JR radios and LiPo batteries

[Rocky Stone]

All,

I've been using 3-cell LiPo batteries in both my JR 9303 transmitters for over a year and I've loved them.

However...

I recently experienced a catastrophic crash that, at first glance, appeared to be complete loss of radio signal with the plane.  While further testing reveals that this may not have been the case, I've re-visited the compatibility of my JRs and LiPos. 

While LiPos were originally recommended to me by Skyler at HobbyProz, the JR transmitter manual specifically prohibits the use of 3-cell LiPos as transmitter batteries:

Q: Can I use a 3-cell Li-Po pack in my transmitter?

A: No. All current JR and Spektrum transmitters are designed to operate using a 9.6-volt transmitter pack. A fully charged 3-cell Li-Po pack puts out 12.6 volts. This higher voltage can overload the power-regulating transistor causing damage and or failure, possibly in flight. Many of our customers have experienced failures using 3-cell Li-Po packs and their use in JR and Spektrum transmitters is highly advised against.

My questions are:

1. Is the risk of powering the transmitter at a higher than recommended voltage cumulative?  Or if there were going to be a failure, would it have happened already?

2.  I've seen it recommended that installing two diodes such as the 1N4001 in series will drop the LiPo voltage safely.  Is this solution reasonable and/or safe?  If so, I'll find out from Charlie or Matt exactly how to do that.

Thanks, oh vast respository of RC knowledge that is SoarABQ!

--Rocky

[Clin Lashway]

Rocky,

 

What this says about the voltage being too high and overloading the internal voltage regulator is a very realistic possibility. That extra 3 V would no doubt add significantly to the power that regulator has to dissipate and therefore it could get hot and burn out. Now, I know nothing about the specifics of the JR radios, but the scenario it very much a possibility.

 

As far as is cumulative damage, the answer is yes and no. Regulators are often designed to shut down when overheating to protect themselves (obviously not the ideal for an RC radio). So it is possible the regulator will be fine once you return to 9.6 V.

 

But, heat is the killer of electronics. So if a part has been run hot, it may very well have less life in it for various reasons. How much less is the big question.

 

I would contact JR about this, since they should be the experts on their radio.

 

Clin Lashway

Raydec, Inc.

505 292-5002

las...@raydec.com

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[David Shoemaker]

In my Futabas:

They were designed to run on the standard 8 cell NiCd/ NiMh.

I switched a couple years after people on RCSE were doing so without complaints.

I have a 1999 yr radio I've run on a 3S, 2500 Lipo for the last three years without problem.  I try not to charge the Lipo to the full 12+ volts, since I can get hours and hours out of it anyway.  I have probably still mistakenly charged it to full voltage 40 - 50% of the time.

I have a 2010 radio that I run on a 3s, 1500 Life that is still good for 2.5 - 3 hrs conservatively.  I bought it, because of the lower voltage range.

Both approaches have the problem of not being compatible with the low voltage warning in my radios, but who cares?

I recharge the Life when the voltage reads 9.7V for 45 mins. - 1 hr., or if it drops to 9.6V, I recharge right away.

I recharge the Lipo when the voltage gets to 11.1V, but that gives me 4.5 to 6 hrs.!

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[Taylor Collins]

Perhaps this would help?

http://www.ebay.com/itm/3s-Lipo-Step-Down-Voltage-Regulator-for-Radio-TX-Transmitter-Futaba-Hitec-/310704235706?_trksid=p2054897.l4275

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[Dennis]

I have been running LiFe batteries for as long as I have had my 9303 and my 11X with no issues. I charge with my Hyperion charger not the supplied wall plug. 

Dennis

Sent from my iPhone

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[Terry Tombaugh]

Using only a 2 cell lipo would be the simplest way to avoid potential problems and is easy to do because several companies make them to specifically fit JR and Spektrum, I've been using a 4 A , 2 cell lipo in my Spektrum for over a year. It runs for many hours without falling to a recharge level. Prices range from $17 (HK) to $70 (Horizon Hobby), my HK version works well.

