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Old Jul 13, 2009, 04:18 AM
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Wrend's Avatar
United States, IL
Joined Jul 2009
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Mini-Review
Eneloop Implementation in T6EX Futaba Transmitter, Run Time Testing, and Comparisons

OK, I got my Eneloops and installed them in my transmitter, thanks to the guys over at my local HobbyTown USA, that stripped two R/C car transmitters for their battery circuit springs. The springs went into my Futaba transmitter battery compartment quite nicely, and for free, I might add. All I bought from them (regarding this slight modification) was the power connector plug with wire leads that I soldered to the two end springs and plugged into the transmitter. There was also a small hole on the top left of the battery compartment that I covered the top half of with a bit of electrical tape, so that the end of the battery wouldn't push back into the transmitter.

Loose batteries have a potential of being problematic, however I am taking a few precautionary measures to help insure that I don't have a sudden power failure. Even so, if I determine that it still seems too risky, I'll most likely end up making a shrink pack out of the Eneloops. Having loose batteries provides some other advantages too, though.

Right now I'm doing a run time test on the batteries at their pre-charged levels. They started out at 10.6V then dropped to 10.0V about 2 hours later, which they have now been running at for about 3 hours. They've already outlasted my NiCd packs at fully charged levels, and seem to have a slightly high average voltage. Once the voltage starts to dip, I'm expecting them to drain faster than the NiCds, though, but we'll see.

After this test, I'm going to slowly "form" charge the Eneloops to their full capacity, then do another run time test. I'll post the results after I'm done.

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Description:

Below are the Eneloop continuous run time testing results, followed by a couple of my NiCd packs, and standard alkaline Energizer batteries for comparison. The testing was conducted on my T6EX Futaba transmitter that has a listed current drain of 170mA. In all of the rechargeable battery tests, I let the batteries sit for several hours after being fully charged.

08-11UJ 2000mAh NiMH Eneloop AAs at Pre-Charged Levels
9:13 Until Alarm Sounded, 0:10 Until Alarm Stopped, 9:23 Total Run Time

Insights: The Eneloops lasted about an hour longer than I expected them to at their pre-charged levels. The majority of their run time was at a relatively sustained higher voltage that then quickly dropped once the alarm on my transmitter sounded, when compared to NiCd batteries.
08-11UJ 2000mAh NiMH Eneloop AAs at Fully Charged Levels
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12:31 Until Alarm Sounded, 0:7 Until Alarm Stopped, 12:38 Total Run Time

Insights: Like in their pre-charged test, the fully charged Eneloops ran about an hour longer than I had initially expected, with an effective capacity of about 2128mAh (used discharged capacity when the low voltage alarm sounded). They discharged the majority of their capacity at very steady voltage levels, between 9.7 and 10.2 volts (a one half volt range) for 67% (two thirds) of their total run time, and between 9.0 and 11.0 volts for 95% of their total run time. The Eneloops appear to have had a pre-charged capacity of about 74% of their total capacity. They also have a slightly high average run time voltage of about 10.05 volts, compared to their 9.6 volt rating.
NT-8JY 500mAh NiCd Futaba Pack at Fully Charged Levels
2:58 Until Alarm Sounded, 0:32 Until Alarm Stopped, 3:30 Total Run Time

Insights: This is a 10+ year old pack that I have taken good care of. It came with my first Futaba transmitter (the Conquest FP-T4NBF).
NT8F6008 600mAh NiCd Futaba Pack at Fully Charged Levels
3:20 Until Alarm Sounded, 0:28 Until Alarm Stopped, 3:48 Total Run Time

Insights: This is a 2+ year old pack that came with my T6EX Futaba Transmitter.
03-2015 Alkaline Energizer MAX AAs at Full Levels
12:39 Until Alarm Sounded, 2:27 Until Alarm Stopped, 15:06 Total Run Time

Insights: The Energizer batteries lasted significantly longer than I had expected. However, given the relatively low current drain of 170mA, the results are understandable. The voltage levels started high at around 12.5 volts then dropped more consistently as time progressed, meaning that more of the capacity supplied by these batteries was at less uniform and less desirable voltage levels. If you include the time until the transmitter alarm stopped, the effective mAh was about 2567 at the current drain of 170mA. The more optimal voltage levels of the Energizer MAX batteries (that is, before the alarm was sounding) had an effective mAh comparable to the fully charged Eneloops.
Conclusion:
Eneloops have a low self discharge rate (purportedly holding as much as 70% of their charge after 2 years under the right conditions), they discharge the majority of their capacity at a very steady and optimal voltage range, they have a relatively high capacity (especially when compared to standard NiCd packs), and they can be recharged in the transmitter with the often provided wall wart charger. Overall this leads me to believe that Sanyo Eneloops are indeed very well suited for use in transmitters.
Note: The Eneloop cells tested and described here are the first generation, not the "new and improved" version.
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Last edited by Wrend; Sep 23, 2011 at 01:00 AM. Reason: Additional Information
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Old Jul 13, 2009, 11:28 AM
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Raleigh, NC
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Hi Wrend,

Can you tell what the current draw of your T6EX Futaba transmitter is?

I replaced the stock NiCD battery pack in my Hitec Optic 6 Spectra with Rayovac 2100 mAh Hybrids and I'm getting approximately the same run time as you do with your Eneloops. The current drain of the Optic 6 with the Spectra module is 250 mAh.

I've only tested the transmitter run time once and that was when I first installed them, but I remember getting around 12 hours before the low voltage alarm sounded.

Do you have plans to test the Rayovac Hybrid batteries?

Bill
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Old Jul 13, 2009, 11:43 PM
どうもありがとうミスターロボット
Wrend's Avatar
United States, IL
Joined Jul 2009
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Hello Bill,

The T6EX has a listed current drain of 170mA.

