GT3B battery mod go to lipo

[Meatwad]

I'm running some turnigy 3s1800mah20c packs although it barely and I mean barely fits. Like the batt door has trouble sliding on fits. Something close to 1400-1600mah if available will work better. Remove the AA tray and there's alot of room in there.

[Honcho Legger]

Ok, they list that Turnigy at 21mm thick so if we know that can just barely be stuffed in there, then I will look for something just a little thinner. Seems to be plenty of room in there for the length and width dimensions. Thanks.

[m1009cucv]

sorry had a the wrong one.. friend said this is the right one. tight but it fits

Sky Lipo 1000mAh 11.1V 30C

[Honcho Legger]

Well, just did this mod to my GT3B today. Ended up ordering the wrong lipo, I accidentally ordered the 20c version of ^^^ that one which the website says is a little thicker than the 30c version so I was worried it wouldn't fit but it actually fits just fine. Was also concerned about the runtime I would get out of a 1000mah pack but I just messed around for about an hour in the backyard and the pack is still at 12.2 volts so it seems like it will work out for me.

Another question I have, for you guys that have done this mod, should I unplug the lipo from my tx when I'm done running for the day? If I left it plugged in will I end up with a fully drained battery the next day or what.

Also noticed right away this GT3B feels like it weighs barely half of what it used to weigh when it was loaded up with 8 AA's, kinda nice.

[crawler2.2]

JusT Finished My Vr Mod And Hack. I'm Running On A 2S So What Would The Recommended Voltage Be Set At For The Alarm?

[jaloos]

Originally Posted by crawler2.2

JusT Finished My Vr Mod And Hack. I'm Running On A 2S So What Would The Recommended Voltage Be Set At For The Alarm?

3.2 volts per cell minimum so for a 2s 6.4 volts.

[losikid]

The new VR needs at least 6.5 volts for the radio to function properly....below 6.5 volts the voltage reading from the radio will be inaccurate

[JokersWild]

Just cause this thread came up again..... I used a kingmax 2200 3s. Fits the best and you forget you ever need to charge it.... Lol. Eurgle also makes same size battery.

[KRAWL]

I ordered a 3s 1300mah @15c (weighs nothing and why c more for a Tx?) and I have heard the Overkill VR nearly doubles your mahs. Dimensions are 75x35x21 so it's good. Got it from a seller named Hobbymate.rc on ebay for 12.80, free shipping. Even has a deans(copy) female and 16awg good silicone wire. I ordered the radio from someone besides Overkill (I don't know why?) and ordered the hack kit, bearing mod, and the VR and Overkill got it to me in like 3 days. So once my radio finally gets here, I'll be ready to solder.

[AnjanBabu]

The radio doesn't necessarily need a voltage regulator mod even if it's powered on a LiPo. But, I have to admit, the stock VR (7805) is a bit inefficient. Stepping down to 5V from ~12V (3S pack/8 AAs), it dissipates all that extra voltage as heat. so if you're powering on a 3S, It's good to replace that VR, if you can afford to, switching VRs are pretty expensive. One of my stock GT3B has a Murata 7805SR which is a drop-in replacement, $10 shipped, for 2pcs from eBay.

For the dudes running custom firmwares, the fix is rather easy, doesn't really need a VR mod and will actually save you some bucks on those packs!
Since you can manually set the low power cut-off voltage on the radio, use a 2S LiPo and set cut-off voltage to ~6.5V
Also, since the voltage is stepped down to 5V from ~8V (2S pack) the heat dissipation is not much. I still have a stock VR on my modded radio and the IC temperature didn't go over 28C after about an hour of use, so that's alright.

Right now, I removed the VR on my modded radio, shorted the Vin and Vout pads and running a 5V boost circuit on the battery line (available on eBay/Aliexpress ~$3) with a single 3.7V 2000mAh 18650 Lithium cell (~$4/cell). Far cheaper and light weight than anything.

[losikid]

Originally Posted by AnjanBabu

The radio doesn't necessarily need a voltage regulator mod even if it's powered on a LiPo. But, I have to admit, the stock VR (7805) is a bit inefficient. Stepping down to 5V from ~12V (3S pack/8 AAs), it dissipates all that extra voltage as heat. so if you're powering on a 3S, It's good to replace that VR, if you can afford to, switching VRs are pretty expensive. One of my stock GT3B has a Murata 7805SR which is a drop-in replacement, $10 shipped, for 2pcs from eBay.

For the dudes running custom firmwares, the fix is rather easy, doesn't really need a VR mod and will actually save you some bucks on those packs!
Since you can manually set the low power cut-off voltage on the radio, use a 2S LiPo and set cut-off voltage to ~6.5V
Also, since the voltage is stepped down to 5V from ~8V (2S pack) the heat dissipation is not much. I still have a stock VR on my modded radio and the IC temperature didn't go over 28C after about an hour of use, so that's alright.

Right now, I removed the VR on my modded radio, shorted the Vin and Vout pads and running a 5V boost circuit on the battery line (available on eBay/Aliexpress ~$3) with a single 3.7V 2000mAh 18650 Lithium cell (~$4/cell). Far cheaper and light weight than anything.

