99GrandTouring

ok I rigged up a discharger from 2 old estes model rocket launchers I have, that have a bulb in them...
Heres what I need to know.
should I set the batteries up in series or parallel.....
The launchers hold 4 batteries each......

In series I'm getting about 10.21v and a draw of .247A
heres some pics of them

99GrandTouring

heres a shot of the amperage......

99GrandTouring

now If I change it and set the batteries up parallel
I get 5.0v at 3.548A
why does the amps shoot up so much? is this bad for the batteries?
and wich way would be best for discharging them?
and lastly how long should I leave them on?
I know on your clinic it says till there .9v a cell so should I just wait untill the voltage reads 7.2v when there setup in series?
or if there setup in paralles wait until it reads 3.6v's?

help me out here, I've almost got something workable setup to cycle my batteries!
Thanks for all the help, it is greatly appreciated.

Heres a pic of the voltage in parallel

99GrandTouring

heres a pic of the amps in a parallel battery setup...

if I am supposed to un them in series I hope I don't burn up this lamp to quickly... It gets pretty bright....

C_Watkins

My Feedback: (10)

First off... if you're getting zero amps hooking it up the way you did, you've blown the fuse.
Open the ammeter, replace the fuse (sometimes you're lucky and there's an extra inside).
Ignore the above if you have some sort of "foolproof" ammeter, which figured
that you didn't really mean to do that, and saved you some trouble.

Anyhow... on to using an ammeter:
Break the circuit somewhere. Positive or negative lead to the fans. It doesn't matter.
Insert the ammeter in SERIES with the load, to read amperage.
(Inserting an ammeter in parallel with the load is a full shunt of the circuit. Not good.)

Afterthought... if you left the leads where they normally are for reading volts/ohms,
then you may not have messed up... yet. Some multimeters have a separate plugin
for reading amps, and some have more than one (micro/milli/amps). Check yours.
If you have only two holes to plug leads into, ignore this afterthought completely.

Enjoy

C_Watkins

My Feedback: (10)

Hmmm... shoulda quoted ya.
Not nice to ask for help, then change the question

99GrandTouring

Thanks though!
I'm on vacation and have been up since 3:00am setting this um, couldn't sleep..
I didnt' realize until I actually read what was on the multimeter there was a seperate for amps...
now just to figure out wich to use, wich setup....
I find it odd that in parallell it pulls so many amps?¿

C_Watkins

My Feedback: (10)

Something does seem a bit fishy there. Dropping voltage raises amps? Nah.
The fact that the lamps are now in parallel would double the draw over a series setup,
but with the voltage cut in half, I'd think it would remain nearly the same.

We're talking a jump of over ten times here, with half the volts.

I have to think this is a wiring problem, to be honest.


DOH... where's the beef?

BRB with a diagram. I think I found it. turn that thing off!

99GrandTouring

if I bypass the light, and use the fans with the batteries in series and the fans wirred parallel.
I get a draw of .170a
I think I'm gonna alternate between this and the light so
1. I don't burn up my only bulb.
well red when you get on plz comment...
Thanks!

99GrandTouring

well, I was figuring it up
in series voltage double, in parralell amps double....
so if you figure .600mah x 8 cells = 4.8a...
and if in sereis you would then take .600mah x 4 cells (cause thats how many it actually is seing 4.8v) = 2.4a....?¿

I dunno about wiring though, its pretty simple no circuits, just wires, a bulb, and a switch.....
the bubl has no rating on it, anyway I can use my multimeter to find out?

I checked the ohms of it awhile ago, would this help?

99GrandTouring

after a while the fans dropped to .157a?
is this normal?
now the light reads .187 where it was about .250a??
heres a pic of the fans....
there actually running but the camera doesn't show

C_Watkins

My Feedback: (10)

You're misusing the ammeter, as stated in my first post
The lights, and the fans... they're not gonna draw much in the way of amps, sorry.

It dawned on me how the rocket launchers work... they send voltage to those clips.
You need a LOAD connected. The lamps, you're not gonna measure correctly,
because of the way the circuit is wired internally. you press the arm switch, and they light,
and then you press the fire switch, to send volts to the clips.


The important thing is, that THIS is the way to rig an ammeter.
You have battery plus connected to the ammeter plus.
Then you connect the LOAD to the other side, and the load back to the battery
(You can do that in the other direction as well... I explained to match the crude pic I made)

Given that the light is still bright in the pics... I have to think that you really need to
internally rewire these rocket launchers for your specific use, too.

