# How to keep my laptop alive in my MH



## sleepym (Jul 6, 2009)

I have a largish laptop with 240v and 12v adaptors. On hookup it works fine, but when I try to run off the batteries (2x85ah) my problems start. There doesn't seem to be enough power to run it. It will run the laptop part of the time (during which the MH lights dim) then it cuts out and my laptop resorts to its battery for a few seconds (and the lights brighten). The MH batteries will not run my laptop and charge its battery at the same time, which is really annoying since it only lasts an hour. It isn't any better running off the inverter.

Clearly my laptop is trying to draw more power than the batteries - on full charge - can supply. What do I do? We ideally want to run two laptops and two large flat-screen monitor so that we can work on the move, but the system runs out of steam with only one laptop. Any comments would be very welcome.

Martin


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## gaspode (May 9, 2005)

Hi Martin

Sounds to me as if you have a battery problem.

You should have no problem whatsoever running the largest most power hungry laptop from 2x85a/h batteries. We ran a very hungry 15.4" AMD64 powered laptop for ages with no problems on a single 85a/h battery in our last van. You're clearly getting a hight volt-drop under load if the lights are dimming so I expect either your M/H batteries are shot or you have a serious wiring/voltage drop issue.


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## Stanner (Aug 17, 2006)

I have a similar problem that I can't understand - If I plug my laptop mains adaptor into my 2000w inverter generator the over load trip goes even if the laptop isn't connected to the adaptor.

But the same generator will happilly run a 2300w electric grill and a small electric kettle at the same time without tripping ( I tried it just to see if that sort of overload would make it trip) - just what is it about the load characteristics of laptop adaptors that causes the problem?

Over to the electrical experts........................... :?


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## gaspode (May 9, 2005)

Stanner said:


> what is it about the load characteristics of laptop adaptors that causes the problem?
> 
> Over to the electrical experts........................... :?


Could it simply be that the laptop adaptor doesn't like the crude AC waveform generated by your inverter? Kettles and heaters will work fine off any old waveform.

For a laptop I would recommend a dedicated 12v converter rather than an inverter, more efficient and no waveform issues.


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## Stanner (Aug 17, 2006)

So it's the adaptor that doesn't like the gennie rather than vice versa?


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## motorhomer2 (May 9, 2005)

sleepym said:


> I have a largish laptop with 240v and 12v adaptors. On hookup it works fine, but when I try to run off the batteries (2x85ah) my problems start. There doesn't seem to be enough power to run it. It will run the laptop part of the time (during which the MH lights dim) then it cuts out and my laptop resorts to its battery for a few seconds (and the lights brighten). The MH batteries will not run my laptop and charge its battery at the same time, which is really annoying since it only lasts an hour. It isn't any better running off the inverter.
> 
> Clearly my laptop is trying to draw more power than the batteries - on full charge - can supply. What do I do? We ideally want to run two laptops and two large flat-screen monitor so that we can work on the move, but the system runs out of steam with only one laptop. Any comments would be very welcome.
> 
> Martin


We had a similar problem in our previous van using a dedicated 12v adaptor. Ran OK on mains. Wouldnt charge & run at the same time and was dim on the 12v. I spoke to some one at one of the shows at the time who advised a plug in nearer to the main 12v socket, rather than using an extenion lead and or use a thicker cable when wiring the 12v in. When we changed our van I mentioned this to Timberland who fitted us two sockets in the van with thicker cable wiring and if remember correctly with a higher fuse. Worked beatifully. No probs.

Motorhomer


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## gaspode (May 9, 2005)

That's a perfectly logical scenario motorhomer, the wiring to 12v sockets in many vans is too small and the runs are too long causing a high volt drop.

The O/P however mentions the M/H lights dimming which would indicate a battery problem rather than a wiring deficiency, unless of course the 12v sockets are in the same circuit as the lights which would be very unusual and completely inappropriate.


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## sleepym (Jul 6, 2009)

gaspode said:


> That's a perfectly logical scenario motorhomer, the wiring to 12v sockets in many vans is too small and the runs are too long causing a high volt drop.
> 
> The O/P however mentions the M/H lights dimming which would indicate a battery problem rather than a wiring deficiency, unless of course the 12v sockets are in the same circuit as the lights which would be very unusual and completely inappropriate.


Very unusual and completely inappropriate wiring has already been found. Apparently some wiring was found to be colour coded the wrong way. I will investigate.

I suspect the wiring is inadequate, but when I did test using the inverter I had the same problem which I would guess indicates knackered batteries. They are in fact an old 100ah and a newer 85ah paired some feet apart, all done by someone with even less knowledge of electrics than me!


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## gaspode (May 9, 2005)

In that case, wire your 12v converter or your inverter directly to the battery terminals via a short lead of adequate cross-section with a 15a fuse in line and try again. If that solves the problem you've probably found the answer.

Having said that, coupling an old 110a/h battery to a newer 85a/h is not a good idea and is likely to destroy both batteries.


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## ChesterfieldHooligan (Oct 26, 2008)

:lol: Hi could you have a problem with the laptop battery :lol: 
Brian and Marion


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## sleepym (Jul 6, 2009)

briannod said:


> :lol: Hi could you have a problem with the laptop battery :lol:
> Brian and Marion


No, it's definitely something to do with the motorhome. I get the same sort of problem (apart of course from the failure to charge) when the battery is removed.

Martin


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