Solar Battery Charger Question

Yeah i do have dual battery system, only thing is i dont always go with my vehicle. Though it probably is a good idea to do it anyway, how is the wiring set up for this? Is it just a cable run from positive and negative to an anderson plug?
Cheers

Where is the fuse in this arrangement.

Having this size battery without a fuse is a serious fire hazard.

Good question, its been a while since i last used it, but i think it was on around 12.3 before i charged it last. Thats just a feeling though and not really certain. I know it never drops below 12v though thats for sure.

So that would be about 50% to 60% discharged.



To replace 50% or 9 a/h you would need close to double that to be able to do it in daylight hours.

I am guessing at a 30W panel and a 5A regulator.

Regards

Derek.

Perhaps a better option would be the car to car charger.

This would charge the battery off the cars battery in about 1hr 30 min.

They are 85% efficient so you would loose about 11 a/h from the car battery but this can be replaced quickly at fast idle.

These units use cigar plugs and are very quick.

Regards

Derek.

Damn didnt think i would need such a big panel. Was obviously given false info from a salesman. Anyway, what is this car to car charger? Is this a portable option or fixed to the one vehicle? So many options i dont know which way to go.

The Car to Car Smart charger is a 7.5A voltage booster. It will take 10V to 15V input and charge at 13.8V to 15V. It switches off at the set time or 15V which ever occurs first.






Regards

Derek.

Derek that looks pretty cool. How much is it and when will it be available, Web site says Dec, is that still right?

Yes, due for release 1st week of December.

Regards

Derek.

I really want one of those car to car chargers...how much?

Very true, but i wouldnt know either. I run one fluoro camping light, i have no idea how much it draws as i brought it 2nd hand and it has no make or anything on it. Its a well built one which probably lights up the same as most. Maybe 1-2 amps. And it also runs a Primus 12v shower which i think to memory might draw close to 2 amps max and only used for about 8 minutes a day max.The light is also only used for 3 hours. Im pretty sure after about 6-7 hours running the light and running the shower for around 15 minutes and sitting for a week it was reading 12.3 amps.

Thanks everyone for your questions and answers too, as it helps me understand whats going on alot better then just getting an answer to what to buy.

The shower is probably used during the day, so the minuscule amount of power it uses is actually replaced as it's used in the same day as it's being used, so you only have to worry about recharging the light.

Fluoro light could use up to 5 Amps (~3 Amps probably) at night (3 hours) without any method of recharging, so it's recharged next day and you will require maximum of 5 amps (~3 Amps probably) replaced in ~6 hours

Mainey . . .

Mainey, I think you are confusing Amps with amp hours. ( Charge)

You need to know how many amps you use over a period. Knowing the number of amps alone will tell you nothing in relation to restoring a battery's charge.

Most flouros use about 1.2A. If you have it on for say 6 hours then it is 7.2AH. Plus if the punp is 6A and you use it for 30 mins then you use 3AH

Add up the charge used by all the devices and you come to a total. Say 10AH. Then you know that you should double it to get a 20AH battery.

Then you know you have say 4 shours to charge the 10AH so you need to charge it at 2.5A, allowing 20% loss - 3A.

That tell you that you need a panel of 3A x 17v or 50W.

Bb,
I believe there's no confusion, I've stated the *total* number of Amps used over the period of a 'day' or 'night', not the Amps used per hour, "Fluoro light could use up to 5 Amps".... this is the total number of Amps used at night.
Yes, this equates to ~1.7ah maybe down to ~1ah, but for the answer as to how much power is actually used you need to know the *total Amps* used, then you know the total Amps your Solar panel must be capable of replacing in full during the PSP.

Bb, your own reply statement above states:
"Most flouros use about 1.2A. If you have it on for say 6 hours then it is 7.2AH"
This of course is technically incorrect, however I'm sure it's just a typo :-)


Personally I believe a 50W panel would be way way over the top, in both physical size, $$ and capacity, I believe it could be possible to use a panel of ~20 Watts because as I say, the shower Amps consumption are replaced (almost) as they're used.
Because the shower is used during the day, the Solar panel would have been supplying max Amps previously, therefore the battery will be fully charged.
A Solar panel of ~20 Watts will deliver max of ~1.2 Amps, so when using the shower pump, which your rating @ 6 Amps, for 10 mins each time, this equates to just ~1ah which is capable of being delivered direct from the Solar panel, without taking power from the battery.
Pictures clearly showing this exact scenario are shown in "my profile" below.

Mainey . . .

Hi there amps/battery/solar experts...I need a little help and your knowledge will be most appreciated.

I have a camper trailer 12volt wired to a deep cell battery 65.

I have a couple of lights in the camper trailer, those ARB lights that draw very little power, so the battery has never run out. It then charges through the anderson plug when we're travelling.

Im impressed with that charging gadget that the battery man has coming out in december...I think I will need one, and my question is?

