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first timer/battery chargers

#1
So i bought my first rc plane yesterday, i flew on a sim at the hobby shop for about 20 minutes, and thats pretty much all the experience i have in the realm of rc planes.
I bought a firebird stratos, was going to go with the champ originally but i decided the stratos might handle the wind here better. I took it out after work today and tried to get it up in the air but the wind was probably 10-15 mph and changing from eastbound to northbound, to keep it short i crashed twice on takeoff and broke a prop cone off the 2nd time (but i hot glued it back on so were good!). But boy when it actually got off the ground that was a rush.
Now that my story is out of the way, the geniuses that built the plane put a car lipo charger in it to charge the batteries, which is great if youre out, but leaving your car keys in your car for an hour unattended and draining your car battery is not, so i am looking for a lipo charger. Im not even sure if i need specific chargers for specific batteries. In any case the batteries are 2s 7.4v 1300mAh. Im also looking for something on amazon since i have amazon prime and hopefully under 50 bucks. Though any sound recommendations are welcome.
 

Craftydan

Hostage Taker of Quads
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#2
Two options:

Simplest - get an AC -> 12v adaptor with a ciggerete lighter adaptor. they can be had for cheap, but current may be an issue. Don't know how much draw your charger needs/wants, so it's hard to spec, but at a 1c charge rate(diffrent form the discharge rate your battery specs), you would need about 1.3A. If it charges faster (it might), you'd need more. If HH's charger is any good (probably is), giving it less current available will just lengthen the charge time.

This one, at 7A, will definitely work.

This one, at 1.0A, might or might not.

The price difference is $15 or $2. There are also MANY other models, so look to balance current and price (and stay away from those that don't spec current).

Possibly better long term -- look for a Lipo Charger. Yeah, there's too many to pick from, and I'm not going to be super-helpful and pick it for you. there is a WEALTH of threads here and elsewhere on charger brands and why person A loves charger X,and MANY reviews out on the web. take the time to read them. in doing so, you'll learn the technology, care and feeding -- these batteries are *trouble* if not treated right -- and probably be farther along to know what size of batteries you'll be charging to know the ugly "how big of a charger" question.

My advice keep the one you have, buy an adapter, and research to get one a plane or two down the road.
 

pgerts

Old age member
Mentor
#3
If RC is something for you then you will buy a "smart" charger with a display. There are combined chargers to use from AC at home and from your car battery when out at the field. Another thing is to open the hood of your car and connect directly to the battery not to drain the car because of all drain you get when the car key is activated. You wil find several chargers like that for <50. Most of them are same inside but different color and button design.
 
#5
How do i know what is compatible with what? My charger says that it has a 1.5 Amperage charge rate, does that mean i need an adapter that is exactly 1.5 amps or is rated at above or below that? Im just trying to keep my batteries healthy.
 

Craftydan

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#6
Sorry Vicissitude, didn't mention that the current rating on the adapters is the max they'll provide and still give a steady regulated voltage. It's a standard, but it's rarely explained.

If your load (the charger) only needs 1.5A, but the charger is rated to 7A, you're just fine -- the charger will only draw the current it needs. Now if it needs 1.5A, but the adapter can only provide 1A, the voltage will drop below the rated 12v and one of a few things will happen:

- the charger could run more slowly (good design)
- it could stop (not as nice, but still good)
- it could freak out and get confused and all bets are off (very bad)
- or the adapter could burn out (not as bad, but you're stuck with a burned out supply)

I wouldn't want any of those, so pick an adapter with a little margin. A 12v, 2A+ adapter should be easy to find and still be cheap.

Also, keep pgerts advice in mind -- take care if charging from your car. Watch it charge (be very nearby - Lipo fires do happen), keep it out of extreme heat, and consider running your car, at least a few minutes after/during the charge -- a 1300mah charging at a 1C rate (1 hr charge time) won't drain your car battery immediately, but it is hard on them. Use the AC adapter as often as you can.
 

colorex

Rotor Riot!
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#7
How do i know what is compatible with what? My charger says that it has a 1.5 Amperage charge rate, does that mean i need an adapter that is exactly 1.5 amps or is rated at above or below that? Im just trying to keep my batteries healthy.
You stated you have a 2s 7.4v 1300mAh battery. This means that the recommended charge rate is 1.3 Amps. Charging at 1.5 is a little bit above recommended but is unlikely to damage your batteries. With the charger I posted above you can charge at 1.3 apms, 1.5 amps, or whatever you want. You can set it up to almost any battery - even NiCd, NiMh, or car batteries!
 
