Gliders > Slope Soaring
West Wings Skylark build thread
rogallo:
I have the 4 ch spectrum rx for 30 euro. New. Can bring to mount l sat week.
Happy Days:
I have to say that I don’t really understand the trend of using Li-Po’s to power radio receivers’ and servos in gliders. :?:
The cost of a 2 cell Li-Po of around 1000mAh capacity is about the same as a 4 cell Ni-MH of the same capacity. The Ni-MH battery puts out exactly the correct voltage for rx and servos to operate with and doesn’t require the addition of a voltage regulator, (call it a Ubec / Sbec or whatever). Therefore the Ni-Mh works out cheaper. :)
Whilst a 4 cell Ni-Mh is heavier than a 2 cell Li-Po of the same capacity that doesn’t really matter because, as Jumbo says, we all have to add weight to the nose of our gliders to balance them anyway. :)
And finally,…….. Although very unlikely in this day and age, but has been mentioned on this forum before, the risk that the more connecters and electrical gadgets you use in a model, (voltage regulator in this case), the greater the risk of something going wrong.
So although the Nickel Metal-Hydride battery is very much “old technology” in comparison with Lithium Polymers, when it comes to non-powered flight, I would say this is one of those rare situations where older is better. 8)
I suggest that the only benefit that a Li-Po can offer over a Ni-MH (in this situation) is that it can be completely recharged in just one hour. :)
Question: Is that one up side worth the downsides? Depends on your point of view!
Finally, while on the subject of batteries for model flight. I read an article today about a new type of re-chargeable battery that is close to production. Based on Aluminium and Graphite is has the advantage of being able to be re-charged in a matter of minutes, and even better from our point of view, it’s flexible and can be moulded into almost any shape. Should be no problem to mould it right into the nose of a glider then!
Even further down the road is the promise of Graphene batteries. This stuff could revolutionise the whole electronics industry,…..but it’s a good few years away yet.
The Keithy will now step down from his soap box, take a gracious bow, and retire to bed. Good Night all.
Little Keith
andrew wallace:
:lol: :lol: :lol: Keith I use lipo's cause they hold their charge and if I wanted to go flying now I can and wouldn't have to wait about for the nimh batteries to charge plus when using spectrum receivers you don't want the voltage to drop and end up browning out
:D
Happy Days:
Hey Andy, :D
You’re right, Li-Po’s don’t self discharge as much as Ni-MH and, as mentioned, they can be fully charged in a hour.
I guess I was looking at it from a personal perspective in that I always re-charge models the night before I fly them, or I “top them up” as I’m driving to the slope. (To be sure, to be sure :lol: )
As for Spectrum Rx’s ‘browning out.’ I’m sure this problem is not unique to Spectrum. Surely any Rx can brown out, either through loss of signal or loss of voltage. In this regard it matters not if the model is being powered by Li-Po’s or Ni-MH batteries. Once the battery voltage drops below the rx’s operating voltage, the rx stops working. Then, when the rx (and all the servos) are no longer drawing any current, the battery voltage will recover slightly allowing the rx to re-boot,….. and the whole process repeats itself.
You know yourself Andy, the knack is to be sure the battery has sufficient charge before you launch, whatever type of battery is in it.
Oh, and the other thing you need to remember is……. to switch the model on before you launch it. Ask me how I know! :oops: :cry:
andrew wallace:
:D :D :D I remember putting a thermal model up on a winch without turning it on :oops: :oops: lol
A small down side to the lipo is its a good bit lighter than NiMH and it means more lead
As you say its personal choice I lost faith in the NiMH battaries as I was always worried of them not holding there charge especially when flying large models
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