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Old May 16, 2001, 10:32 AM
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San Francisco Bay Area
Joined May 2001
332 Posts
Ready to go back to Gas

For my first foray into e-power I've just finished a shiny new Great Planes Fundango... but I am being driven to distraction by the fact that I can't get the motor to run properly. First there was the reversed Schottky diode (thanks to confusing directions from Great Planes). I've got that sorted out (thanks to the Zone!), but now, even after charging the battery for 15 hours (9.6 V 700 mAh 8-cell NiCad, T-400 motor with a C-20 ESC) the motor will only run for 5-10 seconds, and then shut down.

I am now focusing on the battery. Can anyone recommend a charger that is suitable for this battery (9.6 V 8-cell 700 mAh NiCad)? I am particularly interested in one that will charge, cycle, and discharge the battery and read out the capacity. The charged battery reads approx. 9.6 V on the multitester, but I know that is not accurate as it does not have a load on it. Also, what is an acceptable charge rate, and discharge rate for this battery? FWIW I currently have an Intellipeak mini pulse charger.

thanks in advance!

John Webb
Northern California
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Old May 16, 2001, 10:52 AM
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Bill Glover's Avatar
United Kingdom, Bracknell
Joined Nov 2000
11,622 Posts
I'm not familiar with the specific model or motor you have, but I'd guess that your power pack cannot deliver enough current. So the voltage rapidly drops under load and the BEC cutoff activates, shutting the motor down. Do you know what make/type your 700 mAh Nicd cells are? Any idea what current the motor is pulling? What prop are you using?

A great charger is the Super Nova 250, you will find lots of favourable posts on the Ezone. It will give you voltage, current, and capacity, cycles cells, is designed to handle Nimh as well as Nicd cells (and lead acid wet cells too), and has an excellent range of chrage currents (100 mA to 5A). Strongly recommended.
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Old May 16, 2001, 10:58 AM
Balsa Kamikaze
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Germany, NRW
Joined Feb 2001
536 Posts
I have the <a href="http://at.robbe-online.net/cgi-bin/rims_at.storefront/3b02a2a5002fa23d27173e0dc1210610/UserTemplate/1/?ISID=3b02a 2a5002fa23d27173e0dc1210610">Robbe Power Peak Infinity II</a>.


Great charger which charges 1-30 cells, 5A charge/discharge and cycles your packs as often as you want.

I'm really satisfied with this one, but I bought it in Germany. I don't know where and for how much you can get this one here in US.

Jens

[This message has been edited by Jensst (edited 05-16-2001).]
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Old May 16, 2001, 10:58 AM
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San Francisco
Joined Jul 2000
982 Posts
John:

The battery pack should read somewhere around 11.2 volts (on your multitester) after a full charge. If you're only at 9.6 volts the battery definitely isn't charged properly. What power source are you using - according to specs on this charger it is good for only up to 7 cells from a DC power source.

Greg

[This message has been edited by greg morrison (edited 05-16-2001).]
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Old May 16, 2001, 11:02 AM
Mountain Models Wannabe
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Ithaca, NY USA
Joined Mar 2001
4,371 Posts
Hey, don't give up on electric. There are certainly things to overcome but electric has a lot to offer the hobby. I probably fly 5 days out of the week. I'll fly for ten minutes before work, in front of my office, perhaps sharing the controls with work mates. In the evening I'll fly for a half hour or more at the local schoolyard.

I'm flying a 7 ounce model that I manufacture so I'm playing with different setups but that's more an excuse to fly. I use inexpensive WalMart NiMH AAAs and get a half hour out of them if I'm careful with the throttle.

The point is, there may be some things to overcome, but electric flight brings a dimension to the hobby that really cranks up the fun factor. Good luck and hang in there.

Doug
www.geocities.com/duskstik
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Old May 16, 2001, 11:20 AM
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Okemos, Michigan
Joined Feb 2001
277 Posts
Quote:
Originally posted by John Webb:
For my first foray into e-power I've just finished a shiny new Great Planes Fundango... but I am being driven to distraction by the fact that I can't get the motor to run properly. First there was the reversed Schottky diode (thanks to confusing directions from Great Planes). I've got that sorted out (thanks to the Zone!), but now, even after charging the battery for 15 hours (9.6 V 700 mAh 8-cell NiCad, T-400 motor with a C-20 ESC) the motor will only run for 5-10 seconds, and then shut down.

I am now focusing on the battery. Can anyone recommend a charger that is suitable for this battery (9.6 V 8-cell 700 mAh NiCad)? I am particularly interested in one that will charge, cycle, and discharge the battery and read out the capacity. The charged battery reads approx. 9.6 V on the multitester, but I know that is not accurate as it does not have a load on it. Also, what is an acceptable charge rate, and discharge rate for this battery? FWIW I currently have an Intellipeak mini pulse charger.

thanks in advance!

