Boost converter single cell AA battery not delivering enough voltage when connected to Wemos D1 mini

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Amazon Step-Up Boost Converter 0.9V-5V to 5V PFM max 600mA for Arduino DIY Raspberry Pi – 4 stars out of 5 MissBirdler, €4.5/2 pcs
https://www.amazon.de/dp/B07PZ8QLB2/ref=asc_df_B07PZ8QLB21613404800000/?tag=ilovetec-21&creative=22662&creativeASIN=B07PZ8QLB2&linkCode=df0

Product Information
Technical details
Brand MissBirdler
Manufacturer MissBirdler
Packaging dimensions 18.1 x 4.1 x 1.5 cm; 10 grams
Manufacturer reference 4260509788076
Discontinued item (production discontinued by manufacturer) No
Storage type SIMM
Hard disk size 1 KB
Hard disk interface ATA
Batteries included No
Item weight 10 g

Additional product information
ASIN B07PZ8QLB2
average customer rating 3.5 out of 5 stars 4 star ratings 3.5 out of 5 stars

Amazon bestseller rank
No. 24.928 in commercial, industrial & Science ( See Top 100 in Business, Industry Science )
no. 1.397 in & 3D Printer Parts Accessories
On offer from Amazon.de since December 6, 2016

Amazon.de return guarantee
Our Amazon.de return guarantee :Regardless of your statutory right of withdrawal, you enjoy a 30-day right of return for many products. For exceptions and conditions, see Return Details .

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USB DC-DC Converter 0.9V-5V Boost to 5V 600MA Step Up Power Module for DIY – : Teohk 4.4 out of 5 stars €8/4 pcs
https://www.amazon.de/gp/product/B07SSXVHP8/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

Prices include VAT. Depending on the delivery address, the VAT at the checkout may vary. Further information.

0.9 V – 5 V conversion to 5 V USB DC-DC converter 0.9 V – 5 V conversion to 5 V Step Up Power Module supports charging of mobile phones, MP3, MP4, PDA, PSP, etc.
High efficiency Maximum output current: 1200MA. High quality imported chip with an efficiency of up to 96%.
Industrial operating temperature -40 ° C to + 85 ° C
Pack of 4 Valuable 4 pieces per pack with individual packaging in antistatic bags.
Widely used With USB port, the mini size with power indicator can be widely used in small devices.

AZDelivery MT3608 DC-DC power supply adapter Step up module compatible with Arduino including eBook! 4.2 out of 5 stars 16 answered questions €6/5pcs
https://www.amazon.de/AZDelivery-MT3608-Netzteil-Adapter-Arduino/dp/B079H3YD8V/ref=pd_sbs_3?pd_rd_w=xvWwr&pf_rd_p=ad79fb78-2eb6-4fd8-b228-cb6e6b4589d9&pf_rd_r=CG2BWQMAGQKKVER002MT&pd_rd_r=219462d9-fc85-4fde-bcde-a37913975fbf&pd_rd_wg=PLK6F&pd_rd_i=B079H3YD8V&psc=1

Amazon’s Choice for ” dc dc step up “

• The AZDelivery Step Up Converter is used to continuously and efficiently raise voltages. Thanks to precise processing, the energy loss when converting is less than 7%.
• The MT3608 voltage regulator is ideal for raising voltages to a required level. The MT3608 voltage converter processes input voltages in the range of 2-24 volts.
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Product specifications
item number 5x MT3608 modules
Model number mt3608
ean 4260581550455
Specifications for this product family
Brand name AZDelivery

Product information
Number of pieces: 5
Discontinued item (production discontinued by manufacturer): No.
Package Dimensions: 14 x 8 x 0.5 cm; 10 grams
Date first listed on Amazon: January 30, 2018
Manufacturer: AZDelivery
ASIN: B079H3YD8V
Model Number : mt3608
Amazon Best Sellers Rank: # 2,730 in Computers & Accessories ( See Top 100 in Computers & Accessories )

14 in Barebones

Customer reviews: 4.2 out of 5 stars 513 star ratings

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I must power a Wemos D1 mini at 5V (more on that below) (along with 4 LEDs and a DC motor) with a single cell AA battery. I have tried 2 boost converters (Vin 0.9V-5V) and none worked.

