# How to determine how much battery charge left?



## ched999uk (Jan 31, 2011)

We have only had our MH a week so not really been able to test things out. We are going to Peterborough show on Thursday and I am worried if we can manage on our 110amp leisure battery(1 year old). We do have an 80watt solar panel that might help a very little bit.

Anyway is there any way to find out roughly how much capacity you have left? i.e. can I measure the no load voltage and have a rough guess at how much we have left? The control panel does have a 'charge indicator' but again I have no experience of this.

We do plan on limiting our lighting and using as little batter power as we can but I am worried we will not have any power to run the pump...

Any one any ideas/experience ????


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## CliveMott (Mar 10, 2008)

If you don,t use filiament bulb lighting or run TV for hours then your 80 watt pannel should support you at Peterborough with that battery.
There are several "rules of thumb" about open circuit voltage but none are reliable because of the many things that can alter the figures. Just make sure that the van has been connected to a hookup for 24 hours at home before you depart for the show to ensure its fully charged.

Good luck

C.


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## Stanner (Aug 17, 2006)

As an aside to this and in hope of never flattening the leisure battery TOO much - does anybody know where low voltage battery cutoff units can be bought?


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## barryd (May 9, 2008)

How long are you going for?

My van has one 110AH battery and will easily last 4-6 days depending on time of year and usage. I have no solar panel.

LED bulbs and a small telly make a difference as does the time of year (less lights needed)

If your going for less than 4 days I wouldnt worry.


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## rosalan (Aug 24, 2009)

My Solar panel has a battery condition indication in addition to the 'normal' battery test button but for the period of the Peterborough show, I would not be concerned about your battery life.
You already have a good solar panel and a good battery. What more could you do? 
Well LED lighting can make a big difference; watch the demonstrations on the LED stands. :idea: 
You could add an extra battery (if there is space).
What is the very worst that can happen?  
No pump..... ok! Carry some water in a container.
No lights.... sleep. :wink: 
No TV...... talk.
The battery is a luxury to be enjoyed which, if it fails (it won't) will cause you no lasting harm.
From experience, the TV goes awol first, that is the time to turn off extra lights. :wink: 
Alan


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## spykal (May 9, 2005)

ched999uk said:


> Anyway is there any way to find out roughly how much capacity you have left? i.e. can I measure the no load voltage and have a rough guess at how much we have left?


Hi Ched

As alreadystated the battery voltage can only be a "guide" but for a particular battery such as your own leisure battery you can get to "know" the battery if you take enough readings regularily as you use it. ( after doing that for a while you will eventually stop worrying ...as your confidence in the batteries capacity increases :wink: ) ... Tip: use a digital voltmeter ...don't initially trust any readouts from the control panel :wink:

You can try using The chart found here <<<   ( thanks Frank !) 



Stanner said:


> As an aside to this and in hope of never flattening the leisure battery TOO much - does anybody know where low voltage battery cutoff units can be bought?


Hi Stanner

Maplin do one that works quite well ...I think it is a bit hit and miss as again it seems to work on voltage drop which triggers a relay and as it triggers at a low voltage the load does need to be quite high to ensure that it cuts off at the correct time ( as I said a bit hit and miss :roll: )... but it worked OK on my last motorhome if I wanted to extend a stay and use some of the power from my vehicle battery for uses inside the van. ( usually the laptop or the TV) I actually never ever let it get to the cut off stage in use but having it in circuit just made me feel safe ...in case I was distracted and forgot ( I know it is an age thing :lol: )

Battery Protector << ( it seems that they are on the way out and may only be available at some of the Maplin shops where they still have stock)

When I bought one of these devices and before using it while away, I did a test by connecting the TV to the vehicle battery through it and running the TV it until it cut the power. I was then easily able to start the engine from cold :wink:

Mike


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## ched999uk (Jan 31, 2011)

Thanks very much for all your replies, very helpful. 

We are going for the 4 nights. By what everyone has said we should be OK. We have a netbook as our TV, so it has it's own battery  Although I might need to recharge it as the F1 China GP is on 
I do have a multi meter so the chart will be a useful guide and will help for me to 'learn' the battery.

No LED lights 'yet' but I assume the florescents use less power than the halogens?

We have a few bottles of beer, sorry water so we should be fine 

See you all there


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