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HomeTurbineAircraftHelicopterTurbine Helicopters › One battery or two? The need for a second battery?
02-02-2010 05:36 PM  8 years agoPost 21
Chris Bergen

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cassopolis, MI USA

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I guess the solution is for you to try it, and report back any problems you run into.

Techflyer tried it, and fried his ECU. Maybe you'll have more luck...

Chris D. Bergen

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02-02-2010 05:54 PM  8 years agoPost 22
seattle_helorrKey Veteran - Seattle, WA USA - My Posts: All  Forum  Topic

I love batteries. The more of them and the bigger the better as I see it. I've got 2.5 amp hours of capacity in my 500 split between a 10,000mAh ECU batt and 15,000mAh of RX/avionics batts. Even when I fly four times a week (I'll sometimes burn five gallons a day) I charge this bird once every week at the most. Very convenient and the redundancy is a good thing IMO. I don't have redundancy to the ECU, which is an intriguing thought.

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02-02-2010 05:56 PM  8 years agoPost 23
Pistol Pete

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Seffner, FL

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^ ARTistic.

Thats all i can say.

~~Enjoying the hobby one flight at a time~~

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02-02-2010 05:58 PM  8 years agoPost 24
MattJen

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UK

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flipping hell Nick,

i thought i was backup mad,

nice neat setup, how long does it take to charge that lot up ? does the national grid drop in voltage when you plug in your charger LOL,

nice setup

Matt

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02-02-2010 06:00 PM  8 years agoPost 25
seattle_helo

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Seattle, WA USA

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btw, Chris Bergen, do you really think that the fuel pump is truly a LARGE current draw? I hadn't really ever thought of it being that significant. I guess relative to the ECU which has a very nominal power requirement the pump would be relatively large. I might just put an amp meter in-line now to see what it actually is.

nick

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02-02-2010 06:04 PM  8 years agoPost 26
seattle_helo

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Seattle, WA USA

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Matt, the LiPo's take about six hours to top off at a less than 1C rate and the ECU batt can be done either in the same time or overnight. I try to keep the charge rates low overall to baby them. I do love those batteries, after all.

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02-02-2010 06:10 PM  8 years agoPost 27
MattJen

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UK

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I might just put an amp meter in-line now to see what it actually is.

just an idea, wouldn't downloading the ECU data after a flight show how much voltage the pump was drawing at peak times through the flight ?

Matt

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02-02-2010 06:11 PM  8 years agoPost 28
iandavidson99

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Ipswich, England

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Peter, but batteries go flat, that’s what they do. Personally I would always check the battery condition before each flight, as when you’re flying an expensive beast, deploying a battery which you felt was border-line that it would last the brief 10-15 minute flight sounds like something’s amiss. I would never choose to fly unless I was confidant I had a pumped up and healthy battery installed.

Seattle_hello, Wow! That's a stunning and very neat install - I like it! Pity about all the batteries though! Only joking, I'm impressed!

Chris, it seems clear that I'm losing the public vote here, so perhaps I should just bow out gracefully

However, it still seems to me that most people are using multiple batteries not for any thought out technical reason, but simply because "it's the done thing". Also, it appears that the term ‘redundancy’ is often applied incorrectly. Multiple batteries in parallel powering a single device could be considered as employing ‘redundancy’, but one battery to your ECU and another to your RX isn’t – it’s doubling your chance of battery failure

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02-02-2010 06:20 PM  8 years agoPost 29
MattJen

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UK

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However, it still seems to me that most people are using multiple batteries not for any thought out technical reason, but simply because "it's the done thing".

Agreed, i suppose when turbines first came out electrics were very much in their infancy so was the electronics to support them, blimey my first electric was an Eco8/Eolo on 10 cell NIMH, i would get 4 mins flight.

my first turbine ECU came with a 1800 battery, no way would i fly with something that low now. it was and still is the done thing, one battery for radio, one for the ECu as it runs at a higher voltage,

now we have decent voltage regulators where you can run high capacity batteries for servos and radio gear which previously was limited to 4.8v, lypo technology had advanced to the state where people fly 1/4 scale models on them.

so yes, sometimes it takes someone to think out side the box and question the norm and i have to say you have made me think..

