19V Laptop: Wattage Analysis of various methods to power.

[bajadulce]

Ongoing tests/discussion about the various ways to power a laptop (requiring more than standard 12v DC supply)

Made a post in the "best laptop for RV" topic, but want to expand on the power supply end of the process more than the laptop itself. Not interested in laptop specs, how energy efficient, how much power, or latest o.s etc they have. Just the power supply and what fulltime offgrid community might be doing to get around the "conversion" factor.

Years ago (before laptops were so cheap) we built a "12v" computer system with a mini-itx motherboard and 12v flat screen monitor. A nifty DC-DC ATX pin adapter was used to convert the 12vDC to the various lower voltages needed for the motherboard (12v, 6v, 3v, etc). None of the volts were over 12v and so it was pretty simple. Prob not as effecient as it sounds with all the resistance, but there was no need for an inverter nor DC stepup to attain 19v.

Earlier laptops used 12v DC jacks (internal batteries were prob 9v). We ran one directly off a camper battery/solar for 3 months in the winter of 1996. I believe it was a Toshiba? Might not have even had windows95!

Nowadays laptops typically require 19 volt inputs and we are forced to do some kind of conversion for our system to work on 12v battery bank. For myself, a small 300W inverter along with the laptop's AC/DC converter brick has worked decent enough, but the process is not the most effecient. 12DC converted to AC (via inverter), converted back to 19v DC (via the laptop ac/dc power brick) and then charge up a 12v internal battery pack! And Stephen mentioned that the laptop screen requires its own AC and so the laptop does its own internal DC-AC converting as well!

For those that just want to plug into their car battery for limited use, the market is flooded with all sorts of DC-DC step up converters. Maybe a tad more efficient than inversion (tests will show). And so will be investigating this route here soon.

The question tho would seem is it possible to run a "19v" computer without DC-DC stepup nor Inverter-Converter?

Quoting my post:

... an experiment for fun... might try hooking one up to 12v direct even tho the laptop jack requires 18V. My hunch is that this voltage is not the actual voltage required to run the laptop but rather to charge the laptop's battery?

After doing a little research on the internet, I have found several posts describing ppl able to get their 18-20V laptops working with car battery voltage. In all the instances, the users reported that while the computer "ran", but their laptop batteries did not charge. Maybe this was their own particular model or perhaps they were actually powering via the batteries and not realizing it.

Many of us aren't looking for a "portable" computer and don't care if the batteries aren't being charged. In fact, best would be for the internal batteries to be removed for an off-grid application such as an RV. None of the laptops used in our household connected to 110AC have battery packs! And we've used the laptop in the RV off the inverter/power brick batteryless as well. (obviously "backup work" in case of power failure isn't a concern). So if you could get laptop to run as described with12v input into the 19v jack, then that would prob be the end of this discussion. But I couldn't get any of the different test machines to run this way.

And so what about the internal battery pack itself?

Battery sticker reads 11.1V @ 48W/H... ahh now we're getting somewhere and maybe it's just as simple as replacing the internal battery w/ 12v leads?

Unfortunately the computer's battery pack is a little more sophisticated than that (or so it seems). There are several voltages and signals being sent to the motherboard via different battery cell serial/parallel configurations. Looks like about 3 different voltages and 4 connections to the battery configuration. Now, it might be possible to recreate those voltages, but haven't came across any info or hobbyist who has tried this

Which brings up another option: External battery packs.

These batteries boast much larger capacity and can "extend" your battery usage. But the kicker is they hook up to the 19v DC jack and thus start "charging" your dead 12v internal batteries thus equalizing the 2 battery banks. Dumb idea. A backup battery pack should plug into the internal battery compartment, not the laptop charging port! Or at the least disconnect your internal batteries. And how does one go about recharging a 19V external battery pack in a 12v system such as an RV? These are simply meant as extended "portable" solutions. But we're not interested in portability. Instead, this external battery pack should be another "internal" 12v battery pack. In our case a bank of 12v deep cycle batteries with hundreds of Amp hours of use!

So that's where we are. My inverter/converter brick is working fine and have plenty of solar/amp storage, but it is a nagging itch to bypass all the necessary conversion. Some say they were able to bypass the internal "charging" by connecting a lower 12v directly to the 19vDC jack. I couldn't get mine to work. I think a better approach would be to fool the laptop into thinking it's internal 12v battery pack was actually supplying the power NOT the 19v "charging" jack.