John Webb
Northern California
John,

Ugh! Your in the same spot as me! See my thread in Training. About wrong battery... But that isn't the case I think for you. I have the Intellipeak charger like you.... I'm not sure though what model you have.

Mine is the less expensive one with the dial to adjust charge rate. My problem is with the battery (I hope). I bought a 600 maH Nimh pack, which I've been told is too small for speed 400. The intellipeak charger will do 4-8 cells, but I am beginning to think it doesn't charge the smaller cells correctly.

Last night I cycled again the pack I've been trying to get to work. It didn't run more than 30 secounds again before the esc kicked it off. I unfortunatly haven't a multi-meter, so I'm curious what the off charger voltage is..

The thing is the guy at the hobby shop knew darn well I was doing electric planes and still sold me this one. He even advised me on the bum battery I have as well. Ugh... I'm going to definitly buy on-line from people who know what their doing from now on.

Mean time I'm going to cut my losses and get a lite stick to use the batteries I have...


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Old May 16, 2001, 01:37 PM
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Joined Apr 2001
284 Posts
John,
Those batteries can’t handle the amperage(nicad 600ae or 500ar would be a better choice); but they should run more than 5 seconds
I have an Astroflight 122d peak charger which had a hard time charging the small cells for my slow flyer. It kept false peaking… until I cycled the packs a couple of times. you can make an adapter and charge them on your TX battery charger to even them out with a slow charge Then run them completely down .

-fish
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Old May 16, 2001, 02:54 PM
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San Francisco Bay Area
Joined May 2001
332 Posts
My attempts to run the motor have been with the gears/prop off so they are not a factor. The nicads (bought from Tower Hobbies) are Sanyo's. I bought 3 identical batteries, and the same thing happens with all 3 (so I know it's not a random bad cell). I'm using AC with the charger, and it says it will handle 8 cells on AC. I don't know what current the T-400 pulls.

Greg - I'm confused about reading the volts. If I have 8 cells @ 1.2V ea shoudn't it read the total of 9.6V on a full charge?

thanks to all for the input.

John Webb
Northern California
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Old May 16, 2001, 03:18 PM
Registered User
San Francisco
Joined Jul 2000
982 Posts
John:

I can't give you a technical explanation but I know from experience that a fully charged 8 cell nicad pack should be at about 11-11.2 volts off the charger despite the 9.6 volt rating. When my 8 cell nicad battery packs only read 9.6 volts they are pretty much discharged. Since Tower packages this battery pack with the Fundango I'm sure it can handle the amp draw of the Speed 400 motor. Your Intellipeak charger should work fine with these nicads so I would attempt to recharge them again.

Greg



[This message has been edited by greg morrison (edited 05-16-2001).]
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Old May 16, 2001, 03:37 PM
Make Haste Slowly
realdeal's Avatar
USA, KY, Lexington
Joined Nov 1999
966 Posts
Hi John,

Just to eliminate all possibilities try hooking the battery direct to the motor. If it cuts off then you probably have a motor problem.

Keith
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Old May 16, 2001, 04:10 PM
MK
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NJ
Joined Feb 2001
1,093 Posts
John, for nicads and NiMH, a fully charged cell should be almost 1.4V per cell. Like Greg said, when they are at 1.2V per cell they are pretty much spent.
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Old May 16, 2001, 05:41 PM
Registered User
San Francisco Bay Area
Joined May 2001
332 Posts
Keith:

I tried connecting the battery directly to the motor and it ran better but not great (it still ran down pretty quickly). I am guessing that the "fully charged" battery is actually close to the ESC "motor cut off" voltage. At any rate, based on the responses Ive gotten I think I will invest in a different charger. I am dying to fly this thing!

thanks

John Webb
Northern California
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Old May 16, 2001, 08:48 PM
Radix malorum est cupiditas
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Joined Jul 2000
460 Posts
John, sounds like you have the knowledge to hook up your battery pack to the charger you have for your transmitter (as mentioned above)- just splice in a connector compatible with your batteries (observe polarity), most of these little chargers put out about 80mA (look at the label), you should be able to leave this on overnight for a good slow charge and be ready to go tomorrow.
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Old May 16, 2001, 09:51 PM
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San Francisco Bay Area
Joined May 2001
332 Posts
radix2

Thanks for the reinforcement.
That's exactly what I did when I got home from work this eve. This will definitely identify the problem.

John Webb
Northern California
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Old May 16, 2001, 10:43 PM
Registered User
Manahawkin, NJ, USA
Joined Apr 2001
16 Posts
Sounds like you might have a dead cell in your pack. Try using another pack.
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