Charging LiPos inside the model
 

Most electric RC "pundits" will tell you to never to charge LiPos inside the model.
However, in reading electric conversion articles by Greg of www.gregcovey.com I see that he often charges his LiPos inside his airplanes. I get the impression that he is a very knowledgeable guy regarding these matters, so Iwas just wondering... Any comments onhis charging methods?</p>

RE: Charging LiPos inside the model
 

There is nothing wrong in charging the lipos in the plane, it will not cause the lipo to explode. That is a fact. The only issue would be, in the event that a failure happens during charging then you are giving the flames more fuel to burn. Canopies, cowlings are very flammable and not to forget the ply/blasa of the fuse. :) Its rare that a lipo will burst into flames during the charge cycle but it has happened before. Is it worth the risk? You got to decide on that. Family v. hobby inconvenience.

RE: Charging LiPos inside the model
 

When taken out of context, anything can seem more dangerous than it really is.

The assumptions when charging LiPo packs in a plane are as follows:[ul][*] Common sense is required.[*] Use a safe balancing charger like the FMA Cellpro series. [*] Access to the balance charging plug on the LiPo pack is required.[*] Use an Arming Switch to disconnect the ESC from the pack when charging.[*] You are at the field charging in an open area, not at home with your family.[*] You do it only when needed, like in a scale plane that has no real access to the packs (e.g. TWM Ultimate, H9 Corsair)[/ul]
The goal here is to balance safety with necessity. There are some beautiful scale models designed for glow engines where the fuel tank is buried inside the fuselage. When converting these models to electric power, providing easy access to the battery packs sometimes requires a significant amount of craftsmanship to cut a hatch while retaining the required strength in the fuselage. I have found it easier to install the batteries prior to a weekend event and keep the plane assembled until packing up.

RE: Charging LiPos inside the model
 

I have a handful of foamy planes. I take the battery out to charge. Not because I think it will burst into flames, but because I put a charged one in so I can fly while the other battery charges.

I have (2) planes I charge the battery in the plane. I have to take the wing off, unplug the ailerons, flaps, then undo the straps holding the battery. Total pain. I can reach the plug in the cowl, so I charge it that way.

Only problem I see, is "IF" and I do mean "IF" something happens and I need to pull the battery quick, I can not get to it.

I had a problem with my 60 sized trainer I converted to "E" power. I have (4) 2650 3s lipos, I connect them for a 5300 6s configuration. Well, being a human, I plugged one of the (3) "Y" harnesses in wrong and melted (2) of the lipos. They were under the hatch in the nose of the plane, so they were a little easier to get to. If they had been in a plane with the wing on, plane would have gone up in flames.

We can cause anything to go wrong if we loose focus for just a second. I have changed the way I plug the harnesses in so I do not think I will make the same mistake twice.

Buzz.

RE: Charging LiPos inside the model
 

So, what exactly is 'Common Sense' as it applies to this thread ... and does it make any sense to add any protection circuitry(fuses?). Here's my 2 cents of common sense.

There is no problem charging through the discharge connector at a charge rate of even 1.5C as long as one understands the mind/unique chemistry and bouncing voltage levels during charging of say a series wired LiPo, and at least has an inexpensive cell checker. In fact it is actually better to charge through the discharge connector for a couple reasons. For the most part balance charging through the smaller white connector is for those that don't really understand the unique temperament of a LiPo, believe everything they read, etc, etc, etc, etc, and etc, etc. and twinkling red and green Christmas lights give them a warm cozy secure feeling.

If a LiPo can withstand a continuous discharge rate of at least 12C, then it can certainly withstand a charge rate of 1.5C or even higher when charging via the discharge connector. The idea that one has to charge at 0.80C is only necessary when charging a BIG BERTHA LiPo through the balancing connector with its smaller wire size. And then depending on how big BIG Bertha is, even an 0.80C rate through the balancing connector may/IS TOO high of a rate.

Better to always charge through the discharge connector. Even though some may consider this unbalanced charging it is still balanced charging because the cells are wired in series. It is only unbalanced charging if you don't have quality lipos, lipo isn't relatively balanced after restful recovery nap, don't have a cell checker, discharge to LVC of 9.0v instead of 9.5-9.7v(3S-3.2v per cell) or 12.0v instead of 12.8v(4S-3.2v per cell), and believe everything you read, etc (and a couple other reasons).

