Simple electronics circuit to keep power bank alive?

[Oldman]

I wonder if there are members here who may have already solved this question?
I have several trail camera's set up in the garden to video wildlife, all are 6volt and all take 8 AA batteries, that's 2 banks of 4 batteries. Thats lots of batteries and even using rechargeables which report less than 6volts when fully charged as a pack of 4 its still a pitb to keep changing and charging.
I have been using 12 volt alarm batteries with a 12volt to 5Volt USB adaptor which works well as all the camera's have a jack for outside power, but the batteries are bulky.
I have plenty of 5volt power banks for charging mobile phones, I would like to use these to power the camera's BUT they have a current sensing circuit built in that shuts the power bank down when little or no current is drawn.
So I need a simple way of keeping the packs from shutting down, that means giving it either a constant load of (25mA) seems to hold them open. Or some sort of pulse load of 25mA at say 1 minute intervals for 5 seconds which should keep the pack alive without too much sacrificial current drain like a constant 25mA.
I cobbled together a green LED and 2 resistors which gives me 25mA constant load and I can fit that into a fly lead with a USB male plug one end and a jack for the camera on the other end and I'm fairly sure this will work with the background current drain just shortening the usable time some. The camera's take very little on standby, 5-10mA at most, but get loaded when the camera and lighting are busy.

So my simple circuit is probably flouting all convention, but I am willing to take any advice on a cheap and simple way to do this.

 

[Sideways]

Simplest of all would be a 200 ohm resistor across the output of the power supply.
That will drain 25mA from 5V and dissipate 1/8 Watt.
Use a 1/4 or 1/2W resistor to allow for the fact that you will be putting it in something and not leaving it in free air.

If on a trail cam, LEDs are presumably an unwanted feature and the circuit is so simple you don't need to be told it's working.

You don't want domestic extension leads out in the rain so will you be extending the 5V lead to the camera with bell wire and keeping the wall wart indoors ? Be conscious of voltage drop in a long length of thin wire, driven only at 5v.

Or feed the wire at say 12v and put a "7805" 3 terminal, 5v voltage regulator at each camera to drop the voltage. These are ancient tech and just look like a transistor. Very simple to use.

 

[Oldman]

Thanks for the swift reply, its stand alone power banks I will be using just cable tied to the back of the camera's.
Like these or maybe 10000mAh ones https://www.amazon.co.uk/gp/product/B08T1JCXR5

No trailing leads/wires/mains or wall warts will be used or harmed in the making of this project

 

[Sideways]

200 ohm resistors then

Or get really wild with an NE556 dual timer and few passives. One timer to give you a pulse every minute, triggering the second to give you a 5 second long pulse for the power bank to detect.

A schoolkid would probably design you something with an arduino, fully programmable, capable of getting a rocket into orbit and costing less

 

[Oldman]

Seems I need to find a schoolkid now then.
Sitting here watching my power bank lights constantly glowing with 2 x 100ohm 1/4watt resistors in series drawing 24mA from the pack.
I was making a meal out of it using an LED as well.
So 5000mAh pack with no other load (camera) should go for a week at 24mAh before its expired.
I will give it a go tonight and see if it stays alive, thanks for the help

 

[Sideways]

Our neighbour shared some clips of hedgehogs in the garden the other night caught on a wireless security cam that she unhooked and placed where it could see them. Great fun

 

[ChaiLatte]

If the camera takes 5mA on standby, I think your 'keep awake' circuit only needs to draw 20mA, not the full 25mA.

That could increase your battery life by 20%.

I would experiment to see just how low you can go before the powerbank shuts off - if it will stay alive on 23mA, that will gain you a little more.

 

[Oldman]

If the camera takes 5mA on standby, I think your 'keep awake' circuit only needs to draw 20mA, not the full 25mA.

That could increase your battery life by 20%.

I would experiment to see just how low you can go before the powerbank shuts off - if it will stay alive on 23mA, that will gain you a little more.

Yes good point, thanks. I will rig up a trial tonight with 25mA and see how that goes, then try for less until it fails to stay awake.

 

[Oldman]

Our neighbour shared some clips of hedgehogs in the garden the other night caught on a wireless security cam that she unhooked and placed where it could see them. Great fun

I just tried to upload some camera video of our resident hedgehog crawling into the fox's bowl of dog food, having a wonderful time, the fox turned up and was most put out that his snout got pricked while trying to share the food.
There is a whole host of goings on at night here with at least 2 fox families, hedgehogs, rats, cats and come daybreak anything thats left over gets eaten by magpies or seagulls.

Fox with hedgehog in his bowl.

 

[Agent_zed]

could you not add a small solar cell to keep the current batteries topped up?

 

[Oldman]

could you not add a small solar cell to keep the current batteries topped up?

I could but its making it as simple as possible and I cant be sure the sun will always keep it ready for the next night. I need to swop the memory cards over quite often. Every day if I cant wait to see what's been captured so its no bother to swop out the battery pack if its just plug n play.

 

[John Brown]

There is stuff on YouTube to do this. I can't find it right now, but Andreas Speiss(sp) and someone calling themselves "Great Scott", if I remember correctly.

