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HelicopterMain Discussion › Can I run two RX batteries like this?
05-03-2005 01:47 AM  12 years agoPost 21
reilly13

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Binghamton, NY

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Every little bit helps...if not me then someone else here.

I considered going another route but when you compare the horror stories of all, Nicad, Nimh and Lithium, the Nimh seemed most predictable (to me anyway) while still getting maximum flight time.

The duralite/lithium guys are probably shaking their heads but, you gotta go with what you understand. That stuff is too new to me and because the technology is changin so fast with the newer cells I figured they may not have as proven(predictable) a track record yet.

What can I say, I'm a follower!

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05-03-2005 09:12 AM  12 years agoPost 22
mcatech

rrVeteran

Mount Gambier SA Australia

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Hi in one of my helis "camera ship"
I am running 2 2400mah nicad packs via 2 switches into the batt socket and a spare channel on the RX as all RX's use a common power rail
this setup is very very simple and does guard against switch and connector failure however Duaralites are on my wish list mainly for ease of maintenance from a charging stand point

on a note regarding chemistry
I use only nicads and more specifically only sanyo nicads
useing NiMh is seriously asking for trouble I nearly lost a heli a few years back due to this and the discharge cycle of a properly cared for nicad is by far more predictable than NiMh
you only need to do a search here to see how many have lost machines due to NimH Rx batterys
Cheers Michael

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05-03-2005 11:14 PM  12 years agoPost 23
Helinutnz

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below 42 South

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mcatech.
you may be living a bit in the old days. Nimh and nicads have a pretty common discharge curve now. They also have thicker components and some of the weight savings have gone but the cells are much better. The 1950 FAUP's I was talking about have 5 mohms resistance and can handle 40 amps. Two in parallel gives a total resistance of 2.5 mohms. Better than the 4.5 mohms from a 2400 nicad pack. The imac guys recommend a total resistance of 10 mohms or less for low voltage drop.
Nicads are pretty refined technology but nimh is not far behind now.

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05-03-2005 11:33 PM  12 years agoPost 24
DS 8717

rrProfessor

Here wishing i was somewhere else

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You foregot the part about when the voltage goes too low with duralites the cells die.

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

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05-04-2005 12:03 AM  12 years agoPost 25
rob10000

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Western Massachusettes

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And the fact that they should be removed from the helicopter for the charge cycle.

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05-04-2005 04:04 AM  12 years agoPost 26
Helinutnz

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below 42 South

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I have spoken to some really knowledgeable people involved with batteries and there are some myths out there as at times some don't like to let go of past experiences. Thats fair enough as once bitten twice shy. I wasn't keen on the nimh's for the same reason myself. But read the latest information and be open minded about it. I did that with duralites and after reading and researching all the info I decided the drawbacks still didn't overcome the benefits FOR ME. Lithiums have some really great features. The technology is still going through improvement and maybe I'll look at that in the future.

Reilly 13. There is nothing wrong with your thinking and duralites are not necessarily the saviour to heli pilots. Like you say I also think the technology is going through massive improvement and changes and will at some stage be like NIMH's are to nicads now. There is nothing wrong with guys running them at all. It's just what they are prepared to accept to run them. They don't appear to be the "perfect" technology and have just as many drawbacks as the other battery types (IMHO) It's a good thing guys are prepared to use them as the technology will advance and improve. Unfortunately there are just as many sob stories on these battery types here on RR. (heli's burnt to the ground, crash damage rendering a lithium unuseable due to fragility, regulators overheating...get a big heatsink to fix...there goes some weight savings, remove to charge....multiple connections and disconnections aren't good for the connectors, Can't drain the battery too far, cost, req special charger for warranty, only one switch with one connection to the rx, need to unplug the switch or suffer continual drainage after flying session) This is not meant to bag lithiums but present the view that they are not the perfect answer.....yet. Improve the technology, solve the possible problems, reduce the cost and many will change. It is good there are those that will help the newest type of technologies to advance. I like you will "wait and see" a bit longer.

yer I am probably in for some heavy flaming from the duralite or lithium users here (sorry you guys) but thats what healthy discussion is all about. Look at all the facts and then make your choice. what ever you do it will be a compromise.
see ya

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05-04-2005 09:12 AM  12 years agoPost 27
Helinutnz

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below 42 South

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yes it does answer a few. thanks.
I was unsure about li ion versus li poly. The going up in smoke issue is a big one for me. I don't like the idea of plugging and unplugging connectors or switches that need to be unplugged to avoid flattening a battery over time.
I don't believe that you will have a warranty on those batteries should you use a charger other than the one they make and supply for it.
cost is still high.
do you remove the batteries for charging?
cheers

