# Solar



## offgrid (Nov 16, 2015)

Just bought a 100w solar panel kit, what voltage should a healthy battery be at when idle and then with a load on? its a deep cycle 125ah - and if a hook up another in parrallel does that mean the power lasts twice as long? 

Wanting to run a little LED tv and laptop from it - how long in hours approx do you reckon it'll last for,

Cheers


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## karlpe (Nov 16, 2015)

Hi, can't answer you query though interested in answer aswel, also where did you get the solar kit. Thanks


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## trevskoda (Nov 16, 2015)

Try bimble solar or ebay ,i got two 100w panels well under £100.
the ans to how much use just add up the watts on tv etc then devide by 12 which will give the amps,from that you can recon on being able to pull about one third of total from batterys or until the voltage drops to about 11.5,never run the batts down to low as they will never 100% recover and there life span will be very much shortened.


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## witzend (Nov 16, 2015)

offgrid said:


> Just bought a 100w solar panel kit, what voltage should a healthy battery be at when idle and then with a load on? its a deep cycle 125ah - and if a hook up another in parrallel does that mean the power lasts twice as long?
> 
> Wanting to run a little LED tv and laptop from it - how long in hours approx do you reckon it'll last for,
> 
> Cheers



Hard to answer how long as it depends on your solar panels output and the power draw from the telly at a guess I'd say 5 or 6 hrs over 3 days with out the solar and just the one battery


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## eddyt (Nov 16, 2015)

a fully charged battery at idle should be at least 12,8 volt. will drop to 11.5  when flat 
how long it takes depends on age and condition  of battery.


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## Obanboy666 (Nov 16, 2015)

trevskoda said:


> Try bimble solar or ebay ,i got two 100w panels well under £100.
> the anse to how much use just add up the watts on tv etc then devide by 12 which will give the amps,from that you can recon on being abble to pull about one thurd of total fom batterys or untill the foltage drops to about 11.5,never run the batts down to low as they will never 100% recover and there life span will be very much shortened.



Correct me if I'm wrong but when I asked similiar questions an age ago I was told never go below 12.2 volts as this is approx 50% discharged.
11.5 volts is virtually discharged and will knacker the batteries if done regularly.
Searching Google confirms this.


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## offgrid (Nov 16, 2015)

karlpe said:


> Hi, can't answer you query though interested in answer aswel, also where did you get the solar kit. Thanks



just experimenting at the mo, bought it cheap off ebay - £45 solar panel, £25 mppt controller, £20 12v to 230v inverter, couple of leisure batteries from local scrap yard


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## trevskoda (Nov 16, 2015)

witzend said:


> Hard to answer how long as it depends on your solar panels output and the power draw from the telly at a guess I'd say 5 or 6 hrs over 3 days with out the solar and just the one battery



thats about 40/50 amp draw a day,to do that would require a big batt about 120 to 150 recharging through the day to recover.


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## offgrid (Nov 16, 2015)

what about hooking two batteries together, does that make it last longer?


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## Obanboy666 (Nov 16, 2015)

offgrid said:


> what about hooking two batteries together, does that make it last longer?



Yes, just the same as having a larger battery.
I have 2, some members have many more.


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## hextal (Nov 16, 2015)

Obanboy666 said:


> Correct me if I'm wrong but when I asked similiar questions an age ago I was told never go below 12.2 volts as this is approx 50% discharged.
> 11.5 volts is virtually discharged and will knacker the batteries if done regularly.
> Searching Google confirms this.



Thats about the size of it.

It's not so much that you must never take below 50%, rather that it's bad practice to do it regularly as it will shorten the battery lifespan significantly.

Also, traction batteries can be taken down to 80% discharged. So it boils down to whether its a proper deep cycle traction battery or a quasi-deep cycle leisure battery.


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## 1 Cup (Nov 16, 2015)

*100 watt pannel good day 5amps per hour x8 winter*

125AH your pannle could give you 40 amps a day useage
ave you used the battery with your camper or is new 12 .2 volts is as low as you want to go 
On the back of tv should be a pannel to explain Useage mine tv is 35 watts lcd
100 watt pannel should give you up 30 amp a day winter 60 amp or more summer
Charging laptops can be high ampage some are 17/18 volts inverters needed
100 watts = at 5 amps per hour input/ chargeing 30 amps= 100watts
There are charts


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## whitevanwoman (Nov 16, 2015)

My 10" Nikkai TV draws 10 watts and when battery is full, it will give 6+ hours of TV, not sure exactly how long as 6 hours is about the max I use (it also plays video and music).