99GrandTouring

well I have one launcher with the button depressed, and the lamp is on the other one.......?¿

C_Watkins

My Feedback: (10)

Two batteries in series, yes, voltage doubles, available amps remains same.
In parallel, *available* amps double, and voltage stays same.

You won't read more current draw just because you raised the available amps...
unless you were at maximum aperage draw in the first place.

Given a load that draws 250ma at 4.8V...
it will draw 250ma, whether there are 600ma available, or 200AMPS available,
as long as the voltage stays at 4.8.

I'm with you on wanting Red to answer your battery questions... he's the best.
I've known all my P=I*E, I=E/R, BBROYGBVGW, and all that jazz though, for many moons.
Trust me

C_Watkins

My Feedback: (10)

Ignore the lamp internal to the launcher. You have no way, short of rewiring,
to test its draw in this case. Look at the circuit, and connect a load in that way.

launcher neg to launcher neg, and vice versa... if you want to double the volts,
then press both buttons to power, and you'll read the current draw through your load. (fans?)

Ignore the light. It's useful for letting you know it's not blown, but that's about it.

99GrandTouring

Inside its just thin sheets of copper.......

there is two pieces of copper ones about an inch long and the other is 2 inches long directly below it.....
at the end of the one inch piece in contacts teh bulb, then the current goes through the bulb down to the bottom piece of copper then out to the leads and back to battery......
when you depress the button it basically bridges the two pieces of copper right before the lamp, closer to the batts.....
electricity will follow the path of least resistance....

and i have one charger rigged to where the button is depressed because I don't have anothe lamp, so basically its just a battery holder...

I'm confused as to why it won't work?

C_Watkins

My Feedback: (10)

In order for the lamp to provide a meaningful, measurable load...
it has to run THROUGH the ammeter.

Meaning, if you can disconnect the ammeter, and still light the light, it isn't metered.
That's why.
ALL load to be measured must pass through the ammeter.
(Well... *that* sort of ammeter, anyhow. There are some expensive inductive types)

Speakiong of battery holders... it would almost be easier to buy a couple


Not trying to discourage you in any way. You're thinking, which is more than a lot of folks.

Just trying to lead you down the right path, to some readings that might be useful.
As such, I'd suggest removing the lamp completely. Its a minimal draw I'm sure,
but it remains an unknown, that will skew any true science here.

99GrandTouring

hmmmm........
I'm confused now...
with the way it is wired and I depress the last button
I now get a reading of 1.16amps.....
the batterys are coming down in charge?
basically when I press the last button it bypasses the lamp and as if I hooked up the multimeter directly to the battery.....
...??

C_Watkins

My Feedback: (10)

I'll defer to Red now... as this isn't getting through, evidenced by the pic below.
(Showing you shunting two packs in series, into an ammeter. Ouch.)
Hope you get it going, man!

99GrandTouring

if I unhook the ignitor leads from either one of the voltmeter leads it does go off??
heres the launcher

99GrandTouring

well heres my last try before I give up..........

this is how the leads are, positive of one connected to the negative of the other....

I thought this was series, maybe i'm wrong?

99GrandTouring

ok I think I got it......
are you saying that the load or lamp should be placed between the ammeter??

as in one lead of the ammeter on the + side of the LAMP and one on the - of the lamp??

whereas now there bridging the battery?
is that right about the lamp?

C_Watkins

My Feedback: (10)

YES>.. and there's no way to do it with your setup. (with the lamp, I mean)
You can however... do this:

Battery (+) --->Ammeter Ammeter (-)--->FANS FANS--->Battery (-)


I was re-reading, and wasn't clear on your prior post really... but the above is perfect.

It's:

Battery--->ammeter--->load--->battery.

At NO time should you ever have: battery-->ammeter--->battery.

The best you'll get there is a dead short. Think of an ammeter as a straight wire,
and use it to hook a load to a battery in the normal way

99GrandTouring

okay now i'm more confused........lol
I was gonna hook it up



battery+\---------/-multimeter----/-lamp+\----multimeter+\--batt-\

99GrandTouring

when I do it that way the light cuts off when I turn the multimeter on? is it supposed to?

How does that give me the current draw of the light?
I could hook it up this way, this is more like your drawing..

on the launcher there is a key that goes in it to arm it, that key bridges this connection...
I could put the multimeter on the ones labeled as labeled