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05-04-2005 10:23 AM  12 years agoPost 28
Helinutnz

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below 42 South

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ok cheers.
goes a ways towards considering duralite setups.
I'll wait and see a while longer to see how the battery systems hold up. I'll let anyone interested know how my parallel setup goes. Sure has a bit of weight to it. Got my batteries and they are 12.3 ounces for 3900 mah. (4.8volt) Then two one ounce super rockers. The x-spec will be a little heavy I guess but will not affect the type of flying I do. (except auto hangtime may suffer a little)
Ade do you have a 90 size bird? Can't see your profile in this window and too lazy to go back whats the weight? Be interested to know.
cheers

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05-04-2005 01:57 PM  12 years agoPost 29
reilly13

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Binghamton, NY

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Well, I got my dual pack/switch setup installed and ready to fly tomorrow. It does add a little extra weight, but not enough to worry me. Like I mentioned before, the 8 I'm using are no heavier than the 4 subC's I was considering. My hyper 50 will still yank it through the air no problem.

Probably the most noticable thing is that when I turn on the second switch, the servo's instanly sound stronger....maybe even a little faster.
Still the same voltage, the second pack just puts some a$$ behind it I guess.
This puts my total capacity at 4000mah. Over the next couple weeks I'll let you know how many flights I get with all digital servos, 401, and governor. I usually only have time for three anyway so I may never see the bottom of this setup but I'll let you know. My main reason for this was redundancy anyway.

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05-04-2005 10:31 PM  12 years agoPost 30
Helinutnz

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below 42 South

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yep Reilly 13. Thats it. If it were for capacity you'd put in one large gp nimh pack and it would be a little lighter. It's to ensure as you say....lower voltage drop, two switches and two sets of wires and connections ALL the way to the rx for redundancy. All aeroplanes have that (full size) and as they get larger the redundancy systems become greater and greater. The capacity is a big spin off.

It would have been good to find out what cells you made up as some nimh (and nicad) have high internal resistance. If they have 25 mohms each you have halved that to 12.5 mohms. not to far away from 10 mohms or less. They should be fine on your setup. I bought a loaded ESV from hangtimes as well which will load the pack with 500 ma before flight. A battery may show 4.8 volts but under load may drop considerably. (thats why just looking at a voltwatch without wriggling the servo's shows you the unloaded voltage and the battery could be seconds away from dropping right off. wriggling the servos will put a little load on it and the greens will head a bit towards the red. The 500 mah load simulates some flight conditions and shows your batteries true state.

Good luck.
Cheers

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05-05-2005 05:06 AM  12 years agoPost 31
Helinutnz

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below 42 South

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nice. I saw the dyna x in a uk based heli mag. looks awesome.
yer my x-spec is a bit over that. more like 11.5 lbs. I think the dual setup cost me about 5 ounces xtra. I have put on a third brg block on the tail drive shaft. quick uk swash. hirobo stab arms. header tank. gem 2000, has the 91 c-spec PS, temp monitor, gy 601, TJ pro, mixture servo (hs 85) 3rd needle on the carb, changed to all cap screws and stainless control rods.
Put carbon boom supports on which are lighter and I have a carbon canopy which is 5 oz lighter than the stock canopy. 9350, 9252's, 9254, hs 85 and the gy 601 tail servo. I was going to the rx into a crash survival box but thats another 3 oz. I could trim down to 10.9 or 11 lbs ok with a few changes but with my flying the extra weight shouldn't be too much of an issue. soon find out.
cheers

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05-05-2005 11:00 AM  12 years agoPost 32
Helinutnz

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below 42 South

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Yes that sounds like a good benefit. Ade you have gone some way to convincing me to look again at these in the future. I'll stay conservative for now and use my parallel setup. The technology is progressing very fast and I'll keep looking at it with interest. I am not so sure my flying at present would do justice to a very light and responsive heli although it would always help on auto's.

Meanwhile I'd be interested in hearing from reilly 13 about how he found the 2000 dual setup. cheers.
Glenn

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05-05-2005 11:29 AM  12 years agoPost 33
PietervA

rrVeteran

New Zealand

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Have followed this thread with great interest, taken the plunge, and entered the world of LiPoly!

Polyquest 2200mA 3S pack, Helitron mosfet regulator and switch, for a grand 170g (about 6oz).

Wish me luck. If it's good, I'll fly all day without charging, if it's not, then a plastic disposal bag will be particularly useful!

Ciao

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HelicopterMain Discussion › Can I run two RX batteries like this?
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