongue box and then wire them into the trailer. I also have a 3000 watt inverter for ac power and I made up a retactable 30' cord with bannana plugs on the end to pull out to our picnic tables and everyone just plugs in there chargers. We run all day and have never drained the batts. Once I go home I just plug in the battery tender and it's ready next time. When I goto Joe Nall we run all week charging reciever pack on the gas planes all week with no problems.

Nate, excellent idea. When I get a trailer to haul around my 40%er, I will copy your setup since it is so useful for a variety of purposes.

[Judge]

	Quote: Originally Posted by nate540
	When I goto Joe Nall we run all week charging reciever pack on the gas planes all week with no problems.

Sounds like a cool set up. But keep in mind that they were talking about charging large packs, 10S and 12S at rates up around 5 or more amps. That is a whole world different than charging receiver and transmitter packs.

[nate540]

Yes the largest I charge is 3 cell 4000 mah. But you could always go with more deep cycles I have two but there is room for three more. You just have to make sure your wire is large enough. Especially if you plan on running an ac inverter. I run 00awg welding cable into my trailer with a 300 amp plate fuse just incase there is a short. You don't want to burn anything down.

[rmarsden]

	Quote: Originally Posted by Judge
	Sounds like a cool set up. But keep in mind that they were talking about charging large packs, 10S and 12S at rates up around 5 or more amps. That is a whole world different than charging receiver and transmitter packs.

Judge, it is simply about avilable energy. If I divide the total energy stored in my deep cycle by the total energy required to recharge my lipos, and and multiply that by 0.8 or so to account for inefficiency in the lipo charges and to account for not being able to drain every last Watt-Hr from the deep cycle.

Example:

Flight battery: 10S, 5000mA-Hr lipo that is 80% discharged i.e. 4000 mA-Hr required to recharge
Deep cycle: 12V, 200 A-Hr fully charged

Energy available from deep cycle: 12V x 200 A-Hr = 2400 Watt-Hr

Energy required to recharge the lipo: 37V x 4A-Hr = 148 Watt-Hr

Number of lipo charges that can be acheived from the deep cycle:

(2400/148) x 0.8 = 13 recharges

For one pilot this is probably enough for a single weekend's flying. For Nate's setup with two 225 Amp-Hr batts, and your 12S 6000 mA-Hr packs dicharged 80%, the number or possible recharges becomes

(5400/213) x 0.8 = 20 recharges

Sounds like plenty of energy available to me. Flight packs and receiver packs are in the noise for this application. So Nate's setup should certainly get one pilot through the weekend and get two pilots through it if they each flew 10 additional times after depleting the fully charged packs they brought with them.

[gareth.ky]

I came across a cool use for a Hybid vehicle. This guy ran his house off his Prius in a snow storm.

The current Prius has a 288v 6.5Ah main battery. That's 1872 Wh of available power. If you leave the car "on" it will start up the motor and recharge the battery pack and shut itself off when its charged. That's pretty cool!

Now you just need a way to step down 200+ volts to around 24v. Lots of chargers will be happy on more than 12v now, its actually more efficient for charging 4+ cell packs. I'm with Judge on the Hyperion chargers and I think they take up to 28v.

Anyway we would be better off charging from a 24v deep cycle battery or putting two 12v optima batteries in series. even then the voltage and current available will drop as you charge each pack and you will never get near the theoretical number of charges.

The Prius, well, we could run a dozen chargers on that all weekend for a few bucks in gas. The motor would be off most of the time so its pretty quiet.

