Continuously discharging battery bank?

[CluelessBrit]

Hi Guys,

 

So essentially the situation is that I have installed a smart LED strip in my wardrobe as a lights (controlled by app, google home etc) and have powered it via a USB battery bank. It all works fine except when I turn it off and leave it for a minute and it wont turn back on without reinserting the usb cable into the battery bank. I assume this is because the battery bank stops discharging when it detects no power draw? I have tried it with another different power bank to the same effect.

I can't really run a mains cable in as it would look too messy.

 

I was wondering if anyone knew of any battery banks that are permanently on? Or any other solutions would be welcomed.

- I can't really run a mains cable in as it would be a bit too messy.

 

Thanks,

 

(Apologies if this is in the wrong section)

[WereCatf]

5 minutes ago, CluelessBrit said:

I assume this is because the battery bank stops discharging when it detects no power draw?

Yup, this is how most power-banks work. The ones I have require ~70mA+ load to stay on, for example. I do have one no-brand Chinaman power-bank that happily lets you sip as little as you like, but I can't remember where I got it from.

 

As for the fix.. well, you could e.g. fashion a circuit out of NE555 that powers a resistor through a MOSFET ever 20 seconds or so for 0.5 seconds or something like that. It's a pretty crude solution, but it'd work.

[CluelessBrit]

23 minutes ago, WereCatf said:

Yup, this is how most power-banks work. The ones I have require ~70mA+ load to stay on, for example. I do have one no-brand Chinaman power-bank that happily lets you sip as little as you like, but I can't remember where I got it from.

 

As for the fix.. well, you could e.g. fashion a circuit out of NE555 that powers a resistor through a MOSFET ever 20 seconds or so for 0.5 seconds or something like that. It's a pretty crude solution, but it'd work.

Ah okay, i'll have a look into that but I have a feeling that the time invested learning how to do that might not be worth the reward of a working wardrobe light.

Thanks for your response though, much appreciated.

[mariushm]

Replace your power bank with something else.

For example, use 4-8 AA rechargeable batteries (2 x 4AA battery holders) and a 5v dc-dc converter

Here's an example : https://www.ebay.com/itm/Mini-DC-DC-Buck-Step-down-Converter-Adjustable-Power-Module-3-3V-3V-5V-9V-12V-3A/322659010647

The dc-dc converter produces 5v 24/7 and doesn't shut down.... but it may be completely optional.

 

4 rechargeable batteries will give you around 4.8v..5.2v ... your led strip and arduino and the led strip may still work with as little as 4.5v

8 batteries will give you longer life and can be easily charged in a charger easily.

a small power bank with a single 18650 battery has 3.7v..4.2v 2800-3000mAh ... that's kind of equivalent to 4 AA batteries in series.

 

Consider adding a physical switch that disconnects the circuit when the door of your closet is closed ... think limit switch : https://www.digikey.com/products/en/switches/snap-action-limit-switches/198

 

[CluelessBrit]

19 hours ago, mariushm said:

Replace your power bank with something else.

For example, use 4-8 AA rechargeable batteries (2 x 4AA battery holders) and a 5v dc-dc converter

Here's an example : https://www.ebay.com/itm/Mini-DC-DC-Buck-Step-down-Converter-Adjustable-Power-Module-3-3V-3V-5V-9V-12V-3A/322659010647

The dc-dc converter produces 5v 24/7 and doesn't shut down.... but it may be completely optional.

 

4 rechargeable batteries will give you around 4.8v..5.2v ... your led strip and arduino and the led strip may still work with as little as 4.5v

8 batteries will give you longer life and can be easily charged in a charger easily.

a small power bank with a single 18650 battery has 3.7v..4.2v 2800-3000mAh ... that's kind of equivalent to 4 AA batteries in series.

 

Consider adding a physical switch that disconnects the circuit when the door of your closet is closed ... think limit switch : https://www.digikey.com/products/en/switches/snap-action-limit-switches/198

 

Thanks for the idea of using AA batteries! Just connected everything up and it works a treat. 

I measured the voltage and the AA batteries are 1.5-1.6V ea, so the total voltage is over 6v. Do you know if this would affect the longevity of the LEDs?

I'm planning on purchasing some rechargeable batteries, do these generally have lower voltages?

[mariushm]

1 minute ago, CluelessBrit said:

Thanks for the idea of using AA batteries! Just connected everything up and it works a treat. 

I measured the voltage and the AA batteries are 1.5-1.6V ea, so the total voltage is over 6v. Do you know if this would affect the longevity of the LEDs?

I'm planning on purchasing some rechargeable batteries, do these generally have lower voltages?

 

It's possible to damage them, depending on their quality.

Non-rechargeable are up to 1.65v when fresh out the package and quickly drop to around 1.6v and lose majority of their energy down to around 1.1..1.2v

Rechargeable batteries peak at 1.35v and drop down towards 1v..1.1v when they're close to empty... so they're safer to use with stuff that works with up to 5v..5.5v