So if I was not qualified to talk about aeronautics in my post "Driving Versus Flying", I am even less qualified to talk about electricity. I know enough to know that when you throw a light switch something comes on, and that's about it! Which, I would imagine, describes a lot of you who are just getting into RC airplanes...you want to learn about planes, not electricity, right? And yet, since we fly electric planes, suddenly we are confronted with volts, and amps and mAh (milliamp hours), and C ratings and connector types that read like alphabet soup, and battery types like lithium polymer, nickel cadmium, and on and on. It's overwhelming to guys like me that know nothing about electricity BUT YOU NEED A BATTERY TO FLY THE STINKING PLANE!
So, here's what I do know. As I said, I have Park Zone warbirds, and they all fly on 11.1 volt, 3 cell, 2200 mAh, LiPo (lithium polymer) batteries (actually, my original planes came with 1800 mAh, but my most recent plane, the Thunderbolt P-47, came with a 2200). Lithium polymer batteries are the type that most foamies use. The ones that came with the plane were 25C rated, which, when I asked the guys at the hobby store, has something to do with the volume of electricity that can be released in bursts when needed. The higher the C rating, the more energy can be released. The batteries I had were fine, but being a guy who wants to have the best of everything I opted for 30C batteries after that, and have been happy.
Now there are a lot of battery brands out there, and I found that our local hobby store didn't have much on hand. I'm guessing they decided they couldn't compete with the online market, which are almost exclusively made in China. What little they did have were very expensive.
So then I researched brands by looking at chat groups like www.rcgroups.com, and checking out recommended sites for batteries and accessories like Hobby Partz (www.hobbypartz.com) and Hobby King (www.hobbyking.com). I'm sure there are a million sites and brands and the best suggestion I can make is to talk to those who fly a lot and get their recommendations. Nothing beats real endorsements from those who fly and recharge a lot of batteries.
Price is not always a way to determine anything....cheap batteries can have good reputations and expensive batteries can be lousy. I personally have settled on Gens Ace as a battery I have had good success with and it is the middle price point at around $26 from Hobby Partz. I also hear good things about Turnigy, have a couple that have worked well so far, and you can get those at Hobby King for about $12.
Another thing to consider is the connector type. There seems to be no agreement as to a standard connector for ESC's (the electronic speed controller your battery connects to which then connects to the motor) and the manufacturers of batteries. So again, not being inclined toward things electric, when I get a battery, I have the local hobby shop cut the connector off and solder on the EC3 connector that Park Zone uses, as that is what all my planes are. Some of the sites I mentioned have adapters that will get you from the battery connector type to what your plane requires, and that is a cheaper fix.
Now the next thing you have to deal with is charging your battery. The Park Zone batteries came with a charger that you plug into a cigarette lighter (so you can charge while at the field). There is a dial so you set the amount of volts, and a switch to select the number of cells, and off you go. Well having my charger charging in the car out in the driveway with the ignition turned on was not working for me, so I went shopping for a charger that would work off AC, and I could just plug in at my work bench. Surprisingly few chargers had this feature...most required an external power source, as they were primarily designed to be adapted to car batteries and other sources in the field. Again, a frustrating amount of choices and lingo that you have to learn in order to just get a charger. The one main term is "balancing". You want a charger that balances the cells equally (and hopefully lets you monitor each cell's progress), and that is apparently not a "given" in battery charger option land.
The same sites that have batteries have chargers, and through the recommendation of some guys I was flying with, I went with the Thunder AC6 ($43.95 at Hobby Partz). It can charge up to 6 cell batteries (something I had no idea I would ever need, but I was learning to try and think ahead) and several battery types (which has proven to be very helpful as I not only charge LiPo, but now am getting into glow planes where I need to charge the nickel cadmium on-board battery as well as the 12 volt battery that I use for the starter. There are chargers that charge multiple batteries at a time, and I thought about that, but the added expense was not worth it to me. Again, it will take research and talking to a lot of folks, but eventually the lingo begins to sink in, and you become somewhat conversant in what you want. I still don't understand how it works, but I know what to buy.
