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Old 08-25-2004, 02:34 PM   #1
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Default <<( Battery Help )>> EP guys were no help

I started a thread in the Electric Forum and that was a mistake ... I don't think they read the posts:
http://www.rctech.net/forum/showthre...threadid=48505

Maybe they don't like nitro guys, whatever ...

Anyways, I wanted to try and use my flat 7.4V lithium battery pack from my Xray m18, and use it as a reciever pack in my nitro car. It's super light and lasts 4x longer than my AAA pack. It might even last longer at a lower voltage.

Is there a way to regulate it down to 6V?

I'm no electrical engineer, and I was really hoping to run into one in the other forum. So any help and/or answers would be greatly appriciated.

Thanks!
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Old 08-25-2004, 02:43 PM   #2
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You probably need a TRANSFORMER (that is the only THING that it can convert from 7.4v to 6.0v) or some kind of voltage resistence device to trim down to 6.0 V output.........that extra trasnformer will weight a TON.

For your information, those ppl from ELECT are far more intellegent then any college graduate in EE (in my opinion) They can play their 7.2V 3300 like a NASA engineer...............they can't give you a definite answer because you were asking something that is not a very good idea in NITRO or ELECT RC race car...probably not worth to even try.

Use (5)AAA, it will last you a whole day of racing including a 45 minutes or 30 minutes main....my R40 does.

Beside, lithium battery probably not the safest battery to play with....

And on my NTC3....I don't even bother to use AAA......car is way under legal weight already.
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Old 08-25-2004, 02:52 PM   #3
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Rookie, it was something I thought I'd like to try. I got the idea from a HK guy who uses one in his car. I wasn't able to ask him how he did it. And by the way, I'm sure some of the EP guys are very intelligent. That's why I took my question there first. But thanks for your thoughts. I guess it wasn't meant to happen.
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Old 08-25-2004, 03:02 PM   #4
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Default Re: <<( Battery Help )>> EP guys were no help

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Old 08-25-2004, 03:08 PM   #5
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Default Re: <<( Battery Help )>> EP guys were no help

Quote:
Originally posted by kidDynomite
Is there a way to regulate it down to 6V?
this should work. the LM7806 has an max. output of 500mA, should be enough. you can drop C1 if you want, but make sure C2 is there.

becareful with those Li batteries, make sure the discharge rate is high enough, or the protective circuit is still there, otherwise it might overheat really fast.

also check this out, got some interesting circuits for RC.

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Old 08-25-2004, 03:53 PM   #6
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Default Re: Re: <<( Battery Help )>> EP guys were no help

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Originally posted by Data
this should work. the LM7806 has an max. output of 500mA, should be enough. you can drop C1 if you want, but make sure C2 is there.
Data, thank you! And thanks for "Tony's Website", it's already given me a ton of cool project ideas.

The captain should've replace #1 with you long time ago.
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Old 08-25-2004, 06:18 PM   #7
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Default Re: Re: Re: <<( Battery Help )>> EP guys were no help

well running 7.2 volts through your servos might make them hella fast, they wil burn out just as hella fast, if you can, remove two cell so that you only have five cells. sounds like to much work if you ask me, you can buy those flat cells and make a new rec pack if you are looking a flat light pack.
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Old 08-25-2004, 08:05 PM   #8
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Default Re: Re: Re: Re: <<( Battery Help )>> EP guys were no help

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if you can, remove two cell so that you only have five cells. sounds like to much work if you ask me, you can buy those flat cells and make a new rec pack if you are looking a flat light pack.
if you were talking about Li batteries, those 7.2V Li pack has only two cells, each cell is 3.6V.
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Old 08-25-2004, 10:41 PM   #9
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Default Re: Re: Re: Re: Re: <<( Battery Help )>> EP guys were no help

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if you were talking about Li batteries, those 7.2V Li pack has only two cells, each cell is 3.6V.
I did not know that.
I think ofna is who makes those brick cells though.
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Old 08-25-2004, 10:46 PM   #10
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Data, really good info, i just put it in my favorite's folder. I was going to say that maybe you can use a resistor that can be bought at radio shack, and it weighs practally to nothing, but DATA helped you out more than I can.

hahahahaha, at the transformer idea. Those things weigh the same weight as an RC car.
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Old 08-26-2004, 12:08 AM   #11
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Quote:
Originally posted by compaq888
maybe you can use a resistor that can be bought at radio shack,
you can use two resistors to build a voltage divider, but then you need to optimize the resistor's value accordingly. using a voltage regulator is easier and more stable. also you need resistors with power rating >= 1/2W. typical resistors you get at radio shack are 1/4W and 1/8W.

Quote:
the transformer idea. Those things weigh the same weight as an RC car.
not necessary.
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Old 08-26-2004, 02:38 AM   #12
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all i know is that you can use resistors to get different voltage, otherwise I don't know anything about electronics. I took more than a year of electronics but I just don't understand it. Thank god when we had a project to do I got the part of making a frame out of metal, i aced that part, i love working with metal, not electronics, even though my dad built tv's from the ground up without a manual at the age of 15.

I thought most transformers were heavy because our air conditioner transformer blew and I went to like 4-5 stores to get another one, and 95% of them looked to be the same size and weight, it's where the wires came out was different and their working capabilities.
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Old 08-26-2004, 06:56 AM   #13
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Put 2 1N4002 diodes in line with the positive pole. Every diode has about 0.7V drop out.


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Old 08-26-2004, 08:10 AM   #14
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Don't forget, someone already stated that Lithium batteries are not the safest to be playing with.
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Old 08-26-2004, 10:16 AM   #15
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http://www.htbatteries.com/Public_html/Rx%20packs.htm

i use li-poly cells in my m8 and my receiver packs for my 1/8 scale buggy. they are considerably lighter and the run time is longer.

anyway, go to the bottom of the link and you'll see a regulator switch. it'll regulate your voltage so i won't fry your gear.

good luck.
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