[NSRCA-discussion] Part 2-Its a miracle!!!
Wayne Galligan
wgalligan at att.net
Thu Sep 4 06:09:17 AKDT 2008
Ed or Jim O.,
I am running dual 1500 mil 6v NiMh packs in my Ultimate. I am using 2 of the 6v regulated Miracle switches by MPI. I find that one pack is consistently lower after two or three flights. Could it be that the regulators are not matched and one draws more then the other one? Could be a bad battery I'll have to remove and test. They seem to use about the same amount of mil amps but one is lower in voltage then the other. I use a 1amp load when testing after each flight and stop flying when the voltage drops to 5.8v loaded.
Thanks
Wayne
----- Original Message -----
From: Ed Alt
To: General pattern discussion
Sent: Thursday, September 04, 2008 5:32 AM
Subject: Re: [NSRCA-discussion] Part 2-Its a miracle!!!
Keith:
That setup works well. I refer to it as a hot standby, with details covered in a tech tip on the Tech-Aero website. I prefer a different approach, where you just split the battery capacity equally between two packs, each with its own regulator. The regulators must be precisely matched in output voltage setting to allow then to both actively share the load simultaneously. You can make a very light setup with this and there are several advantages to it. First, you can check every flight to see that each battery is being used as expected, which is very important to know. Second, you double your peak load capacity under load. A single 5A regulator such as the JAICCIO or the Tech-Aero can handle the load in a pattern airplane just fine, but it's also good to know that you can have two 5A regulators online at once, providing a 10A peak current capability.
The Tech-Tip on how this all works is at http://www.tech-aero.net/Tech-Tips.htm
Ed
----- Original Message -----
From: Keith Black
To: General pattern discussion
Sent: Wednesday, September 03, 2008 10:33 PM
Subject: Re: [NSRCA-discussion] Part 2-Its a miracle!!!
What I've done is have two batteries and two regulators, one regulator at 5.7 volts and one at 5.3 volts (or any voltage lower). On the higher voltage regulator I connect my primary battery, say a 2000 mah five cell or Lithium. On the lower voltage regulator I connect the smallest battery I can buy, say a 750 Lipo that weighs less than an ounce.
Since the larger battery is hooked to a regulator that outputs a higher voltage all drain comes from the primary battery and nothing is sucked from the smaller battery unless the main battery drops below 5.3 volts (or fails).
This works great and when recharging the smaller battery seldom needs any recharge at all.
I spoke to Jim Oddino before doing this and confirmed that the lower voltage battery would not suck voltage from the larger battery since it was going through his regulator (Jaccio regulator).
This setup has worked great for me and even saved a plane when my primary battery came loose and disconnected once!
Keith Black
----- Original Message -----
From: vicenterc at comcast.net
To: General pattern discussion ; 'General pattern discussion'
Sent: Wednesday, September 03, 2008 11:23 AM
Subject: Re: [NSRCA-discussion] Part 2-Its a miracle!!!
Correct, I still use separate regulators for each battery. This system is smart that isolates the bad battery if something goes wrong. In this way, the bad battery won't drain the good one. The LED in the receiver tells you if the battery has been isolated.
--
Vicente "Vince" Bortone
-------------- Original message --------------
From: "Jay Marshall" <lightfoot at sc.rr.com>
As I read the literature, the dual battery setup is designed to provide a heavier buss for more current. It does not solve the problem of a failed battery(s). This could effectively add even more drain. The ideal setup still seems to be dual battery packs with dual regulators, or some other means to isolate a failed pack.
Jay Marshall
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of vicenterc at comcast.net
Sent: Wednesday, September 03, 2008 11:44 AM
To: General pattern d iscuss ion
Subject: Re: [NSRCA-discussion] Part 2-Its a miracle!!!
Gray,
Yes, high drain could have been the problem. Since the plane is in good condition probably you can check. I think you should consider using two batteries of your preference. I starting to use the 9100 receiver that already has two power inputs. Check details here:
http://www.horizonhobby.com/Products/Default.aspx?ProdID=SPMAR9100
--
Vicente "Vince" Bortone
-------------- Original message --------------
From: Gray E Fowler <gfowler at raytheon.com>
Vicente
The Robbe charger has a setting for soft peak, which is to be used for NiMH. This is what I had. I cycled twice before using this new battery..what I remember was getting about 1300 Mah from this 1450 mah pack. I think there may be a "high drain" problem on the plane in addition.
Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineer ing
Raytheon
vicenterc at comcast.net
Sent by: nsrca-discussion-bounces at lists.nsrca.org
09/03/2008 09:42 AM
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Re: [NSRCA-discussion] Part 2-Its a miracle!!!
Gray,
Yes, that is good news. Clearly the battery was the problem. I had heard that some chargers get a "false peak" and stop charging when the battery is not really fully charged. I wonder if this was the problem.
--
Vicente "Vince" Bortone
-------------- Original message --------------
From: Gray E Fowler <gfowler at raytheon.com>
Lance and I went out and found the plane right where it was supposed to be. Do not know how I missed it the first day, so I am going to say that someone went into the woods Monday night and moved it .
What is amazing in the minimal damage the plane has considering it went straig ht in from 200 feet, albeit at a slow speed. The horrible reverbed cracking sound Keith and I heard was the carbon fiber wing tube breaking. Both wings have limited leading edge damage, the stab has a golfball size divot on the R LE, an easy to repair crack in the fuse (buckle failure) behind one wing and a little nose ring area damage. That is all.
The battery pack had broken the 3/8 bals a stic ks on impact that were bonded into place (my battery packs are not "removeable" per say) and the battey pack was on the ground at the nose of the plane. The plane was standing vertical on the undamage spinner being held up by the tree branches. Once we got home we hooked eveything up and of course it all worked fine. Knowing that the battery pack essentially had the same charge as when the plane went in, Lance took the battery pack home for diagnostics. Using the Robbe charger he cycled the1450 mah &nbs p;pack down....it read 80 mah. He then charged it and it read 1000 mah. Anthony described a NiMH "brown out" and that is starting to make alot of sense. 6 volt packNiMH , drained does not just die like a 4.8 volt NiCad. Also an important note is I now think the plane was going in and out of PCM lock. When I tested PCM lock the throttle did cut, but not to low idle. It cut to about 20% throttle (programming error), hence the pulsing of the throttle that I exper ienced. If this diagnosis is correct then it is a testament to using PCM as I was able to fly the plane for 45 seconds before impact...had I been closer when the problem started I may have even been able to score a "10" FAI landing (not really-I would have gone for the grass instead of the runway).
Anyw ay I am sending the entire radio off for examination, try to see why the battery was so low, and fix the plane for spring.
Thanks for the ideas
Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineering
Raytheon _______________________________________________
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