FPV grounded: Lipo health and Internal Resistance measurement

[@FourDollaRacing]

Good content! My E-flite Blade 400 was underperforming, last weekend, on an older OEM battery. The 11.1V LiPo pack is not-at-all puffy, but reads 37 mΩ resistance for each of the 3 cells. So, that is my answer to your question at the end of the video: equal but higher resistance. The pack was balanced-charged, the flight timer was set at three minutes, and the battery pack lasted ten years....it's just too tired to fly a 3D helicopter!

[@IdeologieUK]

Great, very useful video Wayne! Actually I've just realised my GT chargers actually have this feature but bugger me if I ever knew what it was for. I really like the look of your new charging set up... Seems pretty powerful to me. I've always wondered how well the average charger actually works and more particularly how accurate the readings are... Food for thought!

[@CurryKitten]

+FlyBoySee I've a feeling your lipos will just try and spell out " H E L P M E" - check the ASCII codes :) This new charger seems a bit better than the b6 in terms of getting the cells up at the same point more quickly. Looking forward to being able to do 4 lipos at once though

[@blackmennewstyle]

Damn, why do i not have this function on my LIPO charger :'( Thanks a ton for sharing and have a great new week

[@OMEGOOLIEBIRD]

Date on the batteries is a fantastic idea!! My solution was to buy 12 imax B6 chargers and put them in a guitar pedal case. You can do what you like to 12 batteries charge/discharge/storage/nimh etc simultaneously. Under £200. Great video Wayne.

[@CurryKitten]

+OMEGOOLIEBIRD Pretty good idea - I was thinking about multiples, but then thought about all the power supplies, but I guess you can run them off one big one can you ?

[@OMEGOOLIEBIRD]

Yeah, I just have one 40 amp PSU powering all 12. Works great. Still need more chargers though :-)

[@moodyone99]

Another great video with some really interesting info. Thanks.

[@viktorask]

Finally got answer what is bad and good battery. Thanks!

[@martynsfpvchannel856]

Hi Wayne, Interesting video I've not seen a charger that does an instant IR measurement like that before. The Cellpro chargers I use all calculate the cell resistance as they charge and in the case of the 10S this can take a while the PL6 is much quicker. The figures you're getting are much lower than a Cellpro charger will ever report and if you get 3 mili ohms that would be a good result and likely to be comparable to the 1 mili ohm result you're getting on your charger. The cell resistance is a very good indication of battery health, but you do need to compare the results with a new similar battery. Small capacity cells always have higher IR values and in my experience you don't start to see the really low values until you get above the 1300mah cells. As Cellpro point out it's important that the IR values are all similar across cells in the same pack one bad cell is just as bad as the whole lot being bad as the voltage will drop across that cell since they are all wired in series. One final thing is that the ambient temperature will have a huge impact on IR values this is why LiPo's are crap in cold weather unless you keep them warm before use, so always compare values at the same ambient temp. The best IR values I see are when the ambient is above 22 deg C.

[@CurryKitten]

+Martyn's FPV Channel Yes - I can't really vouch for the accuracy of the IR measurement, and although I've got this finger in the air of

[@jamesb72]

I have a light bulb array so I can put 6amps or 12amps load on lipos depending on size, so a couple of times a year I stick the batteries on one by one and note voltage/balance after 60seconds, this really clearly shows the best and worst packs, so I can weed out the worst for the bin, and use the less bad ones for low load stuff. I found IR not that useful, also found smaller packs always have higher IR than larger - I'm also pretty sceptical about those figures, I use cellpro 10S for IR and that very rarely gives under 5milliohms per cell even on new packs, especially for smaller packs but who knows if that is accurate or if yours is - I guess the comparison between packs is what matters so absolute numbers should't matter. The cellpro calculates IR over several minutes of charging, whereas yours is doing a quick load test, but possibly at low current - maybe thats the difference. Main thing I've found is to bench test lipos so you don't find the bad ones during flights ;)

[@CurryKitten]

+jamesb72 Yes, this charger gives a very quick measurement, so I think the accuracy of the figures could be taken with a pinch of salt - but as you say in comparison terms quite useful. I use the same light bulb thing for a quick discharge before I put lipos back onto storage charge. I noticed Ed from Experimental Airlines used this method of comparing packs - with a little equation for working out IR, so as soon as I get a range of IR values it'll be interesting to compare them using all the methods

[@jamesb72]

+CurryKitten I find on the light bulb load the difference from strongest to weakest cell (which smart meter shows) as well as the voltage drop are the big indicators of pack condition. Would be interesting if you could put a wattmeter inline with IR test to check the load used, I suspect its a couple of amps, I know there is a standalone IR meter with a 20amp load which gives good figures, but its fairly expensive.

