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Post by thevon on Jun 1, 2007 9:40:57 GMT 10
I just discovered that there's a fairly new type of NiMh battery by Sanyo called the Eneloop, the difference to normal nimh being that they don't self discharge. Ken Peters Camera shop showed them to me and they're only $20 for a pack of 4. They're only 2000mAh which is less than the normal ones but reports from digicams say they really last well. They apparently hold 85% of their full charge after 1 year, whereas normal NiMh's lose about 1% per day. So I'm going to give them a try in my next build.
I super-strongly recommend buying quality (Sanyo, Panasonic etc) NiMh's because I was buying cheap ones for our digital camera and I thought the camera had a fault because it kept saying flat batt even when they were fully charged, despite trying different sets, and even buying 2 lots of new ones from Strathfield.
Finally I bought some Sanyo 2700's from Double-L trading on Ebay, and to say I was impressed is an understatement. The camera instantly worked, and now it is a rarity for it to go flat!! Also I got a receiver flat x4AA pack which I put in my Duck, and it just seems to go forever and never goes flat! Whereas I bought new Venom ones and put them in the Drongo, and it always needs charging. With NiMh's, cheap is not good.
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Post by sean on Jun 1, 2007 10:10:23 GMT 10
Hey Andrew, those Eneloops sound like the way to go. I reckon that normal nimhs lose maybe 10% or more in the first day and less each day after. My only concern is that they're AAs. I like using 600mAh AAAs because they weigh next to nothing and fit into tiny spots. If you trickle charge them at 60ma for about 20 hours the first couple of charges they'll hold their charge brilliantly. After that you can charge them how you want (although I never go over 1/2C) and I reckon I could get two or three days flying out of one charge.
As Andrew says definitely buy good ones though! I bought some cheapos and it was a complete waste of money, they won't hold a charge for 5 minutes! I use them now to help layout and build battery cavities in new models, that's all they're good for...
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Post by thevon on Nov 11, 2007 9:24:51 GMT 10
I used Eneloops in the Bat, and after a huge day of DSing yesterday, I just checked and it's still showing full charge! And that's with fullsized HS5475 digital servos too! Not bad, I reckon.
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Post by ezza on Nov 11, 2007 10:27:29 GMT 10
I used Eneloops in the Bat, and after a huge day of DSing yesterday, I just checked and it's still showing full charge! And that's with fullsized HS5475 digital servos too! Not bad, I reckon. That is unbelievable Andrew. Seemed like you were flying that thing for hours! On the other end, I cycled the Opus batteries this morning, and that short flight yesterday took 430ma! The Opus has 6x JR 362 digis, they drain alot of power!! Eric
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Post by skyzking on Nov 11, 2007 10:36:33 GMT 10
I went to buy a rx battery yesterday for my new F3B Eagle, they didnt have any of the Eneloops in the battery pack form. I didnt want to buy and make them my self as this can be very risky. I bought my self a a Ni-MH 2500mAh with the "super lattice alloy" tech. All Ni-MH batteries are very good in holding their charge.
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Post by ding on Nov 11, 2007 12:52:50 GMT 10
I've used these things... they are great. You've got to buy good quality NIMH otherwise it's a world of hurt.
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Post by thevon on Nov 11, 2007 12:56:27 GMT 10
Abdullah, I make my own up and they don't fail. I also have some made-up ones which have failed where the tin strip solders on and if I fix them they never break again at that spot. The trick is to use some thick copper wire, like from the inside of TV aerial co-axial cable - I just cut a few inches and pull the wire out. Give the terminals a light sand and put Bakers Soldering Fluid on. Bend a kink in the wire you're soldering so it "gives" in a crash. Use a large-ish soldering iron very hot, and plenty of solder. Don't use a little electronics iron. I then put Shoe Goo or PU glue between the batteries, tape them in the right shape with insulation tape and let it dry overnight.
Not all NiMH batteries are good in holding their charge. I've had Venom batteries that just wouldn't stay charged, quite hopeless, also some other generic cheapies too. My strong advice is to stick to top brands, but the Eneloops are even better as they don't lose their charge like normal nims do.
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Post by callun on Nov 11, 2007 18:17:33 GMT 10
I've heard it's a bad idea to sand on things that you're soldering because of the silicone (sand) in sand paper which insulates, therefore increasing the chance for dry soldered joints.
I don't know what the option is though.
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Post by laanguy on Nov 11, 2007 18:33:10 GMT 10
Eneloop batteries do come in AAA 800mah and AA 2000mah cells and they are also available in pre-made receiver packs. Will have to check the price but I use them in my camera and seems I never need to change them.
Andrew
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Post by ezza on Jan 2, 2008 20:10:52 GMT 10
I used Eneloops in the Bat, and after a huge day of DSing yesterday, I just checked and it's still showing full charge! And that's with fullsized HS5475 digital servos too! Not bad, I reckon. Just checking in to see how you guys are liking the eneloops? Still performing well? Eric
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Post by thevon on Jan 2, 2008 20:28:50 GMT 10
Yes, definitely Ezza. I have them in the Bat. Can I say more?? I just love everything about that plane! It has digital HS5475's in it but it just seems to stay full charge most of the time. And as you know they've been put thru the rigorous NATA standard ISO accredited "AvB Impact Testing Process". Certainly no complaints or issues!
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Post by ding on Jan 2, 2008 20:48:56 GMT 10
It's amazing.. when they first introduced digital servos they were power munchers. I had 4 digitals + a couple of extras in the pattern ship, and with a 1800mah 5-cell pack (with voltage regulator) I could only safely get 4*12 minute flights!
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Post by atmosteve on Jan 2, 2008 21:00:51 GMT 10
Been using the eneloops for some time in my camera and other stuff, they have been the best nimh i have tried so far too, so obviously they go into my new planes as well. EDIT; sorry if this is a foregone to most of you guys here, but i file the surface of the battery terminal solder points to get back to the bare metal of the contact surface and use a good self fluxing solder with the iron held to the battery terminal surface for less than 2 seconds, for both applying a little solder to the terminal and then soldering the lead tinned wire to the terminal surface. If we keep the heat to the battery as brief as possible to get the job done it should all be sweet.
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Post by sean on Jan 3, 2008 16:07:33 GMT 10
Hey Ezza, I just bought an Eneloop pack for my TX and they seem pretty sweet. Had 10.6V out of the box and several days after charging the voltage hasn't dropped. Very nice when you're used to standard NiCds and NiMhs self-discharging. Don't know how they'll go over time but I think I'll be putting them in all my new builds if possible.
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Post by thevon on Jan 3, 2008 18:53:50 GMT 10
Steve yeah I agree about the soldering. It's a bit of a knack. For the connections I use thick copper wire out of the centre of standard TV aerial coax cable - nice and strong but malleable. Bend a small S bend into the wire, so it can take a tug and not break, and cut to length. I can't use my usual small soldering iron - have to use a bigger one. I sand/ file the contact a bit, and wipe a bit of Bakers Soldering Fluid on. Get it really hot and do a short sharp hot press with the fluxed solder, pushing plenty into a nice pool. Works really well. The only battery contacts I've had come apart in crashes have been when I've used pre-made packs. Those flat thin strips tear, or lift off.
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