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Old Oct 07, 2011, 02:17 PM
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[QUOTE=like2fly!;19488260
The meter also tells me that the Gens ace 25C packs I have are potentially better (not taking into account longevity as I donít have enough cycles yet) performers than the TP 65Cís I have.

Alex[/QUOTE]

Have just done full rate discharge tests on Gens Ace 25c and Gens Ace 55C packs. The IR "Cell" meter readings told me that the 25C pack was going to be slightly superior to the 55C pack (how come ?) and so it turned out. The 25C turned out to be capable of 30C continuous discharge as did the 55C but no more with the 25C holding just slightly higher voltage.
The IR readings took me about 2 minutes to obtain, the full discharge results, about 2 hours.

Sorry can't comment on comparison with PL8 readings as I don't have one.
Does anyone know how they take readings? Is it a calculation based on the rise in voltage at a step current during charging or are they using the 1KHz AC measurement technique ??

Wayne
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Old Oct 07, 2011, 02:33 PM
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Originally Posted by Wayne Giles View Post
Sorry can't comment on comparison with PL8 readings as I don't have one.
Does anyone know how they take readings? Is it a calculation based on the rise in voltage at a step current during charging or are they using the 1KHz AC measurement technique ??
Speculating here but my suspicion is that it's the former. Basis for my postulation is that the PL8 takes individual cell IR measurements during charge cycle and requires ~3 minutes to do such.

Mark
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Old Oct 10, 2011, 01:18 AM
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Mattias,

I am in the process of updating them and will have new ones available in a few weeks. I will post on this thread when I have them.

Wayne
Great - another order will be coming from down under as soon as they're ready!

Cheers
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Old Oct 10, 2011, 04:56 AM
who dares wins
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Originally Posted by Wayne Giles View Post
Have just done full rate discharge tests on Gens Ace 25c and Gens Ace 55C packs. The IR "Cell" meter readings told me that the 25C pack was going to be slightly superior to the 55C pack (how come ?) and so it turned out. The 25C turned out to be capable of 30C continuous discharge as did the 55C but no more with the 25C holding just slightly higher voltage.
The IR readings took me about 2 minutes to obtain, the full discharge results, about 2 hours.

Sorry can't comment on comparison with PL8 readings as I don't have one.
Does anyone know how they take readings? Is it a calculation based on the rise in voltage at a step current during charging or are they using the 1KHz AC measurement technique ??

Wayne
That's odd marketing for you I guess?

I was confident of the 25Cís on the back of testing by other RCG members where it appears Gens Ace are quoting a true C rating.

When their 55C (and other higher C) packs came to market, I didnít expect these to be true 55C.

I guess they are trying to do a Tony Blair and appeal to everyone (although unlike him they are succeeding). That is those who desire a true C pack and those who treat the number like cubic inches, the more the merrier! Or have they changed their marketing tact altogether? A bit mind boggling that both packs are so close. I had a sneaking suspicion the higher C packs may be the same chemistry as the lower C, as the lower (25C) out performs TP 65Cís so how much better (today) can they be.
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Old Oct 10, 2011, 05:36 AM
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55C packs should be more heavy in weight then 25C packs.
In case of the GensAce, this is not the case.

I never will believe that a 183gram 2200 3s pack will have real 55C rating.
If it was +200gram, then I was looking forward to see a test of it

So it looks like they made an error here. Test of Gerd Giese also shows that the 55C 2200pack = about the same as the 25C pack of GensAce

The 25C range of GensAce are the ones to get
And most likely they will release some day, real 55C packs..... but be sure they will be more heavy in weight....and maybe also outperform everything out there.
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Old Oct 10, 2011, 11:05 AM
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This sort of thing just confirms what some of us have known for a long time: that C values are just numbers pulled out of the air by marketing departments, and have absolutely no meaning or useful application in reality.

No rational person should even look at these useless, ridiculous numbers. Thankfully, we now have a tool for quickly, accurately, and economically estimating the true discharge capability of our lipos.
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Old Oct 10, 2011, 11:28 AM
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I agree entirely Harry, the 25C packs are fantastic, so why do they need to exaggerate the performance of the 55C. How many applications actually need a 2200mAh pack to deliver more than 55A continuously?
The only packs that I have ever tested that really met all their C claims were the old air spaced Loong Max packs. The 30C packs really would do a full 30C discharge without excessive temp.rise. I'm not saying other packs don't meet their claims; just that I haven't tested any, but I seem to have tested dozens which don't meet their C rating including some very expensive ones.

BTW I have just checked, double checked and triple checked the PCB layout for the updated version of the meter, but I bet I have missed something!

Wayne
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Old Oct 10, 2011, 07:27 PM
ancora imparo
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Joined Jul 2005
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Unfortunately they do. Perfectly rational modelers all over the world who do not have (or of course need) an understanding of the behaviour of LiPos to enjoy themselves and be expert fliers genuinely believe that a 55C, 2200mAh LiPo will deliver a continuous 120Amps.

