Question on 12 volt power

chrisnchris · Senior Member

Question on 12 volt power

powerstream · Veteran Member

Under those circumstances Yes.
Ian

Yuglamron · Guru

The age old 12 volt debate.

Personally I cannot see how you would go without 12 volt,yes a gennie is a great tool but the times when you cannot run a gennie ie when there are others camped about you and it would be a sound problem.Storing lots of fuel has to be considered as well.

With modern LED lights the power draw can be so low a relatively small solar panel charging a battery will give you light for quite a while.

Fresh food storage generally needs a fridge that can be 240 of course but you cannot run a gennie 24/7.

You can get by without 12 volt but life can be a lot easier with it.

LeighW · Member

As above, the main decider will be if you wish to run a fridge or freezer, if so what type and for how long.

If you have a place to install a three way fridge then you could go that way as it can run on gas and then if you
only need lighting you can use camp lights of some type. Forget trying to run a 3 way off battery power as this
is really only intend to be used whilst travelling and powered by the vehicle. A compressor type fridge will be much
more efficient running on 12V ie 4AH draw compared to 10AH for a three way and much better at cooling under high
ambient temperatures

If you decide you need a compressor fridge/freezer then yes you'll need a battery system of some type. Depending on who long you intend to
stay stopped at one site and wether you intend to use the fridge as a fridge or a freezer will determine how much battery capacity you'll need.
Running a fridge/freezer as a freezer uses a lot more battery power than running it as a fridge.

You can top up with solar but it is expensive and keep in mind that the sun doesn't always shine so don't skimp out on battery
capacity or panel size.

You can always top up with your genie if it has a 12V output but generally these don't provide much output for the cost of operation
on 12V, you would be better to buy a 240V high capacity battery charger and connect it to the genie.

In most situations you will not been very popular with your neighbours if you run the genie at night so you'll need to ensure batteries
are kept in a charged condition to keep the fridge running through the night, nothing worse than a freezer full of of spoiled meat.

Cheers
LeighW

chrisnchris · Senior Member

Thanks everyone for ypur thoughts on our problem
Cheers

johnnz · Senior Member

One of the reason's why free camping is so good is to stop in a nice out of the way location, get away from sometimes noisey campsites. Then another camper comes along and gets thier generator out, that's not so good.

I can't think of anything worse than starting up a generator whenever I stop.

Having a self contained vehicle with solar panels, good capacity batteries and an inverter is in my opinion the only way to go.

Isn't that the attraction of being a Nomad, grey or otherwise. To be totaly self contained.

Johnnz

LeighW · Member

oldtrack123 wrote:
LeighW wrote:
Snip - - - A compressor type fridge will be much
more efficient running on 12V ie 4AH draw compared to 10AH for a three way and much better at cooling under high
ambient temperatures - - - cheers
LeighW
Hi
A minor ???[AH] but misleading use of terminology
Which can cause confusion!!!
A correction is suggested ,perhaps by the poster???
After all, IT is a tech thread

Peter

Ok I was using it as a comparison, worst case scenerio small compressor fridge running continuosly for one hour drawing 4A = 4AH, were as absorption fridge 10A = 10AH.

Less than worst case scenerio compressor fridge will cycle amd abosorption fidge may also cycle depending on make and age, and therefore actually AH used under these this conditions could be less.

-- Edited by LeighW on Monday 13th of August 2012 04:37:27 PM

oldtrack123 · Guru

LeighW wrote:
Snip - - - A compressor type fridge will be much
more efficient running on 12V ie 4AH draw compared to 10AH for a three way and much better at cooling under high
ambient temperatures - - - cheers
LeighW

Hi

A minor ???[AH] but misleading use of terminology

Which can cause confusion!!!

A correction is suggested ,perhaps by the poster???

