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Aug 27, 2010, 09:53 PM
Registered User
Discussion

Light weight lipo battery choices.


I've been looking for a very light battery for the mini dlg.

I have a microstamp 4l, and will be running two micro servos.

The 4l says up to 8v. Can I run a 2s lipo without needing a regulator?

I see people use cr123 batteries and stuff, but I'd like something more plug and play noob friendly.

Are there any setups around 10g?
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Aug 27, 2010, 10:41 PM
Magicsmoke maker
Inflexo's Avatar
It really comes down to the servos in the end - as receivers all have their own built-in regulators which should cope with 8.4V no problems.

If you use 6V rated servos on 2S you'll likely burn them out fairly quickly.

( A miniature regulator with alarm (LEDs) is 2.9g, less if you remove the heatshrink and shorten the wires http://nqrc.com/?vp=PLD-BAC-MINI )

What size servos were you planning on using? 3g ~4g ?
Aug 28, 2010, 02:14 AM
Stuart
srnet's Avatar
Well CR2s are way heavier than 10g, a two pack for around 6V is 24g.

The microstamp will work down to 3V I believe, so why not use servos that will work on a single Lipo, no need for a regulator then.

I have used the 3.3V version of the 2.5G Blue arrow servos in a small 2-3oz glider, and they worked well enough. Even the 5V version of the 2.5g servo worked, all from a single Lipo.

Plenty of small single cell Lipos available very cheap in eBay, they are popular for small helicopters I believe.
Aug 28, 2010, 03:32 AM
Registered User
these are single cell at 5 volts with chger http://www.hyperflight.co.uk/product...s+%26+Switches




http://www.xe.com/ucc/
Aug 28, 2010, 03:45 PM
Registered User
MarksRC's Avatar
Dymond D47 servos have an operating range of 4.8 to 9.6 volts and I run two of them with a 300mah 2S 7.4v lipo pack. Pack weight is 19.7 grams. Electrifly P/N GPMP0700.
Aug 28, 2010, 04:28 PM
Throw it like you hate it
RCPC's Avatar
there are packs out there that are about 10gr but you will likely need to make them yourself. Its not hard, but you need to know how to solder and how Lipo handling procedures (i.e. just respect them and they will not blow up.)

I made a 2s pack for a mini DLG from the 300mAh cells and it worked great!

http://www.all-battery.com/li-polyersinglecells.aspx

Paul
Aug 28, 2010, 09:17 PM
Magicsmoke maker
Inflexo's Avatar
It's a good thing that more and more servo makers are giving us units that can cope with 2S lipos directly. Soon we can do away with regulators and only need electronic switchjacks and low-voltage alarms.
Aug 30, 2010, 12:43 PM
Registered User
David Forbes's Avatar
I've used various of these http://www.all-battery.com/polymerli...h461540-1.aspx just pick one with the right form factor, right now I'm using this one http://www.all-battery.com/polymerli...mah602025.aspx just be sure to not get the protection board, better to toast a $5 battery than your plane.
You don't need 2s for D-47 and a Berg 4L. I can fly for an hour with a 4L and 4 D-47s and put about 60mA back in the pack in my full house 40" DLG. Keep track of flight time on your transmitter.
Dave
Aug 31, 2010, 06:17 AM
Registered User
buildscapeinc's Avatar
I will second that, just fly a single cell lipo. With a Berg and 2 D47s you will have no problem doing so. I have had 3 dlgs now with this setup and it works great. Plenty of flying time and the set up could not be more simple.....no voltage or regulators to worry about and ridiculously light.

Good luck,
Brian
Sep 04, 2010, 02:22 AM
Stuart
srnet's Avatar
Quote:
Originally Posted by registerwing
Well unless they do a version that allows you to use your own battery, those are not as useful as they seem.

If you always have a spare plane to hand, one flying and one charging then fine. But what do the majority of us do when do when the inevitable happens and you turn up at the field with your one plane and find your battery is flat ?

I do use one of the PLDs to charge my lipo (2S 350mahr) whilst its in the plane, but I also carry some spare and charged Lipos. These spares cost around 6, but a spare SmartLipo is around 5 times that sum.

Now if you could buy one SmartLipo device and plug your own batteries into it, that would be really really useful, especially as all you need to charge would be a 5-15v DC source. Such a device would be a real winner.
Sep 04, 2010, 02:29 AM
Stuart
srnet's Avatar
On the subject of RXs that will work at voltages other than the standard 4 cell NiCd\NiMh pack or 5v from an ESC.

Does anyone know of full range receivers for 35Mhz that will work from either a single 1S Lipo or a 2S lipo pack ?

The Berg 4L appears to only available for 72Mhz.
Sep 04, 2010, 02:30 AM
Magicsmoke maker
Inflexo's Avatar
srnet,

Are you spying on my developments?

I've got onboard a 1S lipo boost regulator + integrated charge controller (though to be honest it's really more for a 5V input, not 5~15V, it's designed around being charged with a USB connection). What I've not finished deciding on yet is if I should enlarge it more and add a voltage-readout / audio-alarm to it... the trouble is as mentioned, is that the size increases along with weight and of course, the one thing we all hate, COST :\

Paul.
Sep 04, 2010, 04:32 AM
Stuart
srnet's Avatar
Well you could design the PCB as longish and thin, with the piezo, and possibly the resistors and parts associated with a Vref at one end, so that part of the PCB could be snapped off for those that want a smaller\cheaper\lighter unit.

But a LED in any case, SMT ones dont add much space and add to the feel good factor when they flash reassuringly at power up.

And of course keep it as light as possible, so the range of applications would depend mainly on the particular choice (and weight) of Lipo.

5v charging is OK, but 12v is better since most of us will have 12V handy in the form of the battery in the vehicle. Although I can see the attraction of 5V, less power dissipation to contend with, but on the other hand 5V USB power adapters to plug into a vehicles cigarette lighter socket are only 2 or so.

Good luck
Sep 10, 2010, 11:37 AM
Registered User
captsteve's Avatar
Do any of you guys have any experience or thoughts on these servos?
I want to make a gladiator as light weight as I can.

http://www.hobbypartz.com/exi-servo-s0820.html

Thanks,
Steve
Sep 10, 2010, 12:05 PM
Stuart
srnet's Avatar
I have tried quite a few of those generic type servos, they look similar to the so called 3.7g ones you see on ebay. All of them have been a gram or two heavier that the claimed weight. Not very smooth and they chatter to much for my liking.

I have fitted diamond D47s in both my Gamblers, they are 4.86g.

I use them in a pull string control and they are far better than the heavier HS45HBs they replace.


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