When in fact it won't, and sometimes (often?) isn't 2200 mAh either.

Why wouldn't they? It's written on the label in big letters after all. They get constantly advised to get a battery with a C rating/Capacity combo that is capable of delivering the current they want. It is the major differentiator used to sell more expensive packs. Reminds me of the tortuitous crap used as "Power Rating" in the HiFi Industry. There is always some totally irrelevant measure of "peak/instantaneous/dynamic/pulsed power that might actually be the number quoted. I am sure that these 55C packs can deliver 120A under some conditions. It's just nothing that resembles the use to which they will be put. If OS advertised an engine as a "60" and it didn't deliver the goods so someone measured it and found it was really a 40 internally imagine the outcry and consequences.

It's a great shame that the work of Mark, Wayne and others to determine a more effective performance number that would be fairly easily interpreted and less subject to abuse has never got any support - but then it won't, since it is no one's interest but the consumer.
And invariably a battle erupts with the armchair experts finding fault with some "important" variable that has been overlooked, forgetting that most of engineering design is about making sensible decisions about which variable to take into account and which to ignore.

Sorry about the rant. Must have woken up in Grumpy Old Man mode. It's just that some of these manufacturers are basically lying through their teeth in the same way as the cosmetics manufacturers do using pseudo science on the TV. There's nothing terribly esoteric about specifying battery performance for the sort of use most of us want it for. "This battery will deliver a maximum of x Amps, while maintaining at least y Volts for 80% of the discharge at 20C ambient in still air. It will contiinue to do so for z cycles if charged under the following conditions." Variability due to temperature should be noted but AFAIK this is likely to be much the same for common packs as they all have fairly similar construction - could be wrong on this. I think most other factors are not of relevance to most users.

In the meantime, extensive testing by a few hobbyists who have the commitment and time and know what they are about and/or a reliable IR meter is a pretty good way to go IMO.

Wayne make sure you have thoroughly sprayed that board design with Insecticide.

John
Quote:
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No rational person should even look at these useless, ridiculous numbers. Thankfully, we now have a tool for quickly, accurately, and economically estimating the true discharge capability of our lipos.
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Old Oct 11, 2011, 05:59 AM
who dares wins
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Wayne make sure you have thoroughly sprayed that board design with Insecticide.
Is it that bad where you are
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Old Oct 30, 2011, 04:01 PM
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PROTOTYPE OF NEW VERSION
The insecticide must have worked (!) as there was no error in the new PCB and the prototype works perfectly and first time.
The reason for a re-layout was to get rid of the switch which was too large and clumsy and hopefully save cost, which now looks unlikely.
The unit now has an auto-mode-change, so that connecting the power lead brings up pack voltage in "Pack" mode but inserting the search lead into any two adjacent positions in the balance connector automatically changes the unit to "Cell" mode and displays the voltage of the corresponding cell.
Pressing the operate button displays the appropriate ESR value (either Pack or Cell) for a few seconds and then reverts to voltage as before.
There are minor improvements in layout eg reducing uncompensated wiring resistance in Pack mode.
I intend to make a batch of units but it will still be a few weeks before they are available. I will post here when they are with prices and carriage cost.

Wayne
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Old Oct 30, 2011, 04:32 PM
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Congratulations Wayne!!! As an engineer who designs avionics, I share in your excitement of nailing it the first time with no pwb re-spin or other circuit re-layout necessary!

Mark
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Old Oct 30, 2011, 05:08 PM
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Congratulations Wayne!!! As an engineer who designs avionics, I share in your excitement of nailing it the first time with no pwb re-spin or other circuit re-layout necessary!

Mark
Thanks Mark,

Pre-retirement I was also in avionics (psus) with the inevitable 'A' units, 'B'units and 'C' units but, as you know, there is always a commitee involved changing the spec. Difference now is that there is nobody to argue with me and, more important, if I cock it up, I will have to pay for another PCB tooling charge out of my own pocket which tends to make me very careful. Nonetheless, when it worked first time, I must admit I thought "I must be slipping"!

Wayne
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Old Oct 30, 2011, 07:24 PM
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That's great Wayne looking forward to hearing when they are available and how much they will be, I've had one of these on my must have list for a while.
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Old Oct 30, 2011, 07:31 PM
ancora imparo
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Wayne, when I first started making educational video programs in the early 70's, the video recorders were huge temperamental reel to reel beasts - and we had no decent edit facilities on them so everything was recorded in real time.

Our recording engineer had a saying. "I hate it when everything works first time; it means whatever is about to go wrong will be really serious."

Seriously, this is excellent news and congratulations.

John
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Old Oct 30, 2011, 07:40 PM
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Wayne,

The redesign looks great

Will there be any change in accuracy between the old and the new ?

Cheers
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