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Topic: Place arduino control batteries in place of fixed AA/AAA batteries, easy? (Read 2474 times) previous topic - next topic

syntotic

Can anyone write/point to an intro or primer or FAQ or tutorial for the general problem of substituting standard batteries, with arduino-controlled power/batteries? I can think right away of flashlights. Also, small-sized battery gadgets would benefit from getting more long duration power batteries.  What do you need to know?
Should work if I connect it...

Transistors

Just a clarifying question: What would be the use(s) for the arduino controlling the power supply?

syntotic

8-D if I do tell you with details... But anyway, I have this flashlight I need de-activated by more dynamic means than an on/off button. I cannot modify the on/off button but it uses three AAA batteries so I can use the battery case to fit a nano arduino logic and a rechargeable battery and sensors. So in general I do see several uses to substituting fixed battery sets for arduino/rechargeable/USB sets for a few gadgets that come with standard batteries. I of course do not want to experiment much, lest I destroy the gadget, so a primer mentioning issues I might find would be OK. I knew of a few businesses years ago that were offering battery conversions, but they all seem to have vanished in modern times.
Should work if I connect it...

Transistors

Could you take a picture of the flashlight attach it? That would be helpful. Do you know if the flashlight has any resistors?

syntotic

It is a typical three AAA battery case, and no, it does seem to have no resistors but cannot see deeper inside without destroying the flashlight. Would it matter if it has resistors? I think you just have to match voltages and amperage at the point where the battery case is wired to the circuit, but it is where I am in doubt. Another flashlight I want converted does seem to have some driving circuitry but again I cannot pry inside without destroying the case. That one is harder, the single battery seems to be wired only on one side to the light and the on/off switch touches only the battery on the other pole, as if the circuit wiring was inside the battery or ground was the whole case.
Should work if I connect it...

Transistors

If you use a power FET to power the flashlight it should work. Just connect the gate to the arduino pin you want to use. The source to the arduino 5v pin. And the drain to the flashlight.

syntotic

;D A FET to control the power source. This flashlight is not standard batteries but draws more power and amperage, but I still want to completely stop using the battery source to substitute it for a corresponding USB chargeable battery, of any suitable type if available. In general I want to pick the usual -+ for batteries in a diagram and substitute it for a USB chargeable battery, which brings with it its own circuitry. So I would be adding a FET to interface the USB circuitry to the flashlight the way you say?
Should work if I connect it...

INTP

3 AAA batteries is usually a jank way to get 4.5V in a wasteful package.
If the flashlight is crap, it may just be direct driven.
If it's less crap, it will run through a simple buck circuit to bring down the voltage
If it's even less crap, it will have a SEPIC to both buck and boost, but flashlights that bother with such designs won't be running on a crap 3AAA package.

In other words, your idea of just swapping out 3AAA for a rechargeable lipo cell is either going to be inefficient (as you have to boost voltage only to have it bucked) or not work at all.

A Nano is overkill (and you would have to magically feed it 5V in all that mess). The project is misguided, but if you're fine with wasting your time and convinced even a completed bad plan still has educational merits, then anything you could possibly want to do can be done with a tiny ATTiny 45/85 chip instead of a Nano.

If you're afraid of ruining this probably cheap light, then don't touch it. Otherwise gut it and learn.

syntotic

Yeah, no, well, I seem to have all three kinds of flashlights! Indeed, the best flashlight does have a non standard battery and is quite potent. It is still worth the while for the best two. The most immediate one I definitely think needs more circuitry to not waste the LEDs so quickly and anything smaller than 3AAA will be OK. Nano is OK, I can do something else there and take advantage that it is already in a case.

The other flashlight would need more handling to repackage it and I am quite content with the big battery but not with its control; it fell and the switch stopped working nicely but is now giving flashes instead of modes. That one would be OK with a smaller chip to reproduce the modes, though I am at a loss as to how the switch accomplishes these modes by simply pushing stronger/lighter/in order.

I still have to look for batteries and see what sizes I can find.
Should work if I connect it...

INTP

So if you're dealing with flashlights that have circuitry for modes, then it's even more incompatible with an Arduino handling modes. You can't 'reproduce' modes through the mode circuitry already in place.


For battery sizes, 18650's are just about perfect for most flashlights. 14500's for AA packages if you need a small light, but I just use CR123A's for tiny bright lights even though they're not rechargeable. $1 a pop isn't bad for how long they last with my level of use.

syntotic

So if you're dealing with flashlights that have circuitry for modes, then it's even more incompatible with an Arduino handling modes.
Really? I got overcurious now. This flashlight seems to have the modes inbuilt in the button cap button. And arduino is meant to make lights with modes! It goes from bright to dimmest, then strobe and an SOS pattern, in a cycle. I see no problem in reproducing them with arduino, though the trick seem to be the pushbutton achieves the effect by cutting the current at some level for each mode, after which the battery just keeps "pushing current". The brand seems to be generic, but it may have some patent in there. I also suspect the light can be driven at a higher level but is purposefully bound. It still would be very nice to substitute the broken and failing pushbutton for some other on/off sensor recognition method along with the change to rechargable batteries. (The battery IS rechargeable, but not from the flashlight body itself).

I also suspect my other flashlight is the contrary, the lights are not driven so they are getting straight current and performing suboptimally, which becomes evident from the inferior performance I get when using rechargeable AAA batteries in comparison to brand new disposable brands. Other gadgets I use with those rechargeables show no difference in performance.
Should work if I connect it...

INTP

All I read in all of that, is that you have absolutely no idea what's actually happening inside of your flashlights because you've ruled out simply looking inside of them.

The reason an Arduino would be incompatible with a flashlight that already has mode circuitry is because, as you said, modes are changed by toggling power. The Arduino, at most, would just toggle power. It cannot have a strobe code, for example, as it would simply result in a fast cycling of the modes.

And your random guesses about where circuitry is or how it works, are helping no one and only hurting your actual learning. Your guesses are wrong, and you will waste time unconvincing yourself that you know anything about what's in your lights.

syntotic

The reason an Arduino would be incompatible with a flashlight that already has mode circuitry is because, as you said, modes are changed by toggling power. The Arduino, at most, would just toggle power. It cannot have a strobe code, for example, as it would simply result in a fast cycling of the modes.
INTP means in teepee? Anyway... I think in any circuit you can substitute the  - ___|-|-|__v+ batteries symbol for  - __-|-|-|-__@#$__v+ as long as both v give the same current values. Am I correct? 
Should work if I connect it...

syntotic

Should work if I connect it...

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