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Batteries for 50cc aircraft - 11/21/2007 1:15:37 PM   
jsallade


 

Posts: 45
Joined: 10/13/2004
From: Fairland, IN, USA
Status: offline 		Hi all,
I'm well on my way to assembling my 28% Edge and am considering running redundant LiPo (with regulators) for my flight pack(s). I've seen some posts in other forums making wild claims about the capacity of the battery packs needed. It seems to me most folks are running 2000-3000mah NiMh or NiCd packs (sometimes dual, somtimes not) in this size airplane so I am thinking of running a pair of 2 cell 2100mah LiPo packs with MPI 6V regulators in my airplane. Anyone know of a reason this wouldn't work well? In fact I could run inexpensive (8C) packs since they will never likely see anything like the 16A plus draw they could handle! The regulators probably wouldn't take that anyway. Anyone see why this wouldn't work?? I'm going straight into my receiver from the two regulators (batt-Switch-reg-rcvr). Again, at this size a power bus seems like extra complication for no/little gain.
My thinking is I get a nice stable 6V system courtesy of the regulators at reasonable cost with no weight penalty. I'd run the regulators anyway as they should be very reliable (at least regulators in most electronic devices are) and I'll have redundancy anyway. Using the HD MPI switches and the LiPos will certainly be lighter than the NiMh packs would be. This seems like it will be a good system and FAR cheaper than the full systems being sold in the magazines for (I suppose) those who are unwilling to piece together their own and/or don't understand the technology. Anyone have any counter arguments I need to consider?
       Post #: 1

RE: Batteries for 50cc aircraft - 11/21/2007 2:31:46 PM   
rctom



Posts: 5148
Joined: 5/8/2002
From: Flower Mound (near Dallas), TX, USA
Status: online 		Two months ago I would have said "go for it", this is the setup that I have been using in all my planes for a few years now, and it works well. People have warned me that the Li-poly's are fragile but I never had any trouble at all. All of your logic is correct.

However

I have recently become familiar with A123 batteries, and for me Lipo is now obsolete for powering the electronics in a plane. Lipos I think are still the best thing for motors, but the A123s have several advantages on the receiver/servos.

Think ofthe A123 as the same as a Lipo with 10Cplus current available, actually A123 has 30C continuous with 60C burst. But there are three major differences.

First, A123 cells are 3.3V nominal, which means a 2 cell pack is about 6.6V, even fully charged it's no more than 7.2V and drops back to 6.6 within a few seconds after you start using them. This means no regulators, and voltage stays above 6V throughout the discharge cycle no matter what you do with your plane. No way can you pull them below 6.0v let alone pull them down to 3.5 where the receiver reboots, it's just not possible.

Second, the cells are in alimunim cases that are laser welded, they are extremely rugged.

Third, they cannot catch fire or explode, their chemistry will not allow that to happen. If you severely overcharge them or otherwise abuse them the mostthat happens is the end will pop open.

They are a little bulky but no heavier than a Nimh pack of similar capacity (right now only 2300mag cells are available in pre-made packs). I am happy using one pack in my 35% planes, they have way plenty of current capacity and are rugged enough that I do not feel the need to have two packs for redundancy. I DO run two switches and two connections into the receiver, but only 1 pack which weighs 5.5 oz.

Even though this obsoletes a lot of my inventory I'll be switching over to selling these a123 setups, they are a major breakthrough.

Anybody want to buy a bunch of 2100mah and 2700mah Nimhs? How about a box of 6V regulators? Some 2400 Li-Ions?

Oh, one other bit of information. I have done a lot of testing to see how much power my 35% planes use per flight. In about 1 flights with each of two planes (100" Edge with DA-85 and 106" Giles with DA-100) I have seen power usage between 220 and 375 mah, depending on how I am flying. If I just putter around the sky power usage is low, if I am practicing the IMAC sequence or just flying wild power goes up, but never over 375mah in a 10 minute flight.

