Confusion! (not ELO related)

I would recommend a 2s battery with 3 silicone diodes in series to keep the voltage down. Each diode has a voltage drop of about 0.6-0.7V (regardless of current flowing) to it should take the 7.4V down to about 5-6V, which is fine. Also, this is far lighter and cheaper than using a proper voltage regulator.

Ron if they are the same 5g servos I was running thy model of servo for Years on 1s lipos.
I never had any problems,, servos hae more torque at lower voltages.

I don't know too much about receivers, but as far as I seen, most of them are rated for 4.8V. A particular receiver may or may not work with 3.7V. The effect on range, is for example rather unpredictable. I would consider it a bad engineering practice to run equipment outside of the documented specs.

Yo Ron
With standard Spektrum gear don't not sorry NOT run 1s without something like this,-
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7884

I think Indra uses a vapor type servo/rx combo but the standard Spektrum RX'x suffer from 'brownout' where
the system shuts down briefly (no one knows exactly where) but between 3.5 and 4 volts.

2s without a regulator bye bye servos, not just cheapies. run 6v nimh's through a £100 JR and crank up the BBQ...

Servo's have less torque at lower voltages which is why some bods try to 'hop' them up with higher voltages
instead of buying better serovo's.

The best gear in the world is Powerbox (German) but I think it's all to big for you Ron although once you get to models
weighing 4 or 5 pounds their Digiswitch is one of the best products you'll ever buy because you fit it and forget about it.
I lost a Capiche 140 last year simply because it had a £6 Chinese switch on it. When I found the wreck (Perilously close to the M25 motorway you'da all heard about that if it had came down another 50 yards from where it hit) I could see the switch had failed. When I got home and opened it up there were 6 contact points only 5 of which had solder on them.....

IMO
Andrew above's got the right idea.

Although Lipo's are rated at 3.7 v per cell
When fully charged they're at 4.2 (and a bit) V per cell.

Also Ron yes both the Bacaruda and Old Timer plug straight
Into rx. Weight and space at a premium.

Ok guys,

That helped clear things up, now I have another problem. I have almost no room in the mini spit to install an eliminator or step up regulator. 1s will fit although it's tight. So how small of a 1S can I use? As in mAh? I need to drive 2 servos and an RX. My hummer has plenty of room so no worries there.

Thanks for the replies gents.

Ron -

Your AR6100 is rated for 3.5v ~ 9.6v. Without a boost converter, you're getting periously close to brownout levels, especially if you're near the end of the day and both servos are working pretty hard. I'm headed for class, but I'll look up some possible component substitutions for you when I get out.

andrew

What servo's are you using Ron??.

It seems your reciever is rated high enough for just about anything.

High Voltages aren't much of a prob for RX's it's the servo's that are the 'weak link'.
There are 2s servo's coming on line but them iz VVVVVVVVVVVVVVVVVVVV pricey.


BTW

LIPO's DO NOT like cold weather if using a small 1s I'd wait till it warms up over there guy's.

PV Pilot wrote:What servo's are you using Ron??.

It seems your reciever is rated high enough for just about anything.

Ok,

In the Sig Hummer I have 3 9g servos's ail,ele,throttle.

In the mini Spit I have 2 5g servos rud/ele

Both Hextronics brand.

I plan on using the same rx in both.

I have a brand new 2s 350 mAh that I was going to use in the Hummer. and I have 5 1s 600 mAH that fit in the mini spit from our pal Indra.

My other good pal John Boy. Just PM'd me a link to hobby zone that has a butt load of 1s batteries at a good price, too many choices John!!! Lol good link though!

John, I'm in TX it's always warm! 60F right now at 8:30 AM.

To test models I got the cheapest voltage booster i could, as i presume thats what people would use, the one i got was a couple of dollars from china and works fine

i use a 160mah 1 cell lipo , i still worry how long it goes for so i use a charged cell for every 3 or 4 flights and i dont turn off between , i presume it will last much longer but i have no idea how long they do last

John, I'm in TX it's always warm! 60F right now at 8:30 AM.[/quote]

I hate you



Although oddly we're OK at the Mo,tomorrow is set (aparantly) to be Scotlands warmest February day since records began.

dirk gently wrote:I would recommend a 2s battery with 3 silicone diodes in series to keep the voltage down. Each diode has a voltage drop of about 0.6-0.7V (regardless of current flowing) to it should take the 7.4V down to about 5-6V, which is fine. Also, this is far lighter and cheaper than using a proper voltage regulator.

Yes, I do to, but three 1amp diodes plus additional plug between battery
and diodes for charging besides being a fiddle to make up is perhaps
not the smallest or lightest setup. I use about 140mah 2s, no switch.
I need this for my 1/4 A models but if I was going to 1/2 A would use
larger, perhaps 450mah 2s plus regulator and no switch.
Now looking and making up voltage regulation chips available from Maplins in UK.
Tiny chip. Tiny piece of pcb and two plugs for voltage in and voltage out.
Much smaller, much lighter but have not flown these yet. John

Going with that the 5G and 9G hex is rated up to 6V.

With that, personally. I would stick with a lightweight 2S pack and a 6 volt 5 amp max regulator.

PV Pilot wrote:Going with that the 5G and 9G hex is rated up to 6V.

With that, personally. I would stick with a lightweight 2S pack and a 6 volt 5 amp max regulator.

