Solar

[whitevanwoman]

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.

 

[1 Cup]

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:

 

[Stanski]

Bicycle genny?

.... 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.

 

[Deleted member 9849]

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.

 

[Haaamster]

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.

 

[Teutone]

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:

 

[Johnnygm7lsi]

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:

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

 

[trevskoda]

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.

 

[mac163]

Leisure Battery




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

 

[DavidB963]

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

 

[listerdiesel]

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