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El cheapo Nicad Charging


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marto
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Joined: 08 Jul 2004
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Location: Brisbane, QLD


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El cheapo Nicad Charging

I was just wondering if i can charge drill packs with a normal car battery charger. And tell when there full using a temp sensor and multimeter which i have at home.

Any ideas other than go buy a triton.
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Steven Martin
Twisted Constructions
http://www.botbitz.com

Post Sun May 22, 2005 1:24 pm 
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Philip
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Joined: 18 Jun 2004
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Location: Queensland near Brisbane


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I believe that the AC noise on the cheap car battery charger would drastically shorten the battery life.
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So even the rain that falls isn't actually going to fill our dams and our river systems

Post Sun May 22, 2005 1:59 pm 
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marto
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I thought that Nicads were less sensitive than SLA and Everyone uses them to charge slas?
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Steven Martin
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Post Sun May 22, 2005 2:02 pm 
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Spockie-Tech
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Joined: 31 May 2004
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Location: Melbourne, Australia


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There is no cheap, easy way of charging a NiCd (or NiMh) battery *fast* without some form of temperature monitoring or voltage feedback to sense the "end-of-charge" point.

The quicker you want to pump current back into them, the better your charger needs to be to accurately sense when they are full and stop charging them, overcharging is the biggest killer of NiCd's. If you're prepared to stand there while they charge and constantly feel for them getting hot, you could monitor it manually, but it would be like watching grass grow.. Smile

The best "simple" example of a temperature controlled fast charger I've seen on the net is here.. http://www.capable.ca/rcstuff/fastchg.htm - It could be improved a lot with the replacement of all that discrete circuitry with a micro, and it will only charge 7-cell packs as shown, so dont build it expecting to charge 12 or 24v packs with it. Its aimed at the RC car guys with their 7.2v packs. It could be modified, but you will need someone with some serious electronic skills to assist.

I'm not sure how sensitive to ripple (non stable voltages) on their charging cycle they are though. Lead Acid Batteries are *very* sesitive to it. It does nasty things to the formation of the spongey lead structure created by the acid. Nicad chemistry might not be a little more tolerant, but its probably still a good idea to have the power supply as smooth as possible for maximum battery life.
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Post Sun May 22, 2005 2:16 pm 
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marto
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Joined: 08 Jul 2004
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Location: Brisbane, QLD


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Well looks like i use my rhino and 7.2v packs until i buy a triton. I can charge 7.2v @ 10amps but anythin above that at only 500mah
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Steven Martin
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Post Sun May 22, 2005 2:22 pm 
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andrew



Joined: 16 Jun 2004
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Location: Castle Hill, Sydney. N.S.W


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yes i am quite fond of the Triton charger.

WIll get one sooner or later but not for a good while yet like maybe end of this year as theres been far too much happenming with forking out bucks to make my year 12 metalwork project and Orbit stuff and HSC and a million other things.

Maybe if i et off my butt and get a job but NAH Razz.
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Andrew Welch, Team Unconventional Robotics

Post Sun May 22, 2005 4:22 pm 
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marto
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Location: Brisbane, QLD


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Thats exactly what i though.
Job???? NAHHHH
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Steven Martin
Twisted Constructions
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Post Sun May 22, 2005 11:29 pm 
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Spockie-Tech
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Joined: 31 May 2004
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Location: Melbourne, Australia


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so what you guys are saying is that you would like to own the end-result of someone else's hard work (A Triton for example), but you're not actually willing to go out and spend any of your own time/work to get some money to trade with them in exchange for it ?

Hmm, thats a strange way of looking at things.. Wink
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Post Mon May 23, 2005 12:32 am 
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marto
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Joined: 08 Jul 2004
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Location: Brisbane, QLD


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I will pay for it i just hope to someday find a better way than working.



Someday.......
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Steven Martin
Twisted Constructions
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Post Mon May 23, 2005 7:24 pm 
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Philip
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Joined: 18 Jun 2004
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Location: Queensland near Brisbane


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Find a bloke to give you $10 000 and a free trip to Bali.....
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So even the rain that falls isn't actually going to fill our dams and our river systems

Post Mon May 23, 2005 7:49 pm 
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timmeh
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Joined: 20 Jul 2004
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I have seen the light.

JOB=MONEYS and MONEYS=Pocket bikes robots and cars Very Happy

And other cool stuff.
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Tim Team Reaper.

Post Mon May 23, 2005 9:28 pm 
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Spockie-Tech
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Joined: 31 May 2004
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Location: Melbourne, Australia


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Yep, If you want stuff from other people, then you generally have to offer them something in return.. Jobs are great for that kind of thing..

The good news is, walks on the beach, sleeping in on a rainy sunday morning and lots of other good things in life are still free.. Smile

The free things generally arent much good for Bot building or Cars though.. Rolling Eyes

*ahem, back on topic Brett - where were we ? - ah yes, NiCad charging*

Might be interesting to hear from Jeff J (Still lurking out there Jeff ? - you've been quiet for a while again) - He uses 7.2v RC Car packs to power El-Bravo I believe.

If you dont mind having some pack connectors in your Bot to series daisy-chain them up to a useable voltage, yet still be able to seperate them to charge them with the low-voltage-only cheaper RC car chargers, then that might be an option to get away with cheaper chargers.

Its a lot easier (electronically) to turn 12v (from a car battery) into 7.2v charging than it is to step it up to a higher voltage required to charge a 12v (or more) pack, so your range of available chargers would be much greater for the lower voltage packs
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Post Mon May 23, 2005 9:48 pm 
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marto
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Joined: 08 Jul 2004
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Location: Brisbane, QLD


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Yeah i do work for some moeny its just i don't really have time for work between school and sport. Which prolly means i shudn't have time for bots but i make time for that.


I guess i'll just make sum more 7.2V packs and charge em fast. Wud it be easier to step down one of the 24V Sla chargers?
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Steven Martin
Twisted Constructions
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Last edited by marto on Tue May 24, 2005 7:18 pm; edited 1 time in total

Post Mon May 23, 2005 10:56 pm 
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Rotwang
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Joined: 15 Jun 2004
Posts: 1589
Location: Vic


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Just got home to find our new charger has arrived from Tower Hobbies. Very Happy

It’s an Astro Flight Model 112 Deluxe Digital Peak Charger/Discharger.

Haven’t turned it on yet as I need to set it up with our idiot proof connectors first but it looks good.
Nice and simple to the point of being crude, just the bare essentials but heaps of grunt to charge up to 40 cells at 4 amps or up to 20 at 8 amps.
US $149.94 now to find out how many volts scooter motors can handle. Twisted Evil

Post Tue May 24, 2005 6:54 pm 
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