[NSRCA-discussion] JR 10X conversion to LiPo

vicenterc at comcast.net vicenterc at comcast.net
Tue Sep 23 14:26:57 AKDT 2008 

Troy,

Well, that is clear like water.  Thanks for the feedback.  I was checking alternates since I need to replace the TX batteries for next season.  I will keep using the NiMh as you recommended.  

--
Vicente "Vince" Bortone

-------------- Original message -------------- 
From: "Troy Newman" <troy at troynewman.net> 

> Vince, 
> 
> While its not recommended there are several people that have done it. I 
> will say that because you will hear of XXX people that have done it with 
> no problems. 
> 
> JR does NOT recommend it and here is why: The output of the system is 
> driven by a specific design voltage. In the 72mhz stuff the output 
> transistor would get hot if the system was run at the higher voltage. A 
> 3S lipo pack comes off the charger at about 12.4-12.6V....A fully 
> charged stock battery pack comes off the charger at about 11.5 to 12V. 
> Here is what I think you should look at. The Lipo pack will maintain is 
> "over voltage" condition for a long time. It will stay above 11.5V most 
> of the time you spend flying it. Where as the Nimh or Nicd packs will 
> fall off to about a 10.5V range and slowly come down from there. The 
> high voltage condition is only for a few minutes maybe the first flight. 
> The lipo high Voltage condition is a long time maybe 5-8 flights. 
> 
> The issue with the 72mhz equipment was the output transistor would get 
> hot and start to weaken causing loss of range and possible a failure. 
> This is the same problem as running your TX on 72mhz and leaving it on 
> for long periods of time with the antenna down. The module gets hot. 
> This is un-needed wear and tear on the output transistor. Continued 
> abuse like this will weaken the output transistor...In the lipo you are 
> running it in a "high" volt condition for a longer period of time every 
> time you charge the system up. So yes it will work on day #1 and Day 
> #2....but What happens on Day #50 or 9 months down the road. 1 yr later? 
> Its not a good idea as it will weaken the system and it could cost you a 
> model. 
> 
> Fast forward to the DSM technology. Again we have a similar situation. 
> The output of the system was designed to be run at a given voltage. That 
> voltage is the 8cell (nicd or Nimh) packs. Not the extra 1V of head 
> voltage carried in the 3S lipo packs. I'm not in on the design of the 
> DSM output and can't tell you if it has a similar issue to the one in 
> the 72mhz. However in the 12X manual it states clearly.... 
> 
> "Q: Can I use a 3-cell LiPo 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 LiPo 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 LiPo packs and 
> their use in JR and Spektrum transmitters is highly advised against. The 
> 12X system will operate for over 8 hours using the included 2000mAh NiMH 
> battery." 
> 
> 
> 
> This being the case the 12X is the latest system from JR. SO if it is 
> not Lipo capable the others are not either. Will it work? Yes, are you 
> taking a chance and risking your model YES. 
> 
> I don't understand the rave with the lipo TX packs. The 12X pack that 
> comes standard is a 2000mah pack. A replacement pack would be a 
> 2000-2100mah pack also... So you are not going to get more flight time 
> per charge. The only thing is the lipo will not self discharge as fast 
> as the Nimh. However I find the Nimh packs last for a very long 
> time....Still flyable (10.5V) after sitting for a month untouched. One 
> note I usually charge my TX packs with the wall C/10 charger overnight. 
> I sometimes will use a Sirius charger on them or a peak detection 
> charger for a quick field boost if its getting low. However This is a 
> rare thing. 90% of my charging is with the slow c/10 charge rate. At 
> this the Nimh packs provide extremely good service life and hold their 
> charge well. A guy that is always fast charging his nimh batts will have 
> trouble with the Nimh technology. It doesn't do as well with this type 
> of use. 
> 
> 
> By the way JR makes a 2500mah nimh that I have placed in my 9303 and 
> also have installed in an old 10X battery case. It works great as well. 
> 
> 
> 
> Hope this helps you. 
> 
> Troy Newman 
> Team JR 
> 
> 
> 
> ________________________________ 
> 
> From: nsrca-discussion-bounces at lists.nsrca.org 
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of 
> vicenterc at comcast.net 
> Sent: Tuesday, September 23, 2008 3:35 AM 
> To: General pattern discussion; General pattern discussion 
> Subject: Re: [NSRCA-discussion] JR 10X conversion to LiPo 
> 
> 
> Jerry, 
> 
> Are you using regulator? It looks like JR does not like the high 
> voltage. Probably, I am going to try to call or e-mail JR to ask. I 
> wonder if there is a difference between the 2.4 modules and the old 
> modules in regard taking higher voltage. New TX are designed to work 
> with LiPo. Just wondering. 
> 
> JR sponsored pilits. Can you find out? 
> 
> Thanks for all responding. 
> 
> -- 
> Vicente "Vince" Bortone 
> 
> 
> -------------- Original message -------------- 
> From: Budd Engineering 
> 
> > Yep, and I couldn't be happier. 
> > 
> > True R/C 2500 mAh LiPo's, $30 each, fits inside the 10X 
> battery holder 
> > with a minor amount of trimming with the Dremel tool. I bought 
> one 
> > set to try, liked it so well I bought another and converted 
> the spare 
> > battery pack. That way I can charge them out of the 
> transmitter (not 
> > that it matters, the charge rate is so low that the risk of a 
> mishap 
> > is about the same as with NiCads or NiMh). 
> > 
> > I screwed around with a couple sets of NiMH's for the past 
> several 
> > years, they were a total waste of time, the self discharge 
> rate got to 
> > where I had to re-charge them if I didn't fly within a day or 
> so of 
> > the previous charge 
> > 
> > The LiPo 's pea k up at 12.5 V, essentially the same voltage 
> as a good 
> > set of NiCads, and discharge almost linearly, so it's easy to 
> assess 
> > their state of discharge. 
> > 
> > http://home.comcast.net/~truerc/ready_pack/ready_packs.htm 
> > 
> > Thx, Jerry 
> > 
> > Budd Engineering 
> > jerry at buddengineering.com 
> > http://www.buddengineering.com 
> > 
> > On Sep 22, 2008, at 8:56 AM, vicenterc at comcast.net wrote: 
> > 
> > > Has anyone done the conversion? 
> > > 
> > > Thanks, 
> > > 
> > > -- 
> > > Vicente "Vince" Bortone 
> > > _______________________________________________ 
> > > NSRCA-discussion mailing list 
> > > NSRCA-discussion at lists.nsrca.org 
> > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion 
> > 
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