Inconsistent boot success for battery driven project

I am building a replica sword from Legend of Zelda and plan to put some LED lighting effects in it. I’ve used WLED in the past so was planning on using it again for this project.

This is what I have setup:

I have this all wired up like so:

  • battery goes into 3V and GND on D1 mini
  • in parallel, 3V and GND goes into voltage boost IN
  • from the Boost OUT, I go to the LEDs with the capacitor inline
  • Data from the d1 mini goes straight thru

This works, EXCEPT, it will fail to boot sometimes. If I put the limiter down to 300-400ma it will usually work. I seem to get better results (uncertain tho) if I set the first preset that plays on start to be little/no light. It works MUCH better if I connect the LEDs after the d1 has booted. This all leads me to believe the current draw on boot of everything is interfering with the boot sequence.

I’d like to set the LEDs brighter if I can - but it is running quite a few. The project will probably be around 200 in total. I don’t expect to get beyond 1A, as the voltage booster isn’t rated any higher than this anyway.

Is adding another cap between the battery and the d1 mini helpful at all? What other options do I have?

4V into the 3.3V rail is definitely not OK. Should take the 5V out of the regulator into the 5V in of the board, or at least put the battery to 5V in but then you’ll likely have issues pretty quickly as the battery depletes.

200 5V LEDs at full brightness means about 12A.
The ESP will use 150mA
The LEDs will use about 120mA idle current even being off.

To stay below the 1A capacity of the regulator, which may be already overstated you’ll need the brightness WAY down.

I.e. you need a much more beefy supply.

On the DC-DC converter: those specs can be very dodgy, e.g. 1A but only if you are feeding it the high end of its voltage input, and sometimes they can be unstable starting under load. If you don’t have one, a synthetic load tester can be really helpful for testing regulator and battery output/capacity. I bought mine on AliExpress for $5 + shipping.

1 Like

The other thing to watch out for - check the GPIO you’re using. Some pins need to be pulled HI or LO for a proper boot.

for this reasons the main post tells im using on all projektst the D! Wemos UNO Board
this is well designed has little space and gets all over this problems

you may need at least 470uF Cap to get the stable boot power

It’s the same thing in a different form factor. Won’t “solve any problems” magically.

Great point and very helpful. I was seeing some erratic behaviour and naively recalled there was power conditioning in the D1 mini but that is only in the 5v which I’ve used before. I’ll work out a better method to boost the battery to 5v or supply 3.3v to the D1.

Yeah it’s hard to tell if it’s the D1 failing our the converter. The converter does have a tiny led which is solid when functioning. When it doesn’t work this stays off. Are you suggesting if it gets too low a startup load it will fail and never recover? I hadn’t considered that a possibility…

I’m using 14 - which I’m pretty sure is one of the ‘safe’ ones. Certainly when it all works, it does actually light up LEDs and wled functions as expected. So I think the gpio is all good.

Great suggestions though. I’ll give the D1 some proper voltage as it expects as a first step and see if it gets more reliable.

1 Like

IIRC, I had a Chinese 3A rated DC-DC converter that I eventually tested and found it couldn’t deliver more than 0.75A at the low point of its input range (5V), and no more than 0.5A load at startup else the output was crazy.
The same load tester got me a refund on some dodgy batteries. I highly recommend buying one, as they aren’t expensive.

1 Like

Can you point me to the type of thing you’re suggesting? I did a bit of a search and AliExpress always puts so much guff in front of you if you don’t use the exactly correct search terms. Because you have a point - you don’t always get what you pay for!

My bad; being a complete novice, this is what I bought and I’m quite happy with it:
https://www.aliexpress.com/item/1005004420340409.html
You need to supply your own project box and leads.

It will alarm when input goes below a voltage that you set, so you can just set the load and voltage limits and let it run. [It won’t tell you if the output has ripples, etc; for that you need a scope.]

1 Like

ther is an old fashon 78S05 2A that realy does 2A from 12/24V Bat with a cool brick mounted

thats what i use for the 300Nodes on Holiday display Car Battery

That’s a very poor solution.

The 78S05 is a linear device that throws away the dropped voltage as pure heat.
Very inefficient and hard on the battery life.

Any good buck converter will do a far better job.

I’ve added a voltage boost to before the ESP8266 dev board and wired it into the 5v line. The battery output still goes to the LEDs, with the 1A voltage boost. This now works pretty reliably with the limiter set in WLED at 900mA.

Many thanks for the assistance.