# Battery health



## wp1234 (Sep 29, 2009)

Just wondering if someone can enlighten me. 

I have a 2015 990df with a control panel located above the entry door( the type with curved ends) which gives me two readings for the habitation battery health one in percentage terms and the other in voltage. 
Last weekend after two days wild camping the battery voltage was sitting at 12.7 v but % down to 48% . 12.7 volts is pretty healthy in my view but the 48% worries me .

Any thoughts , do I need to recalibrate the unit and if so how do I do it ?

Thanks all .


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## WildThingsKev (Dec 29, 2009)

Two questions spring to mind.
1. Have you got a manual?
2. Do you have a solar panel?

Kev


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## wp1234 (Sep 29, 2009)

WildThingsKev said:


> Two questions spring to mind.
> 1. Have you got a manual?
> 2. Do you have a solar panel?
> 
> Kev


Hi Kev ,

Yes I do have a manual but doesn't really help and yes I do have a solar panel .
The manual is silent on the % readings which is a little odd


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## WildThingsKev (Dec 29, 2009)

In that case I suspect that your batteries really are at 48% capacity. Without the solar panel your battery voltage might only read about 12.1v/12.2v (or lower if under load). The panel is trying to charge a little but in this gloomy weather is not managing to raise the charging voltage to anything like the 14v you might expect when getting close to being fully charged.

Kev


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## Wizzo (Dec 3, 2007)

WildThingsKev said:


> In that case I suspect that your batteries really are at 48% capacity. Without the solar panel your battery voltage might only read about 12.1v/12.2v (or lower if under load). The panel is trying to charge a little but in this gloomy weather is not managing to raise the charging voltage to anything like the 14v you might expect when getting close to being fully charged.
> Kev


I would agree with this assessment. To confirm this just check the voltage reading in the morning before the sun has struggled high enough to put any charge back in.

JohnW


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## wp1234 (Sep 29, 2009)

Thanks for the info both.
I'm home now so have the batteries on 240v and showing 100% fully charged . Will take off 240v and see what happens in this gloomy weather and report back . 
2 days with no EHU and down to 48% didn't sound too good to me , perhaps I'm being too optimistic .

Wyn


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## Pudsey_Bear (Sep 25, 2008)

wp1234 said:


> Thanks for the info both.
> I'm home now so have the batteries on 240v and showing 100% fully charged . Will take off 240v and see what happens in this gloomy weather and report back .
> 2 days with no EHU and down to 48% didn't sound too good to me , perhaps I'm being too optimistic .
> 
> Wyn


Could be a duff cell in the LB, or something with quite a draw.


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## WildThingsKev (Dec 29, 2009)

Reading your first post again it seems like you might have just the one leisure battery?
If so, then 2 days at this time of year is ok.

Kev


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## BrianJP (Sep 17, 2010)

I suspect the panel has to be calibrated to provide reliable readings. However most of these panels don't do this anyway for many reasons. At the end of the day the only way to get an accurate reading is to use a voltmeter across each battery with no load. That should give you a better idea of battery condition.


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## wp1234 (Sep 29, 2009)

Yes that's right just the one 100ah leisure battery , I don't think I've got room for another .


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## BillCreer (Jan 23, 2010)

Kev_n_Liz said:


> Could be a duff cell in the LB, or something with quite a draw.


If he's seeing 12.7v then it can't be a duff cell.


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## tugboat (Sep 14, 2013)

I agree with Wild Things Kev. I think the panel is just showing the voltage that the solar is producing. I would suggest pulling the fuse on the solar circuit, and then see what voltage is displayed on the panel.

What sort of solar controller do you have? MPPT? Does it have a display too, that you can see the output voltage?

A test meter is your friend at times like these.

Are you sure you can't fit a second battery? I put one in an outside locker near the main LB, and parallelled up with big cables.


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## rayc (Jun 3, 2008)

wp1234 said:


> Yes that's right just the one 100ah leisure battery , I don't think I've got room for another .


I have the 2014 Rapido Equipment and Comfort brochure in front of me. The spec for the 90df series shows as an option "Compartment and cabling for 3rd battery" for all models in the range. I would have thought therefore that there is room?
Without knowing your usage over your 2 days it is difficult to judge whether you are being optimistic in your expectations of a single 100ah battery. Nearly 50% left after 2 days may be as good as it gets depending on usage.


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## wp1234 (Sep 29, 2009)

Just been checking my battery readings over the last week , my mistake in earlierreply I do have 2 x 100 Amh leisure batts not just the one. 

With the van in the drive plus fully charged up batteries, no EHU connectedreadings on Sunday showed 12.9V 100% full then on Tuesday 12.8 V 68% and today 12.8V and 50% . I'm strugglingwith understanding why the battery voltageis a very healthy 12.8 V but the percentage left is showing just 50% . I'vebeen taking these readings at the crack of dawn before the little sun we havehad gets onto the panel.

I'm thinking that the panel has been calibratedwhilst on EHU or having just taken off EHU so its thinking that 14.0V is 100% .

Any ideas welcome ?


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## listerdiesel (Aug 3, 2012)

Battery readings on open-circuit checks are an approximation only, there are loads of things that affect the reading, temperature etc etc.

Your percentage meter is 'should' looking at current flow in and out of the battery to calculate what is in there, using a voltage reading is not good enough.

Our batteries sit around 13.5V or so with a bit of nudging from the solar panels, and will go up to 14.00V on a good day.

We haven't used the chargers yet as the panels are doing the job, same as the trailer where the batteries are at almost identical voltages.

Percentage calculations need to start from a known point of 100% and then deduct or add discharge and charge accordingly.

We have automated fork trucks with these calculators fitted, they rely on the accuracy of the % reading to tell the machine to return to a charging point and get a charge in.

Peter


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## 747 (Oct 2, 2009)

wp1234 said:


> Just been checking my battery readings over the last week , my mistake in earlierreply I do have 2 x 100 Amh leisure batts not just the one.
> 
> With the van in the drive plus fully charged up batteries, no EHU connectedreadings on Sunday showed 12.9V 100% full then on Tuesday 12.8 V 68% and today 12.8V and 50% . I'm strugglingwith understanding why the battery voltageis a very healthy 12.8 V but the percentage left is showing just 50% . I'vebeen taking these readings at the crack of dawn before the little sun we havehad gets onto the panel.
> 
> ...


I suspect that the % readings are allied to the amount of discharge and are provided by the amount of Amps your batteries are taking in. It is a fact that as a battery becomes almost fully charged, the Amps dwindle to a trickle. Instead of showing this with an Ammeter, you have a % figure (why, I don't know, sounds daft to me). If you have a Solar Panel connected then you cannot read anything into the voltage level as it will vary with the amount of light.

My advice is to fit an Ammeter somewhere ....... or just ignore the % figure and put the van on hookup.


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## wp1234 (Sep 29, 2009)

Thanks both . Looking at this in the round I think my best bet is to recalibrate so I know the 100% starts at a full battery state. Anybody know how to do this on the Rapido 990df ?
Thanks


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