Charge my relatively balanced 3S lipos (only after restful nap) to 12.55 volts through the discharge connector at 1.5C charge rate. Then top off each cell individually via the balancing connector at no more than 2 amps until they each have filled capacity to 4.2 resting volts.

Would you charge a 3300mAh capacity 3S LiPo at a charging rate of 1C (3.3amps) via the small wires of the balancing connector ... BOOM !

...edited (clarify LVC for 3S & 4S)

RE: Charging LiPos inside the model
 

To charge through the battery discharge plug we must be able to disconnect it from the ESC? Right?
That being case, assume the following:

A 6S, 4900mAh MAIN BATTERY.
An arming switch/plug is installed between the battery's discharge plugand the ESC. This plug is mounted on the outside of the fuselage
A separate 6v RX battery.
A a switch for the RX battery is installed onthe outside of the fuselage.
We are going to charge the MAIN BATTERY through the discharge plug.

In the above case, if we plug our charger into the arming switch/plug doesn't that mean that the ESC is stil in the circuit?
So in this case how do we disconnect the ESC from the battery? Do we need a second plug for charging, or what????

RE: Charging LiPos inside the model
 

More on my above question:
If we turn off the RX battery switch, what effect would that have on this charging system?</p>

RE: Charging LiPos inside the model
 

Maybe a DP/DT(or whatever is safest/best) toggle that's recessed(with visual/literal indication which way is which) so as not to be accidently switched during flight with a UFO close encounter. Maybe even a green light for arming(charging) and a red light for flight ready. OR would it be the other way around :eek:

Where there's a WILL there's a WAY.

edit ... after spinning my gears me thinks little red light for arming and green light for flight ready ... ya [8D] betcha!
... think Lucky Lindy would be much impressed with a timely article by you as well as every reader.

RE: Charging LiPos inside the model
 

Swift, I think you have already guessed that such an article is already in the making.
May we quote some of your comments?

RE: Charging LiPos inside the model
 

Swift, I think the red light (stop) and green light (go) would be fun.
However, we don't want to over complicate things for the reader.

RE: Charging LiPos inside the model
 

Swift, 5 feet lower or 50 feet less runway and Lindy would not have been so lucky.

RE: Charging LiPos inside the model
 

... ya~betcha (just in case you need a scapegoat)

... but even gas/nitro Harley motorheads like to show-off their Pride&Joy with a few extra touches.

... sounds like the title of an article or a Johnny Cash song.

Bottomline: More than a few of your readers will still be thinking … who in the world would bury their expensive LiPo batteries in the belly of a whale(accessibility, accessibility, accessibility ... or is it location, location, location). You need some pretty good justification.

For example is there really any good reason why accessibility shouldn’t be a *TOP conversion priority from nitro to electric ((or *bottom ballast(below main wing CG) accessibility is OK)).

So, my 2 cents is add a little “Click&Clack” humor into your article. That was what I was doing with my DP/DT toggling. Maybe, the title could be “To Toggle or Not To Toggle” [8D]

RE: Charging LiPos inside the model
 

Yup. They're still going to need to be able to get that battery in and out for inspection and/or service.
Something to keep in mind.
By the way: What has California got to do with it?

RE: Charging LiPos inside the model
 

So noted ... removed comment.

Howard Hughes was an unappreciated genius(whether movies or flying machines). Did it his way which was usually successful even though his critics were quick to belittle him. An example of American ingenuity if there ever was one ... i'd put near or at the top of my list.

Use this opportunity to write a unique article that some may at first glance question ... but on reading ... come away with an appreciation that there is justification for doing your own thing ... and hopefully for good reason ... if only for the joy and satisfaction that it's my plane and my free choice. God Bless America!

RE: Charging LiPos inside the model
 

Yes, but Mr. Hugheswas terribly wasteful of women.

RE: Charging LiPos inside the model
 

And they could be terribly wasteful of men.

Have you checked out Goose’s build photos of his H9 F4U Corsair build thread http://www.rcuniverse.com/forum/m_84...10/key_/tm.htm
or
his TWM 27% Ultimate assembly
http://www.rcuniverse.com/forum/m_84..._1/key_/tm.htm

Between WF, RCG, RCU threads and googling you should be able to find a lot of good info and a ton of photos. What size/range in flying weight do you envision as best application for your inside charging quest article.

