[NSRCA-discussion] Internal battery impedance

Emory Schroeter schroetere at bellsouth.net
Sun Mar 16 09:48:05 AKDT 2008 

Hey...come on Ron. It wasn't my soldering that was bad, just that I  
didn't solder the correct things together:-) That's completely  
different. But, I do think I'll keep my day job as it doesn't not  
involve wires or soldering.

Emory

On Mar 16, 2008, at 11:06 AM, Ron Van Putte wrote:

> I did not publish the schematic.  Some time ago I made a LiPo Doc
> package available to anyone who e-mailed me requesting it and I sent
> it to several, including Earl Haury and Emory Schroeter (Emory, stick
> to dentistry and stay away from a soldering iron).  The LiPo Doc was
> designed by Oscar "Monk" Morris, who designed many of the items sold
> by Radio South.
>
> This package contains a description of the LiPo Doc, schematics,
> photos of construction and a parts list (all available from Radio
> Shack for under $20.  I will warn you that the LiPo Doc is labor
> intensive.  it took me about four hours to construct mine and at
> least that to troubleshoot the one Emory sent to me.  There may be a
> problem for some to read everything in the package, because I have a
> Macintosh and sometimes items can't be read by PCs.
>
> I will make the same offer: e-mail me and I'll send you the
> package.    Please don't put your request for a package on the
> Discussion List; send it directly to me.
>
> Ron Van Putte
>
> On Mar 16, 2008, at 9:42 AM, AtwoodDon at aol.com wrote:
>
>> Ron, did you publish the schematics for this device or was I just
>> not paying attention?  I have some older TP5300s with over 200
>> flights I would love to compare with newer cells.
>>
>> thanks
>> Don
>>
>> In a message dated 3/15/2008 9:28:21 P.M. Pacific Daylight Time,
>> vanputte at cox.net writes:
>> That's true, you do need to know the current.  I should have said
>> that you don't need to measure it.  Most people who have an
>> inexpensive digital multimeter have one that measures voltage, not
>> current.  Using a precision resistor allows the determination of the
>> current with an inexpensive multimeter.
>>
>> Ron Van Putte
>>
>> On Mar 15, 2008, at 11:17 PM, Gordon Anderson wrote:
>>
>>> In general you do need to know the current. The fact is measuring
>>> voltage across
>>> know resistance is measuring current. i.e. 1 Volt across a 1 ohm
>>> resistor is 1
>>> amp. So using known resistance and making voltage measurements will
>>> allow the
>>> measurement.
>>>
>>> --Gordon
>>>
>>> -----Original Message-----
>>> From: nsrca-discussion-bounces at lists.f3a.us
>>> [mailto:nsrca-discussion-bounces at lists.f3a.us] On Behalf Of Ron Van
>>> Putte
>>> Sent: Saturday, March 15, 2008 9:06 PM
>>> To: NSRCA Mailing List
>>> Subject: Re: [NSRCA-discussion] Internal battery impedance
>>>
>>> You don't need to know the current.  Knowing voltage and resistance
>>> is enough.
>>> It is very simple and just as you described,  It does require
>>> precision
>>> resistors.
>>>
>>> Ron Van Putte
>>>
>>>
>>> On Mar 15, 2008, at 10:44 PM, Lance Van Nostrand wrote:
>>>
>>>> This sounds like a way to do each cell, but don't you need the
>>>> current?  If one were to measure the voltage across the battery and
>>>> the current through any resistor whose Ohmage is known then V=I *
>>>> (R +
>>>> internal resistance).  or is this just too naive.
>>>> --Lance
>>>>
>>>> ----- Original Message -----
>>>> From: "Ron Van Putte" <vanputte at cox.net>
>>>> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>> Sent: Saturday, March 15, 2008 8:40 AM
>>>> Subject: Re: [NSRCA-discussion] Internal battery impedance
>>>>
>>>>
>>>>> I'd forgotten Earl had the plans.
>>>>>
>>>>> The Lipo Doc is a very simple device that is mostly a rotary
>> switch
>>>>> and a couple of precision resistors.  You measure voltage on the
>>>>> cells of a lithium polymer battery in an unloaded condition,
>> with a
>>>>> 10 ohm load and a 1 ohm load.  The results are put in a
>> spreadsheet
>>>>> and the internal resistance of each cell is determined.
