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UK Caravanning (uk.rec.caravanning) A forum for the discussion of caravanning undertaken by residents of the United Kingdom, whether in the UK or abroad. It encourages the interchange of views on the merits of models of caravan, makes of tow car, accessories, caravan sites, caravan clubs, and other related topics. The term caravan is to include trailer vans, motor caravans and trailer tents.

Solar power



 
 
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  #1 (permalink)  
Old April 7th 05, 02:51 PM posted to uk.rec.caravanning
robbie rabbit
external usenet poster
 
Posts: 1
Default Solar power

I have a caravelair hermitage with a 110 watt leisure battery. I often
spend 4-5 days at trade shows with no hook up and no option to recharge
using a generator or vehicle. During these periods I would like to use
the lights in the evening and have two showers (meagre if necessary)
per day. Would it be possible assuming average English summer weather)
to keep the battery going long enough to fulfil these duties using a
solarpro plug and play solar charger? and if yes what wattage should I
go for - 30, 50, 75 or 100?

Ads
  #2 (permalink)  
Old April 7th 05, 03:05 PM posted to uk.rec.caravanning
Dave Fawthrop
external usenet poster
 
Posts: 1,941
Default Solar power

On 7 Apr 2005 07:51:11 -0700, "robbie rabbit"
wrote:

| I have a caravelair hermitage with a 110 watt leisure battery. I often
| spend 4-5 days at trade shows with no hook up and no option to recharge
| using a generator or vehicle. During these periods I would like to use
| the lights in the evening and have two showers (meagre if necessary)

You can not reasonably run a shower off a 110 ampere hour battery.
LPG is the fuel for that.

| per day. Would it be possible assuming average English summer weather)
| to keep the battery going long enough to fulfil these duties using a
| solarpro plug and play solar charger? and if yes what wattage should I
| go for - 30, 50, 75 or 100?

There are several alternatives see FAQ below:
If you go for solar, the bigger the better.

You can caravan without that orange cable FAQ
---------------------------------------------

This FAQ is intended to give some pointers on how to caravan without
that orange cable, or at a site where hookups are not available. It
does not try to say what is best, because that will depend on your
individual circumstances, but does try to give basic information about
the methods and the advantages and disadvantages of each alternative.

For general information on batteries see: http://www.batteryfaq.org,
this is a bit US oriented, but lead acid batteries are much the same
worldwide.

Domestic multimeters now cost as little as 2.50 and are useful for
caravan work.

A new fully charged 110Ah Leisure Battery will last most people for a
weekend, but very few a week. For longer than a few days you will
have to recharge the battery somehow. Remember that as batteries get
older and as they have more use/misuse they will hold less charge, and
eventually need replacing.

Leisure batteries are usually *not* the no maintenance batteries
becoming common in cars. If yours allows topping up, always check
your electrolyte, and top up to marks on the body with
distilled/deionized water regularly. You should always charge your
battery(s) before you leave home, either on the bench, or by leaving
the van powered up, you should give either method several days to
fully charge. Cheap chargers make gas, so you must top up the
electrolyte. Expensive electronic chargers do not fully charge the
battery, and make less gas so need topping up less frequently.
Remember also that the electrolyte will evaporate slowly even while
the battery is unused.

There is very little power in a leisure battery so you should use it
as sparingly as practicable. You should use LPG for as many things as
possible. You should also make sure that the your electric appliances
will run off 12 Volts. High power electrical equipment is bad news. A
1000 watt heater used on its own, will run for less than 1 1/2 hours,
500 watts less than 3 hours. 250 watts some 5 hours. As a general
rule something like a TV taking 50W or 4 amps for a few hours per day
is the heaviest load practicable.

The output voltage of a battery falls slowly as a charge is used, and
eventually the 12 V equipment will stop working. TVs etc. need as
many volts as possible. Thin long wires which may be supplied by the
van manufacturer or as a D.I.Y. addition, may have a high voltage
drop. If possible add extra wiring for TV, or other electronic
equipment, of thick wires ?2 sq mm? or preferably more, and as short
runs as practicable.