 

[Oldman]

There is stuff on YouTube to do this. I can't find it right now, but Andreas Speiss(sp) and someone calling themselves "Great Scott", if I remember correctly.

I found this one thanks for that

 

[Scruples]

I wonder if there are members here who may have already solved this question?
I have several trail camera's set up in the garden to video wildlife, all are 6volt and all take 8 AA batteries, that's 2 banks of 4 batteries. Thats lots of batteries and even using rechargeables which report less than 6volts when fully charged as a pack of 4 its still a pitb to keep changing and charging.
I have been using 12 volt alarm batteries with a 12volt to 5Volt USB adaptor which works well as all the camera's have a jack for outside power, but the batteries are bulky.
I have plenty of 5volt power banks for charging mobile phones, I would like to use these to power the camera's BUT they have a current sensing circuit built in that shuts the power bank down when little or no current is drawn.
So I need a simple way of keeping the packs from shutting down, that means giving it either a constant load of (25mA) seems to hold them open. Or some sort of pulse load of 25mA at say 1 minute intervals for 5 seconds which should keep the pack alive without too much sacrificial current drain like a constant 25mA.
I cobbled together a green LED and 2 resistors which gives me 25mA constant load and I can fit that into a fly lead with a USB male plug one end and a jack for the camera on the other end and I'm fairly sure this will work with the background current drain just shortening the usable time some. The camera's take very little on standby, 5-10mA at most, but get loaded when the camera and lighting are busy.

So my simple circuit is probably flouting all convention, but I am willing to take any advice on a cheap and simple way to do this.
View attachment 181272View attachment 181272

I use trail cameras in my garden to watch nightime activity of wildlife, mostly hedgehogs. AA batteries aren't cheap and a better solution, I found, was to mount the cameras on a plywood plinth with a 6V rechargeable (bike) battery enclosed in a plastic box. The supply is fed from the battery box via a lead to the external battery connection on the cameras. I use a small 6V/12V charger (from lidl) to regarge the battery; usually one a week or so depending on the activity recorded.

 

[kinverkid]

I have the same problem with my outdoor CCTV camera which I use to monitor our hedgehog Ralphetta (it was originally Ralph until we realised it's a female). While it's sunny we can connect the camera to its own solar panel to keep it charged. In the winter while she's hibernating we move it to monitor other activity in the garden but need to connect it to a power pack especially since the WiFi capability means it needs to be close to the house where the solar panel will receive the least sun. Around once a week I need to press the ON button on the power pack to charge the camera. No big deal but I'm very interested in what solution you found and the above YouTube video looked promising but will have to find a school kid to knock one up for me. Added this post to my Watchlist.

 

[Oldman]

I have the result of the 5000mAh power bank with 200 ohms connected across the USB output.
Last night was a success, 57 separate 1minute recordings, so at least 260-290mA load each time plus the constant 24mA keep alive used a very unscientific less than 1/4 of the bank looking at the remaining LED display (3 out of 4 lit)

I better add here that not all my power banks will stay alive with 25mA load. I have some big ones that may require 50mA or more so unless you go to the 555 timer circuit the bigger ones may not be worth while for me anyway. The 5000mAh banks are only £5 each so if they last a week on average I will be happy with that and a recharge to go again.

I use a tripod for my camera's mostly as it means I can put them anywhere, the small power banks fit well on the reverse side of the camera in a waterproof bag with just a single cable out to the camera power jack socket.

Log into the camera with my phone and the date and time get auto set so no need to keep any AA batteries inside to store date etc. Once logged in I can see what the camera is looking at and set the tripod with just the view I need.

I am going to fall foul to a mischievous fox at some point where they pick up the camera and walk off with it. I already had a selection of small balls and even flowers in pots picked up and moved, the balls mainly don't come back.

 

[Sideways]

Good news, thanks for the update !
For your cameras, how about trying those corkscrew type tent pegs and a string tether ?
You might get some fun footage of the fox trying to drag the camera away - at least until they work out a way to do it

 

[trvlr]

I've nothing to add here... other than to say simply: "some seriously good ideas/suggestions". Must investigate them and try some of them out anon. Been a long whiles since I got into simple (and not so) ccts. etc.. (My prof. life did include serious maintenance and some simples designs etc. of broadcast, a/v kit.

 

[Oldman]

Hopefully this may be of interest, Fox's love raw eggs, this time of the year they take them back to the den for the kits or the nursing Vixen. They are so careful not to damage the shell.

 

[gmgmgm]

Not a fan of foxes, but I hope you get lots of good hedgehog videos!

You can get USB-to-6v converters off the shelf, very easily. (Most voltages are available now e.g. 12/9v, very handy for powering CCTV/switches/kit etc).

They will probably work better with the larger 10,000mAh battery packs which output 12v USB too.

Some of the power-packs have a mode which allows for tiny power draw, and won't turn off. I know my Anker "Nano" 10,000mAh pack has this (long press of the button). Others may have this feature too, and it may remove the need for custom micro-electronics.

(It might also be a lot easier to use a big 12v/6v lead-acid battery and a long wire! Masterplug sell a very handy "Masterplug Weatherproof Electric Box for Outdoors")