Using LiPo's with the DX7

[SeanM]

I'm interested in replacing my stock battery that came with my Tx and I'm curious to know whether the DX7 can handle 12.6v. I'm looking at the Voltz 2500mah 3S Tx LiPo, but I've been reading that you have to be careful not to use in the Tx at more than 12v.. Is this true?

[th0rg0d]

Yes. The internal regulator is not rated for more than 12v. People still do, including myself. But it is not warrantied by HH. It also comes with most people being very much against it, due to the probability of your Tx failing in flight.


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[SeanM]

So the LiFe pack is the way to go it sounds like. Is there an adapter to convert the jr/spektrum plug to something else? I'm trying to figure out how I'm going to charge it... Or if I can just do so using the port on the side of the Tx. I have the charge lead to go from the Tx to the charger, so I was going to use that and then plug in the balance adapter with the pack still inside the Tx... Is there anything wrong with doing that?

[N017RW]

Not all would agree.

Replacing the OEM NiMhs with low self-discharge, higher capacity NiMhs (Eneloops) is another well accepted way to go. Maintains all of the warranty issues, similar shelf-life to LiPos, still uses OEM wallwart charger, no wear and tear on battery compartment door, less stress on internal components (3.3v regulator).

[Ron~FordTech]

Right off the hop, IMO it is unnecessarily risky to charge batteries inside a transmitter. Period.

Okay.

It depends which LiFePo4 you buy. The Hyperion has a red 4mm dual charge plug, and there is an available adapter that will allow you to balance charge it thru that [just like a LiPo] with a standalone charger as long as the charger has a LiFe routine in its EEPROM. (You'll need a Hyperion balance adapter unless you have a Hyp charger) You would also need the available 3" charge/discharge adapter to convert the dual 4mm red connector to the silly little white plug that the DX7 uses.

The 1500mAH LiFe pack from HK comes with the the silly white plug already attached...and balance charges thru a standard servo connector (an adaptor for which you may already have)

And to backtrack just for a moment...

HorizonHobby states (not suggests or prefers or warns) that the transmitter WILL fail, and the odds are that WHEN it fails, it will be when you are flying, and you run the risk of hurting or killing yourself, or someone else, and/or damaging nearby property.

[heraldo]

3s lipo + 2 0.7v diodes. Best combo


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[RCTada]

Go to radio shack and buy an 8 battery AA holder then buy eneloops AA NIMH from ebay. I love mine. I can even charge it with the stock charger.

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[srgiggles]

Originally Posted by SeanM

So the LiFe pack is the way to go it sounds like. Is there an adapter to convert the jr/spektrum plug to something else? I'm trying to figure out how I'm going to charge it... Or if I can just do so using the port on the side of the Tx. I have the charge lead to go from the Tx to the charger, so I was going to use that and then plug in the balance adapter with the pack still inside the Tx... Is there anything wrong with doing that?

I charge through the port on the side of the tx. Charging on A123 mode on my hyperion charger at 1.0 Amp. Make sure you get your polarity right on your charge lead. If you get it wrong, you blow a 3a fuse in your dx7 that is easily replaced, but still,

If you want to go the extra mile, setup the low voltage alarm on the dx7 using the system menu link to vid here ---

YouTube (Short URL)

YouTube (Short URL)

I based my cutoff for low voltage alarm based on the following from the great Creaky Cactus from these forums....http://helifreak.com/showthread.php?t=271405

The above link is important as it addresses charge limitations, low voltage alarm, burndown test, etc..Shout out to Creaky Cactus for this uber good info
-----
My humble opinion, after about a year+ using a zippy lifepo4 tx pack, i would never ever ever ever ever go back to the stock pack.

[srgiggles]

forgot to mention, I open the back and use the balance leads to balance the cells every other charge. they seem to stay wayyyyyy closer in terms of individual cell voltages than my Lipos. Anyone know why these Lifepo4 TX packs never seem to need to be balanced

[TJinGuy]

I, like many, have done the switching regulator mod on my DX7. This does 2 things. First it allows you to run a 3s lipo without issue and secondly it is far more efficient than the linear regulator, giving about 50% greater run time compared to the linear reg. I run a 3s lipo in mine and keep fairly good records of use. A single charge lasts me 4-5 months, 100+ flights, and several heli setups. It is awesome.

[SeanM]

Thanks for the info! Do you have a link to this mod?

[TJinGuy]

Here is the old thread I started.
http://www.helifreak.com/showthread.php?t=192865

[wqtaylor3]

Don't mean to hijack this thread but I'm looking at a lipo for my turnigy 9x it's a zippy flightmax 1000 mah 25c 3s was just wondering if that's too much battery for it...I'm mainly concerned about the 25c part