Consider 2300mah to be plenty for 6-8 flights without a recharge.


TF

(in reply to jsallade)
       Post #: 2

RE: Batteries for 50cc aircraft - 11/21/2007 2:50:22 PM   
dredknot


 

Posts: 99
Joined: 2/5/2004
From: valley, ANGUILLA
Status: online 		tom

what types of chargers can be used to charge A123 batteries,would i have to by a new charger or can the Fromeco Ion Cube,sirrus or the plug in wall charger be used ,also how long would it take to charge a pack and can it be quick charge

verne

(in reply to rctom)
       Post #: 3

RE: Batteries for 50cc aircraft - 11/21/2007 3:55:54 PM   
zool.on


 

Posts: 15
Joined: 8/13/2007
From: toronto, ON, CANADA
Status: offline 		Hi Dredknot,

I have just started to look at A123 power as well. There is a lot of info in the forums about them and some good info here http://www.a123racing.com/

(in reply to dredknot)
       Post #: 4

RE: Batteries for 50cc aircraft - 11/21/2007 3:59:30 PM   
dredknot


 

Posts: 99
Joined: 2/5/2004
From: valley, ANGUILLA
Status: online 		THANKS zool.on,will check it out

(in reply to zool.on)
       Post #: 5

RE: Batteries for 50cc aircraft - 11/21/2007 4:41:55 PM   
rctom



Posts: 5148
Joined: 5/8/2002
From: Flower Mound (near Dallas), TX, USA
Status: online
quote:

ORIGINAL: dredknot

tom

what types of chargers can be used to charge A123 batteries,would i have to by a new charger or can the Fromeco Ion Cube,sirrus or the plug in wall charger be used ,also how long would it take to charge a pack and can it be quick charge

verne


I know there are several chargers available, I doubt the Fromeco will do it but you'd have to ask them.

I own two. The Hypersonic that is sold by A123 racing charges at 10 amps and balances a 2 cell pack, it will charge a dead pack in 15 minutes. It works fine but gives no feedback, it's just a slam bang get it charged quick deal. Ithink it's mainly for RC cars where you need a fast recharge on a dead cell and don't really care about the details.

The FMA Cellpro is the most popular, it will also do Liions and Lipos. For A123 its maximum charge rate is 4 amps so it takes a little over a half hour to recharge a dead pack. Recharging after flying 2 or 3 flights takes only a few minutes.

The nice thing about the Cellpro is it tells you exactly what it's doing and after you recharge it tells you how much it put back into the pack, this is how I know exactly how much power I have used after a flying session. Very useful information. It will also balance 2 3 or 4 cells.

TF

(in reply to dredknot)
       Post #: 6

RE: Batteries for 50cc aircraft - 11/21/2007 5:10:56 PM   
jsallade


 

Posts: 45
Joined: 10/13/2004
From: Fairland, IN, USA
Status: offline 		Tom,
Thanks for the info. I think I'll go forward for now with my setup as planned. I work in a technology industry (computer networking and telephony) and my experience is use technology when it makes sense but don't get to close to the bleeding edge! I consider LiPos and regulators to be well proven technology if employed properly and the level of redundancy I described makes sense to me. I'll pad them well and isolate them from vibration so anything short of an all on hit into something hard should keep me away from the venting with flame issue! I'll be very interested in the A123s as you roll them out and they get some more road time... sounds like a nice system going forward. Maybe I'll upgrade to those next time around or in the next plane. Thanks again for all the info.

(in reply to rctom)
       Post #: 7

RE: Batteries for 50cc aircraft - 11/22/2007 5:54:37 AM   
pants68


 

Posts: 18
Joined: 2/24/2007
From: N delta, BC, CANADA
Status: offline 		Hi
Im looking at going for the 123 packs on my edge 540. What capacity should i go for?
Should I run 1*2300mah
2* 2300mah
or 1 just one 4600mah?

Also
would a 2300mah single be a good choice for ignition?

