# Battery charging



## jonasw19 (Jun 11, 2010)

My batteries appear to charge better (while driving) if I have the lights on. I saw this on a series of 15 mile hops over the last few days.
I do have solar but itseems barely to keep up even in the south of France seldom seeing above 2.5 A on 100w panel, and flicking up and down even though the light is steady. The leisure batteries are often at12.1v in the late evening with 12.3v showing in the middle of the night.
Another thing, just got hookup for the 1st time in 6 weeks and the batteries are only charging at 2 amps the charger capacity is 20amps

2 x 110ah leisure 100ah vehicle
Sargent ec 325 panel.

So after this incoherent wander
1 is my theory correct
2 why are my batteries accepting so little charge
3 will my control panel only show what the batteries require even if the solar could supply more?

Jon


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## nicholsong (May 26, 2009)

Jon

There may be other more knowledgeable people along later, but I will guess that there is this reason for batteries charging better while driving.

The engine alternator output is controlled by a basic regulator whch is designed to reduce the alternator charging when it senses the vehicle battery has reached 13.8-14v. (unless you have a system like below)

The alternator output is then reduced and there is less charge going to the leisure batteries.

If you run with the lights on, and maybe the wipers and fan on full, it takes longer to top-up the engine battery and for the regulator to reduce the alternator output, thus the leisure bateries get a charge for longer.

I have a system (Sterling B2B - there are others)which basically replaces the normal regulator and produces a higher charge to the leisure batteries until they are full.

Cannot answer the other questions.

Geoff


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## jonasw19 (Jun 11, 2010)

But but I thought that the split charge system only allowed charge to the leisure side if the vehicle battery was at or greater than a certain voltage.
Hence my confusion.
If your reasoning is correct then current flows to the leisure batteries whatever the state of the vehicle battery is in (assuming normal coditions, ie no faults).
I may have to develop another theory.

Jon
In the dark,
Cordes sur ciel
France


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## Mrplodd (Mar 4, 2008)

Looking at your battery voltages I would suspect that the batteries are suspect!!! 12.6 volts is what I would expect to see. 

How old are you leisure batteries????

Andy


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## jonasw19 (Jun 11, 2010)

How old are you leisure batteries????

August this year.

I do see 12.7v and higher on both sides after switching the engine off, but I thought this was likely surface charge confusing things. 
My consumption is lowish probably less than 10ah, so I would expect the solar panel to be adequate, and the batteries to be quickly topped up. There and again things have lasted since 12th September with only 4ah total hookup. Including 10 days not moving.

The other thing that occurred to me, is that the engine battery may be on the way down, though it starts on the button with no woes, it is a 2009 mh on original battery.

Something more to ponder
Jon


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## nicholsong (May 26, 2009)

Jon 

Sometimes the Voltage displays on the panels are not accurate, partly due to too small cables and therefore voltage drop.

Get a voltmeter onto the battery terminals - at least half an hour, preferably an hour, after any charging system was supplying power, otherwise you will be measuring residual voltage. My direct measurement is alwys 0.2 volts over the panel voltmeter.

Geoff


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## jonasw19 (Jun 11, 2010)

nicholsong said:


> Jon
> 
> Sometimes the Voltage displays on the panels are not accurate, partly due to too small cables and therefore voltage drop.
> 
> ...


That is a fine idea, I indeed have a voltmeter, however I also have Mrs Asw19 sleeping above the only accessible leisure battery.
Imagine, if you will, me tapping the sleeping form of Mrs Asw19 in the middle of the night brandishing a voltmeter, and saying that this bloke off the Internet told me to check the batteries....
Perhaps in the interests of marital harmony I should defer the comparison 'til after our return to sunny Dorset.

