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 Post subject: RC Today Show 089: Charger Basics
PostPosted: Fri Sep 06, 2013 12:26 pm 
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Joined: Mon Jul 25, 2011 11:58 am
Posts: 4957
Location: Austin, TX
In this episode: Chris and Bobby talk about new products, a tragic heli accident, and charger basics. Oh, and don't forget about the MSH Brain Giveaway. Tune in!

http://wp.me/p2wnPS-hN

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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Fri Sep 06, 2013 11:33 pm 
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Joined: Tue Oct 16, 2012 1:18 pm
Posts: 179
Location: Nederland, TX
Post a link to the BBQ pit vendor in Hempstead.


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Sat Sep 07, 2013 6:27 am 
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Joined: Tue Dec 18, 2012 1:31 pm
Posts: 268
Hey when you guys get to power supplies next week - I just had a good experience buying a 1150W 24V power supply from solidhobby.com. Only $115. It's actually a pair of server power supplies which you could cobble together yourself. But Jeremy does the work of sourcing the supplies, dealing with any ground issues, wiring them, wrapping them in black monokote, and adding a power switch. He also provides support after the sale.

Just FYI. I starting going down the ebay server power supply route but for $115 it wasn't worth my time to do the research on how to do it right (or the risk).


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Sat Sep 07, 2013 9:35 am 
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Joined: Thu May 02, 2013 11:48 am
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jv8 wrote:
Hey when you guys get to power supplies next week - I just had a good experience buying a 1150W 24V power supply from solidhobby.com.


I'll second the need to talk about server power supplies. If needed I'll even get a source for directions on how to build a very high wattage 24vdc power supply for charging for very little money.

Thanks for talking about chargers.

Because how the RCTS community is promoting 500-550 class helicopters which use a 6S 5000mAh battery I thought it would helpful to walk through building a charging system for this battery.

My expensive and Hobby King LiPo batteries don't mind charging at 5C; they even cool while charging at this rate. Charging in 12 minutes (plus >5 minutes of balancing) opens the option of having two flight batteries, one charger, and swapping the flight batteries for almost continuous flying.

So what is it going to take to charge a 6S 5000mAh battery at 5C? For readability I'm going to call a 5000mAh battery a 5Ah battery (5000mAh / 1000 = 5Ah).

(4.2vdc full voltage x 6 cells) x (5C charge rate x (5Ah x 0.8 aka 80% discharged)) = 504 watts

504 watts / (4.2vdc full voltage x 6 cells) = 20 amps.

Ok so we know we want a charger that can output 25.2vdc (6S) at 20 amps (5C charge rate) which is 504 watts.

So now we need to supply the charger with power. Chargers are 85-90% efficient so to supply 504 watts out it is going to take 579.6 watts input (504 watts x 1.15 aka 115%).

Because deep cell batteries and power supplies are commonly available in multiples of 12vdc; let's look at what we need from a 12, 24, 36, and 48vdc power source.

579.6 watts / 12vdc = 48.3 amps
579.6 watts / 24vdc = 24.15 amps
579.6 watts / 36vdc = 16.1 amps
579.6 watts / 48vdc = 12.075 amps

I only know of one LiPo charger (iCharger 4010 Duo) that is rated to take 12vdc 48.3 amp input, but it is too expensive to recommend for this application. At 24vdc the input amperage is reasonable and there are a few " inexpensive" chargers that can take a 24vdc 24.15 amp input. Going to 36 or 48vdc input voltage is not needed unless dealing with maximum amperage limitations of the power supply or batteries.

They are probably more, but two well know chargers that are <$200 that fit these requirements are:

FMA Direct/Revolectrix Cellpro Powerlab 6

iCharger 306B

You have to buy charging & balancing board cables but deals can be found at Revolectrix's bargin tab for factory refurb chargers. I personally think people expect 1000watt output running off a 12vdc car battery, and when that doesn't happen they return the charger as being defective. Then it gets "refurbished" and sold for much less.

So, if you have read this far, to power the 500-550 class helicopter pick up a pair of Jame's favorite battery, a 24+vdc input 500+ watt output charger, and a pair of deep cell batteries and/or server power supplies, and fly almost continuously while charging at 5C.