[@MicroRCFiend]

Excellent video and info, thanks.

[@CurryKitten]

+MicroRCFiend Thanks !

[@EnglishTurbines]

Interesting video Wayne, reminded me to set storage charge on my batterys...Wondering if you can measure IR using my digital Fluke meter now..?

[@CurryKitten]

+EnglishTurbines I don't know if it has a bang-whizzy setting to do this, but if you generate a load over the lipo and then take the voltage drop over a set period of time you can measure it that way. Ed from Experimental Airlines has a good explanation on his channel. Again, it's more of a comparison tool that a hard and fast scale of good->bad results

[@EnglishTurbines]

CurryKitten Im now in the process of discharging batts to storage level anyway...quite a lengthy process given the discharge rate of my charger...ends up 3.80 v per cell and 50% capacity.

[@CurryKitten]

+EnglishTurbines Yes - same issue on most chargers, I use 3 50w 12v halogen bulbs for a reasonably quick discharge - they draw a nice constant 12a, so I can bring them down to around 3.8v per cell pretty quickly and then use the charger to finish them off and make sure they are balanced nicely

[@EnglishTurbines]

CurryKitten Yes, good idea, my charger only discharges at 0.5 amps...takes forever...I'm halfway through discharging them at the moment, just going to leave a couple for ready use....:)

[@FPVsimon]

Thanks for that mate I'll check mine out this week (Same charger)

[@CurryKitten]

+Bignose13 Nice one Simon - let us know if you get any interesting results

[@xboxice2005]

I have x3 of those balance board been using them for years with no issues.

[@abitropical6306]

well done! amazing video!!😺

[@CurryKitten]

+Abi Tropical Sorry for the lack of Sophie content in this video :)

[@abitropical6306]

That's fine!

[@digerati808]

Supposedly total capacity has an effect on Internal Resistance numbers...the more capacity, the lower the IR.

[@CurryKitten]

Yes - I'd agree with this. What I find (albeit anecdotally) is that a larger cell is a bit more robust. It can withstand higher loads, and the charging seems more gentle to it. Whilst a little pack can get tortured on a few throttle outs and dip into danger levels easily

[@marcnh33]

this is very strange... i have the same charger and did a battery check.... i measured 14 11 13 on a 2200mah turnigy... and 10 10 10 on another (same) battery.... and then i took a swollen battery, i expected high numbers but it was 01 01 01.... so it look likes that the lower the number the lower the quality of the battery ......

[@droner5423]

Very good video!!!!!

[@CurryKitten]

+Laurie Bick Thanks muchly

[@GeorgeGardinier]

i think bruce at xjet has covered this, have you considered this, yes i forget to put mine in storage charge, me bad lol

[@CurryKitten]

+George Gardinier I've no doubt Bruce has covered this in some way, although the explanation that pops up most on KZbin is Ed from Experimental Airlines who explains the concept of how a lipo is loaded and resistance measured. I couldn't find anything on using the charger though - so hence this video

[@SYNFPVPILOT]

Great vid =)

[@jasonkass3563]

How did you know that the charger has this IR measurement feature? Im not able to find that listed anywhere. And how do you access it? I wonder if my similar charger also has this. My options tree matches that of whats listed in this chargers manual.

[@CurryKitten]

+Jason Kass I didn't, it wasn't in the list of features, nor was it in the manual. I literally power it up for the first time and there it was. You'd find it on the "top" menu though - it's not hidden anywhere, so odds on if your charger has it, then you'd have already found it

[@georgeaura]

Where can I get one of those?

[@CurryKitten]

+george aura The charger you mean ? It's this one www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11170

[@georgeaura]

+CurryKitten yes thank you very much

[@urijahflores7159]

thanks well explained

[@DangerDavefpv]

what temp was batterys when tested at what voltage? storage or full ?

[@CurryKitten]

Ambient room temp, and lipos in storage.