Charging a laptop on board

[DoubleEnder]

I may have the chance to spend fairly long parts of the summer on board, but I'll need to use a laptop some of the time. I dont have a shorepower circuit, but I can simply plug in a lead if I am in a marina and use the mains to recharge and run the laptop. However if I am not in a marina, can I run/recharge from 12v? The boat has two 90AH batteries that I use alternately for domestic and starting. The engine is 20hp Beta with a (I think ) 40A alternator. I did have a Sterling regulator fitted but it was problematic and is now out. I was thinking of replacing it anyway - the ability to run a laptop may make this more likely.
Do I need some sort of dedicated kit? The boat isnt big, and I'd prefer a soultion that means drilling as few holes as possible. Can I for instance plug an inverter in to the existing 12v sockets?

Thank you
Graham

 

[TangaraToo]

You can get (Maplins) chargers for laptops that run off 12v using lighter socket. I've used one in the past and it did the job perfectly.

 

[FWB]

There are lots of 12V chargers for laptops. They are DC to DC converters, they step up the boat supply to the required voltage for your laptop, no need to use an inverter. You just need the right one for your particular laptop. Google is your friend.

 

[Barbican]

I use a Lavolta 12v charger, I have one for a Lenovo, and one for an ACER, they plug into a cig-lighter socket, and straight into the laptop. Seem to keep the battery charged. Just need to make sure to get the type with the correct plug for your Lappy.

 

[DoubleEnder]

Fast! Thank you yes that all sounds easy. Much appreciated

 

[RobbieW]

As other have said easy, enough to do with dc-dc converter. However be aware of the amount of power you will take from your battery, the laptop will use +- 3amps. With your setup you should probably try to restrict the times you plug in to those when either the engine is running or you are connected to mains. This is on the basis that batteries are rarely fully charged unless they've been on the mains overnight so you're not starting from a 100% charged position and a batteries longevity is largely driven by the number and depth of charge cycles it is subjected to.

Also, as its not clear that you already do this, designate one battery as engine start and use it only for that purpose - the setup on board should let you do this.

 

[NickRobinson]

FYI, some laptops, eg Dell, will run off a 12 lead but not charge.

Could you use a tablet? The laptop's c. 2/3A continuous could drop to c.1A 20% of the time. I mix and match, laptop on EHU/engine, tablet when sailing.

Finally- get a method of clamping whatever you're using for the inevitable bouncy bits-

 

[jonrarit]

FYI, some laptops, eg Dell, will run off a 12 lead but not charge.

I did wonder about that. My old dell has a 19.5v mains charger but the battery itself says 11.1v .... Am I right in thinking it only uses/needs the other 8.4v for charging of the battery?

Also if wired directly into the boat electrics (which often run over 14v) what are the chances of any voltage spikes or over voltage damaging the laptop?

JR

 

[NickRobinson]

The mains or 12v chargers are 'smart' so volts should be fine. Ditto if you elect for an inverter and the home charger.

Dells and some others have a third needle like pin in the laptop socket to detect the charger. No pin and it doesn't charge

 

[alteredoutlook]

The mains or 12v chargers are 'smart' so volts should be fine. Ditto if you elect for an inverter and the home charger.

Dells and some others have a third needle like pin in the laptop socket to detect the charger. No pin and it doesn't charge

A lot of the dc-dc converters come with a number of different attachment pins. Hopefully one will match your pc!

 

[Aeolus]

Any charger designed for use in a car will work on the boat.

 

[mikenfi]

I have 3 batteries. And charge from leisure batteries I also have solar and wind power charging the batteries.

Invertor will bun more power than it is worth.

 

[ex-Gladys]

I have 3 batteries. And charge from leisure batteries I also have solar and wind power charging the batteries.

Invertor will bun more power than it is worth.

+1... I have a small Belkin 300W portable inverter that I use for a cheap rope cutter or soldering iron (both about 35W). Watching the battery voltage dive, I never use it without the engine running, and that's with solar and a 300AH domestic bank...

 

[Piddy]

+1... I have a small Belkin 300W portable inverter that I use for a cheap rope cutter or soldering iron (both about 35W). Watching the battery voltage dive, I never use it without the engine running, and that's with solar and a 300AH domestic bank...

My Physics is a bit rusty...
If you use a 300W inverter my understanding is that it doesn't use 300W all of the time - that would be about 25A - it will only 'use' 35W (+ any energy used in converting and generating the 240v AC.).
35W at 12v is just under 3A even if you assume your inverter is using 1A to run and do the ac generation that's still only about 4A. For the short periods you cut ropes or solder I am surprised you would need the engine running.

Or have I got it wrong?

 

[GrahamM376]

My Physics is a bit rusty...
If you use a 300W inverter my understanding is that it doesn't use 300W all of the time - that would be about 25A - it will only 'use' 35W (+ any energy used in converting and generating the 240v AC.).
35W at 12v is just under 3A even if you assume your inverter is using 1A to run and do the ac generation that's still only about 4A. For the short periods you cut ropes or solder I am surprised you would need the engine running.

Or have I got it wrong?

We have a 350w inverter and when the telly is on + a 10" netbook (running on 240v but not charging battery), we're drawing around 3 amps.

 

[Hydrozoan]

I use 'universal' type 12V car power supplies and am now on my third in about 10 years - not necessitated by their unreliability, but by the increasing power demand and new tip types of new laptops. I have seen it suggested on here that they are more efficient than small inverters, which is why I've stuck with them and been happy.

Yes, watch out for laptops with a centre pin in the power tip - and it sometimes takes a while for a new laptop model to feature on the PS manufacturers' lists of tips. Although the required tip may be available in the pack (for a related laptop), it can take a bit of digging to be certain.