RE: Charging LiPos inside the model
 

My first hand experience while charging a small lipo inside a model. The battery started to smoke then caught fire. Second time a friend charged a small lipo in side a glider.It too caught fire and partially burnt his camper. There are not any real protection with lipos. Use a fire proof container.We learned the hard way.

RE: Charging LiPos inside the model
 

Hi guys

I see no problem in charging lipos inside the model.

Very easy. Don't buy cheap.
Cheap is beautiful is not a clever thought when purchasing lipo packs.
Most people just see the price, but never consider why there is such a big price difference.
You could buy for example a brand 30C 6S 5000 pack for 300$
or you buy a no name pack from HK also with 30C 6S 5000 for just 60$.

One of the reasons for the price difference is testing.
Here is a list of testsa german vender runs for his offered lipos:

38.3.4.1 - Test 1: Altitude Simulation
38.3.4.2 - Test 2: Thermal Test
38.3.4.3 - Test 3: Vibration
38.3.4.4 - Test 4: Shock
38.3.4.5 - Test 5: External Short Circuit
38.3.4.6 - Test 6: Impact
38.3.4.7 - Test 7: Overcharge
38.3.4.8 - Test 8: Forced Discharge

If acell starts burning or even explodes it is rejected.I don't know if every brand manufacturer runs these testson their cells, but cells of dirt-cheap offersareinmost cases
not tested at all. In europe its a matter of fact thatuntested lipos areprohibited for selling.Butsmall,mostly asian, manufacturers ofcheap cells often just have one certificate
for onesingle kind of cell. This certificate is transferred for every other cell in their offer without further testing.

Anotherreason is the label on a pack.
Everbody can write "30C 5000mAh" on it, butis this pack really capable to deliver the power?
I experienced that it is not. I bought once one of this "togood to be true" offered packs. And it said indeed "30C 5000" on its label. But during flying iwas wondering why myplanes power brokein
after just2 minutes. With my old pack i used to fly for up to 8 minutes without any perceivable lack of power.
After about3min i decided to land just to realize that the 6s pack wasalready hot. After cooling down and recharging it again, a friend of mine measured itstrue power.
We experienced that if the load goes above 80A, which corresponds to only 16C, thevoltage of every singlecell dropped toabout 2.5 volts or even less.The pack voltage broke in to
about 15V.On a fully charged pack of course. The pack became really hot. I never measuredits true temperature, but it was too hot to touch.
I rejected that pack and never bought one ofthese cheap crap packs again.

Just buy a good quality lipo pack and charging inside the model should neverbe a problem.
I just would check the temperature ofthe pack after flying andduring charging.

Regards
Anderl

RE: Charging LiPos inside the model
 

Anderl7890 is right. If you buy quality Lipo packs and treat them as recommended by the manufacturer, the fire hazard should be no greater than when we put petrol in our cars, lawnmowers, strimmers etc, when you can guarantee that somewhere near the filler neck there will be a stoichiometric mixture of air and petrol vapour. Yet I've never seen anyone taking precautions when refuelling their car. In my full size flying days when I was re-fuelling my aircraft, I always connected an earthing line first. I address 'Lipo hysteria' by always buying Thunder Power packs, I use a charger on which I can manually set the cell count, I never draw the maximum 'C' stated, and I am only just coming round to charging at more than IC - and yes, I charge packs in the 'plane - and when doing so I keep an eye on things. In all my years of using Lipo's I have never had an incident, or a problem. Plenty of my fellow flyers have 'tho, and invariably the cause is cheap pack / cheap charger / sloppy handling.

RE: Charging LiPos inside the model
 

I agree with everything you say. However, Iam really curious as to your preference for the very expensive Thunder Power packs. You see, I do NOT believe that you always/only get what you pay for.Oh how Iwish that were really true! But distributors ofover-priced products justlove it when people quote thatol' worn-outbromide.Now, fanackapan, Iam not saying that you said that. But Iam curious as to why you believe Thunder Powers to be better than less expensive batteries. Perhaps you know something about the Thunder Power chemistry or construction that isbetter than and/or /different fromothers?If so, please tell me. NoLiPos are made in the USA. The cellsare made inChinaall using the same equipmentbut sometimes assembled into packs here and name branded by the assembler. Others are assembled in China and shipped already brand named. Nearly all the Chinese manufacturers getthe sameingredients from the same suppliers.The only place where a difference can be realized isin the quality controlexercised by the individualChinese manufacturerlike room temperature, humidity, final inspection, etc. Your thoughts would be sincerely appreciated.