Solar Calling all 12 v battery box experts

[Les321]

hi guys need help
I looking two buy two separate battery's box and wondering if I could joining them together using the Anderson To Anderson plugs to give me 120 ah *Try posting a bit more so your post isn't boring* and is it possible the charge them using a solar panels through a d c / d c while together. ( the one on the left )
as in the photos below, but was told that I could not as all negative wires (earth ) has to come through the same Spot . ??? And the plugs 12 cig would not work as it should, If this is true how do you guys do it ? With two or more batteries.
He also told me that the portable fridge would drain the first battery then the second battery not given me the true 240 ah I would like . If this is true ?
He also told me I would have to take the boxes to a auto elec for him to change the wiring it should take five minutes or so
Or build one myself if any one can help .
Or have any suggestions this would be great
I trying to run a wacoe dz95 the new one , it draws 3.6 + ah when the commpressor is running and 1.25 ah when it's not .
I am thinking of using 250 watt solar just for this project.
Any help would be great.

 

[Bellbirdweb]

Hi @Les321 and welcome to the forum.

Are you planning on putting these batteries in a caravan or elsewhere ?

Is there a reason you want to connect them using an Anderson and not just directly connecting them in parallel.

Ideally you would want to connect them with heavy duty cable, and then the load and change with the positive connection on 1 battery and the negative on the other, although this is not critical if they are connected with heavy enough cable.

As for charging from solar, you would be better of with a good quality MPPT solar controller, and not using a DC to Dc charger.

The battery top would be an overkill on both batteries, but you could have one on a single battery to give you the outlets etc if you need them or just create your own.

There is no reason a cigarette lighter connection would not work.

 

[megcam]

Where are the batteries going to be used/mounted? The best method for joining batteries is per:

so that is why they are saying you will need to rewire. If you want to keep it simple you could just get the 2 batteries and swap the solar and fridge over each day. Eg day 1 you run fridge with battery 1 (compressor on for 12 hours @3.6a + 12hrs@1.25a = 58ah) day 2 you plug fridge into battery 2 and plug solar in to battery 1.

I've never seen the value in those ready made boxes and end up making something to suit my own purpose/

 

[Les321]

I was hoping to have them portable
When I go free camping
The control on top of the box has a d c/ d c and built in mppt 25a controller in one
Just thought you could plug and play so to speak and have the solar charging at the same time .and have enough amps for the night time to keep the wacoe going till the morning .
Just read the solar forum and thought I could do the same with two portable batteries.
Thank for your reply's

 

[Drover]

Agree with the others comments, I would just go for 2 basic boxes, wire the batteries up as per @megcam s diagram, you can use anderson plugs to connect the 2 together and add another 2 andersons to draw power and supply from a solar panel, since most panels come with a regulator another on the box would be not needed really, you would ideally use at least 8 B&S cable................I wouldn't use the cig sockets they can be problematic.

 

[megcam]

I was hoping to have them portable
When I go free camping

Portability will be a challenge when the batteries weigh 35kg each so I take it you are looking for something you can mount in your vehicle when going camping and pull out when home. You could look at a dc/dc charger with solar input and also wire up a feed from your vehicle alternator to charge while you're driving. You're probably looking at $1000 diy with the dc/dc charger. Be worth speaking to your local auto electrician for avv quote too.

 

[Les321]

Hey guys thanks for your reply's
Just done a quick test on 240 v for my wacoe 95
Man was blown away
I plug the wacoe in to 240 v and run for the wacoe for the whole day nice and cool set the freeze to - 15 c and the fridge to 2 c
Then put 2 bag of ice into the freezer ( 15 - already ) then put already chilled beers into the fridge compartment then let it for two hrs before I run a test .
At 8.35 it began to 9.35 at the same temperature as above in one hour the wacoe run 49. 39 min off 1 hr
The air temp was 22.c
Buy my calendar lets round it off to 3.6 to 4 and 1.25 to 2 ( for solar to recharge ) that,s 6 a/ h X 24 hours = 144 a/ h in summer. And I I have a 100a/h battery in the new van .
Should I get another battery fitted or go portable .?

