Laptop Charging

[shaunr68]

Mornin' all. Something in Jagmanx's thread about his battery behaviour got me thinking about how other members' routines for running electronic devices may be different to my own. I didn't want to hijack that thread so thought it best to start a new one.

Do others here charge their laptops and then disconnect them from the power source in order to use them? Or does the term charging in the context of running a laptop refer to just using the device and letting the power settings manage the battery charging as required?

I use a 12v to 19v adapter that plugs into the cigarette lighter socket and must admit that I've always treated this like I would a power outlet at home. The laptop is plugged into the socket whenever in use and I rarely operate the laptop on battery power alone. I'd have thought that charging the device and then disconnecting the power source, thereby constantly going through cycles charging and depleting the battery will reduce the battery life and it's best to use it plugged in wherever possible. Similarly my MiFi device is plugged into USB socket all the time as is my phone.

Thoughts? What do others do?

 

[wildebus]

For something like an occasional charger, I would disconnect it when in a motorhome as there is power being consumed by the electrics in the conversion circuit, albeit a very small amount.
It is not something you would notice at home when you consider that the usuable power that the typical leisure battery delivers in total (around 600Wh) would cost you around 10pence on your electric bill.

I leave my MIFI plugged in 24/7 as it is always in use, but I try and remember to turn off the laptop charger as when it is plugged in - even if it is not connected to the laptop - it stops the inverter from sleeping and so is a waste (as would buying a DC-DC charger when I have a perfectly good Mains one :banana: )

 

[jagmanx]

Depends on solar input

If sunny I use the laptop on charge during the day

Late afternoon or evening I use the laptop on its own battery and recharge the next day

Laptop will probably charge faster if not in use
Mine is currently (Ha Ha) in use showing 19 min to full charge and leisure battery 13.0V

Will turn it off now and wait 10 mins and then power up again to check

For a phone USB charging takes virtually zero but I do not do when it bis dark

 

[QFour]

I have a Samsung Tablet 10" Screen. IMO far better than a laptop but depends what you want it for. If it's just or surfing then its ideal. I can watch films and connect to the TV if I want a bigger screen. I have iGO Nextgen running and CoPilot plus other bits and pieces. It's all solid state and charges from 5v USB. SWMBO uses a laptop at home but An IPad in MH.

 

[delicagirl]

i have an ancient laptop 19amps. i bought an extra large capacity internal battery for the laptop. I had an auto-electrician hard wire its charging lead to one of my leisure batteries, and he also fitted a switch in the hab area to ensure i switch it off, and he fitted a USB socket for my phone charger. i never use the USB AND the laptop at the same time. I use the laptop on internal battery only and then charge it when driving. i can get 4-5 hours useage before the laptop warns of low power, when i will connect it to the habitation battery, if there is enough power, or read a book if there isn't.

 

[colinm]

I only plug in laptops when the batteries get low.

 

[jagmanx]

Not exaclty

i have an ancient laptop 19amps. i bought an extra large capacity internal battery for the laptop. I had an auto-electrician hard wire its charging lead to one of my leisure batteries, and he also fitted a switch in the hab area to ensure i switch it off, and he fitted a USB socket for my phone charger. i never use the USB AND the laptop at the same time. I use the laptop on internal battery only and then charge it when driving. i can get 4-5 hours useage before the laptop warns of low power, when i will connect it to the habitation battery, if there is enough power, or read a book if there isn't.

I think DG is not 100% with electrics
Laptop chargers whether mains or 12v (Input) deliver 19V to the laptop (Output)
Many laptop chargers are rated at 45watts
Thus 12Volts x 4amps gives 48 Watts and so the draw on the LB is 4amps or very nearly
4 amps x 1 hour = 4amp-hours
our LB (1 only) is 90amp-hours so providing I leave enough daylight to topup the LB I am happy to use it plugged in
This is what I am doing now ! and the solar panel is "keeping pace" or better
So NO DRAIN on LB as I compose this post
the voltmeter on my LB is showing 14.2V

 

[delicagirl]

I think DG is not 100% with electrics
Laptop chargers whether mains or 12v (Input) deliver 19V to the laptop (Output)
Many laptop chargers are rated at 45watts
Thus 12Volts x 4amps gives 48 Watts and so the draw on the LB is 4amps or very nearly
4 amps x 1 hour = 4amp-hours
our LB (1 only) is 90amp-hours so providing I leave enough daylight to topup the LB I am happy to use it plugged in
This is what I am doing now ! and the solar panel is "keeping pace" or better
So NO DRAIN on LB as I compose this post
the voltmeter on my LB is showing 14.2V

you are not wrong there !!!! i meant 19volts - which is written the bottom of it. i have never understood the relationship between volts amps and watts and possibly never will!!

i bought a new charger this last week and it says FLC - 90w.

input - 100-240v - 1.5a - 50-60Hz

output 19v - 4.74A

if i have understood your figures properly i can get 4 hours from my laptop charger which is about what i thought.... or i have i still not GOT IT!!

