Preddie Power

[pgkevet]

I'm not going through it all again .. because gasser folk have already heard it. But i need to make changes to Preddies power system.

I want duplicate redundant flight power. At the moment he's got dual lipos dual align regs with dual stepdowns but it;s a pain using the cheap electric ones and for various reasons not easy to mount 2 of the 2;1's switches in an accessible place.. and you need stepdowns for his 9252's.

Options..1 or 2 lipos (I've got lots of 2200 2S jobbies @ 125gms each) and then some form of dual regulator that can be paralleled.. most can't.. with an indicator and dual switch I can mount by the pullstart. I'd probably be happiest with a simple deans and loop type link(s)

Flight power here is 4.8-5.4v (9252's and bls251 and stuff). It'd be nice to avoid stepdowns from 6v systems.

The other obvious option is simple nihms.. a 4600 subC pack (no redundancy) 288gms .. so only 40gm more and no regulator. BUT these come with a chage lead and a Rx lead.. would have to swap the charge lead for a second or third rx lead.. really only can rely on 5A across a servo plug. OR I could run the main lead down to 2 deans type jumper links and the take it back to 2-3 plugs into the rx. OR us more than one AA Nihm.. now there they weight around 220 gms for 2200's and ischage rates are less reliable.. you don't save on weight 'cos you'kd want at least 2 of these.. even three.

I'm thinking as I write here...

the other issue with nihms is losses in storage or enerland cells with sudden drop-offs..

I'm swayed towards lipos and regulators although a 4600 nihm pack two lines off it to 2 switches and back to 2 Rx inputs is simplest. If using deans style jumpers then no sweat to add a third as a charge port..

Brainstom folks.. please

[electricsceadu]

my bell 47 has
twin 5000 mah 4 cell nimh's (sub c cells)
twin switch's
into two rx ports
the rx packs have the futaba and tamiya plugs
ans i've fitted an extention lead from each switch charge point to gain access to use a slow charger to the packs without taking them out
and i have the option of lifting the floor up and quick charging them through the tamiya type plugs if i ever need to

[pgkevet]

my bell 47 has
twin 5000 mah 4 cell nimh's (sub c cells)
twin switch's
into two rx ports
the rx packs have the futaba and tamiya plugs
ans i've fitted an extention lead from each switch charge point to gain access to use a slow charger to the packs without taking them out
and i have the option of lifting the floor up and quick charging them through the tamiya type plugs if i ever need to

One of the routes I considered.. but you fly scale (I assume?) and I would like to keep the weight down a bit.. that's an extra 10oz.

Incidently the HD servo wire can take 6A+...it's the plugs that are limited and they go to 5A.. since you can charge these type cells at 1C .. then you should be able to 'fast' charge at 1C through the switch

[electricsceadu]

yes its a scale heli

twin lipo's with regs would weigh about the same as the one nimh

in my turbulence i use the flight power 8 amp reg
it can take two 2s lipos and has two outputs (i use one lipo, but have plugged in both outpt into the rx)
it has one switch on the reg and the output voltage is adjustable

its another option but if the reg fails then you loose all power

[trillian]

As we spoke about before via email, I'd like to get some kind of redundant power on mine as well. It's too big a lump of hot metal and CF to risk coming down out of control.

I have several Fromeco Arizonas and several Duralites, a batshare and have thought about it but as yet not decided what to use and how.

I might talk to the guys that make the batshare or go on one of the giant scale plank forums and see what it would take to do a hybrid setup of one Arizona reg with a LiPo and a smallish Nimh pack that acts as a backup in the event voltage from the reg drops below a certain amount. (and have a visible warning light if that happens so the idea is the reg and LiPo should do the job but you have a backup and imediate warning to land if anything goes wrong)

[pgkevet]

An electronics guru pointed me at this item.. but wasn't able to mock it up further for me.. he reckoned these could be paralleled up without issue ..just needs mounting and adjusting and sockets sorting...a couple of these runnign off a 3-cell lipo with an indicator off it's balance leads and a link switch would be elegant and cheap?

