Zitat von »Gus«

Hi!
According to the user manual for the aquaero 6 XT the power supply voltage is 12V DC plusminus 5% (and 5V DC plusminus 5%). Both voltages are supplied to the controller using a 4 pin female Molex plug.

Most users of this device probably just plug it to the computer PSU - but I'm not into computers. I don't even have one. I will be using the aquaero to control four fans in my homebuilt heating system on my sailboat. The boat electrical system is 24V DC so I intend to use a DC/DC converter to reduce the voltage from 24V to 12V (and another DC/DC converter for the 5V) before feeding it to the controller. However, many converters for marine use will provide between 13,2V and 14,2V (output voltage).
Since 12V+5% is 12,6V I will have an excess voltage of 0,6V to 1,6V.

Question 1: Will this damage the controller?


Question 2: If yes, is there a smart way to reduce the voltage from 13,2V-14,2V to 12V?
Any help would be highly appreciated!

As for the potential damage, only Aquacomputer can help You. I wouldn't count on it though - since they specify +/- 5% they won't clear You for using a higher voltage.
For me the real question is wheter a higher voltage wiil trip protections on Aquaero, I don't have a schematic of course but I don't think there are any components safe for 12,6 V that would fail with 14,2 V so it really comes down to overvoltage protection in place.
However there is also a question of connected devices that may or may not tolerate higher voltage.

I am not familiar with marine applications but I would presume that your DC/DC converter is meant to charge 12 V batteries and this is why the output voltage is higher. If its output is also unregulated (as it often is for this kind of devices) then I would strongly reccomend stabilising it regardless of anything else.

As for a smart way to generate 12 V, this depends on Your definition of "smart"
It depends mainly on total current consumption of Aquarero and thus on the devices You are planning to connect to it. To put this into perspective, a typical PC fan current is 0,2 - 0,3 A, on higher-RPM fans You can go up to 0,6 A and then You have big fans like AP182 (1,2 A) and industrial ones (sky is the limit). So it is important that You determine that.

If You think that You will stay under 2 - 3 A total, I would try a LVO (low voltage dropout) regulator, these are ~10 € components and when properly cooled can go up quite high amperage, for instance a LT1083-12 can go up to 7,5 A. Since these devices usualy require only two external capacitors the integration is quite easy even if You have little knowledge in electrical engineering.

Actually You could probably hook up a LT108x directly to your 24 V source and get rid of the DC/DC converter all along (if it is really a stable 24 V).

If You really need to push Aquaero to its maximum (10 A) then You could perhaps use two regulators in parallel but it is not as easy as that and somewat clumsy - in that case i would be better to purchase a decent DC/DC converter rated for such currents, but these don't come cheap...


As for 5 V line just go for an 7805 regulator (~0,5 cents) given the rated max current (0,5 A) that is probably even lower anyway, You can probably use it without any cooling (though I wold not reccomend it).

Zitat von »Gus«

Thanx Caronen for a most informative reply!
Conclusion 1:I will stabilise!
I intend to use 8 fans: be quiet! SILENT WINGS 3 PWM (140 mm, 1000 rpm, 59,5 CFM)
According to their website the Current consumption is 0,06A and the Safety current - whatever that is? - is 0,3 A. On the fan it says 0,3A.
8 x 0,3 A = 2,4 A
If I decide in the future to change one or two of the fans to the high speed version (consumption 0,5 A) I will still be within 3 A.

"Safety current" is probably the maximal starting current - a fan will consume more current in order to overcome the initial inertia than in a steady (constant RPM) state. When a rotor is blocked, the curent will also rise. This is actually true for any (synchronous) motor.
A good designer will then provide some means to limit this current so that in will always stay under a certain value. I don't know exacly how they have done it in SilentWings but i would asume that "Safety" means that the fan will either limit the current to 0,3 A (lowering supply voltage if needed) or trip a protection when the curent goes over 0,3 A.

Either way this is what you have to assume with, as always, some margin. So, say 350 mA per fan. Aquaero in PWM mode should not introduce any further loses but again, to be on the safe side I would assume 400 mA per fan grand total. This gives us 3,2 A.

