# Hard wiring battery toy to a DC source

Discussion in 'Electronic Basics' started by Eric, Dec 9, 2004.

1. ### EricGuest

Hello all,

I have three of those Star Wars animated sword battling figures (Darth Mul
and the two Jedi dudes). When plugged into each other at the base, the two
Jedi's gang up on Darth.

Anyways, they each contain 4 banks of 3 AA batteries. I say banks, because
each group of 3 batteries is isolated from the other group ... at least from
the visible exterior.

How do I use a DC converter with two wire (+/-) and wire up one of these?
Should I just soldier up 4 wires, one to each + starting point on each bank,
and another 4 wires, one to each - ending point on each bank, twist the 4
positives together and hook to the DC +. Likewise for the - ?

Actually, I tried this and didn't have any luck. Which leads me to my next
question. How powerful of a DC converter do I need? If there a 4 banks of
3xAA, thats 12 x 1.5 volts? What size of a DC should I use? The one I have
is 3.7 volt, 350 mA.

Thanks for reading and I appreciate your comments.

Cheers,
Eric

2. ### Roger JohanssonGuest

You have to know more about how these banks of batteries are connected to
each other.
If they need so many batteries they need more current than this converter
can deliver. Toys with motors in them often need a couple of Amps.

If you want to continue this project you need to go deeper into the
devices, find out what voltages are needed inside, how the battery banks
are interconnected and how they are connected to the circuit boards inside.

3. ### EricGuest

Ok ... if I open it up, I don't suppose there's going to a labels
inside which state voltage requirements, so how would I learn that?

I was expecting that there would be a formula to determine the amount
of voltage/amperage which is generated from 12 AA batteries, and from
that I would be able to determine how powerful of a DC converter I
would need.

If I open it up and see that each of these backs merely connects on to
the next one, to basically make one huge bank of batteries, then given
an adequate DC powersupply, I should just be able to hook the DC + wire
to the start of the back and the DC - wire to the end of the bank
....... right?

BTW ... here is a link to Darth Maul. He is one of three that plug
together.
http://cargobay.starwars.com/webapps/cargobay/item-detail/6725/5002
Thanks,
Eric

4. ### MikeGuest

A battery has a fixed amount of charge. It's "charge" life depends how fast
a load draws charge from the battery. If load B draws twice the amount of
current than load A, the batteries will last half as long as they did in
load A. Batteries are rated in milliampere hours (maH). This is the amount
of current that can be supplied in an hour. For example, a "AA" battery with
a rating of 1600mAH can provide 1600 milliamps for one hour.

I have hooked up battery powered devices to plug-in adapters before. You
need to determine the right polarity and the battery configuration (e.g. are
all batteries in series? Or are they two parallel banks?).

Best bet is probably to take a picture of the electronics and post.

5. ### Roger JohanssonGuest

The batteries do not determine the current. Some devices draw much
current, other devices draw less current. The size of the batteries can
only give a hint of how much current will be needed.

AA batteries can deliver 1 Amp, or so. If the battery banks are connected
in parallell we might be talking about a few Amps.
Yes, if they are connected in series, that works.
If you had a multimeter you could use the low resistange range to be sure
how the battery banks are connected.

Another method is to insert the batteries, without putting on the lid on
the battery compartment. Turn on power on the device.
Then use a voltmeter to measure the voltage from one end of the battery
bank to the other end.

6. ### Robert MonsenGuest

One quick way would be to get a separate 5V wart for each 'bank', and a
power strip with plug. It'll cost about 10 bucks from a surplus place
like www.goldmine-elec.com.

Actually, a nice product that I haven't seen would be a wall-wart
battery replacement, using flat cable. The cable would have to be flat
enough to allow closing the plastic compartments. It could support
different voltages, selectable using a switch, and offer 'blank'
batteries that are just connectors for the other batteries required. I
have a battery powered keyboard from logitech that eats batteries that
would be a perfect application for such a product.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

7. ### Rich GriseGuest

For this, I use a stick and a couple of brass shims.

Have Fun!
Rich

8. ### Roger JohanssonGuest

I have done this many times and I have used miniature crocodile clips or
soldering to connect the wallwart to the battery connectors in the
battery compartment. It is usually easy to remove a little plastic from
the lid so the wires can be used with the lid on.

9. ### Robert MonsenGuest

That is what I'm using right now... Imagine how many people are doing
this. What a market!

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

10. ### Rich GriseGuest

"Get Audiophile-Quality Sound from your battery walkman at home! Just use
our Nucleosynthetic Battery Supplantation System, yada, yada, ..."

Batterized Ultimate Long Lasting Synthetic Hermetic Incomprehensible
Technology! ;-)

Cheers!
Rich

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