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Old Nov 03, 2002, 08:03 PM
Registered User
United States, NY, Marion
Joined Sep 2001
494 Posts
Question
Will the auto based qualcomm chargers perform

We're considering using qualcomm 830s for our high school club aircraft. (DX-A powered) The auto (12 volt) version of the qualcomm charger seems more available than the desk top version and I'm wondering whether it would function as effectively.

Would a 3 amp. 12 volt Radio Shack transformer power one or two for these chargers?

If you have any better ideas concerning inexpense batterys for a low budget program let me know. Right now my wallet and the goodness of several manufacture's hearts are the two things getting us in the air.

Hugh Mason
Advisor- Newark Electric Flyers
hmason@newark.k12.ny.us
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Old Nov 03, 2002, 09:21 PM
Registered User
Winnipeg Intl, Canada
Joined Mar 2002
662 Posts
Hello Hugh:

The Qualcomm desk charger is available for a darn fair price at:

http://www.cellam.com/pdq800access.htm

I got one and also a few battery packs in the same order. The batteries seem to be of an older date code than the ones most often seen in the pictures posted here on the Forum...they are in a gray heat shrink rather than the green. Some people say the grays are not as good as the greens, but I have none to compare against.

Mine seem to work OK.

The desk charger needs to have few simple mods done to it to fully reach its potential for RC use. If you do some searching on this site, you'll find a million pages of info on the Qualcomm. Here's the general idea:

http://www-personal.umich.edu/~aroge.../qbattery2.htm

I also have two JST connectors on each battery. One connected to the protection circuits for safely monitored charging, the other directly to the battery terminals to allow for full current draw from the cells so the protection circuits don't shut down your radio if your motor draws too much current.

The charger also has a small potentiometer on the circuit board which can be adjusted to set the cut-off point in the charge sequence. I touched mine up a little so they are now charging to about 8.3 volts....I think mine was set about 7.9 or 8 when I first checked it. The amount of extra energy stored is substantial and worth looking into.

This charger can also be used with other LiOn packs, and I have charged some 1300 ma cells from a different qualcomm battery with no problem. These batteries had the protection circuits removed and they charge until reaching the 8.3 volt mark and then stop on their own.

I will be moving into LiPoly cells sometime over the winter and this charger should do the trick with them as well, so latch onto one of the cheap desk top units, put an hour or two into doing the slight mods required and enjoy!

Hope this helps out a little.

Lee Smith
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Old Nov 04, 2002, 11:23 AM
Registered User
Sunnyvale, CA
Joined May 2001
635 Posts
Hugh: I think it's great that you're putting this effort into getting kids interested in flying.

As for batteries, I would highly recommend searching the clearance racks at Walmart, etc. Also, many cellular phone stores have a bunch of battery packs from returned phones. I bet you could get some of them to give you lots of spare battery packs. There will be Nicads, NiMH, Li-Ions, and maybe even some Li-Poly's. The only problem with this is you need to find the right packs (ones that can put out enough current) and you must have some electrical know-how to get everything working. If that's not a problem, I think you can find lots of batteries.

I have a couple of the qualcomm 830 packs that haven't been opened yet. Send me a PM with your address and school info and I'll send you 2 packs.
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Old Nov 06, 2002, 11:27 PM
Registered User
Winnipeg Intl, Canada
Joined Mar 2002
662 Posts
Science guy:

I just stumbled across this site that might be just what the Prof ordered:


http://www.b-p-p.com/C750.htm

Regards,
Lee Smith
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