[NSRCA-discussion] JR 10X conversion to LiPo
Troy Newman
troy at troynewman.net
Tue Sep 23 13:03:48 AKDT 2008
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 <jerry at buddengineering.com>
> 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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