I don't like to run components near max values so I would say the LT1084 (5 A) is the bare minimum but since an LT1083 (7,5 A) will be similarly priced...

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Unfortunately the 24 V source is not very stable. When the service battery bank is fully charged the voltage is above 25V. And when the battery charger runs the voltage is sometimes above 28V. However, I just found out that I allready have a few DC/DC converters installed in the boat. One is a Mascot Type 9460 24/12V. I measured the output voltage to 13,15V.
Conclusion 2: I will put a LT1083-12 (with one 10μF tantalum capacitor on each side) between the Mascot DC/DC converter and the Aquaero.

Well, first of all I’ve looked to the Mascot 9460 datasheet and it is actually a stabilized converter with 13,2 V output voltage. So, this is kinda good news. Then, the datasheet says “output voltage internally adjustable 9,0-14,5 V” - usually there is some sort of a knob to be turned with a screwdriver, but I do not see any on the photo.
Unfortunately the manual says nothing about it being user-adjustable. In fact, the manual barely says anything useful, but You could perhaps contact Mascot – this would solve all your problems…
Of course, setting the Mascot to 12 V is a solution only if You don’t need it to provide 13,2 V something else.

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Question 3: Where do I buy the LT1083? There seems to be several different models. What about this?:
https://www.ebay.com/itm/Ultra-Low-Noise…uUAAOSwtnpXlJSl

I was thinking about a discrete component rather than a whole module. However, it turns out that LT1083-12 is no longer available as it was replaced by LT1083 that is adjustable output voltage instead of fixed. This is still good, but it requires two resistors in order to set a proper output voltage – not a big problem but some soldering would be required...
The module You found on ebay (in fact there are plenty of them) would be a nice.
However, few things to bear in mind I will try to sort it out.
(1) A general remark - these modules usually are of universal input (AC or DC). In order to achieve this, there is a diode rectifier bridge in the input: this in turn means that You have about 1,4 V loss – in your case LT1083 would be fed with 11,8 V. Since LT1083 will drop another 1 V (or even 1,5 V) this won’t work.
(2) You must be careful with the description as sellers of such stuff are clumsy with their descriptions. The module You linked is based on a LT1084 chip.
(3) Moreover, go for a version with a heatsink – the module You have linked doesn’t come with one. This is why they say (at the very bottom of the page) that the device is limited to 2 A.
As for (1) there are two solutions. If You have some experience with a soldering pen, You can simply replace two opposing diodes with wires. The second solution is to connect the module directly to your 24 V source. Because of the diodes Your allowed voltage input is now 1,4 V higher and this gives You a safe margin (LT1083 is rated for 30 V absolute on input). However, since there are other components You have to be sure these are OK.
As for (2) and (3) You just need to find a right device. For example this thing https://www.amazon.fr/SODIAL-dalimentati…e/dp/B0793LNQNV seems to be quite popular all over Internet, You just have to find one available in Your country.

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Question 4: What about cooling? How do I achieve proper cooling?

Well, there is a whole science to it but it all comes down to attaching a piece of metal to the component in order to increase its surface area and allow the heat to dissipate. On the module I have linked from Amazon the heatsink (the black extruded piece) is already in place. Then You just make sure that the heatsink is not covered or otherwise blocked so that the air can go up when heated - an advantage of L1083 is that it is quite efficient and does not heat a lot so no forced airflow will be necessary.

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Question 5: Why are there two different ground pins in the 4 pin Molex plug? I understand that one is for the 12V and one for the 5V - but is it ok to connect them to the same ground? If the Traco and the Mascot are connected to the same ground on the input side, then there should not be any difference in ground level on the output side, right?

As always there is a long story behind. Basically, both wires are supposed to be same potential (ground) and there are two of them in order to increase current carrying capacity. Sometimes these are internally also connected on a device.
However, if you use a LT1083 module with rectifier diode bridge connected directly to the 24 V source, You have to be careful as the output ground sits 0,7 V above input ground. Traco is an isolated converter so it will work but You must connect output grounds from LT1083 and Traco and avoid any connection to the mains (24 V) ground.
And still, it is not an elegant solution, I would rather get rid of this rectifier bridge all along.

