Battery selection thoughts.

[Henderson,Eric]

James,
       I tested them (the usual battery types), over the last couple of years. None of these readings are bad BTW. The Nicads are the heaviest and give one less pattern flight than a similar rated NiMH that gives one less pattern flight than a lighter Li-ion. (all are approx. 1800 mAh's)

To be clear and fair, I use a safety margin of "how long it takes to run a pack down with a jammed retract servo". (remember those?) In practical terms I shoot for a max of 8 consecutive digital-servo-15-minute flights with a Li-ion with no recharge. Of course with NiMH's and Li-ion's you can charge between flights due to no "memory" issues. All my pattern planes use Li-ion's and I don't fly if I see less that 7.2v with the plane switched on.

As an aside I have been using Li-ions in a TX and found it to be very satisfactory so far. It is a bit odd seeing 12.6v on the TX display. NiMH's gave 11.4 fully charged and held it well. These Li-ions hold their charge for weeks and just refuse to take a charge until you use some juice. i can go three 8 flight sessions and still not need to charge the TX. Of course I do due to afore mentioned battery phobic behavior.

Not sure if they are available commercially yet from Bern for TX's - Test of charger etc. BUT totally cool to use,...

Regards,

Eric.

P.S. Winter is nearly over and Buff Miller should get ready for an NJ invasion.............

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Woodward James R Civ
412 TW/DRP (Test Ops)
Sent: Monday, March 31, 2003 5:00 PM
To: discussion at nsrca.org
Subject: RE: Re two batteries, or other ideas


Hi Eric,

Do you happen to know if these trends are better/worse/equal to that seen by
nicads or nimh batterys?
Jim


-----Original Message-----
From: Henderson,Eric [mailto:Eric.Henderson at gartner.com] 
Sent: Monday, March 31, 2003 1:54 PM
To: discussion at nsrca.org
Subject: RE: Re two batteries, or other ideas

Bill,
      I just ran one of my YS 1.40's in an unrelated test and observed the
following readings on a li-ion just for you.

At rest the C-volt showed 8.11v

Idle - 7.9~v

Full rpm - 7.61v

Load tester, RX off, using .5 amp 7.69.

Close enough for a cigar I think.

Regards,

E.

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Bill Glaze
Sent: Monday, March 31, 2003 4:58 PM
To: discussion at nsrca.org
Subject: Re: Re two batteries, or other ideas


Eric:
You paint a persuasive picture for the I4C device.  I put one on a large
gasser of mine, that hasn't been flown for a couple of years.  I also have
one brand new on the shelf.  (I might say I've never crashed that particular
shelf!<G>)
Don't know why I've never related that device with any pattern plane; I
guess I'm a little too weight conscious.  And, while I've got the LED series
device on a very valued Sukhoi of mine, it just doesn't seem as precise as
an Expanded Scale Voltmeter.  BTW: does the ESV agree pretty closely with
the I4C device?  Asking about your experience, here.
After all this, I believe the I4C will find a new life in the Focus.
Thanks for your informative post.

Bill Glaze

"Henderson,Eric" wrote:

> You can go too far with all of this redundancy stuff and still get
failures that are much more common.
>
> I have become a bit phobic about batteries with several "failures" and
"dodged bullets". At first I developed a regimen where I did a pack-test
before and after every flight. Although this was good it did wear out the
charging
> jack in the fuselage side. It also DID NOT test the on-board system.
Perhaps the word TEST is what needs to be most emphasized!
>
> My most recent "peace of mind" comes from using on-board battery
indicators. The $15 string of LED types work well and can be seen on most of
my sport planes. The I4C, C-Volt LCD digital unit drains a meager 10 ma and
tells you a whole bunch of things while you have the flight pack turned on.
It weight approx. 0.4oz and is in all of my pattern or big planes. The big
deal here is that the flight system is on, not just the battery undergoing a
load test with some external device. What you are seeing is what you will be
flying.
>
> It is not cheap @ $40 plus... but has help me spot the following potential
disasters that would have cost $1000's.
>
> 1. Several bad aileron pots that drew huge ma's when the engine was
running.
> 2. Bad connectors to battery. One was arching and melting the plastic
connector...
> 3. Bad servo motors.
> 4. Binding control surfaces (Throttle servo on soft-mount was being
stressed as full power moved motor forward - needed 1/16" less opening to
fix) drained an amp at full throttle. The Voltage shown tracks the amperage
being drawn pretty closely.
> 5. Bad wire on servo lead - black corrosion and non conductive..
> 6. And last but not least, bad battery cells.
>
> I use this digital display because it can handle any RX pack voltage -
8.4v on a Li-ion or 4.8v on a nicad... are all in the range.
>
> One nasty problem (that LCD found of my Focus) was a regulator that was
failing during high current draw. I tracked it down by putting an additional
C-Volt in an RX slot and operating the flight system with the engine running
(tethered of course). The voltage prior to the regulator stayed good but
post regulator was erratic. Bye bye regulator - New one was flawless and
easy to test.
>
> Also when trying new packs all I do is read the display before and after a
flight and log the discharge for each flight, For example my Li-ion come
down .2v per flight with a "digital-servo" ship.
>
> They (I4C_ have and LED version that is a bit heavier as well. Worked good
in an application where the canopy was a bit too dark for the LCD version.
>
>  - This is one of those "Ounce of prevention is worth a pound of cure"
thought processes.
>
> Regards,
>
> Eric.
>
> BTW I'm not saying don't do all the battery back-up stuff if it helps your
phobia but that you can also add an integral read-out device..
>
> Breaking news. They now have a version that doubles up as an onboard tach
using the same LCD and a hall effect sensor to pick up magnet embedded in
spinner back plate - tells you your rpm while ground tuning and give
in-flight peak reading.. more toys ---!!!!!
>
> Regards,
>
> Eric.
>
> -----Original Message-----
> From: discussion-request at nsrca.org
> [mailto:discussion-request at nsrca.org]On Behalf Of tkeithb at attbi.com
> Sent: Monday, March 31, 2003 1:44 PM
> To: discussion at nsrca.org
> Subject: RE: Re two batteries, was Miracle switch failures
>
> > I currently just use one 5 cell NiCd with a RadioSouth 5.1v regulator
and
> > it's the best setup I've had in terms of consistent performance.  I will
> > be repeating this on my next plane.
> > --Lance
>
> So what you're saying Lance is that you DO have redundancy, a second
plane.
>
> :-)
>
> Keith
> > You are right, the backup battery is the simpler (hopefully more
reliable)
> > setup.  I understand.
> >
> > In my experience with circuit board design, I've found regulators to be
> > more reliable than diodes.  This is not intuitive, since regulators have
> > many internal transistors, but they also have bypass protective
circuitry.
> >  If the regulator is wrapped in foam and the connectors are stress
> > relieved so that they can't weaken, then I'd have no problems having a
> > regulator in the circuit.  I
> >
> > I currently just use one 5 cell NiCd with a RadioSouth 5.1v regulator
and
> > it's the best setup I've had in terms of consistent performance.  I will
> > be repeating this on my next plane.
> >
> > --Lance
> >
> >
> >
> >
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