My engel 40 litre fridge usually stays plugged into the car and on occaission I cant use the generator cos Im in a national park. It would be real handy if I could plug it into the deep cell 65 battery in the camper trailer.

If I was to stay a couple of nights (and it would only stay plugged during the night time) how long before I drain the deep cell battery? And as for that little gadget pictured above, will it charge the battery OK?

Mainey, I think you are still confused.
eg when you say in your last comments

I believe there's no confusion, I've stated the *total* number of Amps used over the period of a 'day' or 'night', not the Amps used per hour, "Fluoro light could use up to 5 Amps".... this is the total number of Amps used at night.

This does not make sense. There is no such thing as the total number of amps used over night. Current ( measured in amps) is an instantaneous thing. So a flouro that uses up to 5 A means it could use up to 40Amp Hours over night ( assuming 8 hours).

Are you referring to AMP HOURS which is charge and a function of the amount of current ( A) over time.

Also you say
"Most flouros use about 1.2A. If you have it on for say 6 hours then it is 7.2AH"
This of course is technically incorrect, however I'm sure it's just a typo :-)

No typo, perhaps is is your confusion between current (Amps) and Charge ( Amp Hours). 6 x 1.2 = 7.2 by my calculator. I am referring to a typical 11w flouro.

Your comments are very confusing mixing up current and charge. Your advice is not technically right.

You posted:
"Most flouros use about 1.2 Amps
If you have it on for say 6 hours then it is 7.2 Amp Hours"

please explain how a 1.2 (Amp) light uses 7.2 (Amp Hours) ?

Mainey . . .

Wow....

If a light uses 1.2A and is on for 6 hours, that's 6 times 1.2 = 7.2 AH

Let me ask you a question.

If you have a 55w light that draws say 4A that is on for 4 hours, how many amps is that?

BTW I forgot to ask, what is your answer to your question?

Bb,
Your post:

"If a light uses 1.2A and is on for 6 hours, that's 6 times 1.2 = 7.2 AH"

Is incorrect...

It's NOT the numbers I'm referring to, the TERMINOLOGY is wrong !

Mainey . . .

Boobook2

Yes, I've given up too !

Just because instantaneous fuel consumption litres per hour, certain people here insist on writing instantaneous current draw as amps per hour, ignoring what the rest of the electrical industry around the world uses.

Mike,
in the statement:
""Most flouros use about 1.2A. If you have it on for say 6 hours then it is 7.2AH""

Question: is the above Terminology technically correct?
a simple 'yes / no' answer would be nice.

Yes, the light may use 1.2 Amps
if it's left on for 6 hours it is: 1.2 Amps x 6 (hours) = 7.2 Amps
It won't change from 1.2 Amps to 7.2 Amp HOURS in the equation as posted

Mainey . . .

I've read this three times to see if I am missing something.

My conclusion is clear, Boo's logical explanation is correct.

Jim.

Jim,
you believe if a 1.2 Amp light is left on for 6 hours it is WILL consume 7.2 Amp HOURS as posted by Bb ??

Mainey ...

just to diffuse the argument, can someone have a go at answering my question on engel fridge drawing on a 65 battery

in the statement:
""Most flouros use about 1.2A. If you have it on for say 6 hours then it is 7.2AH""
Question: is the above Terminology technically correct?

Yes, this is correct

If I have a generator that uses 1.2 litres per hour and I have it running for 6 hours it uses 7.2 litres.

Dimensional analysis shows -

Amps TIMES hours gives amphours (NOT amps per hour - a silly measure)

Litres per hour TIMES hours gives Litres.

No definitive answer Zha, as it depends on ambient temp, how often it is opened etc.

BUT, here is a rough guide. An Engel 40 will average about 35 to 40 AH in a 24 hour period. You have a 65 AH battery. In the interest of battery life, they should not be drained below 50% capacity, hence you have about 32.5 AH at your disposal.

Therefore I would suggest any more than 24 hours is looking for trouble. If you're driving every day you'll be OK, but if not you need to find some way of recharging the battery, solar or a generator, both have their good and bad points.

Cheers,

Jim.

Mainey,

"Yes, the light may use 1.2 Amps
if it's left on for 6 hours it is: 1.2 Amps x 6 (hours) = 7.2 Amps
It won't change from 1.2 Amps to 7.2 Amp HOURS in the equation as posted "

This statement shows a very poor understanding of the difference in current and charge.

Try this calculation.

A compressor draws 60A for 1 minute how many amps is that? I'll give you a clue, it is 1 Amp Hour.

Honestly given your lack of understanding in the basics of this, I STRONGLY advise that you don't give further advice to people asking battery / solar questions untill you read up and understand a little more. If you insist you are right then I advise people to IGNORE your abttery and Solar Posts as you are misleading them and may cost people dearly.

Jim beat me to your Answer.

