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Old May 31, 2005, 07:53 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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LiPoly Discharge Tests

Over the past month or two I've been doing battery discharge tests on some of the new batteries that have come out like the Didel/Plantraco 30mAh cell and the Plantraco 160mAh cell, and also some old staple batteries like the Kokam 145. I've put some of these results on a page on my web site. I need to put the 30mAh and 160mAh tests up as well as a set for the ET-250. The Kokam 145 and WES 310mAh tests need to be re-done with voltage cutoffs of 2.8V to be consistent with the other tests. So, these tests are all somewhat preliminary at this point. Still, they may be useful until I get them all up in final form.

Gordon
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Old May 31, 2005, 02:32 PM
Plantraco's Avatar
Saskatoon, Canada
Joined Jan 2003
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Quote:
Originally Posted by Gordon Johnson
Over the past month or two I've been doing battery discharge tests on some of the new batteries that have come out like the Didel/Plantraco 30mAh cell and the Plantraco 160mAh cell, and also some old staple batteries like the Kokam 145. I've put some of these results on a page on my web site. I need to put the 30mAh and 160mAh tests up as well as a set for the ET-250. The Kokam 145 and WES 310mAh tests need to be re-done with voltage cutoffs of 2.8V to be consistent with the other tests. So, these tests are all somewhat preliminary at this point. Still, they may be useful until I get them all up in final form.

Gordon


It's very useful to have this information easily available - Good stuff!
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Old May 31, 2005, 06:16 PM
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United States, MI, Temperance
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Thanks Gordon! Your motor and battery tests provide a great deal of accurate information. Manufacturers should be as through and complete. I hope you plan to include the 90 mAh cell as well.
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Old May 31, 2005, 07:45 PM
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Pete P's Avatar
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I never would have guessed the 145 performed 2x as well as the 170 at 1A... Is that correct?
145- 56% at 1A - Delivers only 81.2mAh
170- 25% at 1A - Delivers only 42.5mAh
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Old May 31, 2005, 08:58 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Pete,
I've heard that the 170's don't perform as well as they used to. I've never owned any 170's until I bought a couple and then did these tests on them. Yes, those results are accurate for at least the cell I've tested. I'm not a battery laboratory who tests hundreds of cells. So, it's always possible I got a bad cell. I did get a really bad ET-250 cell that performed way worse than others of the same cell. If you remember the "Vroom Zoom" plane my boys fly? That's what the 170's are used on now since that plane doesn't have a high amp draw.

Tim,
I will get around the the 90mAh cells. I published an article on the ET-90 when we first found it so haven't gotten around to doing it again yet. I'll do the Plantraco 90 at some point too.

Gordon
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Old Jun 14, 2005, 06:19 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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I finally got around to adding some tests I've done to my battery page. I added the Didel/Plantraco 30mAh, the Plantraco 160mAh, and the E-Tec 250mAh.

Gordon
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Old Jun 14, 2005, 07:02 AM
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Zlatko's Avatar
Melbourne City Hlpt, Australia
Joined Jun 2004
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Thanks for that Gordon.

I was meaning to ask ...
What do you use for your tests ? CBA II ? TriCat?

Cheers
Zlatko
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Old Jun 14, 2005, 12:30 PM
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Gordon Johnson's Avatar
Boston, Mass
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CBA II. But, I do have the Tricat as well.

Gordon
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Old Jun 14, 2005, 01:06 PM
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Gordon- Can you verify these results for the Etec 130 mAh cell?? It seems a very good match for a .5A model (Orange 7mm DD). (I realize the graph is for 2 cell operation, but I found a source for the individual cells)

http://eflightdesigns.com/docs/images/lipoly1.gif

That e130 cell seems like a good performer, compared to the k145 at 4c only gets 11:30 to 3v, while the 130 appears to get 15min at 4c with only a .05A difference in output. Possibly less internal resistance?
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Old Jun 14, 2005, 05:12 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Pete,
That is a very old discharge graph done by Aircraft World. I don't trust their tests for the smaller cells as what they did for the ET-90 cell (not on that graph) was very optimistic and did not agree with what Matt and I did. I've seen other tests of the 130 somewhere and it did not perform well. I did a discharge test quite a while ago with a geared motor and it did not perform well, but this is all from memory. I might still have one of these cells, but am not sure. Also, neither EFlight or Aircraft World is not selling the ET 130 any more. For the very minor weight savings over the Kokam 145 I think you are better off with the Kokam. My sense is when this cell first showed up not long after the ET-90 did that the 130 did not perform near what the Aircraft World graph showed.

Gordon
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Last edited by Gordon Johnson; Jun 14, 2005 at 07:40 PM.
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Old Jun 14, 2005, 11:58 PM
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Alrighty :-) BTW, you can get the cells at http://www.stevensaero.com/cart/cart...category_id=40

I have 2 unused 145 cells, and think they will mate well with your more than generous radio gear and some 7mm orange motors, DD :-) I just hope I can get something together for this weekend. I'll bring the mooch-jack your fellow flyer gave me, just incase I need a charge :-P
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Old Jun 29, 2005, 06:33 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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I have added discharge tests for the Plantraco 90mAh cell to my battery discharge page on my site, link in the first post of this thread.

Gordon
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Last edited by Gordon Johnson; Jun 29, 2005 at 06:42 PM.
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Old Jun 29, 2005, 07:05 PM
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Saskatoon, Canada
Joined Jan 2003
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Quote:
Originally Posted by Gordon Johnson
I have added discharge tests for the Plantraco 90mAh cell to my battery discharge page on my site, link in the first post of this thread.

Gordon

Thanks for doing the test. I'll try to compare with our own discharge tests. We had an improvement made the LP90 cells, so I wonder if this test is with the old build of the LP90 cell.

We have the Mountain Radio discharger, with firmware for small cells, I have some printouts that look flatter for the LP90 cells. I just have a gut feeling that you might get better numbers with the latest LP90 cells. Not sure though, probably I should check my data before posting here.
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Old Jun 29, 2005, 08:07 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Bud,
These are cells from you when you first released the 900mhz system. So, if the cells have improved these tests are with the old cells. I can always test the new cells, once I have some, and see if I get any different results. Since our testing equipment are the same we should get the same results. Don't forget the standard CBA plot is volts versus Ah. I do a bit of work to translate the results into volts versus time. Also, I use a different scale on the volts vertical axis. The CBA uses a range of 1.3V to 4.0V. I use 2.7V to 4.0V. The difference in range will make my plots look less flat. My plots are not the standard CBA plots. I do mine in Excel.

Gordon
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Last edited by Gordon Johnson; Jun 30, 2005 at 05:09 AM.
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Old Jul 02, 2005, 06:50 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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I've added E-Tec 90mAh discharge tests to my site.

Gordon
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