24V to 12V Converter - Lifespan?

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Texas710
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Re: 24V to 12V Converter - Lifespan?

Post by Texas710 » Sat Oct 24, 2015 8:28 pm

Okay, you guys are putting my mind somewhat at ease. I don't think I appreciate half of what the previous owner did on this truck, who knew a voltage converter was this complex. I can see there are other ways to derive 12V out of the system in an emergency situation if you had too. Redundancy is key.

Ron, i'll take the .02 cents all day long. I like your thinking, belts and suspenders, because I do want to upgrade in the future and it's better to have more capacity than less. Know I just have to choose which is right for me.

Always a wealth of knowledge, I appreciate the help.

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audiocontr
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Re: 24V to 12V Converter - Lifespan?

Post by audiocontr » Wed Dec 16, 2015 12:59 pm

Why not use a simple unit like: http://www.amazon.com/HOSSEN%C2%AE-Conv ... +converter

I picked up a few of these when they were a bit cheaper. They power a nice selection of my 12v accessories off of a 24v switched source. Cell phone, gauges, 12v fans, cigarette lighter ports...
1973 712m
(2) 1968 Haflingers 1 For Sale
1978 GMC Palm Beach
1979 Mini Ranger For Sale
1986 Corvette For Sale
2001 F250 Diesel and trailer
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Jimm391730
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Re: 24V to 12V Converter - Lifespan?

Post by Jimm391730 » Wed Dec 16, 2015 4:25 pm

Why not use a simple unit like: http://www.amazon.com/HOSSEN%C2%AE-Conv ...
That is certainly an option; however, there is a difference in how this works compared to Astrodyne or similar: the "simple" unit just wastes away half of the 24 volts, and gives the remaining 12V out to your loads. So if you have a 12V load that uses 5 amps, 5 amps is what is pulled from the 24V truck source. This works, and is simple, but the 12V 5A load which normally uses 60 watts of power (12V times 5A = 60W) now loads the truck system with 24V at 5A or 120W; the extra 60W is wasted as heat. For low power loads this is not a big problem, and these types of devices love to only have small powers drawn from them (because high powers make a lot of heat, and heat is what causes failures to happen).

In comparison the much more complex and somewhat more costly Astrodyne type systems act like a DC transformer - if you need 5A at 12V, then it only draws 2.5A from the 24V source. The input and output power remains very close to the same (the input power is ever so slightly more, since the converter is never perfectly efficient). This leaves more truck power available for other uses.
Jim M.
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TechMOGogy
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Re: 24V to 12V Converter - Lifespan?

Post by TechMOGogy » Wed Dec 16, 2015 5:16 pm

Never knew that
Thanks for the lesson!
72 Pathfinder | 75 710M 2.7i | 94 350GDT | 96 350GDT Worker

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rmel
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Re: 24V to 12V Converter - Lifespan?

Post by rmel » Thu Dec 17, 2015 10:54 am

Jim, this particular converter audiocontr has sighted is actually a switcher at 90% efficiency -- not
obvious looking at the Amazon description :?

The manufacturer is Chinese, Tobsun Electronics Co. Ltd. http://www.tobsun.com -- you
will need Google translate for these guys.

So at 90% efficiency the current draw on 24V would be slightly higher than 1/2 of the current on the
12V output, not bad. The output voltage on this model is just too low at ~12.3V for Auto accessories
one really needs at least a nominal of 13.3V. IMHO I wouldn't buy one of these, or at least not for
running gear I depend on :wink:

The high quality Asian converters are all designed out of Taiwan but assembled in China, although you
then get to move price decimal place over to the right one position :(

I get to deal with some of these rascals for my day job :(
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audiocontr
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Re: 24V to 12V Converter - Lifespan?

Post by audiocontr » Thu Dec 17, 2015 3:01 pm

I wasnt aware of the higher efficiency. Thanks for pointing that out. I also understand the use case for an 24/12v converter (and have a few). I built a 24v Class D amplifier out of an ammo can, and mounted the chinese made option for powering my cell phone as an audio source, allowing for quick removal. The converter was not an option within the space constraints.

I am curious about the comment of 13.3 v needed for audio accessories vs 12. Why?
1973 712m
(2) 1968 Haflingers 1 For Sale
1978 GMC Palm Beach
1979 Mini Ranger For Sale
1986 Corvette For Sale
2001 F250 Diesel and trailer
Company Cars
2017 MKT
2018 F-150

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rmel
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Re: 24V to 12V Converter - Lifespan?