Zha, I would agree with him. I may conclude a bit less than 24 hours, say 20 hours before needing the charge as suggested.

Ok Mainey here is a hand to help you understand.

The total Charge used is equal to the integral from 0 to t, were t is the total time, of the current over that time.

If the current is constant ( as it is in a light etc, but not a fridge), then this can be simplified to C ( in AH) = Current in A x time in hours that you are measuring.

Charge can also be measured in Coloumbs which is the number of amps x seconds. This measurement is more useful for electronics and scientific purposes but less so for day to day stuff for batteries etc.

As Mike R said current ( measured in Amps) is an INSTATANEOUS measurement and has no relationship with time. to think that a current goes up over time ( and especially Hours!!!!) is missing the basics of electrical theory.

Please read up on this subject. It is important for understanding the whole solar basics.

It does also explain your answers to other threads which miss the point.

Thanks Jim,

sounds like I can plug the fridge in for a couple of days...i.e. not for 48 hours straight but certainly for maybe 2 x 10 hours over the 48 hour period should be fine. (while cooking breakfast and dinner then turn if off completely while sleeping if the weather isnt too warm)

As menitoned the fridge stays in the car and hence when we drive off during the day it gets power to cool it then.

thank-you again.

Bb,
your own reply above states:
"Most flouros use about 1.2 Amps.. as Mike R said current (measured in Amps) is an INSTANTANEOUS measurement and has NO relationship with time"
Your original statement:
"If you have it on for say 6 hours then it is 7.2 Amp HOURS" - which has now created the relationship with time ?

I'm prepared to look and learn, please show me the method of working out your original statement ""Most flouros use about 1.2A. If you have it on for say 6 hours then it is 7.2AH""

My belief is a light that draws 1.2 Amps, will definitely use 7.2 Amps in 6 hours, however these Amps are not referred to as 'Amp HOURS' but as Amps Total or just Amps.

'Amp Hour' is the Amps draw when stated per HOUR, as shown in your own statement "A compressor draws 60 Amps for 1 minute.... it is 1 Amp Hour" at least we agree on that :-))

Mainey . . .

"My belief is a light that draws 1.2 Amps, will definitely use 7.2 Amps in 6 hours, however these Amps are not referred to as 'Amp HOURS' but as Amps Total or just Amps. "

- No, if it draws 1.2 amps (an instantaneous measure) then it draws 1.2 amp hours over an hour or 7.2 amphours over 6 hours.

That's why battery capacity is measured in amphours.


My fridge draws 5 amps when the compressor is running. If it runs fulltime it will use 5 amphours over an hour.

If the compressor runs 50% of the time then the fridge uses 2.5 amphours over an hour. Calling this 2.5 amphours per hour is technically correct, but a waste of words. Calling this 2.5 amps average is also technically correct.

"My belief is a light that draws 1.2 Amps, will definitely use 7.2 Amps in 6 hours, however these Amps are not referred to as 'Amp HOURS' but as Amps Total or just Amps.
- No, if it draws 1.2 amps (an instantaneous measure) then it draws 1.2 amp hours over an hour or 7.2 amphours over 6 hours"

Yes, as you say just too many words :-)

All this is because I posted: "Said with no technical gibbly gook"
"Fluoro light could use up to 5 Amps (~3 Amps probably) at night"

Should have posted; 5 Amps per night ?

Mainey . . .

""Fluoro light could use up to 5 Amps (~3 Amps probably) at night"
Should have posted; 5 Amps per night ? "

No, Amps is an instantaneous measure - it has nothing to do with time.

It's as wrong as saying "my generator used 5 litres per hour per day" - it either use 5 litres per hour OR 40 litres per day !

Hi Mainy
A simple question if your lamp uses 1.2 amps & runs of a battery for 6hrs ,how much battery power has to be put back into battery assuming 100% efficiency[ie out= in] & what is that unit power called.

We are gentlemen of leisure, we do NOT get abusive, not even a little bit, with each other, we incite questions and impart wisdom, with nothing better to do as the fish are not on the bite and the wine is cold, the V8 Supercars have not started racing (on tv) when they do I will turn off the comp :-))

I am however very sorry the thread has been hijacked so strenuously though.

However, I still think a Solar panel of ~20 Watts will suffice :))

Mainey . . .

Mainey,

I agree, I reckon 20 watts would do the job required adequately. Might even sneak through with less with lots of sunshine.

Jim.

Very interesting, so a 20w panel but do i need a regulator? I honestly have no idea about this stuff, but i want to do it environmentally friendly and without having to charge off vehicle.

A 20W panel on a 18 a/h battery.

Yes, fit a regulator.

Agree,

A 20 watt panel, unregulated, could destroy your small battery.

Try a cheap $30 reg from Jaycar or similar. It should do the job.

Just disconnect it overnight, cheap regulators can allow reverse charge in the dark, ie the panel can suck charge out of the batt when the Sun is down.

Jim.