REDUCING AMPERAGE for delicate electronics

[Loohan]

DOH! I just had a cosmic flash of insight, getting back to the original topic of this thread.
I already have the buck-booster which converts everything to 12V. Haven't used it yet.
With this logic relay device, I could make the buck-booster cut in at say 13.4V (battery output) and cut out if it went below 13.1V for more than 5 minutes or whatever. That way, I could get rid of the high spikes without losing so much efficiency.

[Loohan]

Just a note, many "wall warts" have a substantially higher "no load/low load" output voltage than claimed. It's not uncommon to see a 9 volt unit putting out 12, or a 12 volt unit delivering 16, or 18. I was rather shocked when I first saw that, but soon learned it was quite common with many manufacturers.

An interesting little tangent. There are other variables, too.
I only recently grasped what Wayne was saying. I recently read that wall adapters put out a specific voltage at a specific load (amperage). So with no load, they should put out more voltage than specified. At a high load, less voltage. However, it is also true that some special adapters are "regulated" to put out the same voltage, more or less, at different loads.
But I discovered that INPUT matters a lot, too:
I tested a 12v, 500mA adapter at home off a cheap inverter that puts out 111V AC, and got 11.12V DC output with no load. The same adapter plugged into a grid wall socket putting out 123V AC produced 17.67V DC!

[SolarJohn]

What we're describing here are "unregulated power supplies". They usually consist of a transformer, diode, and a capacitor. The output voltage changes with variations in the input voltage, and with the load.

On the other hand, a "regulated power supply" would also include a voltage regulator device or circuit. This "regulated" supply would maintain a constant output voltage, even when the input voltage or the load changes.

To protect sensitive electronic devices you might want to purchase a "regulated" dc power supply with the desired output voltage from Radio Shack, or an on-line store such as DigiKey or Jameco.

John

[Loohan]

Yes, definitely control the VOLTAGE, and the current will take care of itself. You just have to make sure enough current is available for the biggest demand that the load will need and fuse it properly, in case there might be shorts.
Cheers
Wayne

Yeah, well, must be something else wrong, then.
I did by the pricey DC/DC converter, PST-DC/2812-8 by PowerStream,
http://www.powerstream.com/dc-buck-boost.htm, and it does put out 12.16V any time I check, BUT it has not helped the problems at all. A total waste of money, as far as I can see. Here's an email thread I had with the seller about it: (and of course the sellers of the items I was trying to run claim that something's wrong with my power supply...)


(quote) This can't be explained by the DC converter. The main thing that blows capacitors is high voltage,
the other thing is putting a lot of AC current through them. Neither can be explained by the
house wiring or the DC converter.

We sell a lot of these converters to people that stabilize voltage in cars and busses, very noisy
conditions and we haven't had any complaints.



Dexter Ator wrote:

> That sounds plausible...
> I should say that the adapter behaved similarly without the buck booster when I had somewhat lower voltage in the walls. In fact, I had them replace a couple under warranty as they failed. This was the main reason I bought the buck booster.
>
> But I have also had similar problems with a mono amp designed for up to 18V:
> http://www.designnotes.com/Merchant2...gory_Code=auha
> Which blew its central capacitor directly on my system before the buck booster, probably at 13-14V. Then again, shortly after I plugged in the repaired unit with the buck booster, it blew its central capacitor. We're talking volcanic eruptions.
> These amps don't blow on a wall wart plugged into 120AC.
>
> So the buck booster does not seem to help at all with the problems that were obvious, and presumably doesn't help on any less-obvious problems that might or might not be there with other devices. I was expecting it would normalize my juice so things would run right. But I see no benefit.
>
> Mark W Lund, PhD wrote:
>
>> Wow this is a real stumper. Is it the laptop adapter that is getting hot?
>>
>> The only thing that I can think of is that sometimes when you have one switchmode power supply feeding
>> another they can drive each other crazy. For example the second converter is trying to draw constant power,
>> so it will increase its amp draw if the input voltage falls in order to keep at a constant wattage. But the
>> first one is trying to regulate to a constant voltage. So if the output voltage falls (say a disk drive kicks in) the
>> first converter will increase the voltage at the same time the second converter is trying to increase its input current.
>> This can set up oscillations, even chaotic oscillations.
>> This rarely happens when the dc converters are properly designed, but since you can't test every possible combination
>> it does happen.
>>
>> Best regards
>> mark
>>
>> Dexter Ator wrote:
>>
>>> Maybe you can help me. I bought a PST-DC/2812-8 several months ago because I have a couple thiings that won't run on my 12V home solar system. I thought this was due to fluctuating and excess voltage.
>>> But the items don't work much better through the PST-DC/2812-8. Although they run fine on a 12V wall adapter plugged into the grid, or a 12V jump-start pack.
>>>
>>> The PST-DC/2812-8 always says about 12.16V when I check it, which should be great.
>>>
>>> E.g. my auto laptop adapter (maybe I should have bought one from you instead of the PST-DC/2812- works dandy on my jump-start pack for hours on end, but on the PST-DC/2812-8 gets too warm and malfunctions after a 1/2 hour.
>>>
>>> __________ NOD32 2696 (20071130) Information __________
>>>
>>> This message was checked by NOD32 antivirus system.
>>> http://www.eset.com
>>>
>>>
>>>
>>
>
> __________ NOD32 2696 (20071130) Information __________
>
> This message was checked by NOD32 antivirus system.
> http://www.eset.com
>
>
>