Zitat

I'd love to measure the temperature at a number of different locations in the boat, but the temp sensing cables supplied with the Aquaero are only 70 cm long.
Question 6: Is there any way to lengthen these cables without getting bad readings? In the manual there is a list of compatible sensors, so I guess any modification would not qualify. But this isn't magic right, it's electronics, and either way you seem to be a wizard, so perhaps there is a way?
The distance from the Aquaero to the fans vary between 7,5 and 9 meters. I intend to use shielded copper cable (Veriflex CY LSZH 4 x 0,75mm2) which would give a voltage drop of only 0,129V.
Aint that smart?

I’m no wizard but I like to look for solutions using the little knowledge I have
You cannot possibly evaluate a voltage drop in your case because You don’t know what method Aquaero uses to measure temperature (neither do I). The sensors are actually resistances that vary with temperature, 10 kOhm being measured at 25 °C. The resistance/temperature curve is nonlinear but if even at 70 °C it is about 50 Ohms per °C.
Now since 10 meters of 0,75 sq mm cable is only 1 – 2 Ohms this should not introduce any error, just pay attention to make proper connections. However, a 10 m nonsymmetrical cable with such a resistance can be a good antenna and pick up some noise that can perturb temperature readings. There is no way to tell but make some tests.

Zitat von »Gus«

Zitat

Well, first of all I’ve looked to the Mascot 9460 datasheet and it is
actually a stabilized converter with 13,2 V output voltage. So, this is
kinda good news. Then, the datasheet says “output voltage internally
adjustable 9,0-14,5 V” - usually there is some sort of a knob to be
turned with a screwdriver, but I do not see any on the photo.

Unfortunately the manual says nothing about it being user-adjustable. In
fact, the manual barely says anything useful, but You could perhaps
contact Mascot – this would solve all your problems…

Of course, setting the Mascot to 12 V is a solution only if You don’t need it to provide 13,2 V something else.

Please stand by for Mascot investigation

-
This thread is rapidly deviating from my initial Aquaero related topic, namely if the Auaero 6XT would handle my overvoltage powersource, and the discussion may not be of interest to anyone in this forum but me? Is it advisable to continue in some other format, e. g. email?

As You wish, in my opinion no need, it can be useful for more than one person.

Zitat von »Gus«

Ok. May I ask you to tell me how to post a picture here. I'm asked to type the picture URL. Does the picture have to be published on internet to get an URL?

Quite frankly I don't know but it seems to be the case. Anyway, it should not be a problem with all these online cloud services.

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I opened the Mascot converter and found an adjustable knob. I managed to set the output voltage to 11,99V. So far so good.

Yeah, this proves the old truth: it is worth to search a simple solution even if the searching itself takes more time than devising another not-so-simple solution
This also points out how important it is to give as much detail as possible when posting a question on a support forum.

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Based on your comment above, and before connecting the Aquaero I figured it would be a wise thing to measure the voltage between input and output ground on the Mascot and the Traco. It turned out that there was no difference between input and output ground on the Mascot. On the Traco however the output ground was 0,54V above input ground. Needless to say I didn't connect the Aquaero.

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Traco is an isolated
converter so it will work

Pls clarify. What do you mean? Is there any way I can use the Traco and the Mascot to power the Aquaero?

A commendable effort even though excessively prudent
To keep things short, you can safely connect Traco’s output ground to Mascot’s output ground.

Even though TEN5 is designed with input and output grounds isolated, it does not mean that they cannot be connected (if it was the case, You would have a warning in the datasheet). It merely means that the user can choose output common reference potential as he pleases (within some limits) so he can also choose it to be the same as input ground.
The measurement that You have done is actually useless because a voltmeter is a high impedance device, so you did Your measurement without actually connecting both grounds. Some multimeters have a low impedance mode that would be useful in this case, but it is a rather rare feature.

I would advocate connecting Traco’s output ground to Mascot’s output ground and checking for heat, flame or smoke (of course there will be none). Then measure voltages between your common ground to Mascot and Traco. If You get 12 V and 5 V respectively then you are good to go.