However running it through a 240v inverter will use more power, so better to use the 12v cable. 

I have a 100 watt solar panel, and for 9 months of year, the leisure battery is fully recharged by about 10am latest. However, this time of year, the panel will only recharge from about 12v to 12.4 during the day, often less. So I have to ration my TV use during Nov - Jan unless battery is fully recharged by driving. 

If you run TV direct off 12v, especially with a solar panel fitted, you will need a 12v stabiliser which means that the current into the TV remains at a level which won't damage the TV - most TV's will work between 12v and 13v input but anymore will damage them. I discovered this whilst listening to radio through TV on a sunny summer day when solar input to battery was around 15v, result was that the sound was ok but no picture, just a black screen. New TV required.

You can get a 12v stabiliser from the Boatshare website for £25. Or only use TV when leisure battery is under 13v, ie, not whilst engine is running or solar panel is charging. 

I never run my leisure battery below 11.9v under load from TV which means that when TV is switched off, the battery settles back at around 12.2v. My battery is 85ma, 3 years old and was secondhand when I got it. When it does eventually go, I will replace with a 110ma battery.


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## hextal (Nov 16, 2015)

band driver said:


> 125AH your pannle could give you 40 amps a day useage
> ave you used the battery with your camper or is new 12 .2 volts is as low as you want to go
> On the back of tv should be a pannel to explain Useage mine tv is 35 watts lcd
> 100 watt pannel should give you up 30 amp a day winter 60 amp or more summer
> ...



I'd be very surprised if you could get close to 40a per day in winter in the UK from a horizontal panel that size.

Its only about 8hrs between sunrise and sunset at the moment, and at Max height the angle is still very low, leaving a side issues such as cloud etc. 

I wouldnt bank on getting much useful from panels this time of year.


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## Deleted member 9849 (Nov 16, 2015)

swiftcamper said:


> Forget solar in the winter it is about as much use as a chocolate fire guard.



I agree with this statement 100%.
Solar is great for most of the year but from Nov-Mar in the UK can't be relied upon to put any meaningful current back into the leisure battery.We have a huge 275 A/H Elecsol leisure battery which can usually last 3-4 days in winter without a recharge,any longer than that and we are looking for a ehu.Remember when it's dark at 5 o clock you will generally use the tv,lights and heating more so that will take a sizeable chunk out of your available amp hours.


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## Tezza33 (Nov 16, 2015)

Last Winter I was in the South of France and a 100W panel struggled even with the blue sky every day, I have since fitted 5x50W panels, new solar charger and two new 100A batteries, last week in Wales no sunshine but bright although cloudy and I still had more power going in than I was using which was 22" 12v TV, 12v Satellite Receiver and the van stereo on for the sound system for probably 5hrs pn, all LED lighting and the laptop using a 12v adaptor instead of my invertor, the point I am making is increase your input and try to cut down on your usage by using low power products, you should have tried doing this 20yrs ago


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## offgrid (Nov 16, 2015)

swiftcamper said:


> Forget solar in the winter it is about as much use as a chocolate fire guard.



Winter project mate while everythings cheap


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## st3v3 (Nov 16, 2015)

offgrid said:


> £25 mppt controller,



That will, without doubt, not be MPPT. It won't charge batteries properly and may well reduce the life of your batteries. Sorry.

Got a link to what you've bought?


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## whitevanwoman (Nov 17, 2015)

swiftcamper said:


> Forget solar in the winter it is about as much use as a chocolate fire guard.



I disagree, I would say that the efficacy is much reduced but that it's better than nothing. Last winter my panel was charging whilst it was snowing, admittedly not much, but there was something going into my battery, which is better than nothing. And I never have to worry about a flat starter battery as the trickle feed which the panel provides in winter is enough to keep the starter battery fully charged even if the van has been stood without being run for several weeks. No need to run the engine or plug into mains elec, and no running costs. 

