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DX7s battery use

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Old 06-05-2012, 10:32 AM
  #1
sirdrakejr
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Default DX7s battery use

I have a DX7s and I cannot seem to get the 4 cell NiMH battery to charge over 5.1 to 5.3 volts. But I also have a 5 cell Spectrum NiMH battery that charges externally to 6.7 volts. The 4 cell is 2000 Mah and the 5 cell is 2650Mah. When I looked inside the battery compartment, I removed the foam filler and the 5 cell battery pack fits perfectly in the compartment.

I called Spectrum ( Horizon Hobbies ) to see why I could not use the 5 cell pack in the radio in place of the Li-Po or the 4 cell pack. They said the charging regulator wont work . But I can take the pack out to charge just like I do now when it is low. I asked the tech to check further and let me know why I could not use that pack since it is lower in voltage than the 2 cell Li-Po. I am still waiting on that email.

But in the meantime I have placed an adapter in the battery wires to allow me to use the receiver plug to connect to the radio. That way I can use the battery pack that came with it or insert a 5 cell pack. Anyone know of any issues using a 6.7 pack in that radio in place of a 5.1 or a 7.3 pack? I think that ability to use a Spectrum 5 cell pack extends the versatility of the transmitter.

Frank
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Old 06-05-2012, 10:51 AM
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Doug47
 
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Default RE: DX7s battery use

A 4 cell NiCad or NiMH is a 4.8v battery, a 5 cell of either is a 6 volt battery so those figures are fine.
You can use that 5 cell pack but he's right to fully charge it you'd have to remove it. The 2 cell 7.4 volt Lipo is different, the internal charger (your radio doesnt have an external charger, that thing is a power supply will work fine on it.
Nicads and NiMH batteries and Lipos have different requirements charging wise.
Your radio also has the option of reflecting that you have in place a 2 cell lipo, showing 7.3-7.4 on the screen when fully charged and a cut-off/warning about 6.6 volts.
When you do install a lipo you'll kick yourself for waiting, the radio will go double plus the time between charges. Doug
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Old 06-05-2012, 06:40 PM
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AndyKunz
 
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Default RE: DX7s battery use

The LiPo will be fully charged at 8.4V, not 7.4V.

Andy
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Old 06-06-2012, 12:43 AM
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Doug47
 
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Default RE: DX7s battery use

Duh Andy !.
He's right of course. I'll never have another transmitter without a Lipo or something newer and even better comes along,and that'll take some doing. Doug
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Old 06-10-2012, 06:31 PM
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sirdrakejr
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Default RE: DX7s battery use

Doug,
I understand that the battery readout will show the voltage of the battery I put in. I also KNOW that I will have to charge the 5 cell pack OUT of the transmitter. But since I already have the 5 cell I see no need to buy a Li-Po. The concern the tech at Horizon had was the voltage. Since the 5 cell is charged to 6.7 VDC there is no problem with it being too high to use in the transmitter. The readout will allow me to monitor the voltage of the pack. I am going to use the 5 cell and watch the time to see how more I get using the 5 cell 2650maH over the 4 cell 2000 maH pack.

Thanks for the responses.
Frank
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Old 06-18-2012, 10:04 PM
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Aerocal
 
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Default RE: DX7s battery use

I hadnt given it much thought.Will a 5cell NiMh physically fit inside the battery compartment?
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Old 06-19-2012, 03:41 AM
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Franco2fly
 
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Default RE: DX7s battery use

Arghhhhh.   batteries again.  Honestly, purchase the LiPo  PLEASEEEE  .  It is so enjoyable not to even have to think about the transmitter battery.  Once charged, it lasts for a month.  I'm more concerned with TOTALLY forgetting to charge EVER.  Once I got mine to 8.2  I keep looking for it to drop out of the 8 volt range.  I actually intentionally left it on last weekend while I was doing some minor adjustments to a plane, trying to get it to drop.  Even though the "No Activity" alarm went off 4 or 5 times, the battery was still at 8.1 when the transmitter was returned to the upstairs shop.  Seriously, I think all new DX8's should come stock with the LiPo.


KKKKFL
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Old 06-19-2012, 05:02 AM
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BuschBarber
 
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Default RE: DX7s battery use

I ordered the LiPo Tx battery for my DX8, shortly after I purchased the radio. I have been flying for a couple of months and it still is above 8v. I have a friend that also has a DX8 and he reports the same results. We fly often so the Tx does not just sit on the shelf.
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Old 06-21-2012, 06:53 PM
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Default RE: DX7s battery use

Last time I charged mine was March 30th. Still shows 7.5 volts.

Gord.
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