Well,  We got a PC power source converted to drive our battery charger.  1st step in the whole electric stunt thingie! LOL!!

Now, what is the guideline as far as discharge percentage of the lipos?  Our charger will tell us what level each cell is at, so I need to know what is safe as far as how much to let the battery discharge.  I know it has been discussed, but then I can't seem to find a % range given.

One more thing, just how "important" would it be to get a lipo "envelope", etc., to place the battery in while it's charging?  First charge, nothing got hot, the battery's weakest cell was 68% before charging began.

First E-Flights should take place before April Fools day!  

Big Bear

Thanks, Tim.  70%-80% discharge is what we will shoot for.  I know there is a "formula" for calculating the rate of discharge, but I am leaving the "mental side" to Aaron.  I 'm gonna stick to the construction side.  He found out which wires go where, and how many to get the PC power source to put out the required 12 volts, what resistors etc., to use where, etc., etc., from the guys here in this forum's tips..  I soldered everything up. Works good that way! LOL!!
We have two 12V posts on top of the case along with a power switch and a red LED to tell us the power source is on.  The "assembly/construction" part was a snap.  Almost looks like someone knew what they were doing! LOL!!

Now it's a job of finding some "affordable" batteries so that one can be charging off the car battery while the other one is in the air.  I would actually like to find two more batteries.  We just have the one that came with the Electric Super Clown ARF combo.  The Brodak ones are good, I'm sure, but I understand we can get "good" batteries for about 1/3-1/2 the cost.  Only "problem" I have been made aware of is the connectors.  I would like to have the ones I get match the four pin Deans.  You know, have my cake and eat it, too! LOL!!

This is a good first project I think.  I have a contest flown Super Clown powered by a McCoy RH .29 Hybrid, so performance can be somewhat judged between the two.  Denny Adamisin developed the power system, and says it can easily fly a .35 size stunter.  We have a couple of those that can be donated to the cause and see how it works for them, later on.  A prett light Fancy Pants comes to mind first.  Or a Brodak Warbird Profile....  this stuff is getting interesting to me, now.

On the "charging envelope/package" for the lipos, I think I will definitely pick up one soon.  it IS better to be safe than sorry.  I have some surplus ammo cans that someone has said will work, but I don't know......  For the initial charging, we monitored it closely.

Thanks, again
Bill

Bill, you may want to read Norm Whittle's article he wrote, primer for electric.
Typically, I have been instructed that you look for a voltage for bottom end cutoff since drawing down past a certain voltage is what kills the cells. I personally dont ever charge my stuff inside a structure. just in case, and NEVER inside a car

Bill,
The charge is the most important piece of equipment for ECL. The one place that people have had trouble with LIPO's has been over charging them with a charger that does not cut off once full charge is reached. I have used the Thunder Power 610C. This has protection circuitry that warns if your pack is to low to charge at full rate, checks and balances the cells as it charges and cuts off once full charge is reached (it actually does a slight discharge if you leave it plugged in after it hits full charge and alarms). In the two years I have been flying ECL I have not had any charger related problems with my packs.

Make sure you have a way of monitoring the charge rate. I think the charging sack is a good idea with your charger. Also monitor your charging rate, for most lipos a very safe rate is 1C (i.e. 2100 mah pack charge at 2amps). Some of the new TP packs can safely go to 3C and saves lots of time. The A123 cells can do 10C, I flew a 3S2P A123 4200mah pack that charged at 10A in 20 mins. Downside to the A123 is weight, hope they get better.

For the 35 size ships you are talking about you could use a 4S1P - 2200 mah pack with a max static draw of 19 amps (Turngy 3542-1000 motor) and one of Dennis's APCE 11x5.5P props at 9100 rpm would be a good starting point. The motor and pack will weigh in at around 12oz not to far from a Fox 35 with muffler and 4oz of fuel.

Best,                     DennisT

Hi Bill,
 You mention having some surplus Ammo Cans which you could use until you get a lipo sack/charging bag. Not sure exactly what Ammo cans are (unless it's the obvious)... but if they are made of metal I would be very wary of using them unless I had lined them with a fire proof none coductive coating. No point in adding a potential disaster to the mix..