So long as you are aware of the limitations, even in winter a solar panel can be the difference between the van starting OK and having to call out breakdown for a jump start. 

Yes, its definitely much less effective, but not useless. On a cold crisp sunny winters day, my solar panel can charge at 13+ v gor a few hours which can be the difference between the battery remaining discharged resulting in damage to the battery, and it being given some recharge which may be enough to prevent damage. 

And the peace of mind knowing that even after standing for a couple of weeks in midwinter, the van will start OK is a big relief for someone for whom their van is their only vehicle.


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## Obanboy666 (Nov 17, 2015)

swiftcamper said:


> Forget solar in the winter it is about as much use as a chocolate fire guard.



Have to agree especially if like me you watch long hours of tv with a sky box and inverter.
My 80 watt panel with mppt controller is great in the spring and summer but in winter it barely covers what the motorhome alarm etc uses standing on my drive.
I take my E20i Genny if wilding in Scotland and use C&CC CL's in England, just had 4 days in Cumbria paying £3.00 per day for ehu.
As I said earlier I would probably use more gas than that with heating etc running 24/7.


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## molly 2 (Nov 17, 2015)

st3v3 said:


> That will, without doubt, not be MPPT. It won't charge batteries properly and may well reduce the life of your batteries. Sorry.
> 
> Got a link to what you've bought?


correct its a con ,check out mppt controllers on you tube .some have a display so you have an idea what's going on .


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## whitevanwoman (Nov 17, 2015)

st3v3 said:


> null



I'm afraid I have to disagree again, my solar regulator was donated secondhand but apparently it only cost the previous owner about £20. I don't think it's MPPT, it has no display, just a charging light and battery full light. It's been on my van for over a year, charges my leisure battery fine, cuts out at 16.5v and my secondhand 3 year old leisure battery is just fine and dandy. In fact, I kind of wish the battery would die as I want to replace it with a bigger one but reluctant to bin something which doesn't have anything wrong with it. Anyone want a third hand battery...?

I realise I may have just been lucky with the regulator but I would say don't discount something or write something off without trying it. 

Am surprised that other people don't give solar any credence at all this time of year as I'm definitely getting some input into my battery from panel, not much but enough to keep both batteries at 12.8v and to keep my mifi on permanent charge ( no signal inside the house so mifi has to stay outside on van dashboard when I'm at my house). Maybe my panel is just cleaner from all the Cumbrian rain....


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## st3v3 (Nov 18, 2015)

I said a £20 controller claiming to be MPPT won't be. The problem is the way they try to fool simple tests to look like MPPT, that I what may cause problems.

PS - 16.5V is way too high!


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## whitevanwoman (Nov 18, 2015)

st3v3 said:


> I said a £20 controller claiming to be MPPT won't be. The problem is the way they try to fool simple tests to look like MPPT, that I what may cause problems.
> 
> PS - 16.5V is way too high!



I thought 16.5v was high but it's not often it gets to that, and only for a few seconds at a time and it obviously hasn't done my battery any harm. If I am concerned I can switch off my panel or just plug in my fridge and put that excess solar power to good use. 

My comments simply reflect my actual experiences with my panel and regulator over the past year. Maybe I am the exception to all the rules.


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## trevskoda (Nov 18, 2015)

A good all round float charge is about 13.7 ,max should be 14.4.
My we set up 2=100w panels through a simple split regulator works just fine and the batts are always up even here with dank dark over cast sky charging 2 100a batts.


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## whitevanwoman (Nov 18, 2015)

When my engine is running my voltage display for leisure battery is usually showing 14.2+ v, up to about 14.4v, depending on whether lights, fan etc is on, drops to about 13.5-14v if mobile phone, tablet etc is on charge. It rarely drops below 13.1v when running unless my leisure battery is very discharged.

There are 2 issues here, one being the efficacy of the solar panel charging system, the other being the draw from the leisure battery by appliances. My draw is limited, mainly recharging devices, led lighting and TV/ media player, with no alarm, GPS tracker, dash cam, fridge etc which take a constant draw from the battery. 