--
Terry

[ezaf...@comcast.net]

My JR 9503 draws about 250 ma, call it 300ma.  A 3 volt drop will generate 0.9 watts.  Not insignificant in a confined space and a small component.  Even if you reduce the voltage with suitable diodes, better give some consideration to the heat generated and cooling.  For comparison, a resistor dissipating 1 watt will be very hot to the touch.

My radio has a 1500 mah Ni-MH battery.  How much more capacity does one need??

Charlie Z

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Subject: Re: [ASA] JR radios and LiPo batteries

[Ed Dresner]

Check out this eBay site.  NiMH JR battery for $27.99 & free shipping.

http://www.ebay.com/itm/2500mA-Tx-BATTERY-FITS-JR-SPEKTRUM-JRXP7202H-XP7202-7202H-/181054624636?_trksid=p2054897.l4276

ed

[Ed Dresner]

Don and I just ordered from the eBay vender I listed.

Ed

On Wednesday, March 26, 2014 11:41:42 AM UTC-6, rockyabq wrote:

[Rocky Stone]

Charlie and Clin,

Thanks very much for the info.  It sounds like I've been playing Russian Roulette since I started using the LiPos.

Charlie, it's not about the increased capacity, the advantage lies in only having to charge my transmitter battery once a month or so rather than every night before I intend on flying.

--Rocky

THANK YOU for deleting my address, any other addresses, and any personal information from this e-mail if you plan to forward it. THANK YOU also for using "BCC" instead of "To" and "CC" when initiating both individual and group e-mails. This helps prevent spammers and hackers from obtaining addresses and thus reduces the proliferation of spam.

[stan.j...@comcast.net]

Guys,

Just remember that NiMh cells have a high self discharge rate and do not store well for extended periods of time.  What does that mean?  When used in a TX that sees weekly use it's not a big deal.  You will be using and charging the pack on a regular basis.  If for some reason you don't use the TX for an extended period of time you should charge/cycle the battery packs every few weeks to keep them healthy.

There are many choices for TX and RX packs today.  My preference is the LiFe packs for TX and RX.  They can be deeply discharged without damaging the cells, they have a very low self discharge rate, you don't need regulators, and they don't have as much voltage drop under load as the NiMh packs.  They are also lighter than similar capacity NiMh or nicad packs.

One mans opinion,

Stan  

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From: "Ed Dresner" <eda...@gmail.com>
To: soa...@googlegroups.com
Sent: Wednesday, March 26, 2014 6:49:40 PM
Subject: [ASA] Re: JR radios and LiPo batteries

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[Ed Dresner]

Stan,

Excuse my lack of knowledge, but I'm not familiar with Life batteries.  After looking on line, some are saying how much better Life batteries are over LiPo's.  I'm wondering why the sport has been turning more toward LiPo batteries, and LiPo prices have been falling?  If Life were so much better, why isn't the industry pushing them over LiPo's, knowing we would spend the extra money?  It can't just be bad marketing.  Or, is life a new emerging technology? 

Ed

On Wednesday, March 26, 2014 11:41:42 AM UTC-6, rockyabq wrote:

[stan.j...@comcast.net]

Ed,

I did not explain the LiFe packs as well as I should of regarding their use in models.  The Life packs are great for TX and RX packs mostly in my opinion because you don't have to worry about over discharging them which is a big issue with LiPo's.  Also, the nominal cell voltage of a LiFe is 3.6V.  So a 3 cell LiFe is 9.6V and a 2 cell 6.6V.  This is the same as an eight cell nicad or NiMh TX pack and a five cell nicad or NiMh RX pack.  No regulators required for most installations.  The down side for some folks is that they require a balance charge like a LiPo.  I've had customers decline to use them because they did not want to purchase a LiFe capable charger.  That's not a problem for most electric flyers as they already have chargers that will work.  The dyed in the wool liquid fuel flyers in the hobby often don't have or wish to buy a balancing charger.

