Charging a 19V DC laptop

[Matlock]

I'm just now getting around to wiring in an onboard laptop charger.
I need 19V DC so I picked up a Kree DC-DC boost module from Amazon. I know how it needs to be wired into my Leisure battery / Blue Sea fuse box. I'm interested in the best way to connect to the laptop with a power jack to charge it. Is there a way to determine which power jack will fit my laptop? I'm guessing Radio Shack might carry both the jack and a matching plug with pigtail, but maybe not.
Any other suggestions?

 

[SternWake]

There are universal types of jacks where one chooses the correct mating tip.

I have a bunch that came with something similar to this picture:

I'd not really want the wires thinner than 18 awg passing current to a 90 watt laptop.

My Dell laptop has a third pin inside the barrell connector delivering some unknown voltage. Without this pin delivering unknown voltage, it will power the laptop, but it will NOT charge the laptop's battery.

My dc to DC adapter wire failed with regarding that third pin. All I wanted was a Pigtail to fix it. Could not find, but did find an 8$ AC adapter for my laptop, ordered it and cut off the cord and spliced it onto the failed cord. That was 4 or 5 years ago, and is flowing power as I type.

 

[blars]

Dell's use an ID chip in the charger to say how much power can be supplied. So your laptop might not charge the battery when turned on if it thinks it is a low-power charger. At one point they recalled their 80W chargers (fire hazard IIRC) and replaced them with 100W ones free.

 

[SternWake]

Dell's use an ID chip in the charger to say how much power can be supplied.  So your laptop might not charge the battery when turned on if it thinks it is a low-power charger.  At one point they recalled their 80W chargers (fire hazard IIRC) and replaced them with 100W ones free.

Yep, If my third pin circuit is not established a screen pops up saying charger is not recognized and to use an approved 100 watt Dell power supply.  The battery icon will say plugged in, not charging.

My PWR+ car adapter was 22$, but I have replaced the Ciggy plug with powerpoles and spliced in a new output cable, making it longer so I can keep laptop a further distance from power brick.

Only issue is is that it knocks out actual TV channel 8, but so does the original 120vac power brick on my PSW inverter, and it consumes at least 15 more watts when doing so.

The MF'ing ciggy plug was certainly an issue too.

 

[ccbreder]

My laptop is the most expensive part of this scenario. I don't want to compromise my files or programs. To get 19 volts from 12 volts, the converter must turn the 12 volts DC to AC, then use a transformer to raise it to 19 volts, and diodes to return to DC. Must be a voltage regulator involved as some times my bank is much more than 12 volts. How reliable can all this be in an inexpensive adapter? I determined my lap top brick uses less than 100 watts. So my solution was a 300 watt pure sine wave inverter and plug my lap top's brick into that. I feel most protected with this set up.

 

[Matlock]

My Asus AC charger/adapter outputs +19V, 4.74A and My Dell charger is 19.5V, 3.34A output.
Both AC chargers have 18 and 22 gauge wires respectively and are 6' long to the AC adapter.
It looks like the power pin on both are 2.1mm center positive OD 5.5mm.... I believe but not confirmed, plus I need the length of the pin, which look to be the same.

I'd like something with a heavier wire (than 18 gauge) and with male to male power pins at least 6' apart.
I should be able to find a bulkhead female that I can attach to the DC-DC boost then wire to the fuse box.

I'm thinking the M to M pigtail going from Laptop to female bulkhead would work ok if I could just find a pre-made heavy gauge wires with w/strain relief.

Just found this on Powerwerx, 2.1mm Right Angle DC Coaxial Power Plug to Powerpole Adapter 3ft.

This 2.1mm right angle DC power adapter is the exact size for Kantronics TNC's. The O.D. is 5.5mm. The coaxial power plug connector is molded with 3 feet of 18 gauge wire and connects to any mating 15/30/45A Powerpole.
Still seems like really light gauge wire though and a short wire too.