If my elec consumption was more, then certainly my 85ma battery and solar recharge would not be anywhere near sufficient this time of year, and I would probably blame the panel for being useless, when in fact it's not useless but just insufficient for my needs. If I used elec kettle, microwave, large TV, satellite, hair dryer etc then there's no way my set up would be anywhere near enough.


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## 1 Cup (Nov 18, 2015)

*power hungry*

Above post 
Do you have them all on a once evan EHU would struggle
:scared:


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## whitevanwoman (Nov 18, 2015)

band driver said:


> Above post
> Do you have them all on a once evan EHU would struggle
> :scared:


Don't even have all those in the house let alone in the van, am just a simple old fashioned country lass who uses a map and compass to navigate and a towel to dry my hair. My alarm has 8 legs and 2 tails.


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## hextal (Nov 18, 2015)

whitevanwoman said:


> Don't even have all those in the house let alone in the van, am just a simple old fashioned country lass who uses a map and compass to navigate and a towel to dry my hair. My alarm has 8 legs and 2 tails.



That sounds like a spider I don't ever want to meet.


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## trevskoda (Nov 18, 2015)

whitevanwoman said:


> Don't even have all those in the house let alone in the van, am just a simple old fashioned country lass who uses a map and compass to navigate and a towel to dry my hair. My alarm has 8 legs and 2 tails.



chernobyl hound.:scared:


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## HelenandJan (Nov 18, 2015)

Obanboy666 said:


> Have to agree especially if like me you watch long hours of tv with a sky box and inverter.
> My 80 watt panel with mppt controller is great in the spring and summer but in winter it barely covers what the motorhome alarm etc uses standing on my drive.
> I take my E20i Genny if wilding in Scotland and use C&CC CL's in England, just had 4 days in Cumbria paying £3.00 per day for ehu.
> As I said earlier I would probably use more gas than that with heating etc running 24/7.



You paid £3 per day for EHU in Cumbria?  Where?

I would charge more than that if you parked on my drive.  Lol.


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## Deadsfo (Nov 18, 2015)

whitevanwoman said:


> Don't even have all those in the house let alone in the van, am just a simple old fashioned country lass who uses a map and compass to navigate and a towel to dry my hair. My alarm has 8 legs and 2 tails.



yeh these Russian Chernoble dogs can be like that.:lol-053:


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## Deleted member 9849 (Nov 18, 2015)

Just to clarify my comment on solar power in winter,I said it can't be relied on to produce any meaningful current in winter.By that I meant contributing towards running TV,lights and heating which in my case is substantial as we like to watch some tele when it gets dark early.This will deplete the leisure battery and even with a substantial sized battery I will have to get an external charge every 3-4 days.I have 180 watts of solar panels on the roof and for 3 seasons of the year have a surplus of energy and here lies the disparity of solar power in the UK.
In the warmer months and long days when not so much energy is required I have a large surplus,when I need more power in the winter months I have a deficit.
I agree with previous posters about keeping the engine battery topped up in winter with a trickle charge after the leisure battery has fully charged,a useful function especially if the van is in a storage compound with no ehu available.
I remain unconvinced about the effectiveness of solar power in winter except for trickle charging the vehicle battery.I have spent a fair bit on solar panels and a 270 A/H leisure battery but even so it is still inadequate in the winter months and I wouldn't want to give anyone the impression that it was.


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## Obanboy666 (Nov 18, 2015)

HelenandJan said:


> You paid £3 per day for EHU in Cumbria?  Where?
> 
> I would charge more than that if you parked on my drive.  Lol.



Crossfells C&CC CL site in Clifton Dykes near Penrith.
Basic facilities, no shower but toilet and chemical toilet disposal. Level hard standings approx 1/4 mile from any roads. Great for dog owners like me as its in a large grassed field. Site is run on trust with very helpful owners who are motorhome owners.
£10.00 without ehu which I use in the spring/summer and £13.00 with ehu.
for a family £13.00 a night is well worth it especially in the lakes imho.


