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Old Mar 07, 2004, 11:27 PM
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Minneapolis, Minnesota
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Why won't my brand new NiMH Aerohawk batteries charge correctly?

I am new to the electric world. I bought two new 800 mAH 8.4 V batteries for the Aerohawk and charged them afresh with my Piranha charger. One gives me ~1 minute of flight before it is dead and the other ~2.5 minutes. What in the world is going on? I have the correct settings on the charger and have the delta peak senstivity at 8. It seems the worse pack only takes in about 150 mAH and it is done charging. Please give some advice if you can. Thanks in advance!
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Old Mar 08, 2004, 12:24 AM
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Joe Ford's Avatar
Olathe, KS
Joined Aug 2003
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you need to slow charge them the first few times....if you can, charge them at .1A...this will "open up" the cells...they wont reach full charge capability for a few cycles...if they still wont work you probably have a bad cell and should send them back.
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Old Mar 08, 2004, 10:31 AM
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Minneapolis, Minnesota
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Thanks for the advice. Will do. Gosh, slope soarers were so much easier!
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Old Mar 08, 2004, 10:53 AM
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Chattanooga, Tennessee, United States
Joined May 2003
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Which model Piranha do you have? Are you sure it can be set to give you only ~80mA charge rate for slow charging. Otherwise you might have to cycle them several times by discharging them down to 1v/cell, then recharging them using the 50mA trickle charge capability - but that will take 20hrs or so to charge them each time [at 80mA it will still take ~14hrs].

Cheers, Phil
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Old Mar 08, 2004, 03:50 PM
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Minneapolis, Minnesota
Joined Jan 2004
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It is the Piranha digital peak charger with no discharge capability. They told me witih NiMH there is no need for discharge. Anyhow, the lowest I can go to charge them is 0.1 A or 100 mA. That is it. Any other suggestions here? Thanks!
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Old Mar 08, 2004, 04:02 PM
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Olathe, KS
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do the slow charges at .1A...a little high but better than quick charging them...for discharge just hook them up to plane and run at 1/4 throttle (thats the easy way...hard way is build a discharger out of auto bulbs)
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Old Mar 08, 2004, 09:38 PM
No splinters=Good landing
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Conestoga, Pa.
Joined Jan 2003
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ucsdgemini

I had the same problem with 2 Aerohawk packs. My question to the experts out there is, can I use a wall wart designed for nicad rx and tx packs at 9.6v and 4.8v for a new nimh pack trickle charge 7 cells 8.4v. What I want to do is charge a new pack on the tx side at 9.6v and 50ma. First, is the voltage too high, and second, can I get into trouble using a nicad wall wart on nimh's.

David
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Old Mar 10, 2004, 06:50 PM
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Minneapolis, Minnesota
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Ok, now I am fed up. I slow charged my packs as described. My 2 new 800 ma packs actually took in all 800. But, everytime I got to fly my Aerohawk, I get 30 seconds and then caput, the thing falls out of the sky. Why am I having such difficulty with these things? Am I missing something?
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Old Mar 10, 2004, 06:53 PM
No splinters=Good landing
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Conestoga, Pa.
Joined Jan 2003
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I had the same problem with mine. I actually got 2 new packs and am in the process of seeing if these work better. If they don't, I am going to assume that there is something wrong with the Aerohawk.
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Old Mar 10, 2004, 06:54 PM
No splinters=Good landing
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Conestoga, Pa.
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Where did you get your Aerohawk from?
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Old Mar 10, 2004, 07:11 PM
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Olathe, KS
Joined Aug 2003
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Give me this info and I'll run some #'s thru motocalc for you. Need motor size & manufacturer, esc and prop. I'll give you a ball park estimate of time you should be getting...it may be that those packs are being sucked dry very quickly. Either that or a bad cell. How many times has the pack been charged & discharged? It takes a little while for the cells to open up.
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Last edited by DrkSdeOTM; Mar 10, 2004 at 07:13 PM.
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Old Mar 13, 2004, 04:18 PM
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Minneapolis, Minnesota
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Everything is stock for an Aerohawk. One of my packs last longer. It is definitely a pack issue. I charged one with the stock charger overnight and I got 45 seconds out of the damn bird. I am so sick of these batteries. I think I will go LiPoly.
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Old Mar 13, 2004, 04:57 PM
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Olathe, KS
Joined Aug 2003
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sounds like you have a dead cell or a bad connection inside the pack...I'd send it back.
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Old Mar 13, 2004, 08:09 PM
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Minneapolis, Minnesota
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Problem is I got it from RCmart in Hong Kong. Took forever and a day to get. I won't even bother for the ten bucks. Thanks for the help.
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Old Mar 13, 2004, 08:21 PM
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Olathe, KS
Joined Aug 2003
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If you know how to make your own packs you could easily check to see if one or more of the cells was faulty, buy a replacement and rebuild the pack. If you dont want to mess with it and are gonna throw it away or something send it to me I'll take it.
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