>>>>>
>>>>> Ron Van Putte
>>>>>
>>>>> On Mar 15, 2008, at 5:25 AM, Earl Haury wrote:
>>>>>
>>>>>> Lance
>>>>>>
>>>>>> I use the "LiPo Doc" built from plans I got from RVP.
>>>>>>
>>>>>> Earl
>>>>>> ----- Original Message -----
>>>>>> From: "Lance Van Nostrand" <patterndude at tx.rr.com>
>>>>>> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>>>> Sent: Friday, March 14, 2008 11:23 PM
>>>>>> Subject: [NSRCA-discussion] Internal battery impedance
>>>>>>
>>>>>>
>>>>>>> Earl,
>>>>>>> How do you measure the battery impedance?
>>>>>>> --Lance
>>>>>>>
>>>>>>> ----- Original Message -----
>>>>>>> From: "Earl Haury" <ejhaury at comcast.net>
>>>>>>> To: <chad at f3acanada.org>; "NSRCA Mailing List"
>>>>>>> <nsrca-discussion at lists.nsrca.org>
>>>>>>> Sent: Friday, March 14, 2008 10:10 AM
>>>>>>> Subject: Re: [NSRCA-discussion] Batteries
>>>>>>>
>>>>>>>
>>>>>>>> Chad, you have a point, however it's important to factor in
>> that
>>>>>>>> the 1P packs are also generally higher C rating. My view when
>>>>>>>> considering batteries initially was that higher cell count
>>>>>>>> provided more failure opportunities, both as individual cell
>>>>>>>> failure and connections. I've disassembled a number of
>> "failed",
>>>>>>>> or no longer pattern suitable packs, and measured individual
>> cell
>>>>>>>> characteristics.
>>>>>>>>
>>>>>>>> Generally, the cells in a lower C pack tend demonstrate an
>>>>>>>> increase in impedance, resulting in lower voltage output for a
>>>>>>>> given current draw over their lifespan until no longer "pattern
>>>>>>>> viable". During this time capacity diminishes - but most cells
>>>>>>>> with high impedance will still retain
>>>>>>>> 80+% of
>>>>>>>> their original capacity. Even though these things generate more
>>>>>>>> heat than the higher C packs - they tend to handle abuse (as
>>>>>>>> you've found) partly because of the retained capacity and
>> partly
>>>>>>>> because of "performance limiting" impedance. Post flight
>>>>>>>> imbalance
>>>>>>>> doesn't change too much as these packs age - suggesting a
>> similar
>>>>>>>> "aging" of the individual cells.
>>>>>>>>
>>>>>>>> Conversely, the high C packs demonstrate very low impedance
>>>>>>>> initially and that appears to be retained throughout their
>> life.
>>>>>>>> However, the cell capacity appears to drop pretty early and
>>>>>>>> continue to do so over the pack life. I've measured some of
>> these
>>>>>>>> with an average capacity loss of 40% after 50 flights - that
>>>>>>>> means
>>>>>>>> a 5000 mAh pack is now a 3000 mAh pack.
>>>>>>>> Even
>>>>>>>> worse -
>>>>>>>> there is often a good deal of variance from cell to cell. Their
>>>>>>>> low impedance will provide little warning (as loss of power)
>>>>>>>> until
>>>>>>>> a cell is injured, real easy to do if you try to take 3500 mAh
>>>>>>>> from the now 3000 pack.
>>>>>>>> Often one will notice the post flight imbalance increasing as
>>>>>>>> these packs age and it will be greater at higher depths of
>>>>>>>> discharge - a sure sign some cells are getting weak. OTOH - for
>>>>>>>> blazing power the high C packs are the way to go - but
>> there's a
>>>>>>>> price to pay in life, weight, & $$.
