How long can I expect a leisure battery to last?

Post by **veedweeb** » 27 Nov 2006, 21:08

I'm just wondering, if I fit a leisure battery (and split charge and all that stuff), and I use it with an invertor to run my laptop, how long can I expect it to last?

Just a rough idea would be great

Cheers,

Steve.

Post by **kevtherev** » 27 Nov 2006, 21:17

Well... I ran a portable telly for 6hrs (not constant) off an inverter..and there was still power left

whats the power rating on your laptop?

Post by **irish.david** » 27 Nov 2006, 21:35

So many things can affect this calculation that it's almost meaningless.

But..... a laptop using 40W - 40W

Being powered by an inverter that's 85% efficient - 40 / 0.85 = 47W

Current being drawn from 12V system - 47 / 12 = 3.9A

Fed from a fully charged 63Ah battery - (63 x 2/3) / 3.9 = 10.7 hours
(assuming battery gets to 1/3rd charge
before undervoltage trips in inverter)

However, you're never going to get that due to having the lights on or the stereo on or the battery isn't fully charged or you're playing games on the laptop or the temperature is low or............. a million other things.

Dave

Post by **veedweeb** » 27 Nov 2006, 21:53

Thanks for the replies...

I realise the question was a bit vague, but I've no experience of using leisure batteries at all, and this electricity stuff is like black magic to me!!

What I was getting at was this...

I'm a surveyor, and it'd be useful if I could work in the van sometimes - typing up reports on site and so on. Maybe a couple of hours work at the most. It's a bit longer than the laptop battery itself will last (having been using it on site on battery power).

From what you are both saying, it looks like it'll be OK.

I wanted to confirm it because I'd have to install a battery and all the magic gubbins to make it work, and I didn't want to go to that trouble and expense if it was only going to last half an hour

Post by **"WEAZLECHIN"** » 27 Nov 2006, 21:56

you know the best thing to do, try it. if it lasts 5hrs, then 5 it is.

Post by **kevtherev** » 27 Nov 2006, 22:01

for that amount of time I'd just buy a battery and charge it up at home with a leisure batt charger attach the inverter...and not bother with the split charge system....unless you intend on camping in it of course

Post by **veedweeb** » 27 Nov 2006, 22:08

I won't be camping in it - it's a Caravelle.

But I like your idea, Kev... I wonder if those solar panel charger things are any good?

Post by **kevtherev** » 27 Nov 2006, 22:11

Post by **veedweeb** » 27 Nov 2006, 22:12

kevtherev wrote:no

That's another brilliant idea bites the dust then!

Post by **kevtherev** » 27 Nov 2006, 22:20

Thats my opinion...no doubt others will give you theirs

I have found that charging up two leisure batteries is enough for a weekend without mains in the winter...running gawd knows what!

Post by **shepster** » 28 Nov 2006, 08:55

Why not just buy a cigar lighter lead for your laptop and plug it straight into the fag lighter?

Post by **"WEAZLECHIN"** » 28 Nov 2006, 09:53

i have to say it, but that would be the obvious answer!!!

Post by **veedweeb** » 28 Nov 2006, 09:59

shepster wrote:Why not just buy a cigar lighter lead for your laptop and plug it straight into the fag lighter?

Wouldn't that just drain the main car battery really quickly?

I suppose I could leave the engine idling, but I'm not too keen to do that for a couple of hours at a time.

Post by **"WEAZLECHIN"** » 28 Nov 2006, 10:09

try it, (on a hill). or carry one those starter packs.

Post by **cumbriankeith** » 28 Nov 2006, 17:24

I have used a jump starter pack for powering a laptop or a telly - mine is 18 Ah and calculated according to the above figures and in practice it lasts around 3 hours.
Maplins have them on offer for about £20. And you get a sort of compressor thrown in too...
A 12 volt lead for your laptop might cost another £15 or more.

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How long can I expect a leisure battery to last?

How long can I expect a leisure battery to last?

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