I have a battery 6V DC with which I want to supply my Arduino (through USB) + the rest of the circuit which operates with 5 Volts. I thought of using a DC-DC-step-down converter, but I didn't find something that gets 6 Volt on input and outputs 5 Volt. They need more than 6 Volt on their input. So, I thought of using a DC-DC-step-up converter to take the input from 6 Volt and boost it to 9 Volt, and then a DC-DC-step-down converter that will take the input of 9 Volt and output 5 Volt.
Can this happen? Or will I have problems with the current? The circuit + Arduino will use maximum 1 Amperes.
Rather than ask us, determine whether the product description matches your current requirements.
In typical applications, this regulator can deliver about 1 A continuous when the input voltage is higher than 5 V (stepping down) and 500 mA continuous when the input is lower than 5 V (stepping up)
Note thought that if the voltage of a "6V" lead-acid battery drops below 5.4 V, it is completely dead and should not be discharged further.
I recently wrote an article on my own website showing a boost converter, and how to set it up and filter it well for an audio circuit. For what you're doing you probably won't need any filtering. The boost regulator I started with is good for 2 amps, and I'm pretty sure you can find them on ebay for about $2 or less. Take a look, and when you see them on ebay you'll likely recognize it. Aliexpress.com is even cheaper, if you can wait on the slow shipment.
Just bear in mind all the caveats. If you boost 6V to 12V, for example, and draw 1 amp on the 12 V side, you'll be pulling 2 amps from the 6V battery. Its just like a transformer in that sense. As for the 5V you need for other things, if its within the allowed current draw for the arduino 5V regulator (about 200 mA total), you can use that for your sensors. Otherwise you'd have to provide your own regulator for that. It may start to get like a rupe goldberg arrangement after a while.
larryd: @PeterPan321, your link under your name doesn’t work.
Thanks. For some reason, though the website entry in my profile says "http://elfintechnologies.com", the forum software changes it to "http://arduino.cc/elfintechnologies.com", which of course points to nowhere. I'll try to edit it a few more times, but I've a suspicion its a bug in the forum code, that may never get fixed.
360modena_cs:
How do I check whether it is below 5.4V? And I don't mean by looking an LCD, but with a sensor or some circuit to sense it through the Arduino...
Assuming you go the route of of using a boost converter to power the arduino, so that it will have plenty of additional voltage to work with as the battery voltage falls, all you'd have to do is use a voltage divider consisting of two resistors (10K will do) between the battery and ground, and measure the point between the two by connecting it to an unused analog input, and use some simple math to determine the battery voltage. When the battery is outputting 6V, the voltage divider will send 1/2 the voltage (3V) to the analog input. Assuming you leave the arduino at its default analog reference voltage of 5V, and a full a/d count would be 1023, 5/1023 = about 0.00489. From that we can derive that when the battery is at full capacity (6V) and 1/2 that (3V) is on the A/D input, you'll get an A/D reading of 3/.00489, or about 614 counts. Applying the same math, the A/D counts will be 1/2 of your 5.4V divided by .00489, or about 552 counts.
By the way, there are tricks you can use to approximate the above without floating point math, which can take more CPU time if you have to calculate often. For example by multiplying the voltages in these calcs by 10000, now instead of dealing with a fraction (like the .00489), you can work with 50000 / 1023, which is about 49. Now you have an easier scale of about 49 A/D counts per volt. You just have to remember to divide the final voltage you get by that same 10000 factor. If you have a count of 1104, then 1104 x 49 counts/volt = 54137. Dividing by 10000 though, and you're back to your 5.4 volts.
I'm interested in hearing what the methods are for running an Arduino on 6V 5Ah SLA. I just scored a dozen or so of them at $2 a pop and they are rechargeable. Running 2 in series and then bucking to 5V is one option that gives a 5000mAh source but I'd like to not need 2 always.
INTP:
I'm interested in hearing what the methods are for running an Arduino on 6V 5Ah SLA. I just scored a dozen or so of them at $2 a pop and they are rechargeable. Running 2 in series and then bucking to 5V is one option that gives a 10000mAh source but I'd like to not need 2 always.
360modena_cs:
I have a battery 6V DC with which I want to supply my Arduino (through USB) + the rest of the circuit which operates with 5 Volts.
I thought of using a DC-DC-step-down converter, but I didn't find something that gets 6 Volt on input and outputs 5 Volt.
They need more than 6 Volt on their input. So, I thought of using a DC-DC-step-up converter to take the input from 6 Volt and boost it to 9 Volt, and then a DC-DC-step-down converter that will take the input of 9 Volt and output 5 Volt.
Can this happen? Or will I have problems with the current? The circuit + Arduino will use maximum 1 Amperes.
Which Arduino, what circuits.
The Pololu 5volt/1Amp buck converter has a very low dropout voltage (< 0.5volt@600mA).
Other types have a higher dropout voltage.
Can't power through USB then.
The (unknown) Arduino might have a 500mA fuse or 500mA diode in the USB supply line.
Leo..
INTP:
I'm interested in hearing what the methods are for running an Arduino on 6V 5Ah SLA. I just scored a dozen or so of them at $2 a pop and they are rechargeable. Running 2 in series and then bucking to 5V is one option that gives a 10000mAh source but I'd like to not need 2 always.
What about the boost regulators like I mentioned in an earlier post. There's no reason to boost to a voltage beyond what offers stable operation. Just maybe 7.5 would probably do just fine. And those boost regs are very efficient. Their only drawback is that their output can have enough noise to cause some problems directly powering an audio circuit. But even that is not an issue when you already are powering the board through its VIN pin, and have the benefit of its on board 5V regulator.
because I have found a DC-DC-step-up converter and I want to know that is the current that this IC uses in order to boost 5 Volt to 9 Volt. Where do I look for this? I see a lot of "current" labels inside...
I have a bias against boosting voltage and losing available current. It's not a good bias to have, because there are obviously times when losing current is acceptable, but it just means I don't have boost modules on hand to tinker with.
The 6V rechargeable SLA sits at about 6.5-6.7, so an LDO reg would work considering its large capacity making the voltage not drop super quickly with meager power demands.