Matt

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02-02-2010 06:34 PM  8 years agoPost 30
PETER ROB

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Devon UK

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Batteries go flat
Ian,I did say worst case senario
I only fly 2 flights, then fast charge, recycle monthly,
Peter R

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02-02-2010 08:31 PM  8 years agoPost 31
hazchem88

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W.Mids UK

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although 2 batteries is sort of spreading the risk,
it seems most people have 1 battery for the FADEC, and one for the receiver, which isn't real redundancy.
If the receiver battery goes you're screwed.
If the FADEC one goes hopefully you can auto.

For true redundancy you'd need 2 batteries on each circuit.

There seems to be so much emphasis on the receiver side of batteries and redundancy;

what about the transmitter!

and so much else can go wrong.

If you're the sort of person to have a crash because you don't time your flights (to keep the batteries charged), or forget to charge them, then you're perhaps the sort of person to forget to put a fuel stopper in, miss a thraid belt, forget to add oil to the fuel.
I make silly mistakes all the time, including forgetting to charge batteries, but it's just one part of the whole

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02-02-2010 08:44 PM  8 years agoPost 32
iandavidson99

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Ipswich, England

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hazchem88, yup I agree with all of that

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02-02-2010 08:51 PM  8 years agoPost 33
hazchem88

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W.Mids UK

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BTW, here's a little tip,

once I made up a whole bunch of cables, with splitters etc all with deans connectors and nicely heatshrunk.

But there was a bad solder joint. So I had to cut nearly all the heatshrink off to find the bad joint.

My advice is use CLEAR heat shrink.
It gives you one more area of your heli you can inspect when you do your maintenance checks

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02-02-2010 09:00 PM  8 years agoPost 34
seattle_helo

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Seattle, WA USA

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Transmitters aren't subjected to the same kind of stresses that the airborne aircraft batteries are. Plus we have the voltage display and battery warning functions of the TX to help us. Of course something catastrophic could happen and result in total TX failure but that has proven to be exceedingly rare as I'm sure most would agree. I've personally never had a TX or TX battery fail like that on me in my nearly 30 years of being involved in RC nor do I know anyone else who has. I have heard a few stories over the years though.

The particular Emcotec box I'm running has dual power paths and is a truly redundant system. Even the LiPo's are a 2S2P configuration for redundancy within the battery themselves. You could clip the cable from one battery feeding the DPSI and it would continue to operate fine although the LED display and warning horn would start to go berserk indicating a problem.

ECU redundancy is an interesting idea. But losing a ECU batt is not remotely as critical a situation as loss of power to the RX. As long as you can do an auto you'd be okay losing the ECU, however unpleasant. If you're going to pick and choose, having redundancy for the RX power system is no contest. Further, having two completely separate RX stations is the next extension of that logic.

I think the concept of redundancy is useful for our models. It's certainly used extensively in full size aviation. But, then again, a nice, non-redundant install of good components can result in a very reliable model as well. Choosing the right components from the get-go, installing them well and maintaining them well are the fundamentals for sure. Everything else just helps the odds a bit more.

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02-02-2010 09:00 PM  8 years agoPost 35
aussieheliguy

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Australia

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But aren't you then running through a reg of some sort to power your radio gear.

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02-02-2010 09:01 PM  8 years agoPost 36
seattle_helo

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Seattle, WA USA

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In my case, yes.

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02-02-2010 09:03 PM  8 years agoPost 37
seattle_helo

rrKey Veteran

Seattle, WA USA

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Matt, yes, the ECU data log does provide the pump voltage of the flight but not the amperage. It would be easy to just put a logger in-line and see what's going on, though.

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02-02-2010 09:04 PM  8 years agoPost 38
craigd

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Sydney Australia

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Hi Guys,

The ECU and receiver require 2 compleatley separate operating voltages. The ECU requiring at least 7.2 volts and the receiver no more than 6 volts. Remember a freshly charged lipo is around 8.4v which our turbines love to be spun up and started on. 2 batteries are required to supply these separate voltages in and unhindered manner. There is also the issue of ECU to receiver interference through the battery leads.

BRG, Craig Dyer.

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02-03-2010 06:10 AM  8 years agoPost 39
WIRLYBIRD

rrVeteran

CAPE TOWN / SOUTH AFRICA.

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Seattle very neat install.
Dave.

PS That's why I have two NH90's , I fly both together at the same time should one fail and crash , I then have full redundancy , and carry on flying the other one.

WHAT GOES UP MUST SURELY COME DOWN.

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02-03-2010 06:19 AM  8 years agoPost 40
seattle_helo

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Seattle, WA USA

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