You should find out how much charge you use on an average day in the
van. The maths is simple 110AH=1320wattHours. watts=12*amps,
amps=watts/12, at 12 V DC. Find how many watts/amps each appliance
uses from labels or instructions. Multiply these by the hours each is
used daily. Add daily charge used in watthours or amperehours used by
each of your appliances together to give daily charge used. You
should replace this charge averaged over 2-3 days. There are many
alternative ways of replacing this charge, the choice is yours, and
will depend on your personal circumstances. Beware especially of red
"standby" LEDs, the circuit behind them uses about 7 watts, which is a
tiny amount of power, but they are on 24 hrs, less the hours they are
used, per day. Allow 12 ampere hours or 144 watthours *each* per day,
which is a significant drain on the battery.

You can use two batteries. An extra battery can be charged in the
back of the car via a split charge relay. This battery should be
securely fastened into the car. The batteries contain Sulphuric acid
which is nasty stuff and if the battery tips over it can do a lot of
harm to the car. Also if you have a crash a battery hitting the back
of your head may cause serious injury. The tiny amounts of hydrogen
and oxygen produced, should cause no problems, in a well ventilated
car. If you use marine batteries, many of these will dump the gasses
overboard via a plastic tube. If you go out in the car and "do"
things on most days while using the van, this should give you enough
charge. If you stay on site or just drive to the local town/beach this
method will not work for you. At some sites battery charging
facilities are available. Swap the batteries daily or at slightest
sign of low voltage. Be warned however that batteries are heavy and
cumbersome to change, and this is not a method for the unfit.

You should ensure that when the van is being towed the battery is
actually being charged. There are no less than three ways in which
the van can be wired, and three ways in which the car can be wired
giving ?5? combinations, some of which do not charge the van battery
when towing. see: http://www.volvoclub.org.uk/towbar_electrics.htm.
If you tour continuously this will be important, but if you just tow
to a site and eventually home again you can probably ignore this
method.

Solar cells are available specifically for vans, but are rated
pointing directly at full sun, which rarely happens in UK, but they do
give some output even on cloudy days, unfortunately the retailers do
not tell you how much. If possible point your cells due south,
slightly below the maximum local elevation of the sun. As a general
rule you will need *big* cells 25 watts or preferably more. If you
calculate charge needed as above, you can get a better estimate of the
size of cells required.

Wind generators are rated at a high wind speed which rarely happens in
an English summer, they give a lower output at lower wind speeds.
The power from a wind generator varies as the *cube* of the windspeed,
so half the wind speed gives a eighth of the power. Many caravan sites
in the countryside are surrounded by trees, which reduce wind speeds.
Other sites by the seaside are better for wind generators. As a
general rule you will need a 25Watt generator or preferably more
powerful. If you calculate charge needed as above you can get a better
estimate of the size of generator required.

Portable petrol driven generators with 240Vac output can be plugged
into your van. They however make a noise which other campers find
objectionable. These generators will also charge your battery, but how
much will depend on the generator and charger in use. Most sites
will forbid their use during the night, so you will need to use 12V
for some of the time.

Invertors which change 12Vdc to 230Vac, are commonly available.
Increase the charge calculated above by up to 20% for things run via
invertors. These should be wired directly to the equipment which uses
230VAC. Do not wire the output of the invertor to the van 230VAC
sockets, which run the charger, which runs the invertor, which runs
the charger ....


--
Dave F
Flight is right
  #3 (permalink)  
Old April 7th 05, 03:05 PM posted to uk.rec.caravanning
Dave Fawthrop
external usenet poster
 
Posts: 1,941
Default Solar power

On 7 Apr 2005 07:51:11 -0700, "robbie rabbit"
wrote:

| I have a caravelair hermitage with a 110 watt leisure battery. I often
| spend 4-5 days at trade shows with no hook up and no option to recharge
| using a generator or vehicle. During these periods I would like to use
| the lights in the evening and have two showers (meagre if necessary)

You can not reasonably run a shower off a 110 ampere hour battery.
LPG is the fuel for that.

| per day. Would it be possible assuming average English summer weather)
| to keep the battery going long enough to fulfil these duties using a
| solarpro plug and play solar charger? and if yes what wattage should I
| go for - 30, 50, 75 or 100?

There are several alternatives see FAQ below:
If you go for solar, the bigger the better.

