Advice sought on Leisure Batteries & laptops

[AlistairW]

Hello,

I am looking at 12v leisure batteries. I reckon at peak load my rig will pull 10 amps, and I think maybe I would image for 6 hours a night. Therefore I am assuming I need a 10x6=60amp/hour battery. But to be on the safe side I should probably round this up to 100amp/hour. Sound sensible ?

My other question is regarding my laptop that is rated at 19V from the mains transformer, or 14.4V from the battery pack. If I wanted to also power this from a 12v leisure battery I am going (I guess) to have to get some sort of voltage step-up transformer. What's the best way to approach this, a simple DC/DC convertor ? - and do I go to 19V or 14.4V ? (I am presuming the 19V is simply extra to charge the laptop battery). Does make me wonder if the laptop would run on 12V anyway.

Thanks

 

Alistair.

 

 

[ChrisLX200]

Sounds sensible to go for the larger battery - in fact, go for the largest you can reasonably handle. You don't want to be running them down flat so capacity will be less than the stated nominal figure. 6hrs is not that long a session during Winter, you may end up with double that for available hours for clear night.

Chargers working from a 12v supply to 19v (or other higher voltages) are available as commercial products so don't bother making one - just search Ebay. I have 2 and they work very very well.

ChrisH

[Bonnylad]

What you're looking for is some sort of inverter. Trawl chandlers and caravan outlets as a start (or other online markets.) All sorts of people have all sorts of gadgets requiring all sorts of voltages to be run off 12v car and boat batteries.

[Owmuchonomy]

My Caravan battery for example is a deep cycle 12V 110 AH version.  I also bought GEL so that there is no chance of spillage.  The major problem with it is that you have to be a weightlifter to carry it anywhere.  I use a small trolley to do so.

[psamathe]

Re: battery capacity: 100A/Hr leisure battery will be quite heavy and something of a challenge for most to carry very far.  You will also probably not get the full capacity out of the battery in real world use (i.e. as the battery discharges so the voltage will drop ...

Re: Laptop power: Much depends on your laptop and accessories availability.  For my laptop I've purchased a car cigarette lighter power supply for the laptop (https://www.amazon.co.uk/gp/product/B00ETB0DRQ).  It was pretty cheap and works well.  But it is dedicated to the laptop so if I change my laptop then that adaptor will no longer be the right one (except in my case it's a Mac so almost certainly would continue to work - it works on both my Mac laptops one 8 yrs old).  If there is such an adaptor available at reasonable price then it is very convenient.  If not then you'll need an inverter and your normal mains psu.  Inverters can be cheap but you probably get what you pay for and remember that being outdoors in damp dewy nights with 240v needs thought and care.

Ian

[Jonk]

I put together a step up voltage regulator to have a stable 19Vdc from a 10-15Vdc source.

http://www.ebay.co.uk/itm/150W-DC-DC-Boost-Converter-10-32V-to-12-35V-Step-Up-Voltage-Charger-Power-TE302-/141752473928?hash=item21011b1948:g:wRoAAOSw3mpXOTsd

My laptop draws about 3.5A which is somewhere in the region of 70W or so.

Whatever you use, make sure it can supply the correct power, else you'll find it'll overheat and possibly damage.

Another power saving tip, is if you want to spend some money, and you know how to do it, I would replace the laptop hard drive with a solid state drive (SSD) unless you already have one. Well worth it, as not only is the laptop quicker, it can double the battery life.

Be very careful with inverters, and understand the requirements and grounding. it's also a waste of power - DC to AC to DC again.

 

[kendg]

I've found that once you start getting into using large batteries and reasonable quality inverters you can get a small portable generator for about the same price. 

When needed I use a 2000 watt generator. Really quiet and gets about 12 hours on a tank of fuel.