$116.50 Pair of Zippy Compact 6S 5000mAh LiPo batteries
$160 Powerlab 6 or 306B charger
$100 24vdc 600+ watt Server power supply or $200 Pair of deep cell batteries

Total: $377 or $477 for continuous flying bliss. :mrgreen:


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Sat Sep 07, 2013 10:35 pm 
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Joined: Sat Dec 15, 2012 11:35 pm
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Location: Longmont CO.
I like the idea of having two 250 watt chargers and three batts that way I'm non-stop flying and if one charger goes up in smoke then I'm not completely dead in the water waiting for repair or replacement. The i-charger 106B+ is a good one, 24vdc 250watt for around $100.


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Sun Sep 08, 2013 3:04 pm 
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Joined: Thu Aug 25, 2011 9:14 pm
Posts: 1910
Location: Bryan, TX
Nice job with the show guys. I liked the different charging options and doing the real math of charger capabilities.

I also liked the talk about the heat in TX. I remember spending Sunday afternoons out in the stifling heat and taking several bottles of water with me to go flying. It's not quite as bad here in the panhandle, but the heat is having one last hurrah before it starts to cool down. On the flip side, things are just not starting to turn brown so we really can't complain too much about the weather here this year.

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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Mon Sep 09, 2013 8:30 am 
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Joined: Sun Jul 31, 2011 6:45 pm
Posts: 1550
Location: McKinney, TX
Those little satellite connectors are JST-ZH. If Chris was trying to use his servo connector crimper to build them, it's no wonder he gave up. I found a dandy crimper that works on all sorts of tiny connectors. The only downside is that you have to do two separate crimps: one for the wire and one for the insulation.

http://www.amazon.com/gp/product/B002AV ... UTF8&psc=1

Regarding using the Hobbywing RPM sensor with both the FBL unit and TM1000, I think what I'm going to do is pull the signal wire out of the HW sensor plug and crimp on a new contact with both wires inserted. There should be room for both wires, considering you can't go much above 32AWG with those JST-ZH connectors.

Telemetry has saved me some potential grief already. I flew with it for the first time Saturday and discovered that I had my BEC set to the wrong voltage for 18 flights. Instead of the 6V I wanted, I had the DIP switches reversed and was actually running 7.4V. I'm surprised my BLS251 is still working.

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Alan
Team Shannon (Only Fine Helis)
DT520E V2, Protos Max V2, Nighthawk 250 Pro FPV quadcopter
ParkZone P-51 BL, Hobby King Skipper


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Mon Sep 09, 2013 1:13 pm 
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Joined: Wed Jul 27, 2011 8:13 am
Posts: 1523
Location: Caldwell, TX
I will try to get a picture of how I am attempting to wire mine up tonight. Basically using the supplied "Y" harness that is supplied with the TM1000. I am plugging the single end into the TM1000's RPM slot with the red wire removed. I plugged the HobbyWing RPM sensor into one of the double ends on the "Y". Finally ran another cable from the other side of the "Y" to the Gov port on the Brain. We'll see how it works. Certainly would be nice not to have to purchase the overpriced Spektrum Brushless Motor Sensor.

I have a small crimper and never had much luck. Just read some instructions on how to do it properly. I think we will do a tech tip in the upcoming weeks on how to properly crimp connectors. Feel free to share info if anyone has any so that we can pass it along.

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DT Helis
Graupner USA


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Mon Sep 09, 2013 1:37 pm 
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Joined: Sun Jul 31, 2011 6:45 pm
Posts: 1550
Location: McKinney, TX
Bobby Barr wrote:
I have a small crimper and never had much luck. Just read some instructions on how to do it properly. I think we will do a tech tip in the upcoming weeks on how to properly crimp connectors. Feel free to share info if anyone has any so that we can pass it along.

The one I bought has little arcs at the bottom of the slots to loop the contact tabs inward. It goes down to 1mm width.

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Alan
Team Shannon (Only Fine Helis)
DT520E V2, Protos Max V2, Nighthawk 250 Pro FPV quadcopter
ParkZone P-51 BL, Hobby King Skipper


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 Post subject: Re: RC Today Show 089: Charger Basics
PostPosted: Mon Sep 09, 2013 4:10 pm 
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Joined: Sun Jul 31, 2011 6:45 pm
Posts: 1550
Location: McKinney, TX
Are you sure it was an electric heli that was doing the 93 mph hurricane, Chris? I seem to remember it being a nitro. Maybe that was a prior year.

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Alan
Team Shannon (Only Fine Helis)
DT520E V2, Protos Max V2, Nighthawk 250 Pro FPV quadcopter
ParkZone P-51 BL, Hobby King Skipper


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