The new FMA 10S LiPo charger is supposed to be able to give you cell impedance during the charge cycle. <br><br><div class="gmail_quote">On Sat, Mar 15, 2008 at 1:18 PM, Emory Schroeter <<a href="mailto:schroetere@bellsouth.net">schroetere@bellsouth.net</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">It certainly will help you be able to see exactly which cell is going<br>
bad in a pack. I built one and after it didn't work, I sent it to Ron,<br>
who was able to undo all the incorrect soldering I had done :-) I have<br>
yet to actually use the spreadsheet, but I'm sure I will eventually<br>
get around to it.<br>
<br>
Emory<br>
<br>
<br>
On Mar 15, 2008, at 9:40 AM, Ron Van Putte wrote:<br>
<br>
> I'd forgotten Earl had the plans.<br>
><br>
> The Lipo Doc is a very simple device that is mostly a rotary switch<br>
> and a couple of precision resistors. You measure voltage on the<br>
> cells of a lithium polymer battery in an unloaded condition, with a<br>
> 10 ohm load and a 1 ohm load. The results are put in a spreadsheet<br>
> and the internal resistance of each cell is determined.<br>
><br>
> Ron Van Putte<br>
><br>
> On Mar 15, 2008, at 5:25 AM, Earl Haury wrote:<br>
><br>
>> Lance<br>
>><br>
>> I use the "LiPo Doc" built from plans I got from RVP.<br>
>><br>
>> Earl<br>
>> ----- Original Message -----<br>
>> From: "Lance Van Nostrand" <<a href="mailto:patterndude@tx.rr.com">patterndude@tx.rr.com</a>><br>
>> To: "NSRCA Mailing List" <<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>><br>
>> Sent: Friday, March 14, 2008 11:23 PM<br>
>> Subject: [NSRCA-discussion] Internal battery impedance<br>
>><br>
>><br>
>>> Earl,<br>
>>> How do you measure the battery impedance?<br>
>>> --Lance<br>
>>><br>
>>> ----- Original Message -----<br>
>>> From: "Earl Haury" <<a href="mailto:ejhaury@comcast.net">ejhaury@comcast.net</a>><br>
>>> To: <<a href="mailto:chad@f3acanada.org">chad@f3acanada.org</a>>; "NSRCA Mailing List"<br>
>>> <<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>><br>
>>> Sent: Friday, March 14, 2008 10:10 AM<br>
>>> Subject: Re: [NSRCA-discussion] Batteries<br>
>>><br>
>>><br>
>>>> Chad, you have a point, however it's important to factor in that<br>
>>>> the 1P<br>
>>>> packs are also generally higher C rating. My view when considering<br>
>>>> batteries<br>
>>>> initially was that higher cell count provided more failure<br>
>>>> opportunities,<br>
>>>> both as individual cell failure and connections. I've<br>
>>>> disassembled a<br>
>>>> number<br>
>>>> of "failed", or no longer pattern suitable packs, and measured<br>
>>>> individual<br>
>>>> cell characteristics.<br>
>>>><br>
>>>> Generally, the cells in a lower C pack tend demonstrate an<br>
>>>> increase in<br>
>>>> impedance, resulting in lower voltage output for a given current<br>
>>>> draw<br>
>>>> over<br>
>>>> their lifespan until no longer "pattern viable". During this time<br>
>>>> capacity<br>
>>>> diminishes - but most cells with high impedance will still retain<br>
>>>> 80+% of<br>
>>>> their original capacity. Even though these things generate more<br>
>>>> heat than<br>
>>>> the higher C packs - they tend to handle abuse (as you've found)<br>
>>>> partly<br>
>>>> because of the retained capacity and partly because of "performance<br>
>>>> limiting" impedance. Post flight imbalance doesn't change too<br>
>>>> much as<br>
>>>> these<br>
>>>> packs age - suggesting a similar "aging" of the individual cells.<br>
>>>><br>
>>>> Conversely, the high C packs demonstrate very low impedance<br>
>>>> initially and<br>
>>>> that appears to be retained throughout their life. However, the<br>
>>>> cell<br>
>>>> capacity appears to drop pretty early and continue to do so over<br>
>>>> the pack<br>
>>>> life. I've measured some of these with an average capacity loss<br>
>>>> of 40%<br>
>>>> after<br>
>>>> 50 flights - that means a 5000 mAh pack is now a 3000 mAh pack.<br>
>>>> Even<br>
>>>> worse -<br>
>>>> there is often a good deal of variance from cell to cell. Their low<br>
>>>> impedance will provide little warning (as loss of power) until a<br>