 

[jagmanx]

Not quite

there are 2 considerations

1a How long will your laptop run for before the battery is too low
1b How long will it take to re-charge you laptop battery using your charger
Given output 19v - 4.74A nearly 100 watts (Watts = Volts x amps ie 20 x 5 = 100)

Thus the charger will draw say 8.5amps from your Leisure Batteries (8.5 x 12 =102 watts)

So if your laptop takes 2 hours to charge it will drain your leisure battery by 17 amp-hours
I believe you have at least 2 LBs and perhaps a capacity of 200 amp-hours but say 120 amp-hours so as not to let them get too low.

So even without solar 2 hours charging is fine.
But even on a moderately sunny or bright overcast day a 120 watt solar panel will supply 5 amps ( at 50 % ) and so this will halve the drain on yourb LBs

I am using my Laptop now whilst charging it
the sun is now good My LB voltage is over 14 so is almost full

I am surprised by the power of your charger but the disadvantage of it taking more amps is cancelled out by the advantage that it will re-charge your laptop quickly thus overall the same.

You are quite right to be cautious but you are maybe a bit over cautious

yes only use you laptop charger during the day off LB when at least a bit bright
I do not tend to use my cahrger after say 5pm BUT if it is a nice sunny evening this would be OK as the solar panel will be supplying 80% of the power to the charger
yes use laptop charger off the engine battery/alternator when travelling

Solar in the summer does the job..as Morecambe & Wise used to sing...

"Bring me sunshine..."
This will not drain your LB's at all
Phones/tablets take minimal power on usb charging but as you I only charge these in the daylight

PS my laptop now displays
96% charged
Time to full charge - 12minutes
LB at 13.6V as the sun has just hidden behind a cloud so maybe 50 watts from panel rather than 100 or the max of 120
Battery now at 13.4V but it will go up again one I unplug the charger in 10 minutes

By the way 10 mins = 1/6th hour so even if no solar 9amps x 1/6th = 1.5 amp-hours
Even with just 1 LB of say 90 amp-hours EASY PEASY

 

[jagmanx]

PS

Laptop battery now full (well 99%)
LB voltage 14.0 as a bit more sun.

Shutting down laptop for now
To topup phone and camera(s)

 

[wildebus]

I try to plug my laptop in whenever it is running, to save on wear cycles on the laptop battery.
If power was at a premium, I would set the laptop's power settings to "battery" mode to save as much power as possible. With a 12v adapter and a big battery bank in the motorhome, this isn't necessary for me.

The Hound with the Hair, He not talk with forked tongue

Unless you are REALLY challanged with battery capacity, just plug in the bloody charger when you are using it!
The difference to the leisure battery SOC between plugging it in when it is dark and waiting until it is daylight is about half of sod-all. And just means the batteries will hit the same level of recharge the next day around 15 minutes later.

Personally I just use my power as I need it and don't think it is worth worrying about "I can't use my laptop until it is daylight" etc.
Bigger ticket items such as maybe an electric slow cooker with a constant power draw - ok, those you time their useage, but a laptop or phone charger? nah.

 

[shaunr68]

The Hound with the Hair, He not talk with forked tongue

Unless you are REALLY challanged with battery capacity, just plug in the bloody charger when you are using it!
The difference to the leisure battery SOC between plugging it in when it is dark and waiting until it is daylight is about half of sod-all. And just means the batteries will hit the same level of recharge the next day around 15 minutes later.

Personally I just use my power as I need it and don't think it is worth worrying about "I can't use my laptop until it is daylight" etc.
Bigger ticket items such as maybe an electric slow cooker with a constant power draw - ok, those you time their useage, but a laptop or phone charger? nah.

Thanks all. This is what I was getting at really. Whether it was really a consideration or not, it doesn't sound like it's a big deal either way and is more to do with personal habits in terms of how you use the laptop. My brother has his laptop on charge all the time in his house. When he wants to use it, he unplugs it and goes to sit on the sofa. Me, I'll always sit where I can plug it in and run it from the mains. Always have done, and I do the same thing in the van.

Adjusting the power settings especially screen brightness is a very good point from Hairydog.

 

[barryd]

Mine is constantly plugged in and fully charged when in use and it does get a lot of use. I use a dedicated 12v adaptor. From April to October its not a problem off hookup because of solar. I have once or twice had to charge it from low and it really hammers the leisure battery so I just figured its best left fully charged and it seems to work. We use the laptop a lot on an evening for watching stuff Ive downloaded rather than the TV which lets face it is generally crap.

