[NSRCA-discussion] IR meter

Mon Mar 30 03:28:19 AKDT 2009

OK Ron,

I didn't "butcher it", I merely attached the wires to the wrong  
locations. Could we maybe just say that I tried to redesign it and  
that didn't quite work? :-)

Emory

On Mar 30, 2009, at 7:07 AM, Ron Van Putte wrote:

> About two years ago I reported on the Lipo Doc, which a friend of  
> mine had designed, to measure cell internal resistance.  It uses two  
> volt meters (you can use one, but two is easier).  I built one for  
> myself and sent the plans/schematic to several people.  A couple of  
> my club members built them and I rewired up one that Emory Schroeter  
> had butchered.  I think Earl Haury made one as well.
>
> It is very inexpensive and all parts can be purchased at Radio  
> Shack.  The problem is that you have to make it yourself and in this  
> ARF-only society, only the avid individual will tackle the job.  I  
> will send the information to anyone who's interested, but be  
> forewarned that it takes about two hours to completely fabricate.
>
> Ron Van Putte
>
> On Mar 30, 2009, at 1:53 AM, krishlan fitzsimmons wrote:
>
>> Interesting. Well, maybe someone will come up with a good one at  
>> some point for those that don't use a Cellpro. I can't say my  
>> Cellpro is accurate, just that it works and gives me something to  
>> base my batteries off of.
>>
>> Jim,
>>
>> Any idea why 2 and 3 cell packs have such a high resistance? Even  
>> new mine are over 20. Hard to tell when they are bad.
>>
>> Something interesting is that on my AFPD sim, I was just flying the  
>> Spark. I haven't flown it much as there are a few things I don't  
>> care for compared to others that I have on there. One was that it  
>> felt underpowered. An easy change normally, just never did it. But  
>> instead of altering the motor, I went and looked into the  
>> batteries. The resistance was set at 13.0. I changed it to 2.0 and  
>> now the plane it silly fast. Not sure that means anything, just  
>> found it interesting.
>>
>> Thanks,
>>
>> Chris
>>
>>
>>
>>
>>
>> --- On Sun, 3/29/09, AtwoodDon at aol.com <AtwoodDon at aol.com> wrote:
>>
>> From: AtwoodDon at aol.com <AtwoodDon at aol.com>
>> Subject: Re: [NSRCA-discussion] IR meter
>> To: nsrca-discussion at lists.nsrca.org
>> Date: Sunday, March 29, 2009, 9:27 PM
>>
>> I agree, since I have to charge anyway, I am going to believe the  
>> CellPro.  I sold the IRM to someone that was unhappy they were sold  
>> out when he went to order......
>>
>> D
>>
>> In a message dated 3/29/2009 8:31:52 P.M. Pacific Daylight Time, joddino at socal.rr.com 
>>  writes:
>> Don,
>>
>> I would say the FMA is closer to the real value.  I'll look at some  
>> inflight data but just as a test of reasonableness I looked at the  
>> data I sent you recently where I was pulling about 98 Amps at 39  
>> volts.  My pack has about 3 mOhms per cell according to the FMA  
>> times 10 cells is .03 Ohms for the pack.  98 x .03 = 2.94 volts  If  
>> the resistance was 7 times higher the drop would be seven times  
>> higher or around 21 volts.  Something is wrong with his algorithm.
>>
>> Jim
>> On Mar 27, 2009, at 5:22 PM, atwooddon at aol.com wrote:
>>
>>> I have one, caught the discussion thread just as it started and  
>>> jumped on the initial orders.  It works as expected. Although the  
>>> IR numbers are substantially higher than what the FMA charger  
>>> reports the relationship of the IR numbers between the cells is   
>>> proportionately the same.  The IRM shows IR ohms about 7-8 times  
>>> that of the FMA CellPro 10S.  Which one is right?  I dunno, but  
>>> when I asked why they were so different, I got a very long  
>>> explanation that I did not understand.  All I know is the ratios  
>>> seem to stay the same between them on the same batteries.
>>>
>>> It is well made tho I don't care for the small plugs for balance  
>>> taps, that is kinda clumsy, but it works as advertised.
>>>
>>> Don
>>>
>>> In a message dated 3/27/2009 11:55:58 A.M. Pacific Daylight Time, homeremodeling2003 at yahoo.com 
>>>  writes:
>>> Did you guys see this yet? Could be helpful if your charger  
>>> doesn't do it.
>>>
>>> http://www.rcgroups.com/forums/showthread.php?t=980290
>>>
>>> Chris
>>>
>>>
>>>
>>>
>>>
>>>
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>> =
>>
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