????

... to be continued.

[Totem]

fantastic write up

[bajadulce]

I haven't got it to work yet

Just thought I'd jot down my thoughts, condense writings and then seek more info around various laptop forums. If you come across anything in your web surfing, link here!

The idea is that a 19v computer doesn't actually need this much voltage to operate (not charge, just run). And to attack the problem at the lowest voltage, the 11.1V internal battery pack, rather than the power charging jack.

I'm not electronically stupid, but am limited to simple knowledge/experience w/ the subject.

There are 4 solders to the battery's control unit from the physical battery cells. These 4 connections would seem the gateway into the computer. I don't have a schematic of this power board, but will try to find one online. The fantasy would be that only the 2 (11.1v +/-) connections would be needed and the 2 lower voltage connections related to the sub cells aren't important or possibly have to do w/ charging the individual cells.

Here's a generic pic from the web showing the typical 4 leads. That 5th wire is a thermistor of sorts that monitors the batteries heat.

[stamar]

Unfortunately this project isn't going to work for me, as the modern laptop switchhes to a low power, less bright lcd hard wired when on battery power.

For this project buying actual batteries would work and switch them out. They actually sell external battery packs for some laptops.

I'm interested exclusively in 19 volt dc

[bajadulce]

Ah good point about the dimmer lcd when powered by the battery pack. This might be a blessing for offgrid use. Lower power consumption would seem a good thing. Wonder if the laptop's battery power options, such as screen brightness, can be adjusted via the computer's BIOS or OS/software?

[stamar]

from plug in mode you can dim the screen and set the cpu to lower.

I do believe if you unplug the battery from the laptop it uses less plug in power, as in it takes the power and wastes it ifi the battery is full.

also

It would take very little fabrication if you can buy the cells to just make a battery pack with more cells adn then you have your 12 volt laptop only using space effecient lithium ion cells not a space retarded lead acid cell.

i wouldnt say it has no use but much less use.

[bajadulce]

...just make a battery pack with more cells and then you have your 12 volt laptop only using space effecient lithium ion cells not a space retarded lead acid cell. I wouldnt say it has no use but much less use.

But how cool would it be to walk into your local Starbucks with a Frankenstein laptop with wires hagning out hooked up to a huge car battery strapped to a dolly!

Point is, that the battery is no longer in the laptop needing 19v to charge, but rather the battery is a 12v deep cylce battery bank (tuked somewhere out of sight in a cabinet etc) with hundreds of watt/hours at disposal and being topped off daily by the solar or whatever battery recharging method already used for those banks. Not some additional charging of internal laptop batteries.

I found a German hobbyist that built a "desktop" unit powered by a solar panel, which is on similar lines. Was a fun read might look for link to share.

[bajadulce]

Bought a regulating DC-DC circuit board on Ebay today for fun. Was really cheap, but will take awhile to get here.

Now can do the full array of experiments and report on the efficiency of the various methods. *#'s to be based on laptop w/o battery pack. CD drive will not be used. Any suggestions on how to keep the CPU usage/internal fan at a constant? Was thinking a video or a game w/ a static menu screen?

• Household 110AC - power brick = numbers to come. Killawatt meter on loan in Oregon
  
• 12vDC - 400W DC/AC inverter - power brick = will check today
  
• 12vDC - DC-DC stepup =
  
• 12vDC - internal battery = battery remains in place with feeds. still experimenting
  
• 12vDC - DC-DC stepdowns bypass internal battery = still experimenting
  

I'm a little confused on the coaxial/shielding etc of the 19v powerbrick supply cord. Have a few old laptops and power sources to experiment with and so 2 are now taken apart. One is chopped from brick (Dell) and other (T60) is dissassembled at power brick. The old dell power supply had 2 shields and the inner 3rd signal wire (which had voltage btw). The disassembled T60 powerbrick has only 2 wire feeds (but also has the 3rd signal wire pin on it's connection prong end). Here's some generic pics from internet:

expecting this

but have this and you can clearly see the "pin". Maybe the T60 doesn't have any voltage on that pin like the Dell did? Will check w/ probe. Probably the dell has 3 wires at its base (need to disassemble).

