[NSRCA-discussion] IR meter

[Ron Van Putte]

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
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> NSRCA-discussion mailing list
>> NSRCA-discussion at lists.nsrca.org
>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>
>> Feeling the pinch at the grocery store? Make meals for under $10.
>> _______________________________________________
>> NSRCA-discussion mailing list
>> NSRCA-discussion at lists.nsrca.org
>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
> =
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
> Worried about job security? Check out the 5 safest jobs in a  
> recession.
>
> -----Inline Attachment Follows-----
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20090330/47d8c016/attachment.html>