[Radioactive]

	Quote: Originally Posted by jongurley
	Just to interject my opinion,, I have been flying model airplanes for about 11 years,, I currently fly a 40% Carden Extra and a 35% Yak for my IMAC and 3d needs,, I have one foamy which i fly in my yard and enjoy practicing 3d with it,, and I own a Trex600 nitro heli, and a couple of misc. glow planes,, to cut my opinion short and sweet,, I am not trying to be the butthole of this thread but to give my honest opinion, I find that electrics over the .40 glow size to be very boring,, I am only 28 years old but I enjoy this hobby more than anything in the world, I love hearing my DA's naw, and my glow motors scream,, If this hobby was mostly electrics, I would flat out quit,, I have never been a fan of electrics other than foamy's, I find them boring for the most part,, but anyway ,, everyone has there on views but these are just my opinions and thoughts,,

Nothing Boring about our 3dhs 89" Exta SHP.. as a matter of fact, i'd bet it will whip some serious IMAC butt!! It is a dream to fly and has unlimited power, with the Hacker A60
Going to put a 3DHS slick with a hacker A80.. and do some imac with it...When it comes to electrics, very few companies, can make the cut here.. strength, and airframe design is critical...With Gasoline powered models the sky is the limit!

[Royster]

Great info and feedback guys, keep it up

[Judge]

	Quote: Originally Posted by rmarsden
	Judge, it is simply about avilable energy.

Thanks for the lesson. My posts are based on running large 10S2P set ups in electric boats that pull over 200 amps and achieve speeds of 75 mph or better. I have eight 10S set ups done with either 2x5S or 4S+6S in the 10,000 to 12,000 mAh range. I also have four 4S2P 10,000 pack arrangements done with 2x4S 5,000 mAh packs. I own three Hyperion chargers (1210i and two 0610iDUO) and have upwards of 75 cycles on some of them, so it is fair to say that I have done a bit of field charging.

It is about more than "available energy". It is about the input voltage that the battery can deliver to the charger under load. Charging two 5S 5,000 mAh packs at 1C will put a load on the input battery of around 24 amps. Under that load I have found that my Optima deep cycle marine 12-volt battery can do one charge easily and maybe a second one if I lower the rate. After that the charger shuts off because the marine battery cannot supply the proper voltage to the charger.

My battery is a 54 amp-hour battery. So with a 200 amp-hour I might get 4 full charge cycles like the above. Your theoretical 13 charges ignores the voltage depression under load that the 12-volt battery will sustain. That will limit the actual number of charge cycles to something well less than the numerically calculated number which ignores the voltage depression.

[rmarsden]

	Quote: Originally Posted by gareth.ky
	Anyway we would be better off charging from a 24v deep cycle battery or putting two 12v optima batteries in series. even then the voltage and current available will drop as you charge each pack and you will never get near the theoretical number of charges.

Gareth,

I believe that both of your statements quoted above are incorrect.

There is certainly no guarantee that charging from 24V is any better than charging from 12V. Our chargers are essentially dc/dc converters which have inherent inefficiencies. Without providing the efficiency of a particular charger vs input voltage and several different output voltages and currents, your first statement is simply hypothesis and not grounded in fact. If you want to take the data and provide it here, that would be useful. To compute charger efficiency, meaure the current and voltage sourced to the charger and the voltage and current going from the charger to the battery being charged. The efficiency of the charger is then given by

efficiency = (Voutput x Aoutput) / ((Vinput x Ainput)

I suspect that you will find only small changes in efficency as a function of input voltage with the efficiency being slightly better at higher input voltages. I also suspect that you will find that efficiency varies more with respect to input and/or output current. The will probably also be lower efficiency at low current because the charger requires a certain amount of power just to operate; for small charging currents the operating power of the charger may be a significant part of the entire power budget.

While it is true that the voltage of a battery drops both as a function of total energy consumed and current being drawn, that does not mean that the nearly all of the energy in the battery cannot be used. What it does mean is that as the battery drains, at some point it will no longer be able to source current above a certain threshold. In our planes, this means we either throttle back a bit or experience LVC unexpectedly. For charging this means that if we draw too much current, we will get the low voltage alarm from the charger. The solution is to reduce the current draw from the battery be either reducing the charging current output to the lipo being charged, or reducing the number of batteries being charged simultaneously. Doing so will allow 90-95% of the capacity of a good quality deep-cycle lead-acid battery to be utilized. Exactly how close we get to the theortical number of recharges then depends on the charger itself.

If I have time tonight, I'll get some efficiency data for my Hyperion 1210i chargers.