Curious as to where these feeds transform to their coaxial shielding in these type of cables?

Good news is, looks like we'll be able to use the dc-dc stepup at the 2 feeds directly. The 3rd signal wire or pin will not be an issue in the T60.

... wattage #'s to come.

[Maineah]

There are + and - pins but I think you'll find that the other terminals are for clock, data and the thermistor. The battery is turned on and off by the computer and the thermistor is to shut down the battery on over heat.

[stamar]

I hate to ut down anyones productive project with great rv knowledge.

I'm actually on a similar pproject just can't afford it.

But answer these two questions.

1: is it as useful as putting 19 volts to the power recepticle from the deep cycle.

2. Is it as easy to fabricate as putting 19 volts to the deep cycle?

A lot of business laptops also have so,ething called an external charger and allow hot swapping of batteries,

Actually dell sells all of these things for lattitude laptops. 19 volts car adapter and batteries,

[bajadulce]

I did quite a bit of exhaustive reading last night on some various electronic forums specifically those that were modifying laptop battery "packs" for other hobbies as well as a lot of information on rebuilding/modifying existing battery packs. In all cases, "cells" were being used which when configured in series/parallel were able to produce the various voltages as Maineah described needed by the laptop battery control unit.

I suppose it would be easy for someone with an electronic background to build a circuit board that would simply duplicate those different voltages from a 12v source, but this is beyond my scope nor anything anyone has tried as far as my limited searching went. Is there a market for something like this? If it would save 1 amp of juice (12watts on a 12v system) in offgrid use, then I believe there absolutely would be. 1 amp/hours of juice might not seem like a lot in savings, and something easily recaptured by even the smallest of solar panels, but amp/hour usage is cumulitive and it does add up.

This topic started as more of a rant/vent/search for info, but now is more of a general report/analysis of the varying "popular and available" methods i.e. Inverter-power brick and DC-DC stepup. Will log the various watt usage for each and come up w/ a report. The topic title has been edited to fit the new discussion direction as well.

@Converted 19v supply:

As mentioned, I have since ordered a DC-DC step up regulator (simple circuit board pulse switch etc. w/ adjustable screw) with what I expect to be able to handle decent amps. I also expect this to be a little more efficient than the dc-ac-dc route. It seems to be the most popular method and it is 1 device converting power rather than 2. Real testing might prove otherwise. To be determined.

Unfortunately these electronics won't arrive in time as I am being dragged and forced to Hawaii for 3 weeks again starting day after Thanksgiving. So major bummer! Tests/results to come at a future date.

[Maineah]

Yes it would be far better to just use a 12 to 19 volt converter then to go from 12 to 120 and back again through the computer power supply to make 19 volts you'll lose about 10% both ways. My guess is that the 19 volts is more for charging then operating the computer most of the voltages in a modern laptop are 5 and 3,3 volts pretty much internally regulated and before any one starts yes the CCFL's are high voltage but it is produced by the 5 volt circuts. The Nicads had a nasty little problem of thermal run away if they over heated and would just keep going until they caught fire that is one of the reason they use a thermistor and it is also used for charging to limit to current by battery temp. I did a test with my 15.3" laptop and its max wattage was during a recharge/start up and it peaked at about 60 watts but I found once the battery was up it would cruse at around 20 watts and maybe jump to 30 even loading pictures or some thing else that worked the hard drive. I think the 30 watt was during a battery charge pulse. Neat tool if you are so inclined all so great for figuring out all kinds of 120 power draws at home. http://www.amazon.com/s/?ie=UTF8&keywords=p3+kill-a-watt+meter&tag=googhydr-20&index=aps&hvadid=4644404337&hvpos=1t1&hvexid=504417&hvnetw=g&hvrand=1549724445169647202&hvpone=&hvptwo=&hvqmt=b&ref=pd_sl_276xbjw734_b

[stamar]

i think it as more effecient as well

however theres no data on the amount of power lost converting the ac back to dc.

the inverter claims to lose very little power converting dc to ac

its more than fair to say 10% but most of that is in converting the ac to dc...

believe it or not my friend is writing a paper on it hes going to technical school as an electrical engineer.

