Boost Converter

Anything electric, AC or DC

Boost Converter

Postby drhill » Thu Nov 21, 2019 9:47 am

Has anybody here had any experience with a boost converter? Like this:
https://www.ebay.ca/itm/LTC1871-Booster-Step-Up-Module-DC-3-5-35V-Converter-Regulated-Power-Supply-100W/183827654038?hash=item2accfb6596:m:mwb79DNuW4Dtel4iE5DOrVg

We occasionally use a laptop to watch movies when the weather is bad. Not knowing when the weather is bad means always carrying an inverter and the laptop charger in case it is needed. Inverting 12 VDC up to 120VAC and then back down to 19 VDC seems rather inefficient. (about 65% efficiency for my inverter and laptop charger). I ordered up one of these boost converters and it arrived yesterday. If the laptop is charged and connected to wifi watching a youtube, it draws 0.7A at 19V and the Boost converter is drawing 1.2 A at 12V. So 14.4 watts in and 13.3 watts out. That is about 92% efficiency! I won't have wifi or youtube when camping, but that is just how I tested it. I did try a fancy boost converter a few years back but it was a retail unit that plugged into the cigarette lighter and had a nice compact plastic case around the electronics. It overheated and let out the smoke. Has anybody had any long term experience with one of these?
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Re: Boost Converter

Postby John61CT » Thu Nov 21, 2019 10:23 am

Sure, dozens of ways to skin that cat, for any load devices that use DC internally.

For many devices, easiest is to just buy a "car adapter", usually sold by the same maker for that specific model.

If DIYing, factors to match from the AC power brick:

Same approximate DC voltage output

Enough watts/amps

Size of barrel/pin connector

+/- polarity

For battery charging, the more intelligent devices can work with a constant PSU / converter input.

But others may require an intelligent charger that knows when to stop charging or drop to Float voltage.
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Re: Boost Converter

Postby RJ Howell » Thu Nov 21, 2019 4:16 pm

This is where I again say work with wattage, not voltage. Step ups/step downs, I've done them both according to the requirement.

Do you have the wattage in the source to convert (step up/down) and supply? The basics applies here. If your supply can only supply 100 watts and what you wish to run takes 110 watts.. It's not going to work.

As long as you stay within the parameters, you're good. I'm about to do the same to charge my laptop. Well... about to... :roll:

Now comes the caveat... Apple tech's tell me not to. I get the wave lenght they're concerned about, and even if correct, they still seem to take issue and advise to proceed cautiously. I'm still digging into this a bit more :thinking:

Do let me know what you learn. I'm still researching and not really seeing why not, yet would rather know before I risk my laptop..

I know... not much help... sorry...
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Re: Boost Converter

Postby featherliteCT1 » Thu Nov 21, 2019 7:10 pm

RJ Howell,

I also have an Apple computer, specifically, a 2017 MacBook Pro. A while back I searched for a DC charger and gave up. One computer tech told me that my model of laptop will not charge with anything other than the Apple AC charger specifically designed for my laptop because of some sort of proprietary device on my laptop charge port that will not read anything except Apple AC charger. That is when I gave up looking.
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Re: Boost Converter

Postby RJ Howell » Fri Nov 22, 2019 8:32 am

featherliteCT1 wrote:RJ Howell,

I also have an Apple computer, specifically, a 2017 MacBook Pro. A while back I searched for a DC charger and gave up. One computer tech told me that my model of laptop will not charge with anything other than the Apple AC charger specifically designed for my laptop because of some sort of proprietary device on my laptop charge port that will not read anything except Apple AC charger. That is when I gave up looking.


Personally, I think that's all it is, the charge port, i.e. connection. Though he did attempt to explain that the charger it's self is unique as well (short of having a apple symbol on it). I've resorted to using my inverter to charge the laptop, it's about the only thing it gets used for, that and to run a second monitor.

I keep looking at one of these, small simple and inexpensive to run the second monitor. Much like what your looking at.
I'll wait till someone designs a DC standard to a MAC compliant connector before trying to charge my laptop with it.


