$8 battery pack ?

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$8 battery pack ?

Postby quarry44 » Fri Nov 18, 2011 6:49 am

I'm just wondering what size cable to use on this pack.Could i use,say,14g with an xt60 connector,plus a normal servo type cable to the rx?I thought I might be able to use the xt60 to charge the pack with my accucell.I do have a banana-to-servo socket set from my old volt checker,but I wouldn't like to put too many amps through that.
Also,is there any benefit to having a balancing lead on a 2 cell pack?I bought the Trustfire ones Bruce showed in the video.thanx peeps.
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Re: $8 battery pack ?

Postby quarry44 » Sat Nov 19, 2011 5:03 am

Hmmm,I've just realized these batteries I bought say"lithium-Ion",3.7v.
Have I bought the wrong ones?I measured one of the two packs I made up,and before charging it already shows 8.1 volts.This can't be good for my Turnigy rx,can it?
I'll take a pic when I've charged the camera.
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Re: $8 battery pack ?

Postby FlyingTiger » Wed Nov 23, 2011 10:11 pm

I'm looking for a definitive answer on how to set my radio with the $8 battery mod installed. I first set it up using the resistor and just let it go as is was. But now I have installed ER9x and I have the ability to calibrate the voltage of the pack and set the low-voltage alarm to whatever I desire. The Trustfire batteries are 3.7v each, so I figure full voltage on a fresh charge would be 8.4v like my 2s Lipo packs. Right? Then, for low voltage alarm, the alarm point should be what? 7v? 6.6v? How low can I safely go?

Thanks for helping.

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Re: $8 battery pack ?

Postby quarry44 » Wed Nov 23, 2011 10:59 pm

I'm looking at the same thing.I think we should stick at a minimum voltage of 7.6v.The nominal voltage per cell is 3.7,so 7.6 gives us a 1volt buffer over dead flat?
Mine arrived pre-charged,and after assembly,1 pack read 8.1v,the other7.9.
Perhaps Bruce or someone else can chime in here and point us in the right direction.
It's a while since I viewed the video,and now I can't find it :( .
Btw.,I should have typed TX pack,not rx :oops:
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Re: $8 battery pack ?

Postby ergocentric » Thu Nov 24, 2011 12:52 am

I believe the $8 battery mod referred to the transmitter pack, not the receiver.

http://rcmodelreviews.com/tendollarbattery.shtml
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Re: $8 battery pack ?

Postby pldb64 » Thu Nov 24, 2011 1:51 am

Found the website write up http://www.rcmodelreviews.com/tendollarbattery.shtml ... couldn't locate teh video though.
Turnigy 9x, FrSky 2-Way/Telemetry DHT DIY, Smartieparts BRD, ER9x FW
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Re: $8 battery pack ?

Postby BillGriffiths100 » Thu Nov 24, 2011 9:31 am

Hi,
My experience with this pack is that it shuts off completely suddenly below 7 volts (it's got a built in protection circuit).
So set your alarm at a very minimum of 7.2 volts and take it seriously, or instantly you'll have nothing.
The behaviour of this battery is a bit alarming in a RC transmitter, it's also a chore to keep opening up and putting the battery on charge.
For this reason I have reverted to using 5 nimh cells (Uniross ultra) that use the new keep their charge technology, they aren't that expensive and they don't suddenly leave you powerless! In a 2.4 GHz set you don't need a voltage much over 5 volts allowing for the drop in the voltage regulator 5.7 will still run everything perfectly well. Excess voltage is used to heat the regulator.
The 9x with the frsky conversion runs at 5.5 with no problem (switching regulator). The original flysky (turnigy) tx module uses a linear regulator and that needs about 6 volts to keep running OK.
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Re: $8 battery pack ?

Postby quarry44 » Thu Nov 24, 2011 8:34 pm

Ok,how long did it take to drop to 7volts?As for the charging socket,there's nothing to stop you connecting the battery through there.I didn't because I put my programming socket in that area.
The Uniross appear to be the usual Chinese batteries rebranded.I don't believe their advertising blurb,there are too many words and not enough facts.
That said,you pays yer money and takes yer choice.It would be a dull world if everybody did the same thing.
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Re: $8 battery pack ?

Postby BillGriffiths100 » Fri Nov 25, 2011 9:30 am

A long time but I wasn't paying attention, I'll set the time on clock to zero next time I charge, I use a balancer for my charging and fast charge (that is an advantage of the life).
If you fast charge through the socket you probably need to remove a protection diode I haven't looked to see if there is one, if anyone's got their Tx open perhaps they could look and let me know.
I've been using the uniross for about a year with good results (also excellent in a digital camera), most things unfortunately are the usual Chinese re- branded stuff these days, be hard put to find something that wasn't! sigh....
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Re: $8 battery pack ?

Postby quarry44 » Fri Nov 25, 2011 9:02 pm

Bill,there is a protection diode.I can't remember if it was at the charging socket contacts,or at the battery socket.I didn't bother to remove it,since I've put separate plugs on my battery pack
I took a few pics,so here they are in no particular order:
Image

Image

Image

Image

You can see where i put the programming socket on the left of the battery tray.Not my idea entirely,I stole it from a mate's mate :mrgreen:

Sorry some of the pics are a bit fuzzy,I'm too impatient to wait for the camera to re-focus.
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