>>>> cell is<br>
>>>> injured, real easy to do if you try to take 3500 mAh from the now<br>
>>>> 3000<br>
>>>> pack.<br>
>>>> Often one will notice the post flight imbalance increasing as<br>
>>>> these packs<br>
>>>> age and it will be greater at higher depths of discharge - a sure<br>
>>>> sign<br>
>>>> some<br>
>>>> cells are getting weak. OTOH - for blazing power the high C packs<br>
>>>> are the<br>
>>>> way to go - but there's a price to pay in life, weight, & $$.<br>
>>>><br>
>>>> These observations have led me to surmise that a pack with a high<br>
>>>> enough<br>
>>>> C<br>
>>>> rating to minimize impedance losses (and accompanying heat) and a<br>
>>>> low<br>
>>>> enough<br>
>>>> C rating to allow good capacity retention should provide the best<br>
>>>> value<br>
>>>> for<br>
>>>> pattern. I have no idea just what construction parameters /<br>
>>>> chemistry<br>
>>>> defines these characteristics. I chose to try the FlightPower F3A<br>
>>>> packs<br>
>>>> because they are mid-C rating and 5350 mAh capacity. So far they<br>
>>>> provide<br>
>>>> good power and generate no more heat than the high C packs I've<br>
>>>> used. I<br>
>>>> expect that the extra capacity (above 5000) offers a little<br>
>>>> buffer if<br>
>>>> there<br>
>>>> is a capacity decline over their life. I see little balancer<br>
>>>> activity<br>
>>>> with<br>
>>>> these packs regardless of depth of discharge (say 3000 mAh vs<br>
>>>> 4000 +) so<br>
>>>> far, time will tell - we're all still learning.<br>
>>>><br>
>>>> Earl<br>
>>>><br>
>>>> Team FlightPower<br>
>>>><br>
>>>><br>
>>>> ----- Original Message -----<br>
>>>> From: "Chad Northeast" <<a href="mailto:chad@f3acanada.org">chad@f3acanada.org</a>><br>
>>>> To: "NSRCA Mailing List" <<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>><br>
>>>> Sent: Friday, March 14, 2008 8:22 AM<br>
>>>> Subject: Re: [NSRCA-discussion] Batteries<br>
>>>><br>
>>>><br>
>>>>> I think a huge part of the 5300 Prolites ability to deliver under<br>
>>>>> extreme abuse (I should know! :) ) is in large part due to a 4p<br>
>>>>> config<br>
>>>>> rather than 1p as in the current packs. In a 1p when that cell<br>
>>>>> gets<br>
>>>>> weak its over, in a 4p when a cell gets weak the other 3 in the<br>
>>>>> 4p can<br>
>>>>> help it along for quite a while before they all get weak.<br>
>>>>><br>
>>>>> I am really convinced that a move to 1p config packs has brought<br>
>>>>> with it<br>
>>>>> lower useful cycle life. I feel you need to be a lot more<br>
>>>>> cautious with<br>
>>>>> the 1p packs than the 4p's, or they will not last you very long :)<br>
>>>>><br>
>>>>> Chad<br>
>>>>><br>
>>>>> mike mueller wrote:<br>
>>>>>> Chris Moon and I have bought the new TrueRC 5000 packs. He has<br>
>>>>>> been<br>
>>>>>> testing them for the last 2 months. They seem as strong if not<br>
>>>>>> stronger than his FP 5350 pack. The cost is only $110 a 5S<br>
>>>>>> pack. I've<br>
>>>>>> bought 4 packs and I'm hoping that they are as good as initial<br>
>>>>>> testing<br>
>>>>>> has shown. I also have 2 brand new TP V2 Extreme 10S 5000<br>
>>>>>> packs. All<br>
>>>>>> the packs at the 10S configuration weigh in around 42oz's with<br>
>>>>>> all the<br>
>>>>>> connectors.<br>
>>>>>> The True RC packs have a lower C rating but this may be a good<br>
>>>>>> thing.<br>
>>>>>> The higher C ratings seem to come at the cost of lower pack<br>
>>>>>> life. Look<br>
>>>>>> at the TP Pro lite's many have exceeded the 200 cycle barrier and<br>
>>>>>> still have a decent pack. The TP Extreme's V1's were dying in 50<br>
>>>>>> flights and I have yet to see much better than a hundred<br>
>>>>>> flights from<br>
>>>>>> the FP's. From my observation the older TP Prolites deliver<br>
>>>>>> plenty of<br>
>>>>>> power for our setups. So I think the TrueRC offerings are going<br>
>>>>>> to do<br>
>>>>>> the trick. Dan from True is claiming over 200 cycles on them. I<br>
>>>>>> hope<br>
>>>>>> that I can get 100. At the $'s he's getting it will be a huge<br>
>>>>>> bargain.<br>
>>>>>> Mike Mueller<br>
>>>>>><br>
