If I were to delete some of these power bricks and wall warts for low power laptops or an LCD monitor, how would I go about determining the allowable voltage range for these devices?
Lets say we have a low power PC and a monitor that both use 19.5 volt AC-DC power bricks, each near 50 watts max. How could I determine the upper voltage range these devices would accept without damage? I would like to find out if these or similar devices could be powered on an 8s LiFePo4 battery that can of course vary between 20-29 volts with out employing a buck converter.
I'd imagine that inspection of the ratings on the capacitors or perhaps some other components nearest the input would be informative but beyond that it could get expensive testing such devices with my variable DC lab power supply to see when things heat up or let out the magic smoke.
Anyone have a rule of thumb to find this kind of information out? Would manufacturers be forthcoming with this information when asked?
I always treat devices such that they need the exact voltage that the wall wart was providing. I have done this with all my AC equipment to make it run on DC (various input voltages). It also provides a better safety-net to do DC-DC stabilizing. I will post a few useful links.
I have purchased a bunch of DC-DC converters from here, as they have a great selection (scroll down the list to see all the input voltage options), this is probably the best link here. I bought a couple here for stabilizing DC-DC for a bunch of routers I had running off battery power.
DC/DC converters for OEMs DC/DC power supplies including car to laptop, modules, bricks, and custom converters, DC/DC regulator
www.powerstream.com
I recently bought a bunch of these for Raspberry Pi's and they seem to work good up to 60v DC input:
Find many great new & used options and get the best deals for 8-60V to 5V Micro USB Adapter Voltage at the best online prices at eBay! Free shipping for many products!
www.ebay.com
This one is a boost rather than buck, but it allows me to connect my Makita XRM10 bluetooth radio/battery charger 24v input to the 12v on my truck:
This one, is good for 12v 6a boost to laptops up to 24v (I had purchased 2 back in the day):
120W Universal DC Adapter for Laptop Car Power Adapter SCDC1260(Car&Fly)(id:3780842), View quality Universal DC Adapter, DC Adapter for Laptop, Car Power Adapter details from AATUU Technology Co.,Ltd storefront on EC21.com. Buy best 120W Universal DC Adapter for Laptop Car Power Adapter...
aatuu801.en.ec21.com
I bought 2 of each these before, for mine and wife's MacBooks:
Find many great new & used options and get the best deals for MagSafe Car Charger Adapter 60W for Apple Macbook 13 Notebook with 2 x USB Ports at the best online prices at eBay! Free shipping for many products!
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and:
Find many great new & used options and get the best deals for 60W 16.5V 3.65A 5 Pin MagSafe 2 Car Charger with 1 USB Port for Apple Macbook at the best online prices at eBay! Free shipping for many products!
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Here's another one I had thought about buying before (also can do boost):
I've also used several of the boost/buck converters like from Drok on Amazon, where you can set the output to CC or CV to get custom setting, like one of these examples (some of their models even have LCD voltage displays):
or:
Buy Voltage Converter Module DC 5-30V to 1.25-30V,Automatic Step Up/Down Converter,Boost/Buck Voltage Regulator,Regulated Converter Module,Over Current, Short Circuit, Over Temperature Protection: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
These style you find on Amazon, don't all do buck AND boost, so if you want both in one converter, then make sure it says boost/buck (or else it may only do one or the other)...
When I'm shopping converters, I always look at the input voltage range, and make sure it falls within my boundaries...
Anyways, you can filter through the above links and decide if any of these seem useful in your scenarios or not...