After all, IT is a tech thread

Peter

oldtrack123 · Guru

LeighW wrote:
oldtrack123 wrote:
LeighW wrote:
Snip - - - A compressor type fridge will be much
more efficient running on 12V ie 4AH draw compared to 10AH for a three way and much better at cooling under high
ambient temperatures - - - cheers
LeighW
Hi
A minor ???[AH] but misleading use of terminology
Which can cause confusion!!!
A correction is suggested ,perhaps by the poster???
After all, IT is a tech thread

Peter

Ok I was using it as a comparison, worst case scenerio small compressor fridge running continuosly drawing 4A = 4AH, were as absorption fridge 10A = 10AH.

Less than worst case scenerio compressor fridge will cycle amd abosorption fidge may also cycle depending on make and age, and therefore actually AH used under these this conditions could be less.

Hi Leigh

I think you are missing the point

A devise draws Amps Not Ahrs

Ahrs is amount of energy used AND must have a time period usually 24hrs, 4A by 24 = 96A hrs used in 24hrs

but it is unlikely to run continously for 24hrs [unless as a deep freeze ],more betwen 30% & 60% RUN TIME

30%[8hrs x4A]= 32Ahrs in 24hrs

60% [16hrs x4A] =72Ahrs in 24hrs

From those figures battery capacity & charging requirements can be calculated

-- Edited by oldtrack123 on Sunday 12th of August 2012 09:10:39 PM

LeighW · Member

Isn't that what I wrote just not in as much details?

An AMP by definition is with respect to hours (see below exact), an amp meter shows how many instantaneous amps an hour a device is using,
when it is operating which is what I believe I wrote in short hand above.

"In practical terms, the ampere is a measure of the amount of electric charge passing a point in an electric circuit per unit time with 6.241 × 10¹⁸ electrons, or one coulomb per second constituting one ampere.^[5"

Note coulomb per second

Cheers

Leighw

-- Edited by LeighW on Monday 13th of August 2012 09:42:55 AM

-- Edited by LeighW on Monday 13th of August 2012 09:44:55 AM

-- Edited by LeighW on Monday 13th of August 2012 09:45:34 AM

-- Edited by LeighW on Monday 13th of August 2012 10:15:33 AM

oldtrack123 · Guru

LeighW wrote:
Isn't that what I wrote just not in as much details?

An AMP by definition is with respect to hours (see below exact), an amp meter shows how many instantaneous amps an hour a device is using,
when it is operating which is what I believe I wrote in short hand above.

Sorry Leigh
But it seems you do not understand that Amp is just an instaneous value
IT HAS NO TIME BASIS
An Ampmeter only shows the Amps AT ANY INSTANT in time ,It has no relation to hrs, minutes ,or even seconds of time
No electrical device can be simply claimed to be using "x "amphrs
WITHOUT STATING OVER WHAT PERIOD OF TIME eg "'x'" Amphrs over 24hrs
You should have simply posted that the fridge's running current was 4 Amps
Then, it would be correct & not confusing /misleading
BASIC electrical theory & UNITS
ONE Amphr is a measure of Current used over time , but may not be ONE hour, but of course is not ENERGY[WATT hrs] used ,
But that 1Amph could be used by 0.01A X 100hrs
OR 100A for 0.01Mins

Peter

Ps I see it took 4edits to get that post to what you believe is right
biggrin
-- Edited by oldtrack123 on Monday 13th of August 2012 02:23:19 PM

-- Edited by oldtrack123 on Monday 13th of August 2012 08:39:54 PM

LeighW · Member

Deleted

-- Edited by LeighW on Monday 13th of August 2012 04:33:53 PM

-- Edited by LeighW on Monday 13th of August 2012 04:34:35 PM

-- Edited by LeighW on Tuesday 14th of August 2012 12:43:45 PM

oldtrack123 · Guru

Hi Leigh

Sorry, but you are just digging a bigger hole for yourself

AND THIS PROOVES IT

[Quote]Sorry Peter you are wrong, an amp meter shows the instanteous amperes per hour being consumed by a device at the time of measurement, if this was not the case the reading would be useless for instance an amp meter shows a device is drawing 4 amps, if it was not related to time then you would not be able to determine that that device if left running from a battery for one hour would consume a total of 4A per hour or 2A if left running for 30 minutes."end Quote]