My charger has been a real workhorse! It has a mode where I can see the individual cells charge, and I can determine if there is anything irregular about the balancing. It came with several cables which I have adapted for different uses, and again, I can just plug it into the wall socket and go!
Now here's an important point....BATTERIES ARE DANGEROUS! Just check out You Tube at look at the videos of batteries that have caught on fire while charging, or after flying, or a crash! We had a guy at our club charging off his car battery and the battery exploded, his car caught fire, and part of the covered staging area burned down! So remember....1) get a fire extinguisher, 2) you should be present (or in the vicinity) when your battery is charging, 3) you should charge them in a special battery bag (a fire resistant bag that retards an explosion or fire), 4) you should store them in something fire proof (I use an ammo can with holes drilled in the top to release any gasses), 5) DO NOT charge them too fast, 6) be sure to disconnect the battery immediately after flying, and 7) disconnect the battery as soon as you can after a crash! Something about impact makes the battery more unstable.
The general rule of thumb is you can charge your battery at an amperage rate of 1C, meaning 1 100th of the mAh. So if you have a 2200 mAh battery, you can charge at 2.2 amps. I was doing that for months, and finding that with relatively few charges, some batteries were swelling and puffing up....a sign that they are going bad, and I tossed them not wanting to take a chance. Think about it...with an electric plane if you lose your battery, you not only have no power, but you lose control of any maneuvering! No control of anything! There goes your plane over a $20 battery! It just isn't worth the risk!
Then a very experienced friend at my club heard me talking about this and asked what rate I was charging at. He said I was pushing them way too hard. His recommendation was that I should be charging at .8 amps, not 2.2! Well that takes up to 90 minutes to 2 hours per battery to recharge, but I will tell you, I have never had a battery swell on me since. Apparently if you want to get a lot of life out of your batteries, they will respond to slower charging rates and last you much longer! Again, being on a budget, that means a lot to me! SLOW CHARGING IS YOUR FRIEND!
As I said earlier, I am just now getting into the world of glow engines and planes, and that is a whole new learning curve in itself. I'm having fun, but it is very different. There is something incredibly simple and pure about plugging in a battery and flying! Not to mention the quiet! One of my favorite times to fly is early in the morning, before work, and the sun is rising, the birds are chirping and I'm all by myself flying my "bird" in absolute silence! It is the best!
Don't forget to set the timer on your radio so that you do not over extend your batteries. Start by setting it conservatively, and then when you re-charge, see how much you have put back into the battery. That will give you an idea how much flying time you can increase your timer by. You never want to go beyond 80% of the mAh of your battery, so again, on a 2200 mAh, you should not be recharging more than 1,760 mAh. I have accidentally done it, and done it bad, but when I do, I recharge, make sure the cells are balanced, and then make a note of the battery (I put a piece of tape with numbers on the bottom of each battery for I.D.). When I fly that battery the next time I only go about half the normal flying time and then recharge again. Usually all is back to normal.
You will also find that the amount of drain on your battery depends a lot on how high your throttle is, and for how long, the types of maneuvers your are doing, how high the wind is you're flying in, etc. You will begin to get a feel when you know you are pushing your battery harder and need to cut the time shorter, as opposed to when you are practicing approaches, and coming in at low throttle a lot and not using much power.
My apologies to those of you who know more about electricity and find this sophomoric! If I have made any gaffs, please leave a comment and I will edit! But again, I'm writing to those who are like me, and trusting there are a few of us out there!
Okay, so there's what little I know, and a whole lot that you are going to have to figure out for yourself, but hopefully I have narrowed the field of questions a bit. I think next time I'll discuss repairs....glues, epoxies, sanding, painting, balancing...how to turn those gut wrenching crashes into a resurrection!
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