Low Voltage Dropout Linear Regulator

[Naartjie - Duck Hatch]

I'm looking to run an Huawei B525 router directly off the boats DC supply. I would like to use a linear voltage regulator to hold its supply at 12VDC

My concern is the difference between Vin & Vout on most regulators can't be less than 2v (Dropout Voltage ). So if the input supply goes below 14V it won't work. 

Has anyone used a Low Voltage Dropout (LDO) Linear Regulator to do the job

 

Edited March 28 by Naartjie - Duck Hatch

[cheesegas]

Best to get a buck-boost converter - more efficient than a linear regulator and can cope with the supply voltage being less than the output. 

 

Plenty of pre made modules on Amazon for not much money:

https://www.amazon.co.uk/Converter-DC5-30V-1-25-30V-Automatic-Regulator/dp/B07WP5KDR5/

[Naartjie - Duck Hatch]

24 minutes ago, cheesegas said:

Best to get a buck-boost converter - more efficient than a linear regulator and can cope with the supply voltage being less than the output. 

 

Plenty of pre made modules on Amazon for not much money:

https://www.amazon.co.uk/Converter-DC5-30V-1-25-30V-Automatic-Regulator/dp/B07WP5KDR5/

Thanks maybe the easiest solution but that takes the fun out of it

Edited March 28 by Naartjie - Duck Hatch

[GUMPY]

These are what I use, 

https://www.ebay.co.uk/itm/204536075277?

If you need higher current then 

https://www.ebay.co.uk/itm/314819408103?

 

Been working well for years.

[Naartjie - Duck Hatch]

9 minutes ago, GUMPY said:

These are what I use, 

https://www.ebay.co.uk/itm/204536075277?

If you need higher current then 

https://www.ebay.co.uk/itm/314819408103?

 

Been working well for years.

Many thanks Grumpy 

Tried and tested works for me

[GUMPY]

2 hours ago, Naartjie - Duck Hatch said:

Many thanks Grumpy 

Tried and tested works for me

I had a 2 amp one on the boat running a Huawei B818 for years it's now in the caravan along with one of the 10 amp versions running the TV/Soundbar. 

The 2 amp one must be 6 years old😲

[dmr]

A lot of stuff that "needs" a 12 volt supply will work ok at 9 volts, as it probably gets dropped down to 5v internally, but you would need to experiment to confirm this.   With various volt drops the supply at your device could be as low as maybe 11.9 volts so a linear regulator will never give you 12 volts, not even a low dropout device.

Buck-boost is the only way to go and as they are switching they are more efficient. If you want fun then buy the chip and make your own circuit, this will likely involve winding a little inductor and that is fun, but a ready made jobbie from eBay will be cheaper.

[jonathanA]

Just connect direct to a convenient 12v socket. Mines been running like that for over a year. By the time you get a bit of volt drop on the typical undersized boat wiring it will be fine. In my experience anyway. 

[Alan de Enfield]

4 minutes ago, jonathanA said:

Just connect direct to a convenient 12v socket. Mines been running like that for over a year. By the time you get a bit of volt drop on the typical undersized boat wiring it will be fine. In my experience anyway. 

 

I agree - until you start the engine and find you have 14.6v at the socket.

[cheesegas]

18 minutes ago, jonathanA said:

Just connect direct to a convenient 12v socket. Mines been running like that for over a year. By the time you get a bit of volt drop on the typical undersized boat wiring it will be fine. In my experience anyway. 

Some routers are more sensitive than others to voltage variations, I’ve heard of a lot of TP Links dying when used like this. Huawei seem to be fine though…and some semi enterprise grade ones like Proroute and Teletonika are designed to be used in cars/trucks so they’re capable of accepting 9-30v DC.

 

As the current draw is low, the voltage drop won’t be massive either - if you have AGMs you’ll see 14.8v during charging. Bit high for some stuff. 

[jonathanA]

5 minutes ago, cheesegas said:

Some routers are more sensitive than others to voltage variations, I’ve heard of a lot of TP Links dying when used like this. Huawei seem to be fine though…and some semi enterprise grade ones like Proroute and Teletonika are designed to be used in cars/trucks so they’re capable of accepting 9-30v DC.

 

As the current draw is low, the voltage drop won’t be massive either - if you have AGMs you’ll see 14.8v during charging. Bit high for some stuff. 

Yes I keep saying I will whip the cover off the who are we and see if it looks like there is any regulation on the input. 

[cheesegas]

Just now, jonathanA said:

Yes I keep saying I will whip the cover off the who are we and see if it looks like there is any regulation on the input. 

There will be some form of regulation and it’ll also have either a dedicated IC or a discrete circuit to derive various rails for TTL etc - 3.3v, 5v, 1.8v. It’s whether the regulators input can withstand over voltage or not, it seems to vary a lot from brand to brand. 

[Francis Herne]

On 29/03/2024 at 18:12, Alan de Enfield said:

I agree - until you start the engine and find you have 14.6v at the socket.

My B525 doesn't seem to mind that at all.

It does occasionally power-cycle when the fridge compressor starts up though...

[Jen-in-Wellies]

On 29/03/2024 at 18:07, jonathanA said:

Just connect direct to a convenient 12v socket. Mines been running like that for over a year. By the time you get a bit of volt drop on the typical undersized boat wiring it will be fine. In my experience anyway. 

Sometimes you'll get away with this, sometimes you won't. All depends how the gadget concerned is designed. You're playing Russian roulette with it. I'd only directly connect to boat 12V if the gadget is marketed for vehicle, or marine use, so it should have been designed to cope with higher than 12V and assorted voltage spikes and noise. Even when dropping from 12V to 5V in home made boat electronics, I'll use a MOV to dump any voltage spikes on the input to the voltage converter.

[IanD]

Given that a suitable buck-boost SMPS costs about a tenner, why would you risk running the router direct from the boat 12V?

[jonathanA]

Both fair points. I personally think the 'dangers' of boat 12v systems are somewhat over stated and belive in the kiss principle.

 

Why would I introduce some dodgey chinese consumer electronics built to the cheapest possible standards ? No thanks. I've already got enough in the router as it is 🤪

 

My choice and I'm happy with it. Maybe I won't be if there a puff of smoke from my router when I start the engine.... 

 

I'm just giving an alternative view not saying there is anything wrong with using some sort of stabilised PSU, just that it's not mandatory.... its a personal choice.