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Discharging NiCd packs-old school
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Discharging NiCd packs-old school
I built this pack-discharger for Tamiya-style connectors close to 30 years ago.



Basically a 12VDC load; intended to discharge the pack.. but not drain it completely. I designed my discharger with a 12VDC automotive tungsten lamp socket (#33 lamp) which induces a significant load to a connected pack.. and also a 12VDC audible alarm/beeper to monitor the "state of discharge."
Here it is; discharging a 9.6VDC AAX8 pack this afternoon after running my 1:8 scale RC Snowmobile.

I connect a pack; the lamp lights.. and the beeper beeps. The lamp is drawing much more current than the beeper. When the lamp dims.. the beeper pulses change.. which alerts me to disconnect the pack.
Here's a useful tip. Save the RED and GREEN plastic "clips" found on some bread-bags.. and clip them on your packs' wiring-harness to easily identify the state of charge of your packs.




Basically a 12VDC load; intended to discharge the pack.. but not drain it completely. I designed my discharger with a 12VDC automotive tungsten lamp socket (#33 lamp) which induces a significant load to a connected pack.. and also a 12VDC audible alarm/beeper to monitor the "state of discharge."
Here it is; discharging a 9.6VDC AAX8 pack this afternoon after running my 1:8 scale RC Snowmobile.

I connect a pack; the lamp lights.. and the beeper beeps. The lamp is drawing much more current than the beeper. When the lamp dims.. the beeper pulses change.. which alerts me to disconnect the pack.
Here's a useful tip. Save the RED and GREEN plastic "clips" found on some bread-bags.. and clip them on your packs' wiring-harness to easily identify the state of charge of your packs.

Re: Discharging NiCd packs-old school
Cool setup its important To drain nicd batry before charge wil help
davidll1984- Diamond Member
- Posts : 2106
Join date : 2020-02-12
Age : 38
Location : shawinigan
Re: Discharging NiCd packs-old school
Also, Roddie, they're good for guitar picks, if your in a jam.(see what I did there).roddie wrote:
Here's a useful tip. Save the RED and GREEN plastic "clips" found on some bread-bags.. and clip them on your packs' wiring-harness to easily identify the state of charge of your packs.

But you knew that.
Bob
dckrsn- Diamond Member
Posts : 2750
Join date : 2010-10-21
Age : 70
Location : Long Island, New York
Re: Discharging NiCd packs-old school
Wait a minute, Roddie. You drop a bomb on us by showing old school technology with respect to old school batteries...
And then only hint at a 1/8 scale sled?
Come on, Brother...show us the goods!
I'm particularly interested in the mini-track drive system.
And then only hint at a 1/8 scale sled?
Come on, Brother...show us the goods!

I'm particularly interested in the mini-track drive system.

944_Jim- Diamond Member
Posts : 1872
Join date : 2017-02-08
Age : 58
Location : NE MS
Re: Discharging NiCd packs-old school
944_Jim wrote:Wait a minute, Roddie. You drop a bomb on us by showing old school technology with respect to old school batteries...
And then only hint at a 1/8 scale sled?
Come on, Brother...show us the goods!![]()
I'm particularly interested in the mini-track drive system.![]()
Hi Jim, The sled I bought several years ago on CLEARANCE at Walmart. They were originally $50.00 and were reduced several times. When they got down to $13.00.. I snagged one.




I haven't taken it apart to examine the internals.. but in the event it stops working.. I might. There are some very cool RC snowmobile vids on YouTube.
Re: Discharging NiCd packs-old school
Bummer...it's a Polaris! Always wanted an RC snowmobile. But found that most are useless unless its hardpack. Otherwise its necessary to do costly upgrades. Probably get more use out of it than airplanes in this glaciated tundra environment!
OhBee- Platinum Member
- Posts : 698
Join date : 2016-03-23
Age : 73
Location : Minnesota
Re: Discharging NiCd packs-old school
OhBee wrote:Bummer...it's a Polaris! Always wanted an RC snowmobile. But found that most are useless unless its hardpack. Otherwise its necessary to do costly upgrades. Probably get more use out of it than airplanes in this glaciated tundra environment!
I was watching youtube vids trying to find a nitro-powered sled..and there "are some"... but most are bigger than 1/8 scale. More like 1/5th.. and having a long-track design. The long-track design is a high-performance/racing-style track. The custom-built "brush-less" sleds are amazing.. but I'm an IC engine purest.
Re: Discharging NiCd packs-old school
I bet David could make that thing Nitro powered...
Cribbs74- Moderator
Posts : 11888
Join date : 2011-10-24
Age : 49
Location : Tuttle, OK
Re: Discharging NiCd packs-old school
Thanks for bringing this up. It brings back memories as I had two of those years ago. The same as yours and I beleive a red and black one.
NEW222- Top Poster
- Posts : 3865
Join date : 2011-08-13
Age : 45
Location : oakbank, mb
Re: Discharging NiCd packs-old school
Do you even HAVE to discharge a nicad pack ? Totally different chemistry than a lipo. What about NiMh packs? Seems nothing bothers them regardless the charge you leave them at. I fly those in an old brushed RC Mustang I have.
OhBee- Platinum Member
- Posts : 698
Join date : 2016-03-23
Age : 73
Location : Minnesota
Re: Discharging NiCd packs-old school
OhBee wrote:Do you even HAVE to discharge a nicad pack ? Totally different chemistry than a lipo. What about NiMh packs? Seems nothing bothers them regardless the charge you leave them at. I fly those in an old brushed RC Mustang I have.
Yea.. AFAIK.. if you don't "cycle" a NiCd pack, it will develop what's called "cell-memory".. which dramatically reduces capacity. The NiMh cells apparently don't suffer from this phenomenon.. and can be re-charged from any state-of-charge.. IIRC..
I bought a pair of LiPo packs (7.4V 800mAh 20C) and the correct (balancing) charger for them.. but have not used them yet.



I bought them for a "Dynam" brushless Flight-Package.. that I had read about a few years ago.. for powering a sm. RC foamie/park-flyer. (some day...)

Re: Discharging NiCd packs-old school
Well, that's neat roddie. I like the package. All there. Servos, ESC, motor, all ready to install into a plane. Great idea.
NEW222- Top Poster
- Posts : 3865
Join date : 2011-08-13
Age : 45
Location : oakbank, mb
Re: Discharging NiCd packs-old school
NEW222 wrote:Well, that's neat roddie. I like the package. All there. Servos, ESC, motor, all ready to install into a plane. Great idea.
Yes Chancey.. I was interested in learning more about Radio Control aircraft at the time.. and was designing/building an appropriate-size Hi-wing trainer. I put a LOT of hours into that project.. which has been on hold.
Back around the time that I bought those electronics.. Tower Hobbies had a special on Great Planes "Electri-fly" ES50 nano-servos. I bought eight of them.

It was an IRP.. (Impulsive Roddie Purchase) but not without a good degree of dreaming.. Here's what it is with me; I know that I'll be able to use these things someday. It's a promise that I make to myself. Same with the building-materials. Balsa, hardwood, plywood.. metal-goods. These materials will remain stable indefinitely if stored properly.
I hope to retire; a musician/model-builder. That's a pretty broad-spectrum..


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