>>>>>>>>
>>>>>>>> These observations have led me to surmise that a pack with a
>> high
>>>>>>>> enough C rating to minimize impedance losses (and accompanying
>>>>>>>> heat) and a low enough C rating to allow good capacity
>> retention
>>>>>>>> should provide the best value for pattern. I have no idea just
>>>>>>>> what construction parameters / chemistry defines these
>>>>>>>> characteristics. I chose to try the FlightPower F3A packs
>> because
>>>>>>>> they are mid-C rating and 5350 mAh capacity. So far they
>> provide
>>>>>>>> good power and generate no more heat than the high C packs I've
>>>>>>>> used. I expect that the extra capacity (above 5000) offers a
>>>>>>>> little buffer if there is a capacity decline over their life. I
>>>>>>>> see little balancer activity with these packs regardless of
>> depth
>>>>>>>> of discharge (say 3000 mAh vs 4000 +) so far, time will tell -
>>>>>>>> we're all still learning.
>>>>>>>>
>>>>>>>> Earl
>>>>>>>>
>>>>>>>> Team FlightPower
>>>>>>>>
>>>>>>>>
>>>>>>>> ----- Original Message -----
>>>>>>>> From: "Chad Northeast" <chad at f3acanada.org>
>>>>>>>> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>>>>>> Sent: Friday, March 14, 2008 8:22 AM
>>>>>>>> Subject: Re: [NSRCA-discussion] Batteries
>>>>>>>>
>>>>>>>>
>>>>>>>>> I think a huge part of the 5300 Prolites ability to deliver
>>>>>>>>> under
>>>>>>>>> extreme abuse (I should know! :) ) is in large part due to
>> a 4p
>>>>>>>>> config rather than 1p as in the current packs.  In a 1p when
>>>>>>>>> that
>>>>>>>>> cell gets weak its over, in a 4p when a cell gets weak the
>> other
>>>>>>>>> 3 in the 4p can help it along for quite a while before they
>> all
>>>>>>>>> get weak.
>>>>>>>>>
>>>>>>>>> I am really convinced that a move to 1p config packs has
>> brought
>>>>>>>>> with it lower useful cycle life.  I feel you need to be a lot
>>>>>>>>> more cautious with the 1p packs than the 4p's, or they will
>> not
>>>>>>>>> last you very long :)
>>>>>>>>>
>>>>>>>>> Chad
>>>>>>>>>
>>>>>>>>> mike mueller wrote:
>>>>>>>>>> Chris Moon and I have bought the new TrueRC 5000 packs.
>> He has
>>>>>>>>>> been testing them for the last 2 months. They seem as
>> strong if
>>>>>>>>>> not stronger than his FP 5350 pack. The cost is only $110
>> a 5S
>>>>>>>>>> pack. I've bought 4 packs and I'm hoping that they are as
>> good
>>>>>>>>>> as initial testing has shown. I also have 2 brand new TP V2
>>>>>>>>>> Extreme 10S 5000 packs. All the packs at the 10S
>> configuration
>>>>>>>>>> weigh in around 42oz's with all the connectors.
>>>>>>>>>> The True RC packs have a lower C rating but this may be a
>> good
>>>>>>>>>> thing.
>>>>>>>>>> The higher C ratings seem to come at the cost of lower pack
>>>>>>>>>> life. Look at the TP Pro lite's many have exceeded the 200
>>>>>>>>>> cycle
>>>>>>>>>> barrier and still have a decent pack. The TP Extreme's V1's
>>>>>>>>>> were
>>>>>>>>>> dying in 50 flights and I have yet to see much better than a
>>>>>>>>>> hundred flights from the FP's. From my observation the
>> older TP
>>>>>>>>>> Prolites deliver plenty of power for our setups. So I
>> think the
>>>>>>>>>> TrueRC offerings are going to do the trick. Dan from True is
>>>>>>>>>> claiming over 200 cycles on them. I hope that I can get
>> 100. At
>>>>>>>>>> the $'s he's getting it will be a huge bargain.
>>>>>>>>>> Mike Mueller
>>>>>>>>>>
>>>>>>>>>>    The link is www.flightpowerusa.com <http://
>>>>>>>>>> www.flightpowerusa.com/>
>>>>>>>>>>
>>>>>>>>>>    I need to buy some packs myself.  Anybody know if they
>> will
>>>>>>>>>> be at
>>>>>>>>>>    Toledo?