[Maineah]

Well this will burst your brain http://efficientpowe...er_ps_paper.pdf seems like there are quite a few variables and models that range from 65% to 90% efficient depending on load. I was under the impression (never believe the manufacturer) that switching supplies are about 90% efficient even more reason to cut out the middle man in a DC/AC-- A/C/D/C situation in theory you could lose a good deal more then just 20% in the conversion.

[bajadulce]

Thnx for linking such an intersting report.

Interesting results showing computers working with lower processor load were less efficient due to the "standby" design of the powerbrick.

I'm hoping for some of those gains w/ the switching supply as well. My only concern might be that the brick offers a more regulated steady source. Tho I do believe that going throug the DC jack versus the proposed battery pack might offer more additional internal regulation/protection? Tho to be fair the battery pack has its own regulating circuitry and could be done safely as well I believe.

Am very anxious to get all my test gear in order and be able to do log my own detailed report soon!

[Maineah]

The voltage regulators in the computer are very sophisticated and well filtered to reduce noise. Reducing voltage with a regulator circuit is a lot simpler then increasing it but to get the results the computer wants to see the best method would be 24 volts reduced to 19 but then the issue is twice the weight twice the charge rate a voltage regulation system and a set up to allow the charging of both batteries at 12 volts with a on board charger. There is also the issue of other 12 volt things (lights etc.)To me two batteries are a good thing for extended stays in the willie wags but primarily for the extra amp hours. I have been 7 days with out charging with my two 80 amp batteries (160 amps combined @ 12 volts) this includes running the water pump a Fantastic fan and watching maybe 2 hours of the Olympics on TV (using an inverter) and a stint of a hour or so with my 100W ham radio. Granted I have gone to great pains to reduce power usage but it can be done. That being said I don’t think a 12 to 19 volt converter would have too much effect on battery life as compared with none at all from what I have seen with my laptops power usage.

[bajadulce]

Sounds like you have a nice setup and have done your necessary homework and tweaking.

Myself, I have a single G27 Gel Interstate battery that is probably going on 7+ years of use now. Thought about adding a second one (buying 2 new) as my battery is showing signs of wear. Debating whether to go back to 2x 6v for more amp/hours than my current setup or even slightly more extended amp hours w/ 2x12v in parallel such as your system. But this is easily another topic.

@2x12v batteries in series for 24v config:

Interestingly enough, the actual output voltage of this particular laptop's power brick reads ~23-24 volts (this might change while under load dunno) and so it might be possible to run 28ish volts (2x ~13.8v fully charged 12v batteries in series) directly to the laptop assuming the internals have some regulation/protection of their own. zzzzzappp.

My solar system charger is most likely dedicated to 12v charging, but maybe it has some options/settings I don't know about (does have a gel/acid setting). I do own two "12v" solar panels, so the input is there if needed to reconfigure. And pulling a lead off of one battery to power the lights might not be too draining on the charging system as a whole (especially a sytem charged in series). The consensus seems to be it is better to charge in series than parallel as well. Is it possible to charge batteries in parallel and still use in series without switches and/or manual reconfiguration? Can't picture this.

I guess if one was running a 24-7 dedicated server off-grid, this 24v battery bank would definitely be a serious consideration. In my case as with yours and most, I'm only running this comp a few hours average/night if that and can't justify the 24v configuration just for this one application. (tho the parallel vs series charging debate might influence a 24v vs 2 parallel 12v config).

One other option that hasn't been mentioned is pulling power from the Solar panels to charge the internal batteries (for later use) or even run the laptop (decent amp array) itself during light hours. Solar panels definitely put out more than 12v by design and might be easier to produce regulated 19v or whatever might be needed rather than pulling from the solar's target battery bank. Basically a system already designed to charge 12v power.

Maybe you're on to something here:

Charge 12v parallel battery bank by day (separate regulated solar feed (pre charger) for laptop day use if feasible) and reconfigure bank for 24v for night use. Guess the tests will answer all this when the stepup regulator finally arrives. I'm sure the energy saved is pretty nominal after all the #'s are in. Hope I'm wrong!