 

[Drover]

What do you actually mean by portable ??? Are you going to be carrying batteries and fridge around on a trolley or just sitting beside the van ?? 12v 100ah batteries aren't really portable.....
Most have an aux battery fitted in vehicle to run fridge, using an Anderson fitted outside the tug to plug fridge or panel into and on van an Anderson fitted outside to plug fridge into with batteries secured in the rigs.
I used to plug my Engel into the van 12v with it sitting on a stand outside, only a 100ah battery running the whole show free camping, powered by 200w on roof and 120w on ground and all is good, but now run oit off tugs aux with a panel on roof of ute but more storage would be better so I would say add another battery to van if you do a lot of free camping.......but don't go for those battery pack jobs most are not much chop in the long run.

 

[Les321]

Hi drover
I think I might poo poo the whole idea of portable unless I want too carry a spare trailer to power the dam thing
And might get rid of the waeco.

 

[Axl]

Hey guys thanks for your reply's
Just done a quick test on 240 v for my wacoe 95
Man was blown away
I plug the wacoe in to 240 v and run for the wacoe for the whole day nice and cool set the freeze to - 15 c and the fridge to 2 c
Then put 2 bag of ice into the freezer ( 15 - already ) then put already chilled beers into the fridge compartment then let it for two hrs before I run a test .
At 8.35 it began to 9.35 at the same temperature as above in one hour the wacoe run 49. 39 min off 1 hr
The air temp was 22.c
Buy my calendar lets round it off to 3.6 to 4 and 1.25 to 2 ( for solar to recharge ) that,s 6 a/ h X 24 hours = 144 a/ h in summer. And I I have a 100a/h battery in the new van .
Should I get another battery fitted or go portable .?

@Les321 calculating the amp draw of a 12v fridge doesn't work the way you are thinking, if your fridge pulls 4 amps whilst the compressor is running and 2 amps at rest??, then your 24hr draw will be approx 48 amps.

Why you ask well the compressor is not running all the time, rule of thumb used widely in the camping arena for working out what you may draw over a 24hr period for fridge's is that the compressor will run for 8hrs in a 24hr period.

Of course this depends on many variables how hot the day is, how many times you open the fridge (kids), if the fridge is in full sun or shade, the lower the temp of the fridge the more the compressor will cycle, putting hot food or drink into the fridge etc etc.

I have done real time testing with my 40lt Engel, 120w panels and 120amp battery using a watt meter whilst drinking beer all afternoon from the fridge and have proved that this is as close as you will get. Engel pulls 2.75amps according to the manual times that by 8hrs = 22amps which is what my total draw over that test 24hr period was according to my watt meter.

So depending on sunlight and what the fridge is used for you could in a perfect situation run that fridge using a 120amp/hr battery and a set of 120w folding panels (mine produce 6-7amps) forever if circumstances allowed.

I am curious though as to why the fridge pulls 2amps at rest?

 

[bigcol]

And might get rid of the waeco.

please PLEASE dont start the Waeco V's Engel debate

my opinion..............
both are as good as you will get for the price

the older Engels were great and run for ever
the older Waeco's were junk with thermostat problems and power cord problems

the newer Engels are junk with cheaper cooling plates that die just out of warranty (and cost as much as a new fridge to repair)
the newer Waeco's are far and away much better than they used to be

both the above statements are what I have found using both the older and newer units of both

my opinion from MY usage of both

 

[mikerezny]

Hi @Les321,
as @Axl posted above there are some questions related to your observations.
If you want to get a good solution to your needs and avoid frustration and wasting money, it is well worth spending some time to become better informed as to your present situation i.e. fridge power requirements, and your future needs, i.e. battery capacity, charging solutions, camping requirements (number of days required without sun etc).