That is utter gibberish

Just googling does not get you the knowledge

A DC electrical devise uses or generates Watts [orAmps & volts]both are INSTANTANEOUS measurements which can be constantly varying over time

Even your Waeco is unlikely to draw exactly the same current over say one hour

You are showing a complete lack of understanding of even basic electrical meters & I suggest you find a 2nd year electrical apprentice & have a talk to him

He will explain the functions of different electrical meters & measurements

Ohm's laws & dirivatives cannot be used with Ahrs ,so I am keen to see some answers to

the above questions

Ps Now 7edits on your last post & still wrong

Forget Google go and get some basic electrical theory

Peter

-- Edited by oldtrack123 on Monday 13th of August 2012 08:37:27 PM

-- Edited by oldtrack123 on Monday 13th of August 2012 08:46:27 PM

-- Edited by oldtrack123 on Monday 13th of August 2012 11:04:18 PM

oldtrack123 · Guru

Muso wrote:
And so it begins. Happens almost every time (sigh)

Yes Musso

It will happen when some make technical statements that are wrong & misleading .

If not corrected ,those misleading statements come to be believed ,over time

That can lead to further difficulties in understanding other areas

Do not believe every thing you read on any forum especially when some post well out of their field of expertise & knowledge!!!

Unfortunately many do go uncorrected!!!

I will stand by all my posts on this thread

Ahrs have no value unless tied to a time period

eg. Ahrs used in 'X' hrs

An Ammeter measures the current at any instant [does not measure over time]

If the amp meter responce was fast enough it could be micro seconds & MOST CERTAINLY NOTHING TO DO WITH HOURS

An oscilloscope can be used to measure Amps & is extremely fast in responding to

INSTANTANEOUS VALUES

Google is not the seat of all knowledge unless some basics are understood

It only those witha little knowledge who do not understand

Perhaps the confusion come from those whose limited knowledge comes from working, with solar , batteries & their Amphrs capacity ,& meters [not Amp meters] that record the cumulative Ahrs used over a time period [ not just for an single hr] the period can be anything from minutes to weeks

eg "X" Ahrs used over 24day

take a device that has a constant current draw of 1A

it will use 24Ahrs of battery capacity over 24hrs

but if it draw was 1A for 12hrs then 0.5A for the next 12hr it would use 18Ahrs of battery capacity over that 24hr period

NOTE THE TIME PERIODS MUST ALWAYS BE GIVEN

The simple fact is that there is no such electrical unit as an Ahr

It is purely a loose term that evolved in the battery industry to give an INDICATION of battery capacity

The True capacity of a battery is WATT HRS

Peter

,

Remember the old saying

"a little knowledge can be dangerious"

-- Edited by oldtrack123 on Monday 13th of August 2012 10:58:22 PM

-- Edited by oldtrack123 on Monday 13th of August 2012 11:01:26 PM

jimricho · Guru

yawn yawn yawn yawn yawn yawn yawn yawn

The village pedants strike again! wink

jules47 · The Happy Helper

biggrin biggrin biggrin biggrin biggrin biggrin biggrin biggrin biggrin biggrin biggrin Ha! (sorry OT)

oldtrack123 · Guru

jimricho wrote:
The village pedants strike again!

It goes further than be pendantic

It is totally incorrect terminology ,but those who do not no better will not understand THAT

To say 4Ahrs is absolutely useless information

After ALL it is supposed to be a technical thread

The CORRECT terminal should be used

Now just to show how useless the statement is

I'll ask a few simple questions

I have a 12v device that uses 200Ahrs !!

[the same sort of statement as" a Waeco uses 4Ahrs", or" my Engel uses70Ahr"]

What size cables do I need?

How much energy [watthrs] @ 12v will it use in 24hrs?

How long will it take to discharge a 200Ahr battery to 50% SOC

What will be the voltage drop in 10M of 6B&S cable??

Jim

Perhaps you would like to show your knowledge ,& do the caculations??

The answers WILL be interesting!!

Especially if you try to use well established electrical formulae.

