DC to DC 12v output

[noelex 77]

Originally Posted by mtompson

@AndyEss, Genasun, up to the normal 14.5v(ish), but I fear that may have been too much for the delicate fans.

For this sort of application the sort of marine DC-DC converter would be way overkill. So forget that suggestion .

There are many cheap electronic devices that will acieve your aim of constant 12v supply, but simple buck converter will not do this as they require a volatge difference of several volts between input and output. Therefore you need a buck/boost converter. Still very cheap and reasonably effecient, but it is becoming compicated circuitry.

A very simple system would be to add a couple of conventional diodes. Each diode will drop the output by around 0.5v and if these are chosen overspec (with a reasonable current rating) they will be very reliable and simple. A KISS solution to consider.

[Moontide]

Don't know about PC fans, but I have a few room fans that run on USB 5 v. Have worked great and very cheap (and lasted for a couple of years so far).

[Sternwake]

Ive had 5 failures of noctua industrial fans. 4 nf-f12 3k rpm were lucky to last 9 months. All were warranty replaced. Quickly. I asked for 140mm industrial 3k rpm when the 4th one failed. They complied. . It just failed after 8 months and my e mail to them said dont bother with warranty, im done with your industrial lineup. All.other fans in same location receiving same voltage lasted years. Industrial, .....my burro.

Noctua's non industrial lineup... ive had no problems. Two of them, 60 and 80mm have seen 16v+ for many many hours attached to my power supply which was feeding distant batteries over long extension cords, or running equalization charges.

There are 5 amp voltage buckers with xl4015 chips. 5 for.12$ on amazon. These drop only 0.3v. I use them extensively on very powerful computer fans. Delta fans are my favorite. I replace the voltage trimpot with wires leading to a fingertwist potentiometer and gain infinite speed control on most fans. Very few failures, and can dial them down to very low amperage speed and noise levels and crank them up.to insane speeds too. Peel back the sticker on all computer fans where wires enter hub and squirt in some dielectric grease or cover solder joints with clear nail polish.

[HankOnthewater]

First of all, like Andy said, make sure your solar controller is right, should not give a voltage higher than around 14.2 Volt (check your battery specifications!)

I am using a few of these:
https://www.ebay.com.au/p/2269759663?iid=292272588642
I have adjuisted the Voltage output of
- One gives exactly 12 volt
- One is set at 19 Volt for the computer.
Both are hardwired.

I have 2 of these hardwired in the campervan as well, and I have 2 spares... just in case, but all of these have been operating for 2 years 24/7, all good. Still have 2 spares

[svmatilda]

You may have problems getting a DC-DC converter to pull the 12-14.7 volts to a stable 12 volts. Normally for a stable conversion the voltage needs to be a minimum of volts higher. So no problem on the higher voltage but wont work when the voltage gets closer to 12 volts.

Fans run from a power supply in a PC that will not deviate much possibly 11.99-12.1 Volts,

You may be better getting a 5 volt fan with the same airflow specs. Then get a DC-DC converter capable of outputting 5 volts. Plenty of different units on sale on Ebay. Just work out the current draw required.

[svmatilda]

I have looked at the Amazon link and here is a clue to why the fans you are using burn out.

12V, 4-pin PWM, These are Pulse Width Modulated control and yes i can see why they would not last.

You need the 12 Volt DC two wire and not 4 wire PWM,

I have been running 12V 2 wire high flow fans on Matilda for several years. These run the cooling for the fridge condenser.

In the long run with the 2 wire fans you possibly wont need a converter at all.

[sailah]

I use a lot of Meanwell power supplies in my business and they work very well and are reliable

Not sure what kind of mA draw you are looking at but this should get you running to 1.25A. 9.2-18V input.

https://www.mouser.com/ProductDetail...hWiflBqsfvY%3D

[Sternwake]

My Noctua industrial IPPC 4 wire PWM fans that failed, 5 of them, were run through Noctua's Own NAFC-1 PWM speed controller.

I run many Delta computer fans 4 wire PWM or not, through 5 amp rated voltage buckers for speed control. Very Few failures. I have run them for months on end well below 12v basically any voltage from 5 to 14.6x volts.

The One 12v computer fan that I have had obvious issues with charging voltages, was the Silverstone AP182 180mm fan, which has its own built in speed controller with external potentiometer, The hub would get too hot at max speed and voltages above 13v. That fan lasted 2 more years after the initial hub overheating, when run on a 3 amp LM2596 based voltage bucker, to limit voltage to below 11.5 volts. That fan was still more than powerful enough at 11.5v.