>>>>>> The link is <a href="http://www.flightpowerusa.com" target="_blank">www.flightpowerusa.com</a> <http://<br>
>>>>>> <a href="http://www.flightpowerusa.com/" target="_blank">www.flightpowerusa.com/</a>><br>
>>>>>><br>
>>>>>> I need to buy some packs myself. Anybody know if they will<br>
>>>>>> be at<br>
>>>>>> Toledo?<br>
>>>>>><br>
>>>>>> Bob Kane<br>
>>>>>> <a href="mailto:getterflash@yahoo.com">getterflash@yahoo.com</a><br>
>>>>>><br>
>>>>>><br>
>>>>>> ----- Original Message ----<br>
>>>>>> From: Verne Koester <<a href="mailto:verne@twmi.rr.com">verne@twmi.rr.com</a>><br>
>>>>>> To: NSRCA Mailing List <<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>><br>
>>>>>> Sent: Thursday, March 13, 2008 6:58:32 PM<br>
>>>>>> Subject: Re: [NSRCA-discussion] Batteries<br>
>>>>>><br>
>>>>>> Hi George,<br>
>>>>>> I'm in the same situation and have decided to go with the<br>
>>>>>> FlightPower<br>
>>>>>> 5350's. Even when the 5300's were fresh, I occasionally<br>
>>>>>> felt like<br>
>>>>>> I could<br>
>>>>>> use a little more punch, particularly on humid or windy<br>
>>>>>> days. I've<br>
>>>>>> competed<br>
>>>>>> with a number of guys that had both the TP 5300's and FP<br>
>>>>>> 5350's<br>
>>>>>> who would<br>
>>>>>> switch to the 5350's when they needed the extra power. My<br>
>>>>>> plan is<br>
>>>>>> to use the<br>
>>>>>> FP 5350's and change props for different conditions.<br>
>>>>>> Nothing is<br>
>>>>>> free however<br>
>>>>>> and you'll pick up 2 ounces in the process. I considered<br>
>>>>>> the 5000<br>
>>>>>> mah 10S<br>
>>>>>> packs from both TP and FP but can't afford to gain 4 ounces in<br>
>>>>>> either of my<br>
>>>>>> existing planes. The FP 5350's are the best solution for my<br>
>>>>>> situation. Mine<br>
>>>>>> just arrived this week and won't be flown until the snow<br>
>>>>>> melts so<br>
>>>>>> my<br>
>>>>>> recommendations come from observations rather than<br>
>>>>>> experience at<br>
>>>>>> this point.<br>
>>>>>> I bought mine directly from FlightPower<br>
>>>>>> <a href="http://www.flightpower.com" target="_blank">http://www.flightpower.com</a> <<a href="http://www.flightpower.com/" target="_blank">http://www.flightpower.com/</a><br>
>>>>>>> . Hope<br>
>>>>>> this helps.<br>
>>>>>><br>
>>>>>> Verne Koester<br>
>>>>>><br>
>>>>>><br>
>>>>>> ----- Original Message -----<br>
>>>>>> From: <<a href="mailto:glmiller3@suddenlink.net">glmiller3@suddenlink.net</a><br>
>>>>>> <mailto:<a href="mailto:glmiller3@suddenlink.net">glmiller3@suddenlink.net</a>>><br>
>>>>>> To: "NSRCA List" <<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a><br>
>>>>>> <mailto:<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>>><br>
>>>>>> Sent: Thursday, March 13, 2008 12:26 PM<br>
>>>>>> Subject: [NSRCA-discussion] Batteries<br>
>>>>>><br>
>>>>>><br>
>>>>>>> Hi All,<br>
>>>>>>><br>
>>>>>>> I've been flying with Thunder Power Prolite 5300 packs for a<br>
>>>>>> while now and<br>
>>>>>>> they are getting very tired. As they poop out, I'm trying to<br>
>>>>>> decide what<br>
>>>>>>> to replace them with. From what I've seen, the Flightpower<br>
>>>>>> "FAI" packs<br>
>>>>>>> are probably what I'll go with, but if anyone has any other<br>
>>>>>> suggestions,<br>
>>>>>>> please sing out. Also, any suggestions as to a source would be<br>
>>>>>>> appreciated.<br>
>>>>>>><br>
>>>>>>> TIA,<br>
>>>>>>><br>
>>>>>>> George<br>
>>>>>>> _______________________________________________<br>
>>>>>>> NSRCA-discussion mailing list<br>
>>>>>>> <a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><br>
>>>>>> <mailto:<a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a>><br>
>>>>>>> <a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><br>
>>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> _______________________________________________<br>
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>>>>>><br>
>>>>>><br>
>>>>>><br>
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>>>><br>
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</blockquote></div><br><br clear="all"><br>-- <br><br>Keith Hoard<br>Collierville, TN<br><a href="mailto:khoard@gmail.com">khoard@gmail.com</a><br><br>