Hot Batteries

Psycho:Active · July 11, 2009, 03:06:37 AM

I've learnt a lot about electronics since I started circuit bending, but I know I still have a lot to learn.
Why my batteries keep getting hot is one of these things.

It's happened in my last two bending projects, where I've replaced the initial batteries with a different type of battery, and they end up heating up a lot. In my last/most current project I replaced 3 button cell batteries with 3 AAAs. The new batteries keep heating up, losing all their power, and being useless very quickly.

Could some one possibly explain to me why, how I can fix it, and why I'm such an idiot for not realising?

Dylan · July 11, 2009, 04:47:31 PM

You replaced three button cells with three AAA's? That could be the problem. Even though they add up to the same voltage, the AAA's are pumping way more current than the toy needs.

Gordonjcp · July 11, 2009, 07:37:12 PM

Quote from: Dylan on July 11, 2009, 04:47:31 PM
You replaced three button cells with three AAA's? That could be the problem. Even though they add up to the same voltage, the AAA's are pumping way more current than the toy needs.

No, they're not. The current capacity of a battery is the *maximum* it can supply. The device won't somehow magically pull more power just because more is available.

Think about it this way - the battery in your car can deliver a couple of hundred amps to the starter motor, and a couple of hundred milliamps to the interior light. Why doesn't the battery "pump way more current" than the interior light needs?

Most people's circuit bending experience would be greatly enhanced by a quick ten minute read of a basic electronics and electricity primer. Ohm's Law might just look like all boring formulas, but it will stop you blowing stuff up.

Now, why are the batteries getting flat? Well, perhaps they're not connected properly, or perhaps the device is damaged. When you were bending it, did you somehow short across the power rails?

Dylan · July 12, 2009, 06:46:43 PM

Ah, never mind then, listen to Gordon, it seems like he knows what he's talking about.

LoFi-Ninja · July 12, 2009, 06:56:23 PM

Your batteries are shorted..

Psycho:Active · July 13, 2009, 02:38:05 AM

I really appreciate all of your responses.

As for shorts I've created, I'm pretty sure I havnt made any bad ones, but I'll double check tomorrow.
I didn't use any resistors inbetween my bends, which included adding an LED. I'll try to post some pictures.

As the 3 button batteries seemed to keep failing to supply enough power continuously I replaced them with 3 AAAs. Two in a battery holder and one soldered to wires, with the connections going to those attached to the battery holder. Might this be an issue?

Yeah I've done some reading on Ohms law, and I definately need to do more. Handmade Electronic Music has been my circuit bending bible which doesn't lay heavy on the theory.

LoFi-Ninja · July 15, 2009, 02:01:34 AM

You soldered on an alkaline battery ?!? There's a reason regular batteries basicly is unsoldereable.. Also you might have wired the extra batt. parallel to the other two.. Make sure they're connected in series..

Gordonjcp · July 15, 2009, 11:45:27 AM

Quote from: LoFi-Ninja on July 15, 2009, 02:01:34 AM
You soldered on an alkaline battery ?!? There's a reason regular batteries basicly is unsoldereable.. Also you might have wired the extra batt. parallel to the other two.. Make sure they're connected in series..

Nothing wrong with soldering to batteries. I do it all the time, particularly for replacing memory backup batteries in my synths.

Nearly everything I have that used to have a 3V lithium (that died a decade ago) now has two Duracells with leads soldered to them taped or hot-glued inside the case.

LoFi-Ninja · July 15, 2009, 12:04:17 PM

Well yeah I admit I've done it aswell, but if your to slow your probably going to start some funky chemical reaction that was not suppose to be..

Psycho:Active · July 15, 2009, 01:11:21 PM

Quote from: LoFi-Ninja on July 15, 2009, 02:01:34 AM
You soldered on an alkaline battery ?!? There's a reason regular batteries basicly is unsoldereable.. Also you might have wired the extra batt. parallel to the other two.. Make sure they're connected in series..

Pretty sure it was alkaline, yeah.

Ah.. so having two batteries in a holder with one hot and ground for both, with another, single battery's hot and ground soldered to the respective connections there... is that bad/could the arrangement of the batteries be the cause for them getting so hot?

Gordonjcp · July 15, 2009, 11:21:23 PM

Can you draw a diagram of how you've got them connected?

If you've got two in series, and then one in parallel across the other two then that would be a bad thing ;-)

LoFi-Ninja · July 15, 2009, 11:58:05 PM

Quote from: Gordonjcp on July 15, 2009, 11:21:23 PM
If you've got two in series, and then one in parallel across the other two then that would be a bad thing ;-)

From what he writes that's what he did..

Psycho:Active · July 26, 2009, 11:45:12 PM

Quote from: Gordonjcp on July 15, 2009, 11:21:23 PM
Can you draw a diagram of how you've got them connected?

If you've got two in series, and then one in parallel across the other two then that would be a bad thing ;-)

This is the battery cofiguration, I hope this sheds more light on my problem.

Any ideas as to how to fix it?

Psycho:Active · July 26, 2009, 11:46:40 PM

WHOAH
In the future I will resize

Circuitbenders · July 27, 2009, 12:20:54 AM

correct me if i'm wrong but you've got the Sony battery wired in parellel with the duracells. The positive of the middle duracell seems to be wired to the positive of the sony when it should be wired to the negative.

EDIT: in fact the sony shouldn't be wired to the far right duracell at all. It should go: far right duracell -ve wired to the circuit negative, middle duracell +ve wired to sony -ve, sony +ve wired to circuit positive