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Old Mar 05, 2003, 10:55 AM
Ian Turner
North Lake WI USA
Joined Feb 2003
69 Posts
Question
Ni-Cad batteries, how do I know when they are fully charged

Hi there. I am a newbie to RC electric flight and just purchased a new Hitec Flash 5X tx. The unit came with an 600 mah 8 cell Ni-Cad battery and wall charger. I was wondering if some experienced person would be so kind as to explain how I can tell when the battery is fully charged. I do not want to damage the battery by over charging. The charger is not of the "Peak Detect" type so it will charge whenever it is plugged in. I have a good Fluke DVOM with a thermocouple and understand how to use it. Is there a certain voltage to watch for to know the battery is fully charged? Should I wait for a certain period of time after disconnecting the charger for the battery to stabilize before I measure it? Or maybe measure it under a load? If so how much load? I have read some stuff about temperature rise but I have not seen any values given. Is there a certain temperature I should watch for? Thanks!
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Old Mar 05, 2003, 11:49 AM
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Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
26,346 Posts
For Nicads, 1.4v-1.5v/cell is average for a full charge. An eight cell pack will read 11-12 volts at full charge.

Of course, your mileage may vary.

mw
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Old Mar 05, 2003, 12:58 PM
BEC
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Auburn, Washington USA
Joined Jan 2001
12,937 Posts
The charge rate put out by those wall-wart type chargers is low enough that you can leave it plugged into your Tx overnight, or even for a day or two, without worry.

NiCds don't have a strict voltage to charge state relationship like lead acid or lithium batteries do, so you can't really pick a particular voltage.
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Old Mar 05, 2003, 01:25 PM
Ian Turner
North Lake WI USA
Joined Feb 2003
69 Posts
BEC from Gaseousfool

Thanks BEC. Can you recommend an automatic charger with peak detection and load cycling that charges faster than the wall wart?
The slow speed of the wall wart will interfere with my flying once the weather here in Michigan warms up. Right now it is too cold for more than 3 or 4 flight batteries worth of flying. The auto chargers seem to be about $130.00 -$150.00 in the catalogs I have looked at. Thanks again.
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Old Mar 05, 2003, 01:28 PM
Ian Turner
North Lake WI USA
Joined Feb 2003
69 Posts
Mark from Gaseousfool

Thanks Mark. Can you recommend a good auto charger with load cycling that will charge the battery faster and unattended? They seem to be in the $130.00 - $150.00 range.
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Old Mar 05, 2003, 01:37 PM
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Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
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I've been flying for a few years so my stuff is a bit dated but my $130 Simprop Intelli-something or another has been a great investment. Similar to the FMA SuperNova but slightly different software. Old Faithful is an $80 Hitec CG335.

mw
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Old Mar 05, 2003, 08:14 PM
Registered User
Austin, TX, USA
Joined Feb 2001
415 Posts
Be forwarned that many transmitters have a protection diode in series with the charging jack. So peak detecting chargers probably won't work correctly through the jack. In that case you can either remove the battery for charging, or modify the transmitter.

Also note that if you replace your transmitter batteries with nimh cells, that you can fly darn near all day, and still slow charge them overnite.
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Old Mar 05, 2003, 08:18 PM
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Brad Trent's Avatar
Canada, BC, Abbotsford
Joined Mar 1999
1,613 Posts
gaseousfool:
I use the Triton charger from Great Planes for all of my charging now. It will do all of your power packs - Nicd, Nimh, Pb, or Lithium, as well as your Tx and Rx pack. It also cycles packs. You can order the appropriate charge leads for you brand of Tx at the same place as your charger. You also need the output leads for your power packs, as they are not supplied with the unit. My charger cost $200 Cdn., so should be about $135 US., if that's where you're ordering from. A very useful, high quality charger, in my opinion.
Brad.
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