ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh) (3PV/4PK/4PM/4PLS/4PX/4PV/7PX/7PXR/16SZ)

ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
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This is the ProTek R/C LiFe Car Transmitter Battery Pack, and is intended for use with the Futaba 3PV, 4PK, 4PM, 4PV, 4PLS, 4PX, 7PX, 16SZ, and 18SZ Transmitters. Lithium battery technology is evolving. With cell dimensions that fit anywhere a standard Li-Po battery will and rapidly increasing capacity, LiFe chemistry will soon set the standard that all others are judged by. With the ability to deliver 1000+ usable cycles, and a life span up to 4 times longer than Li-Poly batteries (when cycled under the same discharge conditions), these batteries offer the user an excellent balance of performance and value. LiFe batteries are more durable than Li-Poly and are able to handle a higher level of abuse when compared to Li-Poly without the risk of pre-mature failure. Unlike Li-Poly, LiFe cells can be stored in a fully charged state with little to no loss in stored power, and can be discharged deeper with less risk of damage to the cells. Most importantly, LiFe batteries are SAFE! There is no risk of combustion! LiFe cells will not catch fire or explode when over charged, or after a deep discharge.

What about the voltage?
A 2 Cell LiFe battery produces 6.6 volts nominal, which is almost a full volt less than a 2 Cell LiPo battery. The LiFe battery is not meant to replace the performance of a Li-Po battery, it is simply another option. LiFe offers the user a battery with a good discharge curve that is better than that of a NiMH battery, but without the risk of damage or fire that exists when a LiPo battery is abused.

NOTE: Brand new LiFePO4 batteries have been found to fail prematurely if they are deep discharged below below 33% capacity too early. A break-in period of 20 cycles is currently recommended. While testing has shown that this battery can be charged at up to 3C rates, it is recommended that this battery not be charged at rates higher than 1C to maximize the lifespan of the battery. Additionally, LiFe batteries should not be discharged below 2.5V per cell to avoid pre-mature failure and maximize battery life span.

We also recommend you REMOVE the batteries from your cars or radios when you are done, or at least unplug them to avoid accidental over discharge if the unit is left on.

1) You will need a LiFe specific charger to charge the pack (NiMH, NiCD or Li-Poly only chargers WILL NOT WORK!)
2) You must not discharge the LiFe battery pack below 33% capacity during the break in period or below 2.5V per cell after break in.
3) It is not recommended that you charge this LiFe battery pack at amp rates higher than  1C.
4) Read the instructions carefully before operating this battery.

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  • Safe chemistry will not explode or catch fire
  • More mAh per gram compared to NiMH cells, meaning lighter models, and longer runtime
  • Virtually no "self discharge", so the battery is always ready to go even weeks after charging.
  • Superior voltage performance under load compared to NiMH cells, with consistent torque and speed.
  • Fast charge time


  • Voltage: 6.6V
  • Capacity: 2100mah
  • Chemistry: LiFePO4
  • Balance Charge Plug: XH
  • Charge Rate: 1C
  • Discharge Plug: JR/Futaba
  • Dimension (LxWxH): 76x41x17mm
  • Weight: 105g

ProTek R/C is an AMain Sports & Hobbies brand.

This product was added to our catalog on February 17, 2010

Verified Owner
Thursday, Jan 29 2015 (about 6 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
Got one for my futaba 4px has worked great so far have used it for 6 hours straight and hasn't moved between 6.5 and 6.4 im new to this type of battery and almost sent it back. After i charged it to 7.2v i unplugged it and voltage dropped to 7.1 then 7.0v i put it in my radio set the battery option for the life battery in my radio. And noticed the voltage kept dropping. I looked around on the net didn't notice much info about this. The voltage dropped down to 6.5v after about 5 minutes. I contacted amain tech and was told this is normal and it will take along time before it drops Again and it was doing what its supposed to do stabilize around the 6.6v level and that 6.5 to 6.4 is normal. its just the chemistry of the Life battery. So far im very happy have got alot of hours on the radio over 5 hours of just goofing in options along with 6 hours of run time running my car and its still at 6.5 to 6.4v great battery Im happy with my purchase.
Monday, Mar 21 2011 (about 10 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
If you are looking for a good battery for your 4pk then look no further! For a weekend racer like me you might only have to charge this thing 1 or 2 times a season. I put almost 10 hours on my transmitter before charging it and only put 850mah back in. Great battery and great price!
Verified Owner
Thursday, Oct 5 2017 (about 3 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
This battery has worked great for me. It lasts a very long time in my Futaba 4PX. I also want to note that this fits inside a Futaba 3PV as well.
Verified Owner
Saturday, Jan 26 2013 (about 8 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
I a using it in my radiopost ts401 since there bigbang life is no longer being made. It fits perfectly, same size as stock battery. Just make sure to change low voltage cutoff
Verified Owner
Thursday, Sep 20 2018 (about 2 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
Ordered one up with my 7px and it's perfect. Better than expected... seems to last longer with every charge. So much better than using AA batteries..

Update: 18 months in and the battery still lasts so long that I charge it less than once per month. If I were hitting up the track 4 or 5 days a week it would be more often, but I still get several hours of use before the battery meter on my transmitters screen shows the capacity drop below 1/2, which is when I typically charge it. I would say Ive only had to charge it a dozen times. The only downside I can find is how long it takes to charge. I never go above 1c but for such a small battery Im surprised at how it takes over 2 times as long to charge as my 6500mah Protek 4s LiHV packs at 1c.
Verified Owner
Friday, Apr 29 2011 (about 10 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
If you have a 4pk or 4pkS and your in a grueling mains this is the battery you need!! makes ur radio 15% lighter and it will last 50% longer!!
Verified Owner
Saturday, Jul 22 2017 (about 4 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
Awesome battery, had zero issues with it so far after about 3 months of use. A lot better than spending so much money on AAs all the time that go bad so fast, this just needs to be recharged. I usually get a few race days on it before i need to recharge it. But once it starts going dead the voltage drops off very quick and will become useless until charged again.
Tuesday, Dec 9 2014 (about 6 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
Works great. Lasts long. Fits in the radio perfectly and it's lighter than the stock NiMh pack.
Verified Owner
Wednesday, Mar 24 2021 (4 months ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
fit perfectly in my new 7xpr without any issues. I didn't even put foam in and no wiggle. Great size and product. I will update in future.
Verified Owner
Sunday, Dec 1 2019 (about a year ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
Works perfect with my Futaba 7PX. Gets me through a whole day at the track. Like to keep one on standby in my 7PX carrying case just incase but honestly, it packs enough power to get you a couple days of use! Definitely beats buying AA batteries every week!
Verified Owner
Thursday, Jul 25 2019 (about 2 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
This is an amazing little battery! I'm using it in my Futaba to get away from using AA batteries. Four hours of run time and battery voltage has dropped at all. Probably won't have to charge this battery but once a month.
Verified Owner
Wednesday, Aug 2 2017 (about 3 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
I have this battery in all of my Futaba radios. The piece of mind and eliminating another variable is well worth double this price.
Verified Owner
Monday, Feb 4 2013 (about 8 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
Perfect battery for your 4PKS much lighter then stock and last many hours between chargers.
Verified Owner
Thursday, Apr 12 2018 (about 3 years ago)
ProTek RC LiFe Futaba Transmitter Battery Pack (6.6V/2100mAh)
I can't believe this battery has 5 stars, I bought one and 3 weeks later one cell went bad, they replaced with a new one and it happened same 2 moths later, I will never buy this battery again, Very disappointed.