 

[wildebus]

With one proviso: if you have a mains charger for your laptop running off an inverter (instead of the preferred option of using a 12v power adapter) the power draw can be significant.

One of my laptops has a 90 watt power adapter, and yes it really does draw 90 watts when running the laptop and charging the battery as well. It gets quite hot, so clearly not all those 90 watts are reaching the laptop.

Run that off a typical cheap inverter, which is about 85% efficient and you are pulling 106 watts from the battery. Assume that is at 12v by the time it reaches the inverter, that's 8.8A

You make a good point there. And if you have a big inverter and a very low power draw that it is supplying, it becomes even less efficient . As an example, when the inverter kicks on to run my Fridge, the Fridge draws 36W and extra load on the system is 44W so around 80% efficiency (and I have a top-grade 2500W inverter) due to a big inverter doing so little when on.

But - depending on your setup - that extra OCCASIONAL power use is of little consequence and - IMO - is not worth faffing around with swapping out your existing AC Mains Chargers with DC-DC versions.
Where I have ditched 240V mains supply and swapping out for a DC Supply is for my Network Router and Radio Booster, as that is on 24/7, and also for my Amazon Echo, as that will be on 24/7 while I am in the van - Having the Inverter running permanently for what would be much less than 10W would be silly.

Thanks all. This is what I was getting at really. Whether it was really a consideration or not, it doesn't sound like it's a big deal either way and is more to do with personal habits in terms of how you use the laptop. My brother has his laptop on charge all the time in his house. When he wants to use it, he unplugs it and goes to sit on the sofa. Me, I'll always sit where I can plug it in and run it from the mains. Always have done, and I do the same thing in the van.

Adjusting the power settings especially screen brightness is a very good point from Hairydog.

The Backlight is the real power hog indeed. With most smartphones, you can check in a setting what is using most power and the screen is the number one typically.

 

[delicagirl]

With one proviso: if you have a mains charger for your laptop running off an inverter (instead of the preferred option of using a 12v power adapter) the power draw can be significant.

One of my laptops has a 90 watt power adapter, and yes it really does draw 90 watts when running the laptop and charging the battery as well. It gets quite hot, so clearly not all those 90 watts are reaching the laptop.

Run that off a typical cheap inverter, which is about 85% efficient and you are pulling 106 watts from the battery. Assume that is at 12v by the time it reaches the inverter, that's 8.8A

i have recently had my laptop "thermally repasted" in the hope that it will stop running so hot. I didn't notice this heat until i started using it on my lap, rather than on my big table. The computer shop engineer said it should run 20degrees cooler. Has anyone else had this done and did it make a difference?

YouTube

 

[jagmanx]

With only 1 Leisure battery

I am just (over)cautious.
LB only 90AH

When at home 1/2 year Laptop always on power.

I see no problem with using the battery (modern Lithium) down to about 50%.

I understand the always on power if you have enough.

Will see what happens over the years with Laptop

 

[Caz]

I use my laptop "off power", as that is what it was designed for, surely? When the battery gets low, I charge it up again - whether at home from the mains or in my van, using the cigar lighter adaptor thingy, from the leisure battery.

I thought that was what I was supposed to do.

 

[jagmanx]

Yes and No

I am training to be a politician..

At home mains power 95%

In Moho a mixture...But I never let the laptop battery go too low
Fully charged earlier now at 90% as using it on battery.
We try to only use Truma blown air heating at night and minimal LED lights
Yes over cautious but our previous battery died because of no solar and therefore mis-use
Leisure battery showing 13.1 V

I do not like battery to go too low
1 Too long to re-charge fully
2 Overcautious re battery (laptop)

Just my thoughts but I do not argue with your "method"

PS will shut laptop down very soon but may fire it up again later for 15 mins or so

 

[barryd]

I use my laptop "off power", as that is what it was designed for, surely? When the battery gets low, I charge it up again - whether at home from the mains or in my van, using the cigar lighter adaptor thingy, from the leisure battery.

I thought that was what I was supposed to do.

I think the main concern here was the best way to preserve the vans hab battery not the laptop battery. Nothing wrong with running the laptop on its battery if thats what you like to do. Most laptop batteries will probably outlive the useful life of the laptop anyway. Mind you I dont think ive ever had a laptop more than three years. They generally end up knackered by then.

 

[wildebus]

I like to leave my laptop plugged in so if I walk away with it I know it will be fully charged.
If you run it unplugged and then recharge when battery is low, it limits the "walk away" ability and reduces the options.