# Battery/inverter



## Jenm (Feb 24, 2011)

Hello,

Having a little trouble with our leisure battery (110ah), its got an indicator thing on it saying its fine (green fully charged, red flat, white dead), but it doesn't seem to hold its power for very long.

When we brought the MH a month or so ago, they guy said it was new (looks new) so shouldn't be buggered already... No lights left on or anything to obviously drain it, so can't figure it out.

Also, we have a 450w inverter fitted, from what i've read, is that not a bit big for a single 110ah battery? We only use the battery for charging our laptop and small appliances on the move (max 30w laptop, phone charger 0.2A i think - not that i really understand what they all mean).

Hope someone can point me in the right direction


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## Addie (Aug 5, 2008)

An inverter will drain a battery at a surprising rate and the chances are if you've drained it to the point that it is flat and will no longer power anything you've probably shortened its life. 

There is no need to use an inverter for charging a laptop it is totally un-energy efficient to go from 12v -> 240v -> 19v - you need to buy a 12v laptop charger. Same for the mobile phone - get a 12v charger for it.

What else do you use the inverter for?

You say "charging on the move" - if this is the case you would be better using the sockets in the cab so you can take the current from the alternator and the cab battery and leave the leisure battery to charge only while driving.


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## Jenm (Feb 24, 2011)

Thanks addie, 

We don't really know what we're doing and the inverter was in there when we brought it so we used it... I don't think we really need it from what you've said.

We're going away for the summer in it and hope to go offsite where possible. How long do you reckon it'll take to charge a laptop off the alternator? Would be handy to know for planning how long we need to travel for to fully charge it up (the laptop has a 63wh battery).

As I said really don't know much about this stuff so am grateful for the help


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## Addie (Aug 5, 2008)

Your laptop will take as long to charge from the cab as it does from any other power outlet - be it 12v, 240v or whatever. You mentioned "charging appliances on the move" and for me I put the laptop on charge under a cab seat and forget about it and arrive to my destination with a full battery. It depends on how your motorhome is wired, in my last van the leisure battery didn't get enough current from the alternator to sustain running a laptop charger and charging the battery itself, for instance. You are better off allowing the hab battery to charge and using the cab sockets.

If you pop to Maplin's website and search for L40BB that 120w Laptop Charger is on offer currently at £19.99 - it's what I use and is very heavy duty compared to some of the cheaper eBay alternatives.

If you join the forum (£10 for 12mts) there is lots of information on LED lighting available and you can ask as many questions as you want - we're a helpful bunch!


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## 747 (Oct 2, 2009)

If you are leaving your inverter plugged in to the 12 volt supply, it may be taking power from your leisure battery 24/7 as there is a small amount of voltage being used by the inverter.


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## CliveMott (Mar 10, 2008)

A H,m
"as there is a small amount of CURRENT being used by the inverter."

The inverter will take a continuous small quiescent current when connected and turned on. If the inverter is not being used it must be turned off.
The 110 ampere hour battery should be OK to run a 450 watt (max) inverter. If it runs your laptop and charger OK then thats fine.
What you need is access to a digital voltmeter to measure the battery terminal voltage. Take measurements when :-
1 The engine is running
2 The hookup is connected

To determine that both methods of charging are working correctly.

After a night connected to the hookup expect to find very close to 14 volts at the battery terminals, similarly with the hookup disconnected but with the engine running.

C.


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## Jenm (Feb 24, 2011)

Thanks guys, all very helpful 

I thought the issue was solely not holding power but went out today after having it on charge all day to find that as soon as I disconnected it nothing would work... not even a little! 

Tried starting it and leaving it running but again not even a flicker... tried the switch to turn everything on both ways in case i'd forgotten the way it went but litterally nothing! Works fine when its connected to the house but nothing on its own... I think the issue maybe bigger than first thought.

Jen


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## Christine600 (Jan 20, 2011)

Some batteries gets worn out much faster than average. Even if they are the same brand and model. So perhaps you're just unlucky with yours.

The battery in my one year old Nissan went dead and would not take a charge. Since it was so new I got a replacement for free but these things can happen. The new battery now has lasted for 7 years.


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