The reason you've not seen a push to replace LiPo's with LiFe's for motor batteries is they don't have anywhere near the current delivery potential of a LiPo.  A 10C rated LiFe is about as high a rating I've seen for the LiFe's.  LiPo's are rated as high as 65C or more.

I hope this clears up the issue for you.  Anyone else in the group have any comments?  My comments are based on what I've read and my own experience with the LiFe's.  I've not really done any real research on the subject.

Cheers,

Stan

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From: "Ed Dresner" <eda...@gmail.com>
To: soa...@googlegroups.com

Sent: Wednesday, March 26, 2014 11:06:23 PM

Subject: [ASA] Re: JR radios and LiPo batteries

--

[Bruce Twining]

I agree with Stan. I used a life pack in a 9303 for years. The NiMh pack in my 11X is still strong so I have not replaced it. 

Bruce

Sent from my iPhone

[skyle...@yahoo.com]

Hey going flying today at bfp dlg and maybe even some sloping Sent from Yahoo Mail on Android

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From: Bruce Twining <bgtw...@gmail.com>;
To: soa...@googlegroups.com <soa...@googlegroups.com>;
Subject: Re: [ASA] Re: JR radios and LiPo batteries
Sent: Thu, Mar 27, 2014 2:06:01 PM

[Terry Tombaugh]

I think NiMH batts. are obsolete in radios as much as they are for motor batts. so I'll stick with LIPOs for endurance and price/availability but what Stan says about LiFe's in radios is certainly true also where their low C ratings are not a limitation. I mistakenly bought one several years ago as a motor batt. and it's useless in that application and the size/shape won't fit in my xmitter 

Terry

[Richard Shagam]

OK, to add to the conversation--I think I know the answer, but can an older LiPo charger ( I have a Hyperion EOS1210i and Hyperion separate balancer) be used to charge LiFe batteries.  It only says it can charge 1S-12S  LiPo's (3.7V - 44.4V), as well as NiMH and lead acid, so I would assume the answer is no.

Also, will a 2S 6.6V LiFe work w/ most receiver/servo setups?  I thought  most servos like Hitec were rated for 4.8 to 6V.  My FrSky receivers will work wi/ LiFe, but I would think that most of my older servos (mostly Hitec) would cook at the higher voltage.  Lately, I've been using 2S LiPo's and 5V UBECs in my thermal ships just to get away from those miserable, obsolete high maintenance NiMH's

Regards, Richard

 

Richard Shagam
Albuquerque, NM

RNSh...@rhizotech.net 

Check out local weather conditions at my residence at:
http://rhizotech.net/weather/weather.html

[Ed Dresner]

Stan, Thanks,

I have a Hitec 4X charger that does not mention LiFe batteries.  Can a LiFe battery be charged with the LiPo settings?

Ed

On Wednesday, March 26, 2014 11:41:42 AM UTC-6, rockyabq wrote:

[Terry Tombaugh]

Based on what Richard says and what it says in his manual (not able to copy here) it can only charge 3.7 volt per cell batts. meaning no LiFe. My later 606i Hyperion does have a LiFe capabilty.

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Terry

[Terry Tombaugh]

This model of the Hitec 4X does have LiFe capability:

http://hitecrcd.com/files/Hitec_X4_Manual_US.pdf

--
Terry

[Bill McLean]

Ed is this the Hitec charger that will charge 4 batteries at once?

 

If so you need to read the manual, as it is a bit tricky getting to the LiFe settings.

 

No do not charge a LiFe battery under the LiPo  settings.

 

Bill

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From: soa...@googlegroups.com [mailto:soa...@googlegroups.com] On Behalf Of Ed Dresner
Sent: Thursday, March 27, 2014 11:46 AM
To: soa...@googlegroups.com
Subject: [ASA] Re: JR radios and LiPo batteries

 

Stan, Thanks,

--

[Richard Shagam]

Rocky, now that you may have a probable cause for why your Electron died, please fix it.  Or at least save the pieces so that someone who is so inclined might do so.  Trust me--it is fixable.

Regards, Richard