--
--------------------------------------------------------------
Mark W. Lund, PhD ** Battery Chargers
CEO ** Bulk Cells and Custom Battery Packs
PowerStream Technology ** Custom Power Supplies
140 S. Mountainway Drive ** DC/DC Converters
Orem Utah 84058 ** Custom UPS
(01)801-764-9060 ** Battery backup http://www.PowerStream.com ** Engineering, manufacturing, consulting

[icarus]

I'm probably too far from the beginning of this thread to understand what the ultimate problem was, (and not smart enough to boot!) but,

We had a bit a problem with our old fashioned 3 watt bag cell phone. When it was connected to the DC wiring of the building, the phone would beep for low voltage alarm, since the house batteries would be underload they would measure ~12.2-12-3 vdc at the end of the load wiring (long load wire). We solved it by adding a small 12vdc motorcycle battery that we plugged the phone into, and then plugged that battery into the building wiring. There was some concern that the 10ahr battery would pull down the 1600ah house batteries, but it has never been a problem.

Perhaps this will work.

Icarus

[mike95490]

The only other alternative I can fathaom is to get a 12 - 12 DC DC converter, from a major company that makes them [Vicor/CUI/YI/TYCO etc...]

Heres a sample Digi-Key Part Number 102-1257-ND
http://search.digikey.com/scripts/Dk...me=102-1257-ND
CONVERTER DC/DC 12V OUT 75W $99

These are commercial / laboratory quality usually, not made in a backyard, and with a wide input range, consistently give you good, clean output. Sometimes EBAY has things like this, but it's buyer beware there.

[El Tejon]

I've been reading the thread and the one thing I've noticed about the initial poster, he seems to have poor record of electronic equipment longevity.

Just my observation.

I have VTVM's, multimeters, DVM's and such that are over 40 years old with no failures.

That said, I did just lose my TS-45 charge controller but that was because a tree fell on the enclosure that housed it as well as some weather instruments and they all got very wet in last week's rain. And we all know how well water and electricity get along.

Ciao

[Wayne from NS Cana]

Yeah, this is a strange situation. There's got to be more going on than we know about. All these capacitors blowing up, it makes no sense if the voltage is anywhere near where it should be, not reverse polarity, nor AC and not loaded with ripple. I spent my working life in hands on electronics, design and repair, so I know more about this issue than many others would.
Heck, when I was a kid, I used to solder 12 VDC caps across the 120 VAC input to radios, then give them so some unsuspecting person to turn on. Haha. I was a bad little bugger. To be making these capacitors blow up, they either have to be supplied with huge overvoltage, reverse polarity, AC, or a combination! Any of those situations would, in short order, destroy the rest of the electronics as well. It's got to be one of three things, there's more to the story than we're being told, or we're being given wrong info, or someone is pulling legs. I don't mean this post to sound sharp or crabby, but with the info we're being given, we're just spinning our wheels.
Wayne

[mike95490]

" REDUCING AMPERAGE for delicate electronics "

is just the wrong question. I've got no answer for it, and thankfully, the original poster appears to have given up.

[Loohan]

Ha, yeah, for sure the title to the thread was misguided.
But there is some kind of weird problem.
The voltage in the walls is way too high. It's supposed to float at 13.4v or something, but the wall voltage when the TS-45 is in float mode is 15.85.

If I bypass all the house wiring, disconnect it all from the unit, and run leads directly from the batteries to the TS-45, and measure the voltage in-line at the controller, it is around the proper float range.

Hence, probably some weird wiring fault is causing the TS-45 to misbehave and allow more voltage in than it is set for.

So, when the weather clears up I need to either find the problem, or route all new wiring somehow.