Mark

(in reply to jsallade)
       Post #: 8

RE: Batteries for 50cc aircraft - 11/22/2007 10:56:58 AM   
danielwidman79


 

Posts: 103
Joined: 11/4/2003
From: Härnösand, SWEDEN
Status: offline 		Hi
Im building the 84" Extra 300
I have found a dealer in Sweden that selling the A123
If i go with these batterys do i have to regulate the power?
I dont think the reciver can handle 6.6 V

(in reply to pants68)
       Post #: 9

RE: Batteries for 50cc aircraft - 11/22/2007 1:54:44 PM   
rctom



Posts: 5148
Joined: 5/8/2002
From: Flower Mound (near Dallas), TX, USA
Status: online
quote:

ORIGINAL: danielwidman79

Hi
Im building the 84" Extra 300
I have found a dealer in Sweden that selling the A123
If i go with these batterys do i have to regulate the power?
I dont think the reciver can handle 6.6 V


You do not need to regulate the A123 batteries. Your receiver can handle over 7 volts and probably even 9 volts, at least most receivers will.

6.6v is actually less than a fully charged Nimh or Nicd 5 cell pack, it will work fine unregulated for any receiver, servo, or ignition.

TF

(in reply to danielwidman79)
       Post #: 10

RE: Batteries for 50cc aircraft - 11/22/2007 2:01:20 PM   
rctom



Posts: 5148
Joined: 5/8/2002
From: Flower Mound (near Dallas), TX, USA
Status: online
quote:

ORIGINAL: pants68

Hi
Im looking at going for the 123 packs on my edge 540. What capacity should i go for?
Should I run 1*2300mah
2* 2300mah
or 1 just one 4600mah?

Also
would a 2300mah single be a good choice for ignition?

Mark


There is absolutely no need for more than 2300mah capacity, your 50cc plane will not use more than 250mah per 10 minute flight. That will give you at least 8 flights without a recharge.

The only reason to use 2 packs is for redundancy, in case a pack were to fail completely because of a bad cell or broken wire. This is a rare event, even more so with A123s because the cells are very rugged with a laser welded aluminum case.

I do recommend 2 switches and 2 plugs into the receiver to increase current capacity and to prevent failure in case of switch failure or if a connector were to come unplugged. You get packs from me or from Tanic with two output leads to connect to two switches.

Adding a second pack adds 5.5 oz. to the plane. I believe it's unnecessary, but it can't hurt if you are not concerned about a little weight.

2300mah will work fine on ignition but is overkill unless you need nose weight. I would either use a small 6v nimh pack 700-1200mah will work fine and weighs/costs much less. Or you can make a smaller A123 pack out of two Black and Decker cells from a VPX power pack.


TF


< Message edited by rctom -- 11/22/2007 2:07:52 PM >

(in reply to pants68)
       Post #: 11

RE: Batteries for 50cc aircraft - 11/25/2007 8:05:23 PM   
Rcpilot


 

Posts: 6534
Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline
quote:

ORIGINAL: rctom
Even though this obsoletes a lot of my inventory I'll be switching over to selling these a123 setups, they are a major breakthrough.

Anybody want to buy a bunch of 2100mah and 2700mah Nimhs? How about a box of 6V regulators? Some 2400 Li-Ions?


TF


You have a PM.


_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

(in reply to rctom)
       Post #: 12

RE: Batteries for 50cc aircraft - 11/28/2007 9:38:18 AM   
BAS



Posts: 1384
Joined: 12/15/2001
From: Altoona, IA, USA
Status: offline 		Tom i have a question on the 123 packs. What kind of switch are you using to be able to plug the deans connector into the switch . All of my switches are regular heavy duty switches with the normal type batt plug on them.

_____________________________

Bruce A Swartfager

(in reply to Rcpilot)
       Post #: 13

RE: Batteries for 50cc aircraft - 11/28/2007 2:36:15 PM   
rctom