u2fast

My Feedback: (37)

Dave Wilshere

Len Todd

Pacific RC has LiFe packs. So does ElectroDynamics.

In the past, I have seen both Jet Cat and Kingtech give you high voltage errors with fully charged LiFes. I personally prefer LiPo. But the new Kingtechs require LiFes. So I am stuck with them for the K-160. The good thing with this requirement is I have finally found a use for all the LiFes that I never used that came with the Jetcats. The K-160 has never given me a high voltage error either. But it did spin the bearings at 260 minutes.

Tec

My Feedback: (5)

I like how the Kingtech 3s LiFe has an 18" deans lead and balance plug out of the box for larger models.

siclick33

I've been using Jeti 5200 Li-Ion on Jetcat P100 and Merlin 140 with no issues. However, I only do about 5 starts between charges.

From my experience the 2600s can't provide reliable starts so it has to be the bigger 5200. I'm not sure how they would work on bigger engines.

patf

My Feedback: (4)

Kevin W has been using the electrodynamics life A123 packs with enough success that I picked up those and had my jetcat ecu updated to accommodate them .DreamWorks has them or direct from andy

Len Todd

LiPo chemistry is designed for applications that need a higher sustained voltage. LiFePo4 chemistry is designed for applications that need higher sustained current. I have found that 2S LiPo's avoid the high voltage errors that I was getting on some of the Jetcats, I have had, with LiFePo4s. But, LiPos also do not provide the current needed for starting once they have used about 50% - 60% of their supposed capacity. It appears that they just can't deliver the necessary current for a kero-start, at that point. If your turbine won't start after a couple runs/tries, the first thing we end up doing is changing the LiPo battery and frequently it will then start. Put the replaced battery on the LiPo checker and it says you still have 40% capacity left.

The new brushless starters on some of the Jet Centrals are using huge battery capacity. We have a couple pilots here that can only get 2 starts/flights on a 2000+ mah LiFe battery. They used to get 4 before JC put on the new starters. These guys are NOT happy. These folks may need to give LiPos a try. Or, put in some larger capacity batteries.

I find that I can get 5 K-160 starts and flights with my 2100 mah LiFePo4s. Never tried for 6. But I usually end up putting ~1600 ma back in on a charge. My 2700 mah LiFePo4 gives me 6. Never tried for 7.

On the P-100, I use 5700 mah 2S 30C LiPos. I can easily get 10 starts and flights on those. The P-100rx is a very efficient turbine. Starts quickly and uses little fuel for the amount of thrust it provides.

The P-140RXi is about the same as the P-100 on battery consumption. But, I am using LiFePo4 for the turbine. Only thing, it is a fuel hog compared to my old P-140rx.

I never charge LiPos in the planes. I have had one member lose a couple planes due to a fire while charging LiPos in the plane. I also saw one this year almost burn down cause the charger was set wrong (i.e. set tp pB versus LiFe.). Lots of smoke and a little fire! I just make sure I can easily pull them out for charging. I always use 2s LiPos on the receiver packs anyway, because I use high voltage servos and Rxers, etc.. As long as you have to take out some batteries anyway, I set the plane up so I can easily get at all of them. I know some planes do not easily allow this. So far, I have avoided those planes.

Steve Collins

My Feedback: (8)

I have used A123s from Electro-Dynamics with my Jetcats for the last 5 years and have never had any battery related errors.

Dansy

My Feedback: (53)

IFLYBVM2

My Feedback: (360)

A123's from Electrodynamics-custom length leads and connectors. Quick, friendly service. The more I use them, the more I like them.
Lipos are just too dangerous and volatile for me.
-Mike O.
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SECRET AGENT

My Feedback: (18)

+1

gooseF22

they sag too much IMO.. I tested them for awhile, and ended going back to a small lipo, and making it easy to swap.. I tried to build or redo all my planes so that its easy to pull the packs, since doing so have gone back to Lipo's except with the turbine pack.

also, it was interesting I got a High voltage warning from my Dreamworks electric Gear off a 3S kingtech batt as well.. just ran the turbine fan in test for a couple secs, and the gear popped up.

ltc

My Feedback: (3)

Dave Wilshere

Zeeb

My Feedback: (41)

The issue with the KingTechs and high voltage when they come off the charger is that the KingTech glow plugs will not take more than 10.0 volts. I bugged Dirk about this and he said that they were serious about that limitation. So just motor the turbine a bit to knock the voltage down to 10 or a little below and it works fine. An Li-Ion isn't going to cut it for ECU, just not enough power output. as for the JetCats, the bigger issue with the 6.0 ECU's was that they had to be converted to run 3 cell LiFe's, the Ver. 10 units will take the Life's or LiPo's. So the only LiPo ECU battery I have left is on the Behotec in my Avanti.

For custom packs, I like WrongWay RC. WrongWayRC.com

Nice work, fast shipping and he stands behind all of his stuff. You can also get real A123's from Richard. I do not know what's going on with Steve at NoBS, but I ordered a JR 12X refill of Eneloops for the cassette and after he got my money and acknowledged it, I didn't hear back from him for weeks. His website says not to call, just email but he ignored every thing I sent him. After 30 days I filed a complaint at PayPal and got my refund from him in a couple of days. So I got the pack from Batteries America, less expensive and it came in about a week. Steve sent me an email saying he'd gotten into a car wreck on his way to the Post Office with a bunch of orders that were all destroyed, he didn't have a car, been in the hospital for awhile, and so on. I suppose it might be true, but he could have answered an email and didn't. So I'm not planning on using NoBS again. Not the same operation since he moved to Florida.....

sirrom

My Feedback: (4)

This is also a problem on the JetCentral turbines also, but you can run the starter motor as if in cooling mode. This will burn off that excess voltage getting rid of the error.
Patrick

RobinLeblond

Holla!
This question and your comments leads me to ask myself if it may exist an alternate solution for this problem. What if:
We connect an external batt while starting, that will reduce the current drain from the inboard batt, allowing us to have a smaller onboard pack? (like we do with the fuel and the taxi tank).
Or, having just having a really big capacitor on the ecu line ? Ok, this one is wrong…
But, you get the idea, address the problem from a other angle, what’s your thought ?

Zeeb

My Feedback: (41)

Looks like more things to go wrong and with the newer engines almost all having an auto restart for the turbine if you want to enable it, you'd need the bigger battery for an air restart.

sirrom

My Feedback: (4)

Robin,
I vaguely remembered that a friend of mine had this very setup on one of his old RAM 1000 and I did a search and found it from 2002. Go to the attached link and look at post #9. I saw this work and it was the bomb. I bet this would be great for starting today's engines and carrying maybe a small 1100 mah battery to just run the pump.

http://www.rcuniverse.com/forum/rc-j...m-500-ecu.html

Patrick

Len Todd

I do like to keep things simple. But this external battery suggestion could address the 1-2 starts that the Jet Central Guys are seeing out of the brushless starter motors. Then again, there is the cool down cycles that draw a lot too. Seems like going to a bigger battery and moving it back toward the CG would be simpler, depending on space available.

RobinLeblond

Yes, good point about the cool down cycle!

causeitflies

There are some guys that have been doing this for years.
This from another thread:
Quote:
Originally Posted by LA jetguy
Sandro and Carsten... If you are designing a device to measure ECU battery consumption, please note that most of the new ECUs go through cool down process when the receiver has been turned off (I.e. no power to CTU)

Thanks
we checked that also , after measuring most turbines used less then 50 mah on cool down , so not really needed to measure this without having a lot of extra cable work..
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