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## Johnnygm7lsi (Nov 18, 2015)

sidthekid said:


> Just to clarify my comment on solar power in winter,I said it can't be relied on to produce any meaningful current in winter.By that I meant contributing towards running TV,lights and heating which in my case is substantial as we like to watch some tele when it gets dark early.This will deplete the leisure battery and even with a substantial sized battery I will have to get an external charge every 3-4 days.I have 180 watts of solar panels on the roof and for 3 seasons of the year have a surplus of energy and here lies the disparity of solar power in the UK.
> In the warmer months and long days when not so much energy is required I have a large surplus,when I need more power in the winter months I have a deficit.
> I agree with previous posters about keeping the engine battery topped up in winter with a trickle charge after the leisure battery has fully charged,a useful function especially if the van is in a storage compound with no ehu available.
> I remain unconvinced about the effectiveness of solar power in winter except for trickle charging the vehicle battery.I have spent a fair bit on solar panels and a 270 A/H leisure battery but even so it is still inadequate in the winter months and I wouldn't want to give anyone the impression that it was.



Well done, first sensible post on solar power I have seen, I haven`t got enough space on my roof for solar panels to keep my 660 Amps of battery power charged up, and if I had it would only be in the summer, you see numerous posts saying,,, my panels keep my battery charged up enough to charge my phone, lights and MIFI, even in winter


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## whitevanwoman (Nov 19, 2015)

Johnnygm7lsi said:


> Well done, first sensible post on solar power I have seen, I haven`t got enough space on my roof for solar panels to keep my 660 Amps of battery power charged up, and if I had it would only be in the summer, you see numerous posts saying,,, my panels keep my battery charged up enough to charge my phone, lights and MIFI, even in winter



Well, mine do. But then I only need about a tenth of your elec consumption. Not quite sure what your reference to charging mifi implies.

I have to disagree with generalisations which are different to my experiences.

I would have thought that it is sensible to get a range of experiences, as everyone has different requirements and set ups and consumption and then the OP can make an informed choice as to what best suits their needs, dependent on their anticipated consumption. We don't actually know what the OPs needs are, they may be a low elec consumer like me, or they may need much more elec like you. 

I agree with the surplus in summer, deficit in winter statement, but that does not mean that solar is useless. Solar works in winter to a significantly lesser degree than in summer - I simply adjust my consumption and expectation accordingly but that doesn't mean it's useless. For some people solar doesn't adequately meet their needs in winter. For me, if I'm careful, I can manage. I'd much prefer to have my panel in winter than be without it. 

If all the posts in this thread bar one are not sensible, perhaps you shouldn't bother reading it or becoming involved in it.


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## portiapug (Nov 19, 2015)

whitevanwoman said:


> Well, mine do. But then I only need about a tenth of your elec consumption. Not quite sure what your reference to charging mifi implies.
> 
> I have to disagree with generalisations which are different to my experiences.
> 
> ...



Another sensible post which takes a different view on matters.

For a start, there was a post saying that despite spending money on lots of solar panels and big batteries, the power only lasts 3 to 4 days in Winter ..... Sorry, what do you expect and why is someone wildcamping for days on end in one place? Of course your batteries will be depleted because you have not driven anywhere else to top them up again. You probably used a big inverter to Microwave lunch or run your Satellite TV system. The power source is not finite and needs careful management.

Having used the van in Winter with only a 90 watt freestanding panel, I am not talking hypothetically. The 19" TV does not get used, instead we use an old 10.8" TV that uses slightly more than 1 amp, which is probably around 20% of what a 22" TV will use. Moving on to another spot puts more charge into the leisure battery/ies.


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## 1 Cup (Nov 19, 2015)

*amps*

Storage
 is king  12v 105ah battery fits in locker,
 so thats all we have 
So I have 50 amps
4 days = 96 hours = .5 amp an hour = solar pannel better help out :juggle:


No ehu in wilds turbine or generator or both together 

What should I do?


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## kris (Nov 19, 2015)

eddyt said:


> a fully charged battery at idle should be at least 12,8 volt. will drop to 11.5  when flat
> how long it takes depends on age and condition  of battery.



I am running a split charge system +2x 115 a LB and the gauge never shows more than 12.6 when fully charged at rest.It reads 14v  when van is running but settles to about 12.6 after a few hours with no load and van standing.The answers to how low a reading can be are very varied? Any final answers?