I hadn't planed on testing the Rayovac hybrids, but I've heard they're comparable to the Eneloops.

They must be pretty good if you're getting that long of a run time out of your somewhat higher drain rate, but then the Rayovacs are listed at a slightly higher mAh too.

The Eneloops seemed to warm up a little earlier than I had expected while I was charging them, so I'm going to just do an extended trickle charge on them to see if it affects their performance any. I'm going to stay away from doing such a tedious run time test again. I was checking the voltage every 15 minutes for over 12 hours straight. But, I wanted to see how well the Eneloops performed, because I haven't used them before, and have heard a lot of good things about them.
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Old Jul 14, 2009, 12:41 AM
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I didn't do a fancy graph like you did. I just turned the transmitter on and waited for the low voltage alarm to go off and noted the time on the built-in time-on counter.

The odd thing about that time-on counter... It will only go to 200 minutes and then it starts over again. That's 3 hours and 20 minutes and it rolled over 3 times with some more minutes showing (don't remember exactly how many now), so that puts it at least 10+ hours.

Can't understand why the counter starts over again at 200 minutes. You'd think it would go to 999. I asked Hitec about it but they never gave me an answer.

Seems like I can only find Rayovac around here, so that's what I use. Got most of them at either Walmart or Target, I can't remember which, but can't seem to find them any more. Don't know why they stopped carrying them. I heard Costco carries some brand but I don't have a membership so couldn't buy any there anyway.

Bill
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Old Jul 14, 2009, 12:49 AM
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Quote:
Originally Posted by Wrend
The Eneloops seemed to warm up a little earlier than I had expected while I was charging them, so I'm going to just do an extended trickle charge on them to see if it affects their performance any. .
Sanyo recommends charging at no more than C/2, or 1 amp for the AA cells. I charge mine at this rate and they just barely get warm, just above ambient when charging.
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Old Jul 14, 2009, 04:57 AM
どうもありがとうミスターロボット
Wrend's Avatar
United States, IL
Joined Jul 2009
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I was charging them at a pretty low rate, about C/5, and they didn't get too hot, just a little warm. I don't know.

I am curious to see what the trickle charge run times are, if they're any different. Maybe I'll post them up top too.

Someone wanted to know how the Eneloops compare to regular alkaline AAs, and I'm kind of curious, so I'll do that next. Although, now that I think of it, I seem to remember the 6EX manual saying not to use dry cells. Here, I'll check. No, it looks like it was just that the receiver isn't supposed to.
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Old Jul 14, 2009, 09:39 PM
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Sir Raleigh -- I just stumbled on this thread and saw your input about not being able to find eneloops. Costco does carry them, and my wife has a membership. I think you get 8AA's, 2AAA's, a charger and some "C" and "D" size battery adapters in the kit they sell for $20.

My summer is not going how I thought it would. I have some projects that are taking WAY longer than expected. I flew my son's blu-beagle over the house the other day, and it is the only flying i've done in about a month!! Not sure if I would have any free time to get to meet you and fly with you.

If you are interested in the eneloops and are not in a hurry, then let me know. I will be more than happy to have my wife pick up the kit from Costco and convey it to you whenever we could get our paths to cross.
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Old Jul 14, 2009, 10:20 PM
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Thanks for the offer nikg, but I have enough Rayovacs at the present. I bought a bunch when I first found them and don't need any more since they're still going strong. But I will keep your offer in mind.

Bill
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Old Jul 15, 2009, 08:23 AM
どうもありがとうミスターロボット
Wrend's Avatar
United States, IL
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Hey nikg, are you sure that it isn't 4 AAs that you get in that set? Otherwise that deal is almost too good to be true. My 8 pack of Eneloops was around $20, and Amazon is selling AA 4 packs for about $11.
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Old Jul 15, 2009, 10:24 AM
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Costco Eneloops

Awesome instant rebate price of $19.99 is good until 8/31/09.

Short thread here...

http://www.rcgroups.com/forums/showthread.php?t=1044841


rc
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Old Jul 15, 2009, 10:30 AM
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edit. duplicate post.
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Old Jul 17, 2009, 03:45 PM
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Over here in UK - and I imagine they must be available worldwide - we get 'Instant' cells which are similar to Eneloop thechnology but half the price. I've been using them for a couple of months now. A whole lot better than what was supplied in the 6EX.
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Old Jul 19, 2009, 04:18 AM
どうもありがとうミスターロボット
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I'll take your word for it on the quality of the Instant cells. I haven't used, nor seen them, though I might have heard of them from other Brits before. I'm not really sure. I agree that the 600mAh NiCd pack the 6EX comes with isn't a lot of juice, but then with a current drain of 170mA, the T6EX doesn't really need as much to make due as some other transmitters. I just couldn't pass up the advantages (and apparent lack of any disadvantages) quality NiMH hybrids have. Time will tell if they hold up as well as my 10+ year old NiCd pack.
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Last edited by Wrend; Jul 19, 2009 at 04:32 AM. Reason: Clarification
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Old Jul 19, 2009, 10:32 AM
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Compare notes in ten years then?
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Old Jul 19, 2009, 12:04 PM
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For anyone curious, there have been tons of tests done on the Eneloops, and the other varieties of LSD cells, over at candlepowerforums.com. Basically, the Eneloops will hold their voltage under load better than any of the other LSD cells, but that's with a caveat. The Duracell pre-charged AA's with white top and made in Japan are a rebadged Eneloop, so their performance is the same. Duracell AAA pre-charged are made in China and are rebadged Rayovac Hybrid, so not the same as Eneloop, of course.

I've pretty much ditched everything else for the Eneloop; it's just that good.

Oh, one other thing; Sanyo Europe has confirmed the Eneloop does leave with 75% charge.
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