You can caravan without that orange cable FAQ
---------------------------------------------

This FAQ is intended to give some pointers on how to caravan without
that orange cable, or at a site where hookups are not available. It
does not try to say what is best, because that will depend on your
individual circumstances, but does try to give basic information about
the methods and the advantages and disadvantages of each alternative.

For general information on batteries see: http://www.batteryfaq.org,
this is a bit US oriented, but lead acid batteries are much the same
worldwide.

Domestic multimeters now cost as little as 2.50 and are useful for
caravan work.

A new fully charged 110Ah Leisure Battery will last most people for a
weekend, but very few a week. For longer than a few days you will
have to recharge the battery somehow. Remember that as batteries get
older and as they have more use/misuse they will hold less charge, and
eventually need replacing.

Leisure batteries are usually *not* the no maintenance batteries
becoming common in cars. If yours allows topping up, always check
your electrolyte, and top up to marks on the body with
distilled/deionized water regularly. You should always charge your
battery(s) before you leave home, either on the bench, or by leaving
the van powered up, you should give either method several days to
fully charge. Cheap chargers make gas, so you must top up the
electrolyte. Expensive electronic chargers do not fully charge the
battery, and make less gas so need topping up less frequently.
Remember also that the electrolyte will evaporate slowly even while
the battery is unused.

There is very little power in a leisure battery so you should use it
as sparingly as practicable. You should use LPG for as many things as
possible. You should also make sure that the your electric appliances
will run off 12 Volts. High power electrical equipment is bad news. A
1000 watt heater used on its own, will run for less than 1 1/2 hours,
500 watts less than 3 hours. 250 watts some 5 hours. As a general
rule something like a TV taking 50W or 4 amps for a few hours per day
is the heaviest load practicable.

The output voltage of a battery falls slowly as a charge is used, and
eventually the 12 V equipment will stop working. TVs etc. need as
many volts as possible. Thin long wires which may be supplied by the
van manufacturer or as a D.I.Y. addition, may have a high voltage
drop. If possible add extra wiring for TV, or other electronic
equipment, of thick wires ?2 sq mm? or preferably more, and as short
runs as practicable.

You should find out how much charge you use on an average day in the
van. The maths is simple 110AH=1320wattHours. watts=12*amps,
amps=watts/12, at 12 V DC. Find how many watts/amps each appliance
uses from labels or instructions. Multiply these by the hours each is
used daily. Add daily charge used in watthours or amperehours used by
each of your appliances together to give daily charge used. You
should replace this charge averaged over 2-3 days. There are many
alternative ways of replacing this charge, the choice is yours, and
will depend on your personal circumstances. Beware especially of red
"standby" LEDs, the circuit behind them uses about 7 watts, which is a
tiny amount of power, but they are on 24 hrs, less the hours they are
used, per day. Allow 12 ampere hours or 144 watthours *each* per day,
which is a significant drain on the battery.

You can use two batteries. An extra battery can be charged in the
back of the car via a split charge relay. This battery should be
securely fastened into the car. The batteries contain Sulphuric acid
which is nasty stuff and if the battery tips over it can do a lot of
harm to the car. Also if you have a crash a battery hitting the back
of your head may cause serious injury. The tiny amounts of hydrogen
and oxygen produced, should cause no problems, in a well ventilated
car. If you use marine batteries, many of these will dump the gasses
overboard via a plastic tube. If you go out in the car and "do"
things on most days while using the van, this should give you enough
charge. If you stay on site or just drive to the local town/beach this
method will not work for you. At some sites battery charging
facilities are available. Swap the batteries daily or at slightest
sign of low voltage. Be warned however that batteries are heavy and
cumbersome to change, and this is not a method for the unfit.

You should ensure that when the van is being towed the battery is
actually being charged. There are no less than three ways in which
the van can be wired, and three ways in which the car can be wired
giving ?5? combinations, some of which do not charge the van battery
when towing. see: http://www.volvoclub.org.uk/towbar_electrics.htm.
If you tour continuously this will be important, but if you just tow
to a site and eventually home again you can probably ignore this
method.