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## whitevanwoman (Nov 19, 2015)

band driver said:


> Storage
> is king  12v 105ah battery fits in locker,
> so thats all we have
> So I have 50 amps
> ...




Work out your likely daily power consumption first. What appliances will you want to power?


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## whitevanwoman (Nov 19, 2015)

kris said:


> I am running a split charge system +2x 115 a LB and the gauge never shows more than 12.6 when fully charged at rest.It reads 14v  when van is running but settles to about 12.6 after a few hours with no load and van standing.The answers to how low a reading can be are very varied? Any final answers?



My display unit reads 0.1v lower than the actual battery voltage, so double check your battery level using a multi meter direct off the terminals. There may be a voltage drop because of long thin wires. 

I've found varied answers too about what is the lowest safe level so I stick to 11.9 as my very lowest when not under load and try to make sure that the battery is recharged asap, if not enough solar the next day to do this then I run engine or go for a short drive to get it back up. A friend lets his go to 10.5 but not sure how long his batteries last for if regularly discharged that low. Under load from TV it can drop to about 11.5 which, when TV is switched off, bounces back up to about 11.9v. At 11.5 I turn TV off and read a book! This only happens very occasionally during Dec and Jan. I often just run the engine for 20 mins to warm up van and reduce condensation.


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## 1 Cup (Nov 19, 2015)

*2 battery*

When rested are both batteries the same volts when not connected 12.6  a and b 12.8
And same ampage hours 125ah
12.6 one battery is not fully charged
If unconected for 30 mins and winter
100% Fully charged 12.7 and above upto 14.4 100%
12.5  90%
12.42 80%
12.32 70%
12.20 60%
12.06 50%
11.9 40%
11.75 30%
11.58 20%
11.31 10%
10.5 
still can charge  and leve for 30 mins take reading?

Been told the weakest battery is what you work with. but i have only one battery? 
:bow:


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## Stanski (Nov 22, 2015)

*Bicycle genny?*



band driver said:


> .... No ehu in wilds turbine or generator or both together  What should I do? ....



Why not buy a bike and an axle stand - connect a suitable 13v generator and pedal.  Keeps you fit whilst keeping you busy and you could watch TV ot listen to music all at the same time.


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## Deleted member 9849 (Nov 23, 2015)

portiapug said:


> For a start, there was a post saying that despite spending money on lots of solar panels and big batteries, the power only lasts 3 to 4 days in Winter ..... Sorry, what do you expect and why is someone wildcamping for days on end in one place? Of course your batteries will be depleted because you have not driven anywhere else to top them up again. You probably used a big inverter to Microwave lunch or run your Satellite TV system. The power source is not finite and needs careful management.
> .


You are right to mention that ''The power source is not finite and needs careful management'',which was the basic tone of my reply regarding solar power during the winter months i.e.the sun cannot be relied on to contribute much towards power requirements so you have to be careful how you use it if you don't have a backup charging source.I fully expected to have to recharge the leisure battery(ies)after several days without moving the van so it wasn't a surprise as you insinuated in your reply.For your information I rarely wildcamp for several days in one place but have occasionally had to do this without a hook up,I think it useful and informative to let fellow members know about my experiences so they can make an informed decision about solar power.
The reason for my post was to advise members who may be considering a solar installation that even with a good sized solar array and large leisure battery it will produce only a fraction of what can be achieved in the warmer months and to have a back up charging system available if for whatever reason you are staying in one place.
I am certainly not criticising the principle of solar power and would always have a solar panel on my motorhome,it's great in the warmer months to achieve electrical independence and useful in winter to trickle charge both the engine and leisure batteries,just don't expect too much from solar panels in winter.


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## Haaamster (Nov 27, 2015)

Have any of the people with solar tried it in the alps, most days there can be fair bit of sun when out of the shade, do they work there, just asking cos I will be heading that way about xmas time.


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## Teutone (Dec 20, 2015)

just my 2p.....

you can read a lot about solar charging with people having polar opposite results. Without looking at EACH individual installation etc you can NEVER compare the results. When I added my 2nd leisure battery I made a very small wiring error (conceptual not physical) and as a resul my second leisure battery was almost not used. Would have been easy then to blame the solar panel for not charging properly, don't you think?
Only by accident I found my error in the wiring. I had bought a new inductive amp multimeter and wanted to play with it and that quickly showed where I had gone wrong.