I need 5V for 2 of the LEDs, which are in series and 5V is perfect for them.

The motor will be driven with the 3.3V pin on Wemos D1 mini.

All the boost converters I tried deliver 5V unconnected. However, the moment I connect them to D1 mini, voltage drops around 1.5V. I tried with a power supply at 1.5V, same result.

I wonder, what I am missing. The specification says 600mA output current. I also tried to put a 100μF capacitor either to input or output side for sudden current draw. Supplying >3V worked fine. Dropping from 3V to 1.5V worked for a short while and then the output voltage dropped to ~1.5V. D1 mini draws ~70mA 5V. I wonder if I am missing something? Here are the converters I have tried:

EDIT: as a test I tried with MT3608, which requires >2V. I supplied it with 3V and got 5V out. It worked just fine. I guess all these cheap undocumented boost converters are bad.powerbatteriesbooststep-upShareEditFollowFlagedited 12 hours agoasked 13 hours agoSaren Tasciyan24111 silver badge88 bronze badges

• 1What does the datasheet say? – marcelm 13 hours ago
• 2All those loads boosted from a single AA cell? Seems like you’re asking for too much current from a feeble battery. – glen_geek 13 hours ago 
• 1@marcelm No datasheet. All I have found was 0.9V-5V input and 5V 600mA output. – Saren Tasciyan 12 hours ago
• 1@glen_geek Even my power supply fails to work. Boost converter draws >500mA 1.5V from it but can’t deliver stable 5V output. – Saren Tasciyan 12 hours ago
• 3No data sheet = totally untrustworthy. Even if you could pull enough power from an AA battery to do all that. – TimWescott 12 hours ago

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2 Answers

ActiveOldestVotes2

What voltage is the battery when operating?

It will also be good to look at the battery voltage with a scope because the voltage may drop significantly when the switch in the converter is conducting but rise during the rest of the cycle. I find that it is essential to use a very low ESR capacitor at the input of the converter – a conventional small electrolytic is probably not adequate, try a tantalum or polymer electrolytic.

Make sure that the leads from the battery are heavy enough gauge, you can easily drop a 100mV or more across the leads.

Another source of voltage drop is the battery holder – the common ones for AA cells use steel springs on the negative end with a fairly high resistance – in one case I had a significant reduction in voltage drop by putting a short length of copper wire across the spring.

Also it can be very difficult to measure the input current at low voltages because the meter itself may drop 200-300mV which together with the voltage drop the cell will experience under load may drop the voltage below the 900mV limit and stop the device working.ShareEditFollowFlaganswered 11 hours agoKevin White20.7k11 gold badge2828 silver badges3939 bronze badgesAdd a comment1

I wonder, what I am missing. The specification says 600mA output current.

Well well.

These cheapo DC-DC converters always spec the biggest number they can find in the datasheet with the unit of “Amps” dangling at the end. Usually it’s the big number in the title of the datasheet, which means…

Datasheets usually put in the title the biggest number they can find with the unit of “Amps” dangling at the end, which means…

It’s the internal switch maximum current. Example.

So yeah, this is a “2A” boost converter which means the internal switch has a maximum current of 2A. This corresponds to the peak input current, at the peak of the inductor ripple current.

In your case, the peak switch current is 600mA, then the average inductor current will be about 450-500mA. Let’s go with 450mA. So, with a 1V input from an AA cell, at this current it can take in 0.45W. Assuming 85% efficiency, there will be 0.38W at the output. With a 5V output, that’s 76 mA. So at 5V output, it’s a 75mA boost converter.

This is absolutely normal for a 600mA switch current limit.

The “output current 600mA” in the amazon product description is bogus, of course.ShareEditFollowFlaganswered 11 hours agobobflux39.6k33 gold badges5050 silver badges117117 bronze badgesAdd a comment

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