Once you get it actually flying you won't look back, No mess to clean up, repeatable performance, You can even run the motor up in the house, go try that with a fox35. I've been electirc for nearly 3 years now and so far I have had 3 battery failures, 2 due to physical damage (Figure 9). Only one has died of it's own accord, all the others seem to be as good as ever. I may be on borrowed time but so far once you have the one time purchase items sorted out it's proving cheaper than a wet set up at least for me.

TTFN
John.
 

A lipo sack is pretty handy but almost any container that will not burn is better than doing it on the kitchen table next to your newspaper. With metals, the problem is the metal may be conductive. ... and you don't want to short circuit a LiPo.

Actually, I have shorted a small LiPo pack and nobody died. Surprisingly, not even the pack. In a brain fade, I went and shortened both wires of the pack in one go. The contact was probably short enough that things did not heat too much.

I know what the 4S is. I understand 2500 mah. But what is 25c ?

Ward-O  

C is how much current, discharge or charge, the battery can handle. Like if you have your  2500 mAh 25C battery, it can stand 2500 X 25 mA discharge: 62500 mA = 62.5 A.

Batteries can have a few different C values: Continuous, Peak, Charging. Peak means what it can take for a few seconds, Continuous obviously means how much it can keep giving you for a while, and Charge means how fast charging it survives.

Bill,

Looks like you and I are going to the same place! Only I'm trying to get to the Classic sized ships without going to the Brodak eC/L "trainer" first. I just couldn't find enough details on the Brodak set-up to satisfy my curiosity.

This seems like a good place to ask this battery question...

I know what the 4S is. I understand 2500 mah. But what is 25c ?

Ward-O  

Hi Ward,

Sorry, but I still have no clue what "25c (or any other "__c") stands for.

Aaron found the ARF Elec. Super Clown package for well less than 1/2 price, so it couldn't been passed up, I guess.  Everything there and all still shrink wrapped.

Denny Adamisin developed the "package" and he has ensured me that the motor set up will fly a plane around the size of a Dolphin, Brodak Warbird, etc., so it will get used past the Super Clown, but we will start there,obviously.  Still looking for spare, "compatible", batteries that will work, but not cost what the Brodak ones do.

This electric stuff is confusing to say the least!  We never realized that you couldn't use the battery charger (pretty important part of the equation) unless you had a spare car battery somewhere!  That was the reason for making the converter out of the PC (it was free and almost brand new) power supply.  Nothing in the literature that we can find says anything about that.  A lot is taken for granted that the buyer already knows something about this stuff.  Still a good place to start, but if we had not found this, it would have been a tough decision to shell out the necessary funds to get started.  Still not sure that we will be able to fly enough to make a "savings" from Electric versus glow.  If someone is already set up with plenty of engines, etc,. then the initial out lay to convert over is nothing to sneeze at.  A good set up with spare batteries is at least what a complete PA pipe set up was going for.  And I have enough engines and pipes to keep going for a while, not counting the other engines here, so the "over the long haul saving" thing is not making a LOT of sense right now.  Gonna have to do a LOT of flying to make up the difference if I get a system to fly a SV-31, or similar.

Bill

But that is not at all different from the glow stuff, if you have never used it or don't have a friend helping you.

Glow? What makes it glow? Oh, you need a battery. How do you connect the battery to the engine? What? A 12V battery is too much?
Ah-ha, the prop needs to be tightened in a certain position to make it possible to start the engine.
Prime? What is that? How do I do it? How much?
Why do I have to move the tank this way and that, to make the engine run?
Fuel filter? But I put in clean fuel, so clean fuel should come out too, right?

And last but not least:
Honey, this plane smells good. Why can't I hang it from the living room ceiling?

Yep, you are correct.  But, it just didn't seem that far from something that we had already done, or at least the instructions told you what to use.   I was rebuilding automobile engines when I was around thirteen, and had already been long into sweat soldering copper pipe, and other "construction" types of work, etc., so an internal combustion engine was not something I wasn't at least a bit familiar with...  Now, the more advanced things like trimming a tank, etc,. are things that had to be "learned".  But then, those are more "advanced things".