Step up converter for Arduino Battery operation - Page 1
Forum section: electronics / general

author: Frank_MV
author_rank: Regular Contributor
timestamp: March 02, 2021, 07:09:33 pm
content: Hello,I hope I am in the right sub forum here.I need a Step Up Converter for my Arduino project ( ATMEGA 328) and I don't know which one to use.It is important that it is safe and does not harm my Arduini and its shields.I want to use 2 AA batteries, when fully charged they have about 2.6V.So I need a converter with 2V input voltage, output voltage would be 3.3V, preferably adjustable.The circuit shown is probably the simplest principle, but is it safe ?Would a fast diode have to be connected at the output as a precaution ? There could be a voltage peak at the moment of switching on.What is your opinion about this ?

author: Lindley
author_rank: Regular Contributor
timestamp: March 03, 2021, 11:57:48 am
content: Probably cheaper to buy a ready made module, though depending on your arduino circuit and program code , doubt you will get a long run time from 2 AA batteries.

author: Frank_MV
author_rank: Regular Contributor
timestamp: March 03, 2021, 12:13:28 pm
content: I thought of these modules, they exist from different sellers, but with mixed reviews.https://www.amazon.de/gp/product/B085NMV6LW/ref=ox_sc_act_title_1?smid=AS8JK4HNTE2NO&psc=1

author: Zero999
author_rank: Super Contributor
timestamp: March 03, 2021, 10:31:34 pm
content: Quote from: Frank_MV on March 02, 2021, 07:09:33 pmYes.QuoteNo, there won't be a voltage spike when power is applied. The circuit will work as is, without any additional diodes.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 03, 2021, 11:13:08 pm
content: The only thing to consider when using a step-up converter with batteries is that: batteries will have increasingly lower voltage as they discharge, and thus, for a given output current, the input current will keep increasing as batteries discharge. This could get bad if the converter keeps working with very low input voltages. So ideally, you need to make sure the converter you use will stop working gracefully when the input voltage goes below ~2V, or 1.8V. But if a particular converter happens to keep switching even with much lower input voltages, then your batteries may severely heat up. Alternatively, you could add a voltage supervisor controlling the enable pin of the converter.

author: Frank_MV
author_rank: Regular Contributor
timestamp: March 04, 2021, 07:23:48 am
content: Great, thank you very much for your detailed description.Yes, that is a good idea to add a voltage supervisor controlling.I will do this.This is at the same time also a protection against deep discharge of accus if I use themBest regards,Frank

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2021, 09:16:16 am
content: Good point about over-discharge protection. According to the MT3608 data sheet, it has a maximum under voltage lockout of 1.98V, but it doesn't mention the typical, or minimum and any lower might be bad for the batteries.A comparator with a voltage reference could be connected to the enable pin, so it cuts out, when the battery voltage drops below a specified level. It's a good idea to add a little hysteresis, otherwise it will oscillate, as the battery voltage will rise, once the DC-DC coverter is disabled, causing it to turn on again.I had a quick Google and there are a few ICs which contain both a comparator and voltage reference in one package: TLV3012, MAX931, ISL21440, LTC1440, LMP7300.

author: Microdoser
author_rank: Frequent Contributor
timestamp: March 04, 2021, 12:14:09 pm
content: Have you considered using something like a 3.7V 14500 battery (or two)?The current requirements for the batteries would be lower and when the battery voltage lowers you would not need to increase amperage demands on the batteries to keep the wattage up.

author: Frank_MV
author_rank: Regular Contributor
timestamp: March 04, 2021, 05:01:40 pm
content: Quote from: Microdoser on March 04, 2021, 12:14:09 pm>> many thanks for the tips

author: Frank_MV
author_rank: Regular Contributor
timestamp: March 04, 2021, 05:03:49 pm
content: Quote from: Frank_MV on March 04, 2021, 05:01:40 pmI would like to use 2 AA Eneloop accu's. These have 1.3V each when charged = 2,6V max..

author: Microdoser
author_rank: Frequent Contributor
timestamp: March 05, 2021, 11:23:02 am
content: I notice I didn't say in my post but obviously there would still be some DC/DC conversion. Stepping down would mean less current draw on the batteries when their charge state is reduced compared to stepping up.

author: oliviasmithh900
author_rank: Contributor
timestamp: March 08, 2021, 12:47:46 am
content: There are many boost convertors available but I have once designed boost convertor using IRFz44n and it worked fine, although I have used it with PIC Microcontroller.