Permanent usb power source

[Retroanaconda]

I am using an old phone as a basic tracker in the car, and I want to tuck away a permanent power source for it to keep it topped up. I can easily wire up a cigarette lighter socket and then use a USB adaptor but it strikes me as an untidy way of doing it for a permanent and hidden installation.

Is there anything available off the shelf that I can more simply provide with a permanent 12v supply from the vehicle battery and which has a USB to plug the phone into? Doesn’t need to be very powerful as it’ll just be keeping it topped up, and I don’t want it draining the battery too much. 

[Retroanaconda]

Okay, I upped my Google game and found this. Seems suitable?

https://www.amazon.co.uk/Ytesky-Inventor-Converter-Transformer-Adapter/

[BogMonster]

The Bluesea socket that I bought from MUD are supposed to have a very low parasitic drain of 1mA. I've not tested it that way, as mine is wired to the back of the cig lighter so goes off with the ignition.

Whether you trust a dingaling branded cheap item off Amazon with being permanently live in the car is a personal risk assessment but with 2 people I distantly know having had their house catch fire in the recent past due to cheap Chinesium phone chargers going pop, I wouldn't touch anything like that with a barge pole personally.

https://www.mudstuff.co.uk/products/blue-sea-carling-compatible-usb-socket?_pos=7&_sid=5984398e0&_ss=r

[Retroanaconda]

Yes, I have several of those which I use for phones/tablets etc. but it seems untidy and a waste of a nice device to wire it in behind the dash or something and then leave it hidden away. I will if I need to, but I’m keen to see if anyone has any other solutions.

I’m aware that cheap and nasty power adaptors present a risk, but they are all made in China anyway - hence looking for others experience.

[FridgeFreezer]

I generally dislike anything mains powered or containing a battery from China for the reasons BogMonster outlined, but for an in-car USB socket there's thousands of options all over eBay with varying degrees of nasty blue LED's and the like, just wire one to your permanent live and call it done.

[simonr]

3 hours ago, BogMonster said:

The Bluesea socket that I bought from MUD are supposed to have a very low parasitic drain of 1mA.

They look good!  I've just ordered one.

Thanks for the link Steve.

[smallfry]

Don't these things have some sort of transformer inside, similar to the wall outlet ones used in the home ?

Apart from the parasitic drain, there is a (small) fire risk if they do. Also, will permanent connection reduce the phone battery capacity, like it does with laptops, limiting the time the tracker will work if disconnected ?

Would it be better to have a plain socket/adaptor, with a resistor in line to reduce to a suitable voltage, which will have no drain, other than the phone itself ? 

 

[Bowie69]

No transformer, they only with AC, with simple electronics the voltage is dropped down to 5V. No way to avoid this. 

A resistor would have to dissapate a very large amount of heat and wouldn't regulate the voltage properly anyway, so you'd end up not charging in the phone, have a hot resistor and even more of a fire risk. 

Permanent connection doesn't affect modern batteries as much as it used to, especially compared to old NiMH laptop batteries, so a valid concern, but not to the same scale as it used to. 

 

[Eightpot]

I used to run a cheap amazon tracker that took a cheap giffgaff sim and worked ok, but would drain the battery if left for a few days, then there would be problems with the sim expiring which meant dragging the thing out from its hidey place to swap and a bunch of other problems which meant it was not working more often than it did. 

Just swapped to a TruTrak fmt100 that I picked up cheap from thier ebay shop (£29 for a ref I think), it just has a 12v and earth wire, works as soon as you connect it and after you're free 14 days its a fiver a month, not much more than I was spending on my old contraption.  The tracking app is great, and after I'd had it switched on for an hour, they gave me a call to say hello!  Very pleased so far, not sure how long the built in battery lasts so might get a seperate little 12v power source just in case.   It's not a full on managed service, but I quite like that they can track it for you if your stood next to an empty parking space and your phone was in the glovebox etc..

[TSD]

While you are taking note of the very small risk of the power supply bursting into flames, don't ignore the potentially much larger risk of a permanently powered lithium ion battery hidden away and forgotten. In the past couple of years I've found three (*) hidden away in various parts of my office, all worryingly swollen. And they were all in a benign environment, and not being charged. I didn't notice the battery swelling in the mapping tablet in the Ibex until it was pressing on the screen so hard it changed the colour in the middle of the screen.

Not super dangerous, but certainly an increased risk, and I'd be far more worried about that than the risk from random ebay electronics that didn't die within the first few hours of use. I'm not saying don't do it, just another thing to consider.

 

(*) - #1 was in old camera, and had and had swelled enough to burst the outer casing. 

#2 was on the circuit board  of a former colleagues abandoned project.

#3 was the worst - contained in a parcel of 'treasure' from a customer having a clearout. What appeared to be a box full of large LiIon battery chargers turned out to include 1 LiIon battery, about the size of a motorcycle battery, and somewhat(!) swollen.

