Using the T-Maxx EZ start with a 12 volt supply?

[Steve Godfrey]

Hi

When I'm trying stuff out at home I'd like to be able to start my
T-Maxx using a 12 volt 1:1 car battery.

Can someone point me in the right direction for the value of resistors
needed to achieve the voltage drop, or any other suggestions for
starting the T-Maxx from the 12 volt supply.

Could I get away with just using the 12 volt supply without any
resistors, I'm guessing it would fry the EZ circuitry.

Thanks

Steve G
Bristol, UK
RS4 MT, T-Maxx, Mini-Z Overland

[Bubba]

On Sun, 02 Mar 2003 20:07:56 +0000, Steve Godfrey
<SGodfrey@Blueyonder.co.uk> wrote:

>Hi
>
>When I'm trying stuff out at home I'd like to be able to start my
>T-Maxx using a 12 volt 1:1 car battery.
>
>Can someone point me in the right direction for the value of resistors
>needed to achieve the voltage drop, or any other suggestions for
>starting the T-Maxx from the 12 volt supply.

Build a regulator. Takes, if I remember right, 5 components (the
regulator. 2 capacitors, and 2 resistors) to make it work. Put it on
the smallest perf board Radio Shack (ok, Maplins for you ;) has and
bolt a heat sink to the regulator. An LM1084 5a adjustable regulator
should do it. Just need the 1084, 2 10uF capacitors, a 100 ohm
resistor, and a 540 ohm resistor. That'll give you 8v output and will
handle 5 amps. I'm not exactly sure how the starter setup works, but
if it's what I think (6 cell pack in a box with a switch and a strange
connector) then it'll work fine. Just put the right connector on the
regulator board, plug it in in place of the battery, and hook 12v up
to it. Never worry about your starter battery being dead again ;)

>Could I get away with just using the 12 volt supply without any
>resistors, I'm guessing it would fry the EZ circuitry.

Might work, actually. Is there any circuitry in there or is it just a
box, battery, and switch?

I think I'll just stick to electrics. I know the magic smoke will get
out if I hook a 12v battery up to my ESC so there's no confusion
involved ;)

Bubba
Losi XXXS- http://home.swbell.net/lt1_z28/xxxs.html
HPI Micro RS4- For sale
AE RC10LSS- Also for sale:
http://home.swbell.net/lt1_z28/rc10lss_for_sale.htm

[Garry P]

I have done this before with my MAXX, 4TEC and Rustler- a total resistance
of about 2.5 ohms is between the 12V supply and the glow plug. This is
*instead of* the 1.65 ohm resistor used in the EZ start. If you try using
the EZstart at 12V then the EZstart will survive longer than your glow plug
does....
The resistor would also have to be about 50W power rating - it will get very
very hot.
It is best not to place a resistor in series with the EZ start since the
motor normally connects direct to the NiCAD battery. If the motor became
disconnected then there is a chance that there would be extra V across the
plug and it would blow.
I also tried using a regulator (10A output) but dropping from 12V to 1.5V
(on the glow plug) caused it to overheat. Dropping to 7.5V worked better
but still had problems.

Most of the time I now use a NiCAD clip glo battery and run the motor
through the EZstart from a 12V battery. The motor has survived fine so far

Garry

"Steve Godfrey" <SGodfrey@Blueyonder.co.uk> wrote in message
news:ito46vobp1p0p236f6ftbvgpafq2h36ri5@4ax.com...
> Hi
>
> When I'm trying stuff out at home I'd like to be able to start my
> T-Maxx using a 12 volt 1:1 car battery.
>
> Can someone point me in the right direction for the value of resistors
> needed to achieve the voltage drop, or any other suggestions for
> starting the T-Maxx from the 12 volt supply.
>
> Could I get away with just using the 12 volt supply without any
> resistors, I'm guessing it would fry the EZ circuitry.
>
> Thanks
>
> Steve G
> Bristol, UK
> RS4 MT, T-Maxx, Mini-Z Overland