>>>>>>>>>>
>>>>>>>>>>    Bob Kane
>>>>>>>>>>    getterflash at yahoo.com
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>    ----- Original Message ----
>>>>>>>>>>    From: Verne Koester <verne at twmi.rr.com>
>>>>>>>>>>    To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>>>>>>>>>>    Sent: Thursday, March 13, 2008 6:58:32 PM
>>>>>>>>>>    Subject: Re: [NSRCA-discussion] Batteries
>>>>>>>>>>
>>>>>>>>>>    Hi George,
>>>>>>>>>>    I'm in the same situation and have decided to go with the
>>>>>>>>>> FlightPower
>>>>>>>>>>    5350's. Even when the 5300's were fresh, I occasionally
>>>>>>>>>> felt
>>>>>>>>>> like
>>>>>>>>>>    I could
>>>>>>>>>>    use a little more punch, particularly on humid or windy
>>>>>>>>>> days. I've
>>>>>>>>>>    competed
>>>>>>>>>>    with a number of guys that had both the TP 5300's and FP
>>>>>>>>>> 5350's
>>>>>>>>>>    who would
>>>>>>>>>>    switch to the 5350's when they needed the extra power. My
>>>>>>>>>> plan is
>>>>>>>>>>    to use the
>>>>>>>>>>    FP 5350's and change props for different conditions.
>>>>>>>>>> Nothing is
>>>>>>>>>>    free however
>>>>>>>>>>    and you'll pick up 2 ounces in the process. I considered
>>>>>>>>>> the
>>>>>>>>>> 5000
>>>>>>>>>>    mah 10S
>>>>>>>>>>    packs from both TP and FP but can't afford to gain 4
>> ounces
>>>>>>>>>> in
>>>>>>>>>>    either of my
>>>>>>>>>>    existing planes. The FP 5350's are the best solution
>> for my
>>>>>>>>>>    situation. Mine
>>>>>>>>>>    just arrived this week and won't be flown until the snow
>>>>>>>>>> melts so my
>>>>>>>>>>    recommendations come from observations rather than
>>>>>>>>>> experience at
>>>>>>>>>>    this point.
>>>>>>>>>>    I bought mine directly from FlightPower
>>>>>>>>>>    http://www.flightpower.com <http://www.flightpower.com/
>>>>>>>>>>> .  Hope
>>>>>>>>>>    this helps.
>>>>>>>>>>
>>>>>>>>>>    Verne Koester
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>    ----- Original Message -----
>>>>>>>>>>    From: <glmiller3 at suddenlink.net
>>>>>>>>>> <mailto:glmiller3 at suddenlink.net>>
>>>>>>>>>>    To: "NSRCA List" <nsrca-discussion at lists.nsrca.org
>>>>>>>>>>    <mailto:nsrca-discussion at lists.nsrca.org>>
>>>>>>>>>>    Sent: Thursday, March 13, 2008 12:26 PM
>>>>>>>>>>    Subject: [NSRCA-discussion] Batteries
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> Hi All,
>>>>>>>>>>>
>>>>>>>>>>> I've been flying with Thunder Power Prolite 5300 packs for a
>>>>>>>>>>    while now and
>>>>>>>>>>> they are getting very tired.  As they poop out, I'm
>> trying to
>>>>>>>>>>    decide what
>>>>>>>>>>> to replace them with.  From what I've seen, the Flightpower
>>>>>>>>>>    "FAI" packs
>>>>>>>>>>> are probably what I'll go with, but if anyone has any other
>>>>>>>>>>    suggestions,
>>>>>>>>>>> please sing out.  Also, any suggestions as to a source
>>>>>>>>>>> would be
>>>>>>>>>>> appreciated.
>>>>>>>>>>>
>>>>>>>>>>> TIA,
>>>>>>>>>>>
>>>>>>>>>>> George
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> NSRCA-discussion mailing list
>>>>>>>>>>> NSRCA-discussion at lists.nsrca.org
>>>>>>>>>>    <mailto:NSRCA-discussion at lists.nsrca.org>
>>>>>>>>>>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>    _______________________________________________
>>>>>>>>>>    NSRCA-discussion mailing list
>>>>>>>>>>    NSRCA-discussion at lists.nsrca.org
>>>>>>>>>>    <mailto:NSRCA-discussion at lists.nsrca.org>
>>>>>>>>>>    http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
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