#8
You stated you have a 2s 7.4v 1300mAh battery. This means that the recommended charge rate is 1.3 Amps. Charging at 1.5 is a little bit above recommended but is unlikely to damage your batteries. With the charger I posted above you can charge at 1.3 apms, 1.5 amps, or whatever you want. You can set it up to almost any battery - even NiCd, NiMh, or car batteries!
I have an eflite, which looks to have an ec2 connector. That webpage you linked is really vague on what kind of connectors it comes with so i have no idea if it will work with what i have. All the reviews i read on it were dated.
 

Craftydan

Hostage Taker of Quads
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#9
If you choose to go the route of new charger (not a bad decision, but you'll have to learn more sooner) the adaptor you'll need for Andre's (colorex) recomendation would be:

http://www.hobbyking.com/hobbyking/store/__25658__EC2_to_Banana_Plug_Charge_Lead_Adapter.html

Keep in mind, the charger you already have is set up to run without any settings changes. It knows it's a 2S 1300mah, and will charge it at a conservitive rate. Any generic charger you buy will need to be told this information (in setup), probably every time you charge, and most will want to know it in less than freindly ways. I'd highly recomend reading *and understanding*:

http://www.rchelicopterfun.com/rc-lipo-batteries.html

It's not long, and covers the bases well. If you have questions, ask. Batteries are our nessicary evil. Without them we'd be burning dinosaurs. They can be dangerous if mishandled, but safe as kittens if you take the right precautions.

Well, safe as fire breathing kittens.
 
#10
If you choose to go the route of new charger (not a bad decision, but you'll have to learn more sooner) the adaptor you'll need for Andre's (colorex) recomendation would be:

http://www.hobbyking.com/hobbyking/store/__25658__EC2_to_Banana_Plug_Charge_Lead_Adapter.html

Keep in mind, the charger you already have is set up to run without any settings changes. It knows it's a 2S 1300mah, and will charge it at a conservitive rate. Any generic charger you buy will need to be told this information (in setup), probably every time you charge, and most will want to know it in less than freindly ways. I'd highly recomend reading *and understanding*:

http://www.rchelicopterfun.com/rc-lipo-batteries.html

It's not long, and covers the bases well. If you have questions, ask. Batteries are our nessicary evil. Without them we'd be burning dinosaurs. They can be dangerous if mishandled, but safe as kittens if you take the right precautions.

Well, safe as fire breathing kittens.
I was hoping for some sort of write-up, thanks. Im studying to be an electrical engineer, so i am familiar with alot of the stuff, but some im not like mAh (which i assume is milliamps per hour, like watt hours). You make a good point for the adapter and i think im going to go with that for now. Though i like the hobby im probably not going to look at new planes until i break the firebird or get really good with it.
 

Craftydan

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#11
Vicissitude,

mAh is millliamp-hours (not per hour), and is more commonly used in battery powered systems. It's not quite the same as W-h, but similar concepts. W-h formally measures the "energy" capacity (or energy consumed), where Ah is a measure of current capacity for an unspecified voltage. Most batteries provide a near constant voltage, so the battery's average voltage can be used to convert between the two.

One of the reasons we'll use mAh instead of mWh is that most of the parts we use are't rated by watt tolerance, but amp tolerance. In that case, it's a more useful spec to use.

There's a lot to learn on both the flying and wiring side, and most of us are learning too. If you have questions, don't hesitate to ask!

And enjoy your Firebird for as long as it's running . . . then fix/re-enforce/mod it and enjoy it some more. Embrace the crash! Repair keeps you out of the air, but really can be half the fun of the sport.
 
#12
yeah the wind was great (nonexistent today). I did my first loops, but unfortunately it ran into a light pole. After alot of tape and hot glue have it in decent shape again, im sure at some point ill buy a new fuselage. Whoever designed the wings put alot of thought into them, they are well made and stand up great to crashes.