[Bowie69]

5 minutes ago, TSD said:

not being charged.

This is the bigger problem with lithium, long term storage you need to have them around 70% charged or they begin eating themselves, and the aforementioned swelling becomes an issue. 

[simonr]

What you need to do is replace the battery with a pair of Super-Capacitors in series (they are 2.7V max, LoPo are 4.2V max, so you need two to make up the voltage)

I use an old mobile in my Van as a tracker using 2 x 500F Super Caps https://www.ebay.co.uk/itm/204229022629

Unlike a battery, they don't care how discharged they get, though the power density is low compared to a battery.  The pair gives me about 24h on standby - but you might need to parallel up more than one pair to give you the life you need.

It makes for a very relilient solution!

I also built this out of 25 x 360F Super Capacitors as a Super Jump Pack.  It will deliver thousands of Amps for an instant which is ample to start any engine.

 

[TSD]

It's not always straightforward to boot phones without their matching batteries, even if you provide the power the battery management/protection circuits can get in the way. But I'd much prefer a supercap hidden away and forgotten than a LiPo. One of my trackers from years ago (I've built many) has a small supercap which provides just enough energy for transmitting a single data burst, so most of the time it runs from a very small, very efficient power supply that can only supply enough current to operate the receiver, and charge the supercap.

[Bowie69]

For the lack of faff, I'd just buy one, and pay the service subscription for £5pm.

[TSD]

To avoid faff, buy a Toyota that will do most things better and be so boring no-one will steal it anyway. The only reason I do any of this stuff is because I find it interesting...

Edited July 23, 2023 by TSD
cant trype

[smallfry]

On 7/23/2023 at 8:37 AM, Bowie69 said:

No transformer, they only with AC, with simple electronics the voltage is dropped down to 5V. No way to avoid this. 

A resistor would have to dissapate a very large amount of heat and wouldn't regulate the voltage properly anyway, so you'd end up not charging in the phone, have a hot resistor and even more of a fire risk. 

Permanent connection doesn't affect modern batteries as much as it used to, especially compared to old NiMH laptop batteries, so a valid concern, but not to the same scale as it used to. 

 

I know nowt about electronics, I can't understand it, so just pointing out stuff I have heard or read !

Mostly via the internet, so it MUST be true. 

[Bowie69]

Yup, at last count, 98% of stuff on the internet is utter tosh. 

Also, apologies for my typing in that last post, atrocious. 

[FridgeFreezer]

On 7/23/2023 at 7:26 AM, smallfry said:

there is a (small) fire risk if they do

1. That's what fuses are for

2. Everything electronic, even a wire, carries a small fire risk.

There is another option instead of LiPos and supercaps which is to just get a dead boring simple reliable small lead-acid battery...

https://uk.rs-online.com/web/p/lead-acid-batteries/0597835?gb=s

Easy to charge from the main battery, dirt simple, safe and reliable.

[Peaklander]

My tracker costs me £72 per year, although there was an initial purchase cost too. The cost hasn't changed for the 8+ years I've had it.

It also works all over Europe (at least), but not in Serbia where there was a big hole on the map!

[muddy]

I bought some like the ones you linked to, none of them worked, however these have been going well for a few years. I can pick up a power source and snake them through the dash on my vans for phone charging.

 

@simonr that powerpack looks like another spanner vaporiser if ever I saw one!

[simonr]

1 minute ago, muddy said:

@simonr that powerpack looks like another spanner vaporiser if ever I saw one!

Only a screwdriver so far!

An unexpected behaviour of Capacitor based power banks is that it will start a vehicle where it's only just too flat to start, only using the flat battery to charge itself.

The car battery still has enough energy in it, but when you engage the starter, the voltage sags enough that it will not crank.  If you connect the bank to the battery for a minute or so, it will charge the capacitors and build up to nearly the no load terminal voltage.  Then when you crank the engine, the capacitors can deliver the current with almost no sag & the vehicle starts.

Chris GBMug was amazed when we did this on his 110!

[Mo Murphy]

1 hour ago, simonr said:

Chris GBMug was amazed when we did this on his 110!

🤣🤣🤣🤣🤣🤣🤣🤣

[fmmv]

So if you left a supercap bank permanently connected it would more or less guarantee a start, and consume no energy?

Edited July 24, 2023 by fmmv

[simonr]

I hadn't spotted that!  🤣

[simonr]

40 minutes ago, fmmv said:

So if you left a supercap bank permanently connected it would more or less guarantee a start, and consume no energy?

I think so!

It used to be used on EV's to deliver & absorb high currents back in the days when Lithium Batteries couldn't.

It would still get to the point where the voltage is just too low - but it would allow you to use a titchy battery and still deliver very high currents.