I've had a Hextronix Hx12k on the rudder of my 69in QQ Yak for ever.
The price was laughable but it keeps doing what it does.
BOY does that servo get abused.
Great budget servos.

All good info! I'm learning!

That being said what should I be looking for mAh wise? Sorry if all the questions are bothersome. I really have no clue as to what I am doing.

Edit: I think proctor already answered this....

As an anecdote, I seem to recall that I once seen a chinese "device" marketed as a voltage adapter for receivers working with 2 cell LiPos. Something like a voltage regulator with BEC, but without the voltage regulation part. Anyway, upon disassembly, the device turned out to be 3 1N4007 in series. That's all

If you want to be cheap like me, find a small brushed speed controller and run that to your receiver battery port. (not the throttle port, you'll need that for your throttle servo) Plug your 7.4v lipo into speed controller and you will be good.

It regulates the voltage to exactly 4.8v. Mine never gets hot, but you can put a heatsink on it if you want.

I would start out with a 250mAh depending on the power system. Use a low voltage buzzer.

cribbs74 wrote:All good info! I'm learning!

That being said what should I be looking for mAh wise? Sorry if all the questions are bothersome. I really have no clue as to what I am doing.

Edit: I think proctor already answered this....

2-3 servo's,,lighweight low wing loading planes,, 3 to 600 mAh range.

Been using these G force batts for some time, purchased from here.
http://www.valuehobby.com/power-systems/lipo-batteries/2s-lipo.html

Do a rough calulation on battery size limitation in your electronics area and then see what you can squeeze in there. Watch the weights as well on your pack selection, you want to keep it light obviously.

Over thinking this guys...what is wrong with inexpensive NiMh at 4.8VDC or 6VDC? as an example Bernie sells me a lot of these for my dinky Rc 1/2A birds

http://coxengines.ca/product.php?productid=369&cat=11&page=1

4.8 Volts - NiMH
Capacity: 220 mAh
Max charge rate 1 Amp
JST Connector
L 25mm (1") x W 30mm (1.2")
H 22mm (0.9")
Weight: 28gr (1oz)
Brand new Current Production item

He will sell the same pack in 7.2 Volts - 2/3 AAA - NiMH for $2.95 with instructions on how to remove a cell or two to make a 4.8VDC pack

Capacity: 220 mAh
Max charge rate 1 Amp
JST Connector
L 37mm (1.4") x W 25mm (1.0")
H 19mm (0.75")
Weight: 38gr (1.3oz)
Brand new Original Cox item

I have charged these packs and put one in the airplane with a servo tester feeding full range motion and the pack lasted over 20 minutes before sagging below receiver needs. My dinky birds are only good for 2 to 5 min per flight so three packs fills my saturday fun just fine. They also recharge fairly fast as they only hold 220mAh

Nowt wrong with those Fred.
In my Bacaruda I've got a 220mah nimh 1/3rd AAA
Weighs 15grams. Already has rx plug on with 2x HS 50's
Never got close to half discharge. Would have put one in
The OT as well but for the fact it was tail heavy so needed
A bigger Batt up front.

Btw
Over your side there's a guy on fleabay sells the 150mAh
Losi batt. I got one of those as well 12g did have to swap plug
But if you've got field chargers (if not why not) small is beautiful
Charge every second flight.
J

fredvon4 wrote:Over thinking this guys...what is wrong with inexpensive NiMh at 4.8VDC or 6VDC? as an example Bernie sells me a lot of these for my dinky Rc 1/2A birds

http://coxengines.ca/product.php?productid=369&cat=11&page=1

4.8 Volts - NiMH
Capacity: 220 mAh
Max charge rate 1 Amp
JST Connector
L 25mm (1") x W 30mm (1.2")
H 22mm (0.9")
Weight: 28gr (1oz)
Brand new Current Production item

He will sell the same pack in 7.2 Volts - 2/3 AAA - NiMH for $2.95 with instructions on how to remove a cell or two to make a 4.8VDC pack

Capacity: 220 mAh
Max charge rate 1 Amp
JST Connector
L 37mm (1.4") x W 25mm (1.0")
H 19mm (0.75")
Weight: 38gr (1.3oz)
Brand new Original Cox item

I have charged these packs and put one in the airplane with a servo tester feeding full range motion and the pack lasted over 20 minutes before sagging below receiver needs. My dinky birds are only good for 2 to 5 min per flight so three packs fills my saturday fun just fine. They also recharge fairly fast as they only hold 220mAh

Fred,

Nothing wrong at all except no way one of those will fit in my tiny spitfire. It will fit fine in the hummer except I would have to purchase another charger. The charger I have now will do 1s-3s so I can use a larger Lipo in the Hummer. So the cheapest and easiest way to go would be Lipo's at this point.

That being said I plugged in all my stuff last night an bound my receiver. I used a 1s on both planes and they seemed to work fine. I will definitely go 2s with my Hummer but, for a function check it was fine.

I noticed a couple things. The servo's "chattered" the whole time, not sure why. Maybe it was due to the Lipo's not being on full charge. I also noticed once the juice was drained the control surfaces stopped moving which makes sense but, I did not lose the receiver(no brown out) I figured low battery the receiver would drop first.

One other question..... Is it ok to operate servo's not going full range? What I mean i that the servo still has a lot more swing but mechanically they are limited by the control rods etc.

Radical RC has some nice battery backs of different shapes, this one is particularly easy to place in narrow fuselages;