[Maineah]

I think if that is some thing I needed to I would invest in a pair of 18 amp gel cells and charge them with the solar collector @ 24 volts then use a voltage regulator to produce 19 volts and dedicate them to computer use. They are pretty light and have a lot of reserve the jumper packs to start cars have an 18 amp gel cell in them so that's a pretty good load. This would enhance the KISS effect as far as creating a series/parallel battery systems with blocking diodes or relays (read loss with both) I chose the standard group 27 batteries "A" because they are cheap and every one has them and "B" I saw no real need for 225 amps and 160# of weight and when you get down to it 160 amp deep cycle power is nothing to scuff at for less then the price of one T105. One big MH energy saver I use is an accumulator tank on the water system it reduces the pump cycling big time, motors take a lot of current stating and of course nothing but LED's for light. My wife just bought a tablet that charges with 5 volts and about 11 hours of battery use I think that is where I'm going instead of caring around my 15.3" laptop just to Skype and check my mail whilst I'm on the road.

[bajadulce]

Charging a separate 19v external battery pack for the laptop thru solar array would be a good option too. Good suggestion and hadn't thought of adding that to the discussion.

Accumulator tank is a smart idea. LED's a given. And the smaller 5v tablet seems like a winner too if it does all you need it to do. I imagine those 5v tablets have inexpensive car charging adapters as well as the AC/DC brick? Might have even came w/ one?

Not to stray too far off topic, but:

Good point on the $$ T-105s. Have had them in other MHomes (came with the vehicle), but would never spend that kind of $. No way are the gains worth it. Tho in all fairness, golf carts are really hard on batteries by nature and they are the gold standard in the golf industry. But the golf industry is HUGE, and so there must be a lot of competive brands out there. Good chance some are even sold under a different name to mega retailers. The lead plating in 6v batteries might even be damn similar among the various makers too.

When you mention the weight issue w/ the 2x6v's vs the 2xG27's are you using them as hybrid use for starting the car as well? Or do you have a 3rd starting battery? The weights seem about the same? Only ask because am in need of a battery/batteries here soon and I see Costco/Sams Club have a 6v battery for about $75 ~ 210ish advertised AH vs the 220 T-105.

G24 ~ 50# 80AH

G27 ~ 60# 100AH

G31 ~ 70# 125AH

T-105 ~ 65# 220 AH

Costco 6v ~60# 210AH

Maybe these figures are too generic.

[stamar]

Some of the tablets are 5 volt and some are not.

The ipad is, my friend has a more fancy toshiba that is not. Needs the ac brick to power not usb.

The trend is more powerful ones as In using more power.

[Maineah]

No, just a pair to run all the stuff and a start battery. Lead is heavy the better the battery the more it weights. I'm sorry the batteries I'm using are 24's @ 80 amps X2 not 27's they are fairly small and easy to find places for them. You can find them for around $60. If you decide to go with two I’ll give you an over looked hint, when you parallel them do not draw power from the posts of one battery draw the + for one and the – from the other this ensures the draw down will be the same on both batteries. Trojan batteries can't be beat I had a group 31 that had been through two popups and the motor home had the water boiled out of it twice and at 9 years old has about had it. I guess you do get what you pay for. Stamar I can’t vouch for all of them but the one we just bought is the very popular Nexuis 7 and it is 5 volt USB recharge. If you are going to do heavy duty computing I guess a tablet is a little light on memory in general but for surfing, mail, Skype and so on I don’t think they can be beat and we are getting a good 11 hours out of a charge. It’s real easy to regulate 5 volts from 12. It will do enough for me to the point I’m going to buy one and leave the big laptop home they are so portable.

[zero]

Ongoing tests/discussion about the various ways to power a laptop (requiring more than standard 12v DC supply)

Made a post in the "best laptop for RV" topic, but want to expand on the power supply end of the process more than the laptop itself. Not interested in laptop specs, how energy efficient, how much power, or latest o.s etc they have. Just the power supply and what fulltime offgrid community might be doing to get around the "conversion" factor.