First, the Murata 7805SR has a minimum input voltage of 7.5 volts. So those shouldn't be used with a 2s Lipo.

Next, the stock regulator, lets call it a generic TO-220 7805, has an minimum input voltage of about 7.3 volts. So those shouldn't be used with a 2S lipo.

And finally, I would recommend strongly against using a "cheap" boost regulator to run a 1s battery. I have experimented with this, and they are very inefficient and when the the battery gets close to dead there is massive amounts of glitching

[rockhugger]

this is all you need.

Turnigy 1450mAh 3S 11.1v Transmitter Lipoly Pack

[Mongol Pete]

What's up guys,

This thread has been dead for a while I see. I just ordered a FS GT-3B and this voltage regulator https://www.digikey.com/product-deta...BqaFA5ckJDdCJ9. Please tell me:

Is it the right part?

If that is the right part, and I am able to run 3s lipo, which pack would be best?

If that VR part is wrong, what would be my best option? Just sticking with rechargeable Nimh AAs?

Thanks,
MP

[Natedog]

I soldered connector on power wires in transmitter, removed AA tray, used this battery with small peice of thin foam to hold it all snugly in my radio. No voltage regulater needed. Turnigy 1450mAh 3S 11.1v Transmitter Lipoly Pack. After convering mine, it would run all day for couple days on one charge.
https://hobbyking.com/en_us/turnigy-...poly-pack.html

The GT-3C is even nicer imo because it comes with single cell 1S lipo battery (lightweight and compact) and battery can never get out of balance. Hobbyking also offers larger mah 1S battery for about 8$, works even longer on one charge.

[Hydrocarbon92]

Pete it states it emulates LM78xx pinouts, that's the correct style. Looking at the P/N side, it's IN+/GND/OUT+.

Almost any 1w or better 5v regulator will work, it just needs the 3 wires connected to the correct board connections. You could even use a cheap 5V BEC, you'll just have an unused ground wire. I used a $0.50 switch-mode regulator, which is essentially the same thing. The type you bought is the same thing sealed in a miniature case.

Speaking of non-3S batts, if you do the PSX hack you can adjust the battery warning level on the GT3B so you could run a 2S or even a 4S (original reg is 18v max).

[Mongol Pete]

Originally Posted by Hydrocarbon92

Pete it states it emulates LM78xx pinouts, that's the correct style. Looking at the P/N side, it's IN+/GND/OUT+.

Almost any 1w or better 5v regulator will work, it just needs the 3 wires connected to the correct board connections. You could even use a cheap 5V BEC, you'll just have an unused ground wire. I used a $0.50 switch-mode regulator, which is essentially the same thing. The type you bought is the same thing sealed in a miniature case.

Speaking of non-3S batts, if you do the PSX hack you can adjust the battery warning level on the GT3B so you could run a 2S or even a 4S (original reg is 18v max).

Hello HC,

The only advantage I could see of running 2s is that they are cheaper. I ordered the VR because I want to practice my new soldering skills, and because I found it for under $4. I will install that VR when it gets here and run this 3s lipo https://hobbyking.com/en_us/turnigy-...-and-3pks.html, and I hope that is all I will need to do to have a good-value radio that runs cheap RXs.

Peace,
MP

[Hydrocarbon92]

Yep, you'll be happy with it. It's a great value and now powering it will be very cheap. That batt actually has 15% more capacity than 8x alkalines, but should last 2x longer with the reg mod. 3S will be fine, that reg is just a few % more efficient with a 2S.

What I suggest is you clip the old reg out rather than desolder. Solder the new reg to the old pins. Otherwise you need to remove the LCD, which can be damaged easily.

[Mongol Pete]

Originally Posted by Hydrocarbon92

Yep, you'll be happy with it. It's a great value and now powering it will be very cheap. That batt actually has 15% more capacity than 8x alkalines, but should last 2x longer with the reg mod. 3S will be fine, that reg is just a few % more efficient with a 2S.

What I suggest is you clip the old reg out rather than desolder. Solder the new reg to the old pins. Otherwise you need to remove the LCD, which can be damaged easily.

I ended up ordering this one https://www.ebay.com/itm/FUTABA-3PK-...72.m2749.l2649 instead for shipping reasons. It isn't as nice as the Tunigy, but I hope it gets the job done.

-MP

UPDATE: The ebay seller says he can't ship that pack to my address so I ordered the nano-tech from Hobbyking after all....

[NitroDarwin]

Sorry im reviving a dead forum but, i have a few questions. 1 I'm concerned about leaving a lipo charged in my remote for prolonged periods, so is every one storage charging them when jk ot going to be used for awhile? 2 I have had my gt3b get turned on a drain a set of batteries so wondering if anyone has added a low voltage cutoff when adding lipo battery to prevent deas lipos?

[magic_yeti]

It depends. If i use my TX the next days i just disconect the lipo. If i don't use it the next 4-5 days i set it to storage Mode.


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