Turnigy 9x transmitter li-ion battery conversion

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Re: Turnigy 9x transmitter li-ion battery conversion

Postby bmsweb » Tue Aug 02, 2011 3:55 am

Just received the batteries and installed in the Eurgle and I'm about to do my son's Turnigy next. Just wondering if I let the battery level go down with this mod until the TX audio warning kicks in, will I still have a good signal? Or do I keep it charged so I never get the warning? Sorry if this is a silly question
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby RCModelReviews » Tue Aug 02, 2011 4:50 am

I often fly my radio down to 9V indicated on the LCD and have had the transmitter alarm sound when I was testing -- the radio still worked perfectly with full range.

In selecting a resistor I opted on the side of safety so there should still be about 30 minutes of safe flying left when the alarm kicks in.
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby bmsweb » Tue Aug 02, 2011 4:57 am

Thanks Bruce, I didn't realize just how fine the soldering needed to be, but it all worked out fine. I still need to do my son's Turnigy. Interestingly I only gave the batteries a 40min charge at 0.2amp on the Lipo 2S setting, so they're not fully charged. I've got the Radio in the car with me and its been running for 2 hours so far. Can't wait to see how it goes with a full charge.

The other big advantage is the battery compartment closes properly now!! :lol:

Thanks
Paul
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby lawndart » Thu Aug 18, 2011 3:09 am

I did Bruce's $8 mod exactly as set out in his original instructions (same 2C pack from dealextreme cells, same resistor) and used my 9x without trouble for a year.

Today I flashed the firmware to er9x. After flashing the radio still read 10.2V as usual, while my pack's actual voltage sat at 7.66V. Since this firmware allows adjusting the low battery alarm I decided to remove the 8.2kΩ resistor and have it read the pack's actual voltage. That's when things got weird.

After removing the bridging resistor the radio reads 1.2V. I inspected all the copper tracks and they seem good. I also checked the original surface-mount resistors with my multimeter and they seem okay too. I spent an hour or so trying to scrape and trace the copper tracks with a bit of solder in case there was a break I couldn't see, but the radio still reads 1.2V. Finally I decided to reinstall the 8.2kΩ resistor (which I also checked for correct resistance), but now the radio is reading 5.5V!

I'm assuming one of the surface mount resistors is not making contact but I don't know which. Based on these symptoms can one of the resistor gurus suggest a solution? For instance, if I know the the 8.2kΩ resistor makes it read 2.16V below the actual voltage, what resistor can I use to solve the problem? Thanks in advance for all assistance offered.

Dave
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby lawndart » Thu Aug 18, 2011 8:24 pm

24 hours later and I think I've solved my problem.

I still couldn't see any breaks in the copper trace but assumed there must be one somewhere. So using a very fine insulated wire I made bridges over the connection-points where the 8.2kΩ resistor had been. This meant a bit more scraping of the green stuff to expose more trace, then soldering in two bridges: one from the trace over the messed-up area directly to the end of the lower surface-mounted resistor, and the other from the left edge of top-most surface resistor to a cleaned portion of trace below the adjacent capacitor.

I know that probably doesn't make sense but thought I should close the loop. For anyone else reversing Bruce's resistor trick, be careful about not damaging the trace. If it doesn't work when the resistor's out assume the trace is damaged and bridge it with wire, not solder. #LFMF.

Dave
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby bmsweb » Mon Aug 22, 2011 9:40 pm

Hi Bruce, Its been over 3 weeks and 20-30 flights or more and I haven't had to charge the Radios, this mod is fantastic.
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby avrflr » Sat Jan 14, 2012 4:39 am

I attempted to do this mod and my transmitter never worked again. At least the batteries were cheap :)

I had better luck with soldering directly on to the component on the board. Every time I tried to solder on to the exposed track it would short something out and the transmitter would not turn on.
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby GTiDon » Thu Feb 02, 2012 7:55 pm

Hello

Will this mod be ok with a FRsky DIY module installed? I havent found any info reguarding this together
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby chrisjunkie » Thu Feb 02, 2012 10:50 pm

GTiDon wrote:Hello

Will this mod be ok with a FRsky DIY module installed? I havent found any info reguarding this together


Sure will. All the components in these radios are all just 5v. The voltage is regulated down on the board. This is why it's stupid to use 8 AA's!
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Re: Turnigy 9x transmitter li-ion battery conversion

Postby John_Edward » Fri Feb 03, 2012 6:36 pm

Just have to remember, that the voltage regulators used are crappy, and actually need a lot more juice than the 5V they produce.
I think they use around 1.8V, so the lowest fully safe voltage is around 6.8V, after that the regulation won't work correctly, and the 5V starts to drop.
How much it can drop before something stops working, I don't know.
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