I've got three RVs or sorts but do not always drive an RV. I've found an alternative power source that has exceeded all my expectations for running a lap-top, TV and DVD player, etc. Duracell sells a "Powerpack 600." It has jumper cables and it is the best jumper pack I've ever used. I've started a few dead diesel trucks with it. This thing has a radio, three 120 volt outlets, one 12 volt power port, two USB power ports, light, and a built-in 600 watt inverter Basically it is a very handy portable 120 VAC power supply. Weighs 32 lbs. Can be recharged at home in an AC outlet or in a car plugged into the cigarette lighter. Has an 26 amp-hour AGM battery inside of it. The inverter can surge near to 1000 watts. When we first had it something came up where we had to sit in our Dodge minivan for two hours. We had a 19" TV/DVD combo packed in back. So we took it out, plugged it into the Duracell Powerpack and watched a movie. Worked great. My wife is home-schooling our latest little kid. Now when I go in the woods to cut trees in the summer - she brings her laptop and the Powerpack. Then setups up the Powerpack in the woods and uses for hours. Never ran it dead yet. Anybody with an RV that isn't wired for an inverter or lacks enough power in the 12 volt power port can use this power pack. It is one of those rare tools I've bought that far exceeded my expectations. My oldest one is now 4 years old and is showing signs of a weakening battery. It won't hold a charge for more then a few weeks when sitting idle. I may take it apart soon and find a generic replacement for the battery inside.

[bajadulce]

Just got back from vacation and dc-dc converter package was waiting.

Results based on a T61 laptop without internal battery pack :

• Following based on AC/DC powerbrick in tandem w/ a fanless 300W DC-AC inverter
  AC-DC powerbrick (standalone) ~.5amps ~6watts
  Idle desktop ~2.2amps ~24watts
  desktop running program ~4.0amps ~48watts
  

• Following obtained w/ a small DC-DC converter set to 20.5DC (identical output of powerbrick)
  DC-DC converter (standalone) ~.04amps ~1watt
  idle desktop ~1.6a ~19watts
  (approx 5 watt savings vs inverter/converter)
  desktop running program ~3.3amps ~40watts
  (approx 8 watt savings vs inverter/converter)
  

So roughly about 5-8 watt savings vs the inverter route or about 1/2 an amp. Worth it?

The little gizmo cost about $4 including shipping. The voltage of course can be regulated w/ a little screw, and haven't done any tests to see what minimum voltage laptop actually needs to run (tho am curious for sure and will). I doubt the draw would change significantly or at all w/ a lower voltage. Unfortunately, some electrical component of this cheapo dc-dc converter is putting out a high pitch squeal. It's not deafining loud, but definitely annoying. Will have to investigate. Prob a case of "get what you pay for"

So that's that and might look into some additional DC-DC converter info on the web. Anyone have a DC-DC converter to comment on?

@smaller computer/tablet etc:

Sounds like a good option. TV commercials seem to constantly bombard us w/ some new "must have" tablet or phone that's for sure. Myself, I like to play computer chess and wife has her own low processing power games she enjoys. So a non-laptop might be all we would ever need to fullfill our occasional entertainment needs.

@Powerpack 600:

That sounds like a pretty handy all-in-one power source for a lot of different uses especially the portable uses you describe. I can see how it would be very handy for the typical RV'er.

[stamar]

nice i had that device linked up several times on ebay.

several people think its either magic or supressed by the us navy or area 51.

im not sure what iq level is needed to tell the difference between a dc ac dc converter and a dc transformer is what i might be called.

If you got it via my link cool. Ive never tried the bare board like that but ive used the things you can buy online that are made from it.

in the event that it works, its worth linking for people that are looking for it.

I believe the board youre using is less effecient than the one im using but i have no figures and it might be negligible.

The plug in devices connect that same board to a cigarette lights and a switch but its still the same thing.

the most recent ones on ebay are made by samsung.

Im going to throw one in the order line for jan

http://www.ebay.com/itm/150W-DC-10-32V-to-12-35V-Boost-StepUp-Converter-for-Notebook-Laptop-Power-Supply-/261142779349?pt=LH_DefaultDomain_0&hash=item3ccd5295d5

here just for the sole purpose of linking it for people confused by the electrical psycho babble looking for a direct link of something to buy.

[stamar]

i havent and wont test anything for you but im using something related to this

http://www.amazon.com/gp/offer-listing/B009DAHHJ0/ref=dp_olp_0?ie=UTF8&condition=all

something for a golfcart or forklift.they are aparently part of all of them.

I have no idea about noise tthey are not made with quietness in mind in general.