Thanks jon


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## nicholsong (May 26, 2009)

jonasw19 said:


> That is a fine idea, I indeed have a voltmeter, however I also have Mrs Asw19 sleeping above the only accessible leisure battery.
> Imagine, if you will, me tapping the sleeping form of Mrs Asw19 in the middle of the night brandishing a voltmeter, and saying that this bloke off the Internet told me to check the batteries....
> Perhaps in the interests of marital harmony I should defer the comparison 'til after our return to sunny Dorset.
> 
> Thanks jon


Does she sleep 24 hrs a day? Poor you.>


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## jonasw19 (Jun 11, 2010)

No indeed she doesn't sleep 24/7, however I thought I should be checking at night so no solar, and no hook up, and also no current draw. Hence the middle of the night by torchlight. I still think she will get shirty, and the doghouse doesn't have a duvet.
Jon


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## WildThingsKev (Dec 29, 2009)

jonasw19 said:


> That is a fine idea, I indeed have a voltmeter, however I also have Mrs Asw19 sleeping above the only accessible leisure battery.
> Imagine, if you will, me tapping the sleeping form of Mrs Asw19 in the middle of the night brandishing a voltmeter, and saying that this bloke off the Internet told me to check the batteries....
> Perhaps in the interests of marital harmony I should defer the comparison 'til after our return to sunny Dorset.
> 
> Thanks jon


Is there a hint here that your 2 leisure batteries might be separated by more than the usual 30cm of cable? If so, then maybe over long, under sized wire has something to do with it. Perhaps one battery not fully charging and the 2 batteries then equalising post charge?

Just a thought.

Kev


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## Mrplodd (Mar 4, 2008)

Jon

Where in Dorset? Anywhere near Weymouth?

Andy


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## jonasw19 (Jun 11, 2010)

WildThingsKev said:


> Is there a hint here that your 2 leisure batteries might be separated by more than the usual 30cm of cable? If so, then maybe over long, under sized wire has something to do with it. Perhaps one battery not fully charging and the 2 batteries then equalising post charge?
> 
> Just a thought.
> 
> Kev


Cables are not what Brunel would have fitted and the two batteries are probably 5m apart, so I can recable. 
I do wonder if the second battery is necessary, as keeping one battery in a higher state of charge might suffice.

Jon


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## jonasw19 (Jun 11, 2010)

Mrplodd said:


> Jon
> 
> Where in Dorset? Anywhere near Weymouth?
> 
> Andy


Dorchester
And I hope it will be sunny when I return, as the van sprang a leak last night just where senior management has her lair.

I will have to get the mastic gun , purchased only a few weeks ago, to work again for the second time this trip. Fortunately the French still have proper ironmongers. It is lucky that Autosleepers build a van that keeps them in business!

Jon


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## Pudsey_Bear (Sep 25, 2008)

jonasw19 said:


> Cables are not what Brunel would have fitted and the two batteries are probably 5m apart, so I can recable.
> I do wonder if the second battery is necessary, as keeping one battery in a higher state of charge might suffice.
> 
> Jon


I would always prefer to have more than one LB even if it didn't get used much.

5 meters seems a huge distance, or is that electrically rather than physical, you would need a fairly humpty cable in either case.

An absolute minimum of 25mm2 but I'd consider 50mm2

http://www.vehicle-wiring-products.eu/product.php/1030/battery-starter-cable


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## WildThingsKev (Dec 29, 2009)

jonasw19 said:


> Cables are not what Brunel would have fitted and the two batteries are probably 5m apart, so I can recable.
> I do wonder if the second battery is necessary, as keeping one battery in a higher state of charge might suffice.
> 
> Jon


In that case the wires between the batteries are probably fundamental to your problem. I think you will find that the second battery is not fully charging then after the charging completes the first battery trickle charges the second as they equalise.

Try measuring the terminal voltage on both batteries whilst charging (by engine would be best). After a decent run separate batteries and measure them again whilst not under load. Also measure them both immediately after a period of heavy use.

Could be more to it than that as I'm a bit puzzled why the mains charger is only outputting 2A, what is battery 1 voltage at this point? Use mulimeter and check callibration of panel.

