Car charger socket attached to 12V battery to power laptop

[antobag]

I am currently in the process of setting up a 200W off-grid solar panel system to charge a 12V battery, which will in turn power a laptop and some other devices. I have decided against using a DC to AC inverter, as this will leech away some of the already-scarce power that I have, and pretty much everything I'm using can run directly off DC current.

Instead, I would like to connect the battery to a car charger socket (http://www.amazon.co.uk/Practical-Motorbike-Tractor-Cigarette-Lighter/dp/B00C7MXQAU/)
I will then plug my laptop into this socket using an appropriate adapter (ie. for my laptop I will use a 12V-19V step-up adapter such as this one: http://www.amazon.co.uk/In-Car-Charger-Samsung-R440-Laptop/dp/B00JS0M30I/ref=cm_cr_pr_product_top)

I just have a couple of questions about the car charger socket. According to my laptop's AC power adapter, my laptop runs on 19V, 4.74A (90W). The car charger socket comes with an in-line fuse holder with a 3A fuse. I am certain my laptop will occasionally need more power than the 36W that this would provide.

Question 1) Would it be okay to go ahead and put a 5A fuse into it to create 60W of power, or might there be a chance of it overheating?

Question 2) If the 5A fuse is okay, what would happen if my laptop happened to need more than 60W? Would it merely start using the internal laptop battery, or worse?

 

[Bluejets]

I'd suggest you get a car cigarette lighter socket and a bakolite fuse holder and put a 10 amp fuse in there and wire it together yourself.

The one shown says 120W but I doubt very much that the plastic fuse holder shown would handle 10 amp let alone the adaptor.

 

[KrisBlueNZ]

I agree. I don't know how much current a car cigarette lighter socket is supposed to be able to supply safely, but I wouldn't go putting a bigger fuse in there - I would use a different connector for the laptop's voltage booster; one that is rated for the current you need.

I don't know for sure how the laptop will behave if the 19V supply droops, but I wouldn't assume it will just draw the extra required current from the battery and just keep working as if nothing happened. In other words, you should make sure your 19V supply can provide the maximum specified current.

 

[davenn]

I agree. I don't know how much current a car cigarette lighter socket is supposed to be able to supply safely,

Generally 10A is the max

 

[Gryd3]

I agree. I don't know how much current a car cigarette lighter socket is supposed to be able to supply safely, but I wouldn't go putting a bigger fuse in there - I would use a different connector for the laptop's voltage booster; one that is rated for the current you need.

I don't know for sure how the laptop will behave if the 19V supply droops, but I wouldn't assume it will just draw the extra required current from the battery and just keep working as if nothing happened. In other words, you should make sure your 19V supply can provide the maximum specified current.

Hopefully the op is still using the Laptop's battery, which will help if the source voltage dips or get's interrupted.

 

[antobag]

Thanks everyone. This is my first post on this forum and I'm blown away by how many people have replied so quickly, I really appreciate the advice.

In terms of wiring it together myself, would the following be appropriate?:
Socket: http://www.ebay.co.uk/itm/12v-24v-2...upply-Outlet-High-Quality-Cover-/360643893924
Bakelite fuse holder: http://www.ebay.co.uk/itm/Bakelite-Fuse-Holder-c-w-20A-Fuse-Triumph-BSA-Norton-/151369481072
Cable: http://www.maplin.co.uk/p/twin-core-20a-figure-8-cable-priced-per-metre-xs73q

Would I need anything else? I assume I just do the following:

• Connect the socket to the red (positive) and black (negative) cables
• Cut the fuse holder cable and connect it to the red cable
• Connect the ends to the 12V battery (What sort of connector should I use for this?)

Apologies for the newbie-ness, this is all very new to me.

 

[Bluejets]

Parts look ok..... fuse goes in series with red lead.
As far as terminals, it depends on what type of battery. If lead acid (car battery) then like pic below.

 

[antobag]

I was planning on getting one of the following. It's an AGM battery, would those terminals still work?:
http://www.ebay.co.uk/itm/12V-Xplor...Itra-Deep-Cycle-5-Year-Warranty-/171376568297

Also, as I've already bought the 120W car charger socket that I mentioned in my original post, could I just swap out its little fuse holder for the 20A Bakelite one (and put a 10A fuse in there)? I'm just asking because I'm concerned that the rest of the parts (ie. the cables and the socket) wouldn't be able to deal with the heavier load.

 

[Bluejets]

Battery terminals should be fine.

As far as the original socket, pretty much goes without saying that if the fuse holder is not up to the job then the rest of the assembly will more than likely follow suit.

 

[antobag]

Ah that's a shame. I guess I'll just have to buy more sockets and terminals then!

On that note, can I connect multiple terminals (the ones pictured above) to the same battery?

 

[antobag]

Just another quick question: these blade-type fuse holders seem to be cheaper but have the same 20A rating as the Bakelite one mentioned above:
http://www.ebay.co.uk/itm/2-x-In-Li...arts_Vehicles_CarParts_SM&hash=item3a9046df8a

Would there be any difference in using the blade-type fuse holder over the Bakelite one?

 

[lilmatt119]

Those terminals will work.

My advice, if you plan to add other devices beside this 12v socket, is to run hot wire from battery to a multiple position barrier strip with a jumper strip installed, and then do the same on the ground wire. that way you have multiple points to add/remove wiring without the hassle of everything coming loose like it will if added straight to the terminal. Keeps everything nice and neat as well. I use the barrier and jumper strips in my cars when I add lights and radios and such. Velcro the strip inside a project box or something similar, cut holes for the wires to run through.