|05-13-2006, 10:11 PM||#11|
RCC Master Contributor
I am: John R
Join Date: Feb 2003
Location: Cambridge Ontario
Radio of choice:
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Thanks for the link. You can never stop learning. I just printed it and will post it in my shop.
I cycle my batteries every fall and spring using an accucycler. I must admit it sometimes takes a few cycles until I am happy with the capacity. I have been trial and erroring and stop cycling when I can't get any more capacity in.
What's the deal here on field quick chargers? I build a lot of 2300 nimh rx packs and usually keep them topped during flying season using my Hobbico field charger. I do it around 1.2 amps. I was always under the understanding that:
1) you can charge at a rate up to 2X capacity for nicads or nimh and 2) That you couldn't top your pack out with a low trickle charge.
aka Johnny Versatile
Hespeler Model Aviators Inc.
Cambridge Float Flyers
I don't have the answers, but I have a personal relationship with the Guy that does.
|05-15-2006, 10:10 AM||#12|
RCC Junior Contributor
Join Date: Sep 2003
Location: ontario Canada
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Thought you guys might like an update on this subject .Today i phoned Energizer . To recap -- I have just got 2 new 4-packs of AA's 2500mhN/hd , not made up . Have charged both on a slow rate & on my Piranna at fast rate . 5 times each charged &then on the Accu-cycle . one pack max was 2000mh other was 1750mh max . So Energizer told me ---- " the amount of batts that we make it is impossible to have them all read the 2500mh , 1750mh is good " I said how i read that below 70% value of a batt; we should dump them . That 1750 is already 70% of 2500mh. They said "cycle batt; & one should use the cycle figure i;e; 1750 as the figure to deduct the 70 % from , rather than the 2500mh "
I have friend who bought a batt; from hobby store & has same deal with the cycle reading . This puts a whole new light on the throw away time doesn't it !!!
taildraggers fly best
|05-15-2006, 10:47 AM||#13|
RCC Senior Contributor
I am: Bob the Builder
Join Date: May 2005
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One note... the Accucyle cuts off charging (switches to trickle) after q5 hours. If you charge at 25 mA, the max it will put in is 375, but due to efficiency you will read something less. On 50 mA it will only put in 750... more likely something less... these numbers sound similar to what you got in your original post.
Second point... save yourself a headache... buy Sanyo batteries. They are the only brand battery I can recommend. The capacities are always good. There is an industry standard on rating capacity, and 1750 70% is not it! (I think it's like 90%-95%... can't remember).
Some GREAT Sanyo cells are the 1950 FAUP and the 1100... don't know the designation. It's in the NOBSBatteries site... it has very low (7mo) internal resistance.
Initial charge should be at C/10 (or 250mA for a 2500mAh pack). The Sanyo data sheets say the charge their batteries for 16 hours at this rate... I wouldn't go quite that long... I'd go 12 hours. I also put a temp snesor on them so if they get warm the charge stops.
Companies rate discharge at C/5 (500mA for a 2500mAh pack).
Also, Red Schoefield (RC Battery Guru) says to discard (recycle NiCd) packs when they drop below 80% capacity. Also... if you charge your packs and let them sit for a week then test them, if they test a lot lower than they were you should toss 'em... seperator is breaking down and they are discharging themselves.
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