Solar cells are available specifically for vans, but are rated
pointing directly at full sun, which rarely happens in UK, but they do
give some output even on cloudy days, unfortunately the retailers do
not tell you how much. If possible point your cells due south,
slightly below the maximum local elevation of the sun. As a general
rule you will need *big* cells 25 watts or preferably more. If you
calculate charge needed as above, you can get a better estimate of the
size of cells required.

Wind generators are rated at a high wind speed which rarely happens in
an English summer, they give a lower output at lower wind speeds.
The power from a wind generator varies as the *cube* of the windspeed,
so half the wind speed gives a eighth of the power. Many caravan sites
in the countryside are surrounded by trees, which reduce wind speeds.
Other sites by the seaside are better for wind generators. As a
general rule you will need a 25Watt generator or preferably more
powerful. If you calculate charge needed as above you can get a better
estimate of the size of generator required.

Portable petrol driven generators with 240Vac output can be plugged
into your van. They however make a noise which other campers find
objectionable. These generators will also charge your battery, but how
much will depend on the generator and charger in use. Most sites
will forbid their use during the night, so you will need to use 12V
for some of the time.

Invertors which change 12Vdc to 230Vac, are commonly available.
Increase the charge calculated above by up to 20% for things run via
invertors. These should be wired directly to the equipment which uses
230VAC. Do not wire the output of the invertor to the van 230VAC
sockets, which run the charger, which runs the invertor, which runs
the charger ....


--
Dave F
Flight is right
  #4 (permalink)  
Old April 7th 05, 03:25 PM posted to uk.rec.caravanning
bill lord
external usenet poster
 
Posts: 2,533
Default Solar power

On 7 Apr 2005 07:51:11 -0700, "robbie rabbit"
wrote:

I have a caravelair hermitage with a 110 watt leisure battery. I often
spend 4-5 days at trade shows with no hook up and no option to recharge
using a generator or vehicle. During these periods I would like to use
the lights in the evening and have two showers (meagre if necessary)
per day. Would it be possible assuming average English summer weather)
to keep the battery going long enough to fulfil these duties using a
solarpro plug and play solar charger? and if yes what wattage should I
go for - 30, 50, 75 or 100?

We frequently go away for a fortnight on Cl's where there is only
limited facilities to recharge batteries. I have two 110 amp batteries
and use the electric in the same sort of way that you describe, and
have found that providing both are well charged at the begining of the
fortnight I change the battery twice so that the equivalent of three
fully chrged batteries lasts me a fortnight.
I have thought about a solar panel to do the chrging for me and
thinking about how much charge we use each day I have decided that
when I eventually do this I will buy a 30 watt panel and would expect
to replce the charge I use on most days with this sort of set up. At a
rough guess you would expect to replace something like 15 to 20 amp
into the battery each day with a 30 watt panel.


(remove the spam to reply)
I don't suffer from stress..................I'm just a carrier
  #5 (permalink)  
Old April 7th 05, 03:25 PM posted to uk.rec.caravanning
bill lord
external usenet poster
 
Posts: 2,533
Default Solar power

On 7 Apr 2005 07:51:11 -0700, "robbie rabbit"
wrote:

I have a caravelair hermitage with a 110 watt leisure battery. I often
spend 4-5 days at trade shows with no hook up and no option to recharge
using a generator or vehicle. During these periods I would like to use
the lights in the evening and have two showers (meagre if necessary)
per day. Would it be possible assuming average English summer weather)
to keep the battery going long enough to fulfil these duties using a
solarpro plug and play solar charger? and if yes what wattage should I
go for - 30, 50, 75 or 100?

We frequently go away for a fortnight on Cl's where there is only
limited facilities to recharge batteries. I have two 110 amp batteries
and use the electric in the same sort of way that you describe, and
have found that providing both are well charged at the begining of the
fortnight I change the battery twice so that the equivalent of three
fully chrged batteries lasts me a fortnight.
I have thought about a solar panel to do the chrging for me and
thinking about how much charge we use each day I have decided that
when I eventually do this I will buy a 30 watt panel and would expect
to replce the charge I use on most days with this sort of set up. At a
rough guess you would expect to replace something like 15 to 20 amp
into the battery each day with a 30 watt panel.