Kev


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## jonasw19 (Jun 11, 2010)

Kev I agree with you and nicholsong about calibrating the panel.
This thread has given me some useful homework. I can only get at one of the batteries easily, the other requires the front seat to be removed, so I will defer 'til end of November.
The battery charger output also surprised me, usually on ehu the charger runs at 8 or 9 amps dropping gradually, and if the batteries are quite "full", it drops back quickly to a base of 1 or 2 amps.
This time it never got above 2 amps. This could imply that the batteries were indeed fully charged or that the panel is giving misleading readings.
I have just reset the control panel and will see what happens.
Jon


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## jonasw19 (Jun 11, 2010)

quote=Kev_n_Liz;1721138]I would always prefer to have more than one LB even if it didn't get used much.

5 meters seems a huge distance, or is that electrically rather than physical, you would need a fairly humpty cable in either case.

An absolute minimum of 25mm2 but I'd consider 50mm2

http://www.vehicle-wiring-products.eu/product.php/1030/battery-starter-cable[/quote]

Kev_n_Liz
Distance is about right as the second LB was abandoned in the back of the mh whilst the original is under passenger seat.
The loads are not great, 5 amps would be max, mostly less than 3A unless charging.

I do on occasions run a 350W inverter (with a 40W load) to charge a laptop. This is connected directly to the LB at the back with properly sized, short fused cables.
I appreciate that this will also require an equalising current from the first LB, however this has been done only 3 times in the last 6 weeks and the behaviours described seem independent to this.
Pondering
Jon


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## Bagshanty (Jul 24, 2005)

I agree, unless you are taking a lot of current - over 10 amps, then the vo;tage drop should be minimal. I often turn my fridge off if I need to put in a lot of charge, say after several days wild camping - the fridge takes 15 amps which could be going to the batteries. The fridge will stay cold all day quite happily


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## jonasw19 (Jun 11, 2010)

WildThingsKev said:


> In that case the wires between the batteries are probably fundamental to your problem. I think you will find that the second battery is not fully charging then after the charging completes the first battery trickle charges the second as they equalise.
> 
> Try measuring the terminal voltage on both batteries whilst charging (by engine would be best). After a decent run separate batteries and measure them again whilst not under load. Also measure them both immediately after a period of heavy use.
> 
> ...


OK today was a bit too warm for cycling.

Measured the voltage with engine at tick over
Engine bat. 14.23v
Leisure bat1 14.07v
Leisure bat2 13.67v
So 0.4v lost in the wiring.

With just solar 
Engine bat. 12.5v
Leisure bat1 12.5v
Leisure bat2 12.5v
The control panel gave 12.5v for both engine and Leisure batteries

After ruing engine on tick over for 10 min I switched off and put a small load on the inverter (est 3.5A max) 
The voltmeter showed
Engine bat. 12.73v
Leisure bat1 12.49v
Leisure bat2 12.39v
The control panel gave 12.5v for engine and 12.3 for Leisure batteries 
Conclusions
From the first set of readings there is indeed a voltage drop between the leisure batteries of 0.4v. So I should reduce that with larger wires (kev_n_Liz and WildthingsKev)
The control panel seems to report accurately (nicholsong)
My solar panel may be poor though new in August
The solar controller may not be brilliant.

What else could I do?

Jon


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## Spacerunner (Mar 18, 2006)

Clean the solar panel.
I thought my two panels were clean until I got up on the roof for the twelve monthly and gave the panels a good scrub.


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## jonasw19 (Jun 11, 2010)

I agree the panel may be dirty, but the only way up , without a ladder, is a tottering pile of cushions on a flimsy table and a heave up through the biggest rooflight.

Back down is easy as gravity seldom sleeps, though the colateral damage is frequently severe!
Back in the day, I could do all that sort of thing with ease......... Now I have to content myself with the vaguest memory of what happens below the waist.

Portly 
Jon


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## listerdiesel (Aug 3, 2012)

Just for reference purposes, both of our sets of batteries on solar charging ONLY, were sitting at 13.30V and 13.20V, the lower reading was the larger ones in the Mercedes, and later in the afternoon when it was starting to get dark.

Set 1 is 110AH sealed lead-acid with twin 80W panels and an MPPT solar controller (Main hab battery for the trailer)
Set 2 is 55AH sealed lead-acid with twin 80W panels and an MPPT solar controller (runs the winch and engine room lights)

Sets 3 and 4 are both 225AH AGM sealed lead-acid with twin 100W solar panels and MPPT solar controllers.