As any well trained electrician would know

Peter

Muso · Veteran Member

And so it begins. Happens almost every time (sigh)

03_troopy · Guru

Thanks Oldtrack, it's also one of the things that bugs me, incorrect use of units when quoting current draw, battery capacity etc (almost as much as cable size units.. mm auto wire, AWG/B&S and mmsq cca). To most it seems trivial, but then again they don't work with the stuff every day.

PeterD · Guru

LeighW wrote:
An AMP by definition is with respect to hours (see below exact), an amp meter shows how many instantaneous amps an hour a device is using,
when it is operating which is what I believe I wrote in short hand above.
"In practical terms, the ampere is a measure of the amount of electric charge passing a point in an electric circuit per unit time with 6.241 × 10¹⁸ electrons, or one coulomb per second constituting one ampere.^[5"

Your first sentence is completely out of order. The last sentence is straight from http://en.wikipedia.org/wiki/Ampere If you go to the first sentence of the paragraph you quoted from you will see "The ampere (SI unit symbol: A), often shortened to amp, is the SI unit of electric current."

Now if we look up http://en.wikipedia.org/wiki/Electric_current you will see "The SI unit for measuring the rate of flow of electric charge is the ampere, which is charge flowing through some surface at the rate of one coulomb per second. Electric current is measured using an ammeter." This is a flow rate and not a quantity.

If we look further we will find http://en.wikipedia.org/wiki/Ampere-hour "An ampere-hour or amp-hour (symbol Ah, AHr, A·h, A h) is a unit of electric charge, with sub-units milliampere-hour (mAh) and milliampere second (mAs). One ampere-hour is equal to 3600 coulombs (ampere-seconds), the electric charge transferred by a steady current of one ampere for one hour." Here we have a quantity of electric charge defined.

So we have two terms, the ampere which is a flow rate and the ampere-hour which is a quantity. We should use these terms correctly or it shows doubt in the rest of what we are saying.

LeighW · Member

Deleted!

-- Edited by LeighW on Tuesday 14th of August 2012 09:06:36 AM

-- Edited by LeighW on Tuesday 14th of August 2012 12:42:57 PM

LeighW · Member

Deleted

-- Edited by LeighW on Tuesday 14th of August 2012 09:31:15 AM

-- Edited by LeighW on Tuesday 14th of August 2012 12:42:19 PM

LeighW · Member

Ok, to stop the waste of space I made an error:

Amp hours applies to battery capacity.
Amps refers to current in a circuit.

It never ceases to amaze me how the "so called technical experts" rarely offer any useful information first off
but sit back and wait for someone to make an error and then critique them.

The original poster was obviously happy with the post and anyone with any electrical knowledge
would have known what I meant and seen it as it was, just trying to give them some useful input.

Cheers
LeighW

-- Edited by LeighW on Tuesday 14th of August 2012 12:35:05 PM

oldtrack123 · Guru

chrisnchris wrote:
Hi
Hubby and I debating ? over whether 12 volt is necessary .We will be free camping where possible
Thanks
Forget to add we will have a generator as well

-- Edited by chrisnchris on Thursday 9th of August 2012 08:36:19 AM

Hi Chris

Sorry for your question being buried

Now to your question

YES if you expect to do a lot of free camping ,A good 12v set up is essential.

But I would suggest it be based on 12v equipment & solar

Generator are useful in an emergency but are expensive to run as a main source & you may have problem in some areas such as National parks where they are often banned & with neighbours in other areas'

You should use gas for ALL heating & cooking

Forget about trying to run anything like that from your solar & batteries unless you spend BIG money

I would also suggest you forget about inverters ,they have inbuilt inefficiencies & are potentially dangerous unless the 240v side is permanently wired into the van system IN THE CORRECT MANNER

What you need to do is sit down & list :-

[1]what appliances you wish to use

[2]how long per day you expect to use each of them

[3]the WATTAGE rating of each

[4]Multiple the hours of daily use of each by IT'S Wattage rating

Add up all in [4]

That will give you your expected DAILY requirement of ENERGY[Watt Hrs]

Then determine the period that you may wish to free camp without other means of recharging the batterries

From that the solar panel requirements can be caculated

You may be able to use the geny for emergency recharging subject to location but you would need to have a large capacity charger for fast charging [NOT THE 12V output of the generator]

If you do frequent driving while free camping ,your vehicle alternator can also assist

"Power Stream " can help in that area

Lots of points are required to be considered before you will have a set up that will meet all your needs

Others include:-

importance of cost recovery .