So keep in mind, one solar install isn't the same as the other. With 12Volt systems, a small mistake can be dear. The whole thing needs to be looked at as a package. You can buy the most expensive hardware, wire it wrong and the result will be: "solar is rubbish"

I well matched set of components, installed properly and the result will be: "My solar works just fine"

getting my coat now.... :wacko:


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## Johnnygm7lsi (Dec 20, 2015)

band driver said:


> When rested are both batteries the same volts when not connected 12.6  a and b 12.8
> And same ampage hours 125ah
> 12.6 one battery is not fully charged
> If unconected for 30 mins and winter
> ...



How come 100% is 12.7v and 14.4 is also 100%


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## trevskoda (Dec 20, 2015)

Johnnygm7lsi said:


> How come 100% is 12.7v and 14.4 is also 100%



Because 12.7 is at rest 14.4 is max from engine alt when charging,once stopped it will go to rest in about half hr and you will not get any more in charging above this and it will boil the battery  and shorten its life.


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## mac163 (Dec 20, 2015)

*Leisure Battery*





Here is a chart for battery usage ... hope it helps ?
Cheers
Mac


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## DavidB963 (Dec 21, 2015)

Just for information and my 2p worth.

MPPT at the low powers and current levels we use in MH's are largely a waste of money.  That is for a real MPPT controller not the cheap pretend ones on eBay etc.
PWM controllers will suffice for our needs and for the Radio Amateurs amongst have the bonus of being able to switch the pulse frequency if it interferes with your set up.

My set up 2 x 150W panels,  currently delivering roughly 2.1A on a winters day in Scotland, not much but still a charge the batteries would not get.  These feed 2 x 115Ah batteries for domestic and a 110Ah for Radio use, fed by a PWM 20A twin battery controller set at 70:30 to the domestic side.

Over many years of fitting panels to my various caravans and motorhome I have found that what makes the biggest difference is getting the correct cables, sufficient to carry the current required with minimal voltage drop and ensuring that all connections a good, clean and tight to ensure the same.  You will lose more on the wrong cable and bad connections than anything else.

Regards
Dave


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## listerdiesel (Dec 21, 2015)

swiftcamper said:


> Not strictly true but when you really start looking into charging batteries it becomes very complicated your head soon starts to spin, the boating fraternity are the ones to listen to,most motorhomers have not got a clue.



Interesting comment!

I wouldn't agree with such a generalisation as many motorhomers are very knowledgeable about different parts of their vehicle, but not necessarily ALL of them.

There are a lot of products on the market in the consumer leisure area that are pretty close to Snake Oil, especially when it comes to electrical items.

MPPT or Maximum Power Point Tracking is a fairly complex process whereby the solar panel output is kept at its optimum and most efficient value, while charging a battery at a lower voltage. To do this properly involves some interesting electronics that are not cheap, so MPPT controllers tend to be in the £80 level rather than the £15 items you see on ebay.

Look inside both types and you'll see where the money goes.

Our solar panels are working OK, both on the trailer and on the Mercedes. Both have MPPT controllers and both are sitting the batteries at a decent float rate of 13.50V or thereabouts.  As my latest pair of controllers have LED's that are lit all the time, there is a bit of power to make up each morning, but even in winter we can get a reasonable output.

Fitting bigger and bigger batteries is no use unless you fit bigger charging facilities. We have 2 X 26A mains supplies in the trailer, one for the habitation batteries and one for the winch and engine room batteries. If we need to charge the batteries quickly we just plug into an EHU supply or run our little Chinese generator.

The Mercedes has 2 X 50A mains supplies for each battery set, only single rate charging but we already have three-stage charging with the solar controllers, so no need to duplicate the effort.

We aim to get the batteries charged up quickly after discharging and not leave them sitting around discharged for any length of time. That is very important for Lead-Acid batteries of all types, but particularly for any VRLA or sealed types. 

Most built-in motorhome chargers are inadequate for additional batteries, although a B2B charger can help a lot if you are driving daily.

Peter


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