From: hutto@SMTC.engr.scarolina.edu (Brent Hutto)
Subject: Re: Misc R/C Car Questions
Reply-To: hutto@smtc.engr.scarolina.edu
Organization: NIST Southeast Manufacturing Technology Center
Date: Fri, 22 Jan 93 13:41:27 GMT

In article <1jndudINNi9a@flop.ENGR.ORST.EDU>, slezal@gyro.ECE.ORST.EDU (Lee Slezak) writes:
>
>Hi all-
>
>I just read a posting about r/c car questions so I figured I would
>post away.  First off, does anyone know where to to get nicads
>cheap?  I like to build my own 6 and 7 cell packs and I am looking
>to build more but I am sick of spending tons of money on my
>battery packs.  Maybe I am getting a good deal you tell me,
>I can get matched sanyo 1400 indvidual cells for $3/cell (low numbers)
>$4/cell (decent numbers) and $5/cell (good numbers), (when I
>say numbers I mean similar discharge rates, etc.)  Where can I get
>cheap cells of 1400 to 1700 mAh??

    The most reasonable place I know of for Sanyo 1400mah SCR cells
    is B&T Racing in Rougemont, NC. They usually have a small ad in
    R/C car action. The most recent price I've seen for matched packs
    was 3 or more packs at $18.00 each (285+ seconds at 20A). He also
    has unmatched single cells for, like, $2.00 uncycled or $3.00
    cycled, which doesn't sound a lot cheaper than what you have
    already. B&T's prices are not all that low on Sanyo 1700mah SCR
    cells, although they are quite reasonable.

>My next question also deals with nicads, I would like to build a 
>peak charger, anyone have any plans?

    My advice is to be very careful doing this. You are looking for
    quite small delta voltages at peak, a few 10's of millivolts,
    while charging at high currents, several amps, over a long period
    of time. With a analog (capacitor) peak hold circuit, the leakage
    over the 20-30 minute charge period can fool a poorly implemented
    charger into thinking that the battery hasn't peaked yet, which
    *will* destroy your battery if you aren't standing there making
    sure the battery stays cool.

    I think that a home-built charger would only have to fry a couple
    of good batteries before you would have been better off buying a
    $40-$80 commercial peak charger. OTOH, you can use a digital-type
    peak detector (sample and keep track of the voltage digitally)
    that can be quite accurate. I bet you'll end up spending over $50
    on it, though.

>How can I make my stock motors faster?  Can you make them like
>modifieds or what?

    I will dig up an article I posted on this once before and repost
    it later today. A "juiced up" stock motor will always be more
    expensive to run and less efficient than a good modified motor of
    the same power output. I recommend racing in the modified class
    and avoiding the whole "stock motor" scene.

>Lastly I was wondering if anyone else out there is still using the
>old RC10 gearbox (prior to the stealth).. I use it, simply for
>to avoid purchasing a stealth.. But if anyone else still uses it
>do you have any tips?

    I've never had an RC10. The only advice I know is to open up that
    gearbox and polish, polish, polish them teeth. Keep it clean and
    replace any slightly worn gears. A hand-fitted "RC10 Classic"
    tranny can be 90% as efficient as a stealth. It's just frustrating
    to have to work your fingers to the bone to go as fast as a kid
    who put his stealth together in 30 minutes and has run it for a
    year without cleaning it. ;-)

>Well take care and thanks-
>
>Lee Slezak
>slezal@scrooge.ece.orst.edu
-------------------------------
Brent Hutto
hutto@SMTC.engr.scarolina.edu
Newsgroups: rec.models.rc