What are you prepared to spend actually annual use

how long you may wish to follow the lifestyle with the same van

Then specific items of eqipment need to be considered including the advantages & disadvantages of each

The most contraversial is the FRIDGE type[absorption3way ,or compressor type]

Compressor type involves considerably more investment in solar & battery capacity for long term free camping

Peter

We are here to help

Some here are qualified to answer any further questions,so do not hesitate to post with more questions

-- Edited by oldtrack123 on Tuesday 14th of August 2012 01:06:00 PM

jimricho · Guru

The original poster posed a simple and straight forward question and appropriate simple and straight forward responses was all that were required. The poster was simply enquiring on the merits of having 12v, a perfectly reasonable and sensible question. Fortunately there were a couple of sensible responses before the compulsive pedants hijacked the thread.

Many members without technical backgrounds will come here to seek advice and we should respect them with responses they can understand rather than hijacking the thread with pedantic and irrelevant posts such as those above.

For folks new to 12volt issues in caravans and RVs the terminology can be a little mysterious and a simple and respectful explanation of the difference between an amp and an amphour that can be understood by non-technical people was all that was required.

Lacking technical knowledge does not make a person dumb or stupid and it is ill mannered and disrespectful to imply they are, even indirectly. It is also ill mannered and disrespectful to hijack a thread such as this and in this manner before it may have "run its race".

Happywanderer · The Master

Have to agree with Jimricho. Not all of us understand the ins and outs of the common electrical workings.

I just want to know if I plug it in or pull it out and if it will work.
Leigh, I am sure you will find if you can edit your posts you can also delete a lot of it.

oldtrack123 · Guru

LeighW wrote:
I agree,

Admin, please feel free to delete all my posts after my intitial entry as they add no value
to the original discussion.

Cheers
LeighW

-- Edited by LeighW on Tuesday 14th of August 2012 09:31:15 AM

Hi

I believe the posts should stay

As they do highlight how easy incorrect advise can spread & it appears supported by another

The poster still does not understand that ALL his follow up explanations for his original AH statement show a total lack of understanding of even basic terminology.

Peter

oldtrack123 · Guru

Happywanderer wrote:
Have to agree with Jimricho. Not all of us understand the ins and outs of the common electrical workings.

I just want to know if I plug it in or pull it out and if it will work.
Leigh, I am sure you will find if you can edit your posts you can also delete a lot of it.

Hi

ALL are not expected to understand, but surely they would like to have the correct info

LW made a post which had an error

HE refuses to accept that is an error

He continues to try to make the point that it is not an error,by posting extracts from Googling that he simply does not understand

That error is so basic it is of ZERO use to anyone

I posted a series of questions based on using that terminology,to obtain important info for anyone looking to set up a 12v system

I see no answers by LW or his supporter

I wonder WHY?

IF LW wishes to have any of his posts ,now or in the future on electricals ,taken with more than a grain of salt, then INHO it is necessary for him to show he understands the BASICS

Peter

oldtrack123 · Guru

LeighW wrote:
Peter,

Agreed, AMP is the flow rate PER HOUR, if it was not per hour the reading would be useless,
like a meter showing a 6 Litres flow rate, 6 Litres per what:

A sec, a day, a year, 6 Litres remaining, 6 Litres used since time began?

Without a base the reading is useless, and amp meter displays Amps Per hour being used steady state condition!

Your the one that wrongly assumed I meant Amps and not AH.

Cheers

Leigh

-- Edited by LeighW on Tuesday 14th of August 2012 09:06:36 AM