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Discussion in 'Rocketry Electronics and Software' started by dave carver, Dec 30, 2014.
Nice, huh? /sarcasm off
Guess which battery I buy from now on, at least as far as rechargables go...
I'd be REALLY suspicious of the labeled capacities with that kind of a weight discrepancy. Best do some discharge testing. Or just be prepared for the light ones to fail quickly.
30 years of flying electric powered RC airplanes experience tells me to be really suspicious about batteries that seem too good to be true. They usually are.
Then you would know, how good are the Tenergy batteries? The set I have are my primary batteries for my Nikon with the Tamiya's back-up. The light weight ones I got to replace the AA in my launch remote boxes. They are junk, stay away from them
While I have not used the Ni-Mh from Tenergy, I have 4 or 5 Li-Po's that I use from them and have had no problems. I also have a couple of battery banks and a charger with the Tenergy name that have worked good for me. I'm not sure who owns the Tenergy label but I have been buying them from, "All-Battery.com", and have been happy with the product and service.
I agree 100% with BEC, that good battery deals are usually not good deals. While I hate to pick on one country, most batteries seem to come from China, and the quality is all over the place. There appears to be little or no control over the stated capacity and quality of imported batteries. Weight is a good indication of quality but not always. If it can be cloned, it will be. Even Duracell has had problems with batteries with their name on them, but not manufactured by them.
A "smart" charger, that tells you how much current goes into a battery during charging, will help to determine if the stated capacity of a cell is true or not, as well as giving you a idea of the overall health of a cell.
Then it time for a smart charger. Those blue batteries are junk and I have a lot to test.
http://www.williams-knights.com/?p=58 Review of the BYT 2500 mah batteries.
NiMH battery technology is very mature and most legitimate manufacturers are honest and their rated battery capacities are, or exceed the written specs when new (it may take up to 5 charge/discharge cycles for the battery innards to stabilize however.). While the internal structures can yield somewhat different peak current values, the specific capacity in Joules/gram or (Watt-hour per unit weight) should be very similar between brand because they all use the same chemistries. When a battery weighs 1/3 the weight of an equivalently labeled product, one of them is lying. You don't get something for nothing!
Personally I would avoid AA batteries in a rocket because unless they are assembled as a pack chances are that they will leave the battery coupler during the flight and you will end up with unpowered electronics.
I had 8 AA batteries in my 3rd level rocket per circuit and there were 2 circuits. I had no worries about any battery even moving, I potted the whole schemer with silicone
For AA NiMH batteries I recommend this charger.
This charger is not cheap but is a great investment. It is a very impressive charger and will save a lot of time and money if you use a lot of rechargeable batteries. It is reviewed in the video below which is part of an excellent review of NiMH battery facts and fictions.
In fact it's so good they wanted you to see the particulars...twice
I'm sold. Just ordered one.
Dang, out of the budget for this month, next month for sure. That and a few 4 packs or best specials I can find on Sanyo batteries. I read something about 4th generation, is that what I want?
Anyone have an opinion on the charge rate vs longevity of rechargeable batteries. I have seen multiple sides of the debate. Slower is better, no difference. I'm sure there are reasons for the different opinions, probably battery chemistry. Does the battery "heating" up mean it is detrimental to the lifespan?
I use the Powerex smart charger. It has a fast, soft and refresh function. It does 8 AA or AAA batteries with each cycle.
That's probably a pretty good charger, one you would use most of the time as its greatest feature is it can charge 8 batteries at a time, however depending on the default conditions, it may tend to overcharge/overheat AAA and older AA NiMH batteries which will shorten their lifetime by up to 25%. http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride presents one view on recharging NiMH batteries. The are somewhat vague and contradictory in their 0.5C initial charge rate and point out the pitfall of that method but not provide alternatives. They do however point out that NiMH batteries should not be overcharged and should be removed from the charger once they are fully charged.
I bought a La Crosse BC1000 so I can measure the battery capacity automatically and bin like batteries together. I have other NiMH chargers and will continue to use them when I have to recharge a bunch of batteries at the same time, however I will run my several dozen AA and AAA batteries thru the Lacrosse monthly just to make sure they work when I need them.
I have a couple stacks of AA batteries that are for my Canon Flash along with my race track scanner.
I've tried regular alkaline as a last sec backup and smoked them with in minutes in my flash.
I have a good charger for them and they still seem to go dead too soon.
I bought some Sanyo Eneloop
Much better as holding a charge longer when not in use.
The Eneloops have the best reviews I've read. Plan on a pack of 4 to start, they kinda spendy
I just received a pack of Tenergy AA batteries, now I have 2 sets for my Nikon A mailer from Amazon has the little brother charger to the La Cross on sale for about $42 shipped. Slower charge rate but same features overall.
It works great. I've been playing around with the BC1000 for a week. As you said, the major difference it the max charge rate. The BC1000 package is ~$60 but includes 4 AA and 4 AAA batteries, a travel case and 4 sets of adapter that allow the use AA batteries in C and D cell applications. Since I was going to buy the extra NiMH cells anyway, it was a good deal.
I also use BC1000 because in addition to AA batteries, there are other types of NiMH battery in use.
Once put together a spreadsheet for work concerning the economics of rechargeable AA batteries.
In my view, you're buying mAH/$, or milliamp-hour per dollar. The more mAH you are getting per dollar spent, the less expensive your batteries. The conclusion was to purchase 3000 mAH or better batteries, as they offered the best price point. You might spend more per battery, but you will get longer useful life per charge, as well as a longer overall lifetime, since NiMH/NiCad batteries have their lifetime measured in number of charges and the longer you can use a battery before having to charge it, the less time you have to charge it given a fixed timespan.
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