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[trillian]

Well the big plank and jet guys have been there and got the T-shirt so I am inclined to see what they're doing.

[pgkevet]

Well the big plank and jet guys have been there and got the T-shirt so I am inclined to see what they're doing.

don't forget to report back!

[euan galloway]

pred power

Hello,
I mainly fly large<upto 7 mtr span > scale gliders and also play around with helis,i normally opt for the simple option of two 5cell nimhs and an S@M services battery backer with a pair of JR heavy duty switches or as an alternative two 5cell/4cell nimhs two HD Jr switches a y lead with a diode in it.I have 30% petrol powered scale aerobatic models and have used lipo regs with powerbox distributer boards in the past but wasted a lot of money doing the same job.My own Predator uses a good quality 4 cell 4600 nimh with a single JR hd switch that is always checked with an external batt tester before flight without trouble.At the moment iam fitting radio into a large Vario turbine powered Jet Ranger and will be using two good nimhs and the S@m battery backer ,
just my two cents Euan.

[pgkevet]

What is this battery backer, please? As in what does it do and how?

As I exlained I want dual redundant power after his attempt to go wandering at it would be nice to try and keep the weight down a bit rather than using 2 sets of 4-sub-C packs.. but agree that is simplest.

I really don't feel like investing n another on-board generator here (yet) and i don't trust the AA packs to have enough smooth output.

With your 4600 pack are you using one or two supplies to the rx..or does this backer power the servos directly?

[euan galloway]

pred power

Hello,
The battery backer is a clever british made electronic unit that uses dual battery inputs converted to a single rx input ,it monitors the batt voltage of both batts and will switch to either if it should fail.You can use one large capacity nimh and one smaller or as most do two of the same capacity.a visual indication of each batt is displayed.It powers the rx batt input and not switchable to just servos<heli guys appear to want to overcomplicate most things?>I have used the backer in some very large models with 100% reliablity .Have alook at S@m services web site,
cheers Euan

[pgkevet]

If I read their website correcty then they only do 6v dual battery backers.. the 'powersave' units use 6v on backers but 4.8v (my requirement) either shared with rx or (again if I understood) option of one batt for the rx and 1 for the powersave?

It looks a bit chunky though. Having said that it's a decent price for the option of powering each servo seperately...

[euan galloway]

pred power

yes,
i forgot the bit about 5 cells only,Have a look at motor and rotors web site he has a good range of suitable dist boards.How about using two 2s lipos and a pair of perkins regs with a diode in one side of a y lead,6v or 4.8 are available cheap and lightweight,
cheers Euan.

[pgkevet]

yes,
i forgot the bit about 5 cells only,Have a look at motor and rotors web site he has a good range of suitable dist boards.How about using two 2s lipos and a pair of perkins regs with a diode in one side of a y lead,6v or 4.8 are available cheap and lightweight,
cheers Euan.

there ya goes again using long words I don't uderstand.. 'perkins regulator' ?
At the moment it's got two align regs onboard but they are only rated to 6A each and 5A when used with stepdowns (dual).

Why your Y lead? If that is to join the reg outputs to one stepdown then again against the theory I understand... firstly your adding extra junctions with the losses they give and secondly you are breaching the theory of limiting each junction to 5A..and the reason i wanna do this is to have redundancy in case of a power draw surge..

Please, I'm not getting at you with the above ..just trying to sort a solution with minimum joints and max power potential in case of an issue... once bitten as they say..

[euan galloway]

Pred power

Hello,
Ok if you are thinking of a pre made y lead then yes i agree more connections to fail,but if you wire up and solder a y lead yourself you eliminate the chance of a connector failure .The diode is to stop any one battery simply draining into the other.This will provide a single input into your rx,the Perkins regulator is available from JPerkins via any model shop and very good value at £7.0 ish <very reliable and run cool> also can be used for 4.8 or 6volts with an input of upto 5s lipo.Powerbox equipment is good but a bit bulky and overpriced/hyped ?
When i can re charge my camera i will post some photos of installed units,
cheers Euan.