https://www.ebay.com/itm/FP5139-100W-DC-Boost-Step-up-Adjustable-Voltage-Power-Converter-LED-Voltmeter/142697805000?epid=1602267931&_trkparms=ispr%3D1&hash=item213973b4c8:g:FxsAAOSwnD1dyOgb&enc=AQAEAAACQBPxNw%2BVj6nta7CKEs3N0qUK3h4VtqXQ3B4ATxySTKphhQXyagmH4lqNphYEpcN%2FuYMcCqsP6FOz%2BQRxK8T9V%2B%2BlCfIOZznWchz0owcIskeDmvulxvGKIrwhMD%2BWbGW4TUybowndZTiHsR4r85hKkAefezdlzQtJz3OZYRzNKCLXZIVjrfd%2BKWoVoKlZHVXJXzwQvuotHajaBCpILGH2%2FoY3O5MkIr4460%2BRkEiZOTskgNIcC3ocLUT%2FVtm9iegxmSK56DqwsWWUlr3rOTJqMs90tylyw2S3t7SUaCF9FD8POwAcXSjDAkD4z0dfII%2FGYfiVyElyzI39uAhgt98G88lEFu0FMqgvKVLJ4oG7hXOEA5%2FYtuM6VTCMwRYLjkUurRube2GfvpDdkay52yZ8ZBu1oiSm8iI2ucfG8N5xbaMsQTEP19QAkaOUAXbZzuXBxOz4Kae9bh8P4cVReRng8%2BtuWtLPpwc60WaEDp3FaC3SU8Xn%2FuUtttLtwv41T49OQlG3GeYUJUew%2Bh62tVXXl81ULGB3qn5mZ50Rfzu%2BQfcs%2BeT8qhzHcgz4zVctqrWfrDhrsTLTfDS%2FVx47kryV2U2pfaA1Bi23L1%2B614c4NqtCjB9hBKzAxmHd0iFCEtzPTrt48JzLHGSsjD9Gsbl9AXYRlWlKGbg318AIZqcHZuG22pbd2hRIAu9BV2LgrhEyDiG%2BJ0DxK9mnrTp855S%2B2M8kNKRiixaUsnYLQtrYKCIkY%2BhGaWpsVqMuG9LAR8JOTw%3D%3D&checksum=142697805000b35228c20b5c44919aec41cf4dc7bf07&enc=AQAEAAACQBPxNw%2BVj6nta7CKEs3N0qUK3h4VtqXQ3B4ATxySTKphhQXyagmH4lqNphYEpcN%2FuYMcCqsP6FOz%2BQRxK8T9V%2B%2BlCfIOZznWchz0owcIskeDmvulxvGKIrwhMD%2BWbGW4TUybowndZTiHsR4r85hKkAefezdlzQtJz3OZYRzNKCLXZIVjrfd%2BKWoVoKlZHVXJXzwQvuotHajaBCpILGH2%2FoY3O5MkIr4460%2BRkEiZOTskgNIcC3ocLUT%2FVtm9iegxmSK56DqwsWWUlr3rOTJqMs90tylyw2S3t7SUaCF9FD8POwAcXSjDAkD4z0dfII%2FGYfiVyElyzI39uAhgt98G88lEFu0FMqgvKVLJ4oG7hXOEA5%2FYtuM6VTCMwRYLjkUurRube2GfvpDdkay52yZ8ZBu1oiSm8iI2ucfG8N5xbaMsQTEP19QAkaOUAXbZzuXBxOz4Kae9bh8P4cVReRng8%2BtuWtLPpwc60WaEDp3FaC3SU8Xn%2FuUtttLtwv41T49OQlG3GeYUJUew%2Bh62tVXXl81ULGB3qn5mZ50Rfzu%2BQfcs%2BeT8qhzHcgz4zVctqrWfrDhrsTLTfDS%2FVx47kryV2U2pfaA1Bi23L1%2B614c4NqtCjB9hBKzAxmHd0iFCEtzPTrt48JzLHGSsjD9Gsbl9AXYRlWlKGbg318AIZqcHZuG22pbd2hRIAu9BV2LgrhEyDiG%2BJ0DxK9mnrTp855S%2B2M8kNKRiixaUsnYLQtrYKCIkY%2BhGaWpsVqMuG9LAR8JOTw%3D%3D&checksum=142697805000b35228c20b5c44919aec41cf4dc7bf07

Edit: Huh, looks like the same unit! Yours is direct from China and mine is already shipped here and $2 more...
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Re: Boost Converter

Postby John61CT » Fri Nov 22, 2019 12:46 pm

Some model Apple HP and Dell have proprietary handshaking circuitry to ensure you have to buy their overpriced car adapter.

In some cases people have hacked which specific resistor works around the issues.

GIYF if you happen to be a victim of such evil practices.
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Re: Boost Converter

Postby drhill » Fri Nov 29, 2019 4:08 pm

So I have had this Boost Convertor for a week now. It is way past camping season in the great white north, so I have just been bench testing it. Just now I have had it running my laptop for over 3 hours and the chips are barely warmer than the ambient air. I should mention I bought the "style 4" with the heat sink. It comes with the heat sink shipped loose and a self adhesive strip to attach it. I haven't attached it yet. I probably will but it appears that it works fine for the light load I am putting on it.

There are two push buttons, one turns the display on and off and the other sets the display to input volts or output volts. For my testing I had to fumble around with the multi-meter to get the amperage readings. This display will be handy to monitor the input voltage to make sure I am not drawing the battery down much.

Fortunately - my laptops are HP, Compaq and Acer and all use fairly standard barrel connectors. I say fairy standard as none are actually the 5.5 mm OD x 2.1 mm ID that are the most commonly available. Fortunately, the old commercial converter I had ( that burnt up) came with 8 different connectors. Some day soon we will all have USB-C charging and no proprietary connectors.
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Re: Boost Converter

Postby John61CT » Fri Nov 29, 2019 4:22 pm

Yes that DC5521 spec (O.D. 5.5mm, I.D. 2.1mm) is the best "lingua franca" for obscure connectors.

You can pick up "universal" kits with 18-30 different pinouts.

The best let you swap polarity rather than buying separate sets for each.
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