Post by rmel » Thu Dec 17, 2015 3:48 pm

The 13.0V+ comment was based on experience. Got bitten with some equipment running poorly
to crapping out with voltage near 12.0V. I have had failures with Computers designed for "12V"
re-booting with an inputat 12.0V, HAM gear poorly there as well. My ICOM 7200 has a nominal spec
of 13.8+-15% and does not run well transmitting when the battery is near 12V.

I was a bit too dogmatic perhaps stating 13.3V :wink: But. I think one does run too close for comfort
picking a converter that has an output below the nominal value of a lead acid battery, that's why
I stated 13.3V as a better nominal to pick. This way you cover for wiring losses and equipment that
may be a bit more sensitive. Although some stuff works fine at or below 12V if it's designed to do so.
I usually go for 13.3 to 13.8 -- more margin so I don't have to worry about it.

cheers,
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Jimm391730
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Re: 24V to 12V Converter - Lifespan?

Post by Jimm391730 » Thu Dec 17, 2015 8:58 pm

Ron, thanks for the info about that particular converter. My gut reaction when I see heavy heatsinks is that it is just a resistive voltage drop. Decent switched mode units don't require such large heatsinks (although large ones are not a bad idea). IMHO, the "cheaper" ones are not decent switching mode converters.

But it is good for others to know about the two technologies, and what they might be getting themselves into.

And as Ron has suggested, I have set my converters to output 14.0-14.2 volts as a general rule, for the same reasons he has stated. I have not yet run into any "12V" rated unit that has had a problem around 14V.
Jim M.
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audiocontr
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Re: 24V to 12V Converter - Lifespan?

Post by audiocontr » Fri Dec 18, 2015 7:34 am

Very good info. Thank you.
1973 712m
(2) 1968 Haflingers 1 For Sale
1978 GMC Palm Beach
1979 Mini Ranger For Sale
1986 Corvette For Sale
2001 F250 Diesel and trailer
Company Cars
2017 MKT
2018 F-150

Texas710
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Re: 24V to 12V Converter - Lifespan?

Post by Texas710 » Sat Mar 25, 2017 10:27 pm

I have finally gotten around to switching out my converter. Ended going with the Mean Well converter, so far no complaints. FYI, I believe they make a backing plate for the converter but mine did not come with one, didn't know, so I made one out of diamond plate. The converter sits off the plate for air flow. I matched the plate to what was there previous and didn't have to drill any additional holes.

I made the decision to go ahead and upgrade to the SSI system while I was in there along with two new Yellow Top batteries. I thought I would add some pictures with the install. Jimm391730 was very kind in helping me work out some details and he also recommended a capacitor to help with any sudden power draws which I had not heard of, but I am not one to second guess the advice. No issue with the truck starting with this added. I kind of got crazy with the shrink wrap but it will keep the dust out and hold everything together

So far, so good. All the previous 12V equipment works great and the truck runs really well. Bonus on the clean look of the engine without all the wires going over the fan. Overall both were pretty easy installs.
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712 Walt
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Re: 24V to 12V Converter - Lifespan?

Post by 712 Walt » Sun Sep 17, 2017 8:28 pm

I haven't posted here for quite a while, after getting smoked for giving a heads up on the availability of Pinz 718's on Government Liquidations. However, the question is worthy of a good answer. I've had a 24 to 12 volt converter in my 712 Pins for the last 10-years. I installed it immediately below the glove box. The secret in keeping this type of consumer grade electronics going is to keep it away from moisture, heat and vibration sources and to keep the draw at 1/3rd to 1/2 of the rated amps. Most of this grade of equipment is rated by component or, at best, a bench test. My own experience is that the ratings are based on bench built prototypes. The testing is done a lab level temperatures, no vibration and protected from other types of environmental stressors. Acceptance specs must be at around a 50% failure rate. Everything goes down from there. The component and assembly quality sinks because the overseas factory is cost, not quality, driven. So, keep it cool, dry, free from moisture and well below its rated capacity and hope that the solder joints don't crack.

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rmel
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Re: 24V to 12V Converter - Lifespan?

Post by rmel » Tue Sep 19, 2017 9:38 pm

The biggest killer of some of these converters are the cooling fans. Just look at Texas710's PIX of the dust
on that Sanel converter.

If your converter requires a fan for cooling it is forcing that dirty air right into the fan bearings, some of these
fans are open bearing and will eventually fail. If you run the trails your going to be better off with a hermetically
sealed converter that has a large heat sink and convection cooled rather than forced air. The converter I use
for my EFI is just that, it is physically large due to the heatsink. All my mission critical converters are fanless.
If you run these guys up to the edge they are more likely to exhibit poor regulation first, that said it's a good
idea to derate and run at no higher than 70% the rated output.
Puller: 710K 2.7L EFI
Follower: Sankey MK 3, 3/4 Tonne
Driver: Ron // KO0Q

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