As I said, just for reference, one is 3 miles away on farm storage, the other is outside the house.

No loads of any kind on either.

I haven't had a sunny day recently to check, but would expect those figures to rise a bit on a good day.

Peter


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## WildThingsKev (Dec 29, 2009)

I think once you have uprated your cables between the batteries you will find both the 240v and solar charging current will increase. The low 240v charge may just have been due to having full batteries after a decent drive, perhaps the same with the solar though the wires on this may also be quite long and under sized. Is the panel completely unshaded by, for example, roofrack, sat dish etc?

Kev


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## jonasw19 (Jun 11, 2010)

Peter
My batteries are being used daily. I don't drive more than 30 odd miles, sometimes substantially less, so the solar is rather important.
I am concerned that I am missing something either in understanding ( quite likely) or management of resources.
I think that that 100W solar and a bit of driving should give better battery voltages given my quite modest loads. I have all led, no big loads, just a couple of tablets and a phone. Once a week max fire up the inverter and charge the laptop, 40W for a couple of hours.
It seems that my leisure batteries need a bigger wire between them, they are unavoidably separated by about 5m.

I am missing something, though I haven't much idea what.

Jon
Ps haven't run the batteries below 12v (under small loads) yet, usually ~12.2v in th middle of the night


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## jonasw19 (Jun 11, 2010)

WildthigsKev
Solar wiring up,to less than 10cm of the controller, are very manly
Panel is in the only place possible, and I only take much notice when the sun is high , so it is then unshaded.

Presently in Southern France where it is generally quite bright, but it doesn't seem to be doing as well as the previous solar panel only of 70W, despite uprating the wires, but leaving the controller the same. It is a built in Sargent Ec325.

Jon


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## listerdiesel (Aug 3, 2012)

I think that you need to stop and get the batteries right up on charge, then try again.

At present you have no reliable starting point for your calculations, daily usage is not accurately monitored and so on.

The heavier cable would help, but I don't think it is the cause of the trouble, unless it is really small.

Peter


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## jonasw19 (Jun 11, 2010)

listerdiesel said:


> I think that you need to stop and get the batteries right up on charge, then try again.
> 
> At present you have no reliable starting point for your calculations, daily usage is not accurately monitored and so on.
> 
> ...


Peter, before we left I charged each battery for a week. They were new in August
The daily usage scarcely alters unless I charge the laptop, I itself only 60watt hours from empty.
Otherwise it is a few hours of lighting at approx 5watts a few minutes of the water pumps at 1.5A and charging a phone , mifi and tablet. 
So 2.5AH for lights 1AH for water pump 10 AH for the phone etc est 15AH at worst.

Charging by solar 100W panel flat on roof, driving approx 30 miles per day, 1000 miles since 12th Sept
Fridge on gas all the time, one hook up for 2 hours at 2amps on the panel into all 3 batteries.
Though we are OK I wonder why the batteries are ,not more charged, it has only rained 4 times and 2 were at night.

Jon


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## listerdiesel (Aug 3, 2012)

The other option is to check the meter(s) as has already been discussed.

Peter


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## jonasw19 (Jun 11, 2010)

listerdiesel said:


> The other option is to check the meter(s) as has already been discussed.
> 
> Peter


Peter,
I checked the panel against my voltmeter whilst solar was working, they agreed within 0.1V
My panel however does not discriminate between the two leisure batteries, it just gives a single reading for leisure and I can also select the engine battery

Jon


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## listerdiesel (Aug 3, 2012)

Pity you're so far away, it would be nice to get into the system and try and find a fault in there.

Peter


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## jonasw19 (Jun 11, 2010)

I think that I will rewire between the leisure batteries, and review the solar panel installation. The alternator seems OK but I could have that checked, finally I should check all batteries, the engine battery, though it starts fine, is in a 2009 vehicle so more than 6 years old

Sadly there is not much I can do to test this before we slope off in February to Spain.

Thanks to all for your suggestions 
jon

Off to try something Roquefort Cheese tomorrow


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