(remove the spam to reply)
I don't suffer from stress..................I'm just a carrier
  #6 (permalink)  
Old April 7th 05, 04:01 PM posted to uk.rec.caravanning
Secret Squirrel
external usenet poster
 
Posts: 81
Default Solar power

robbie rabbit wrote:
I have a caravelair hermitage with a 110 watt leisure battery. I often
spend 4-5 days at trade shows with no hook up and no option to recharge
using a generator or vehicle. During these periods I would like to use
the lights in the evening and have two showers (meagre if necessary)
per day. Would it be possible assuming average English summer weather)
to keep the battery going long enough to fulfil these duties using a
solarpro plug and play solar charger? and if yes what wattage should I
go for - 30, 50, 75 or 100?


look up http://www.solartechnology.co.uk for some useage tips.
  #7 (permalink)  
Old April 7th 05, 04:01 PM posted to uk.rec.caravanning
Secret Squirrel
external usenet poster
 
Posts: 81
Default Solar power

robbie rabbit wrote:
I have a caravelair hermitage with a 110 watt leisure battery. I often
spend 4-5 days at trade shows with no hook up and no option to recharge
using a generator or vehicle. During these periods I would like to use
the lights in the evening and have two showers (meagre if necessary)
per day. Would it be possible assuming average English summer weather)
to keep the battery going long enough to fulfil these duties using a
solarpro plug and play solar charger? and if yes what wattage should I
go for - 30, 50, 75 or 100?


look up http://www.solartechnology.co.uk for some useage tips.
  #8 (permalink)  
Old April 7th 05, 04:27 PM posted to uk.rec.caravanning
Dave Fawthrop
external usenet poster
 
Posts: 1,941
Default Solar power

On 7 Apr 2005 07:51:11 -0700, "robbie rabbit"
wrote:

| I have a caravelair hermitage with a 110 watt leisure battery. I often
| spend 4-5 days at trade shows with no hook up and no option to recharge
| using a generator or vehicle.

Two fully charged (on the bench at home) 110Ah Leisure batteries, would
last 4-5 days.
The only problem would be changing the batteries, which are unwieldy and
heavy.

--
Dave F
Flight is right
  #9 (permalink)  
Old April 7th 05, 04:27 PM posted to uk.rec.caravanning
Dave Fawthrop
external usenet poster
 
Posts: 1,941
Default Solar power

On 7 Apr 2005 07:51:11 -0700, "robbie rabbit"
wrote:

| I have a caravelair hermitage with a 110 watt leisure battery. I often
| spend 4-5 days at trade shows with no hook up and no option to recharge
| using a generator or vehicle.

Two fully charged (on the bench at home) 110Ah Leisure batteries, would
last 4-5 days.
The only problem would be changing the batteries, which are unwieldy and
heavy.

--
Dave F
Flight is right
  #10 (permalink)  
Old April 7th 05, 11:15 PM posted to uk.rec.caravanning
Peter K L Milnes
external usenet poster
 
Posts: 448
Default Solar power

If you go for the largest available solar panel you will get far better
service than the lower power ones. Thus the one to go for would be the
100Watt panel. This should be capable of supplying an initial current of
over 8Amps which should be enough to keep a 110Amp/hr battery well charged.
Incidentally batteries are rated in Amp/hrs which is a sustained rate of
discharge at 100% efficiency. The efficiency falls off as the battery ages
and if the battery has behaved satisfactorily for about 3 to 5 years you
should be able to return it to 100% by fully charging the battery then
emptying out the electrolyte, thoroughly washing the cells to remove
sediment, then refilling with fresh electrolyte of 1.275 Specific Gravity
(diluted Sulphuric Acid). Follow this by a trickle charge to top up the
charge retained from prior to the washout.

Cheers, Peter.

"robbie rabbit" wrote in message
oups.com...
I have a caravelair hermitage with a 110 watt leisure battery. I often
spend 4-5 days at trade shows with no hook up and no option to recharge
using a generator or vehicle. During these periods I would like to use
the lights in the evening and have two showers (meagre if necessary)
per day. Would it be possible assuming average English summer weather)
to keep the battery going long enough to fulfil these duties using a
solarpro plug and play solar charger? and if yes what wattage should I
go for - 30, 50, 75 or 100?



 



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