 

[frater secessus]

To get 19 volts from 12 volts, the converter must turn the 12 volts DC to AC, then use a transformer to raise it to 19 volts, and diodes to return to DC. Must be a voltage regulator involved as some times my bank is much more than 12 volts.

That's the second time I've heard someone say that in a month.  It seems the "must" part is not as absolute as one might think, although that might be the easiest/cheapest route.

https://en.wikipedia.org/wiki/Boost_converter
https://en.wikipedia.org/wiki/DC-to-DC_converter

 

[SternWake]

Thanks for the links.

I cannot explain how the DC to DC converter is exactly more efficient, but I can measure it, and no way will I intentionally use my PSW inverter to power original power brick, compared to the PWR+ Dc to DC adapter.

I don't have Capacity(Amp Hours) to burn and it is nearly 1 Extra AH, each hour that the laptop is fired up.

That is more than my fridge usually consumes.

With the batteries, My dell wants a 19.5v converter, but the battery is 3Series 3Parallel of 18650 cells.

4.2v is the maximum voltage of each 18650 cell.
4.2 x 3 = 12.6v

Each 18650 cell is considered fully discharged somewhere around 3.2 volts
3.2 x 3 = 9.6v

19.5 divided by 3 is 6.5.

My laptop battery pack itself says 11.1 volts.

11.1V = 3.7v X 3, which is considered 50% charged on an 18650 cell.

So it appears there is a huge discrepancy in voltage. The power supply needs to hit 19.5, but the battery itself can somehow power the laptop down to 9.7 volts.

Wonder if the laptop has its own DC to DC converter?..... but it makes little sense from an efficiency standpoint

I wonder what kind of electronic wizardy goes on between laptop barrell connector input, and battery (+) and (-) outputs.

Wonder if one can just feed laptop direct from their 12v lead acid battery system. Since 9.6v is well below the 100% depleted level (10.5v) of lead acid batteries.

Note: I am not recommending this.

 

[rvpopeye]

Sounds like a job for an old XP laptop ?

 

[becida]

This is what I used, less than $9

https://www.amazon.com/gp/product/B012VHFZM2/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

 

[ccbreder]

"SW; Wonder if one can just feed laptop direct from their 12v lead acid battery system. Since 9.6v is well below the 100% depleted level (10.5v) of lead acid batteries."
I have thought of this myself as Li ion batteries do not need 100% charge. Might be worth a test some day. I am sure the laptop battery has a management system to avoid over discharge and under discharge.

 

[becida]

The laptop needs 9v not 12

 

[ccbreder]

our lap tops use 19 volts from the charging bricks. if yours needs 9 volts, that is much easier to get out of a 12 volt battery.

 

[SternWake]

 I am sure the laptop battery has a management system to avoid over discharge and under discharge.

I have taken apart three 9 cell  budget battery packs to harvest the 18650 cells within.  There is definitely circuitry and battery temperature sensors inside the packs.

The harvested cells are low quality, low capacity and can't really power much for very long, at least compared to my Panasonic ncr18650B cells rated at 3400mAH.

I'm not really interested in hacking the Laptop to wire it directly to 12vDC. Whether feeding the barrell connector with 12.x vDC, will work, is unknown to me.
 My DC to DC PWR+ car adapter's electronics works perfectly.  The only issues have been the Fooking  miserable clown ass of a Ciggy plug, and the output cable broke the wire to the 3rd pin.

Now if one had an old laptop, with no working power supply and no usable battery, perhaps then one could figure out which was (+) and (-) where the battery mates to laptop, and feed it directly with 12.x volts, but I will not be expending any effort in this regard, and the simpler feeding the original barrel connector 12v will also go untested, by me.

My regular 150 watt voltage booster has so far only been used to make small 12v computer fans into hover craft at about 28 volts.

 

[becida]

our lap tops use 19 volts from the charging bricks. if yours needs 9 volts, that is much easier to get out of a 12 volt battery.

My bad.. 19v rather than 9... thanks.