One item I would like to recommend you get is a little device used by the Radio Control community for managing charging and discharging.
Just do a search on eBay for Battery Power Analyzer

You can pick one up on eBay for less than $10. It measures instantaneous current, watts, and voltage. But it also measures accumulated watts and current. So, ideal for keeping track of you actual power draw of your fridge over a set period. 24 Hours is a good time since this will capture both the high day usage and the low night usage. It is also ideal for keeping track of how your solar panels are performing. If you can make accurate measurements you may well save yourself hundreds of $ and needlessly carting around more solar and batteries than you actually need.

Electrical terms can be confusing. If you put an ammeter in series with your fridge it will measure current in Amps (A) . In contrast, when you buy a battery, you would be interested in its ability to deliver power to a load. Thus a battery has a rated capacity usually expressed in Ampere-hours (Ah). Thus a perfect 100Ah battery would deliver 10A to a load for 10 hours. It is very common to mix these two terms.

So, in your case, you are measuring the changing load of your fridge by measuring A, then using this to estimate the power taken from the battery in Ah.

I am also perplexed as to why your fridge is drawing 1.25A when the compressor is not running. Is it possible that the fridge has an internal light and that it is not turning off when the lid is down?

Testing straight after the fridge has been loaded is too soon. Hot air will have entered both the fridge and freezer, and, regardless of the temperature of what was put in, this air needs to be cooled. Also, the items you added will not be EXACTLY the same temperature as the fridge. So, either the fridge stay off until the items you added warm up or the fridge will be working harder to bring them up to temperature.

cheers
Mike

 

[mikerezny]

@Les321 calculating the amp draw of a 12v fridge doesn't work the way you are thinking, if your fridge pulls 4 amps whilst the compressor is running and 2 amps at rest??, then your 24hr draw will be approx 48 amps.

Hi @Axl,
I cannot follow this calculation.

Here is my understanding of your calculation. If the fridge, at rest, draws 2A, then if the compressor NEVER turns on, the total consumption over 24 hours would be 2 * 24 = 48Ah.
Or have I missed something?

I read that the compressor was off for about 50 minutes (49.39) in the hour. If that was typical, then over a 24 hour period, the compressor would be on for 10 minutes each hour which is 4 hours, and off for 20 hours over a 24 hour period.
So the consumption would be 4h * 4A = 16Ah + 20h * 2A = 40Ah. The total is 56Ah per 24 hours.

cheers
Mike

 

[Axl]

@mikerezny I didn't really look at @Les321 figures to be honest, I simply wanted to let him know that his calculation of "6 a/ h X 24 hours = 144 a/ h" is not correct as the compressor wont be running for 24 hours straight. A lot of people use the rule of thumb and have done for many years that over a 24 hour period your compressor will be running for 8 of those hours.

It is not exact science mate its just a rule of thumb that is used but it is pretty accurate. As I've said there a lot of variables that can play on this and your fridge may pull more power or it may pull less.

So if the said fridge uses 4amp whilst the compressor is running and 2amp whilst it isn't this equals 6amp, 6ampX8hours=48amp. As I said mate its not exact but it is a bloody good guide.

Still cant work out 2amp usage whilst fridge is sitting idle though, if it was a light doing this I would be disconnecting it quick smart. I don't believe anyone was starting Waeco V's Engel debate as mention above but there is no way id own a fridge that pulls 2amp whilst doing nothing regardless of who makes it.

That watt meter you have pictured is one of the handiest gadgets you can have when measuring either power in or power out of a battery. Put an Anderson plug on each end and place it inline to or from the battery and you can see whats happening.

You can just see mine in this pic showing me the amps flowing into the battery.

 

[mikerezny]

So if the said fridge uses 4amp whilst the compressor is running and 2amp whilst it isn't this equals 6amp, 6ampX8hours=48amp. As I said mate its not exact but it is a bloody good guide.

Hi @Axl,
ok, thanks for the explanation. Now I understand how you arrived at the conclusion.

One further question. Why have you added 4A to 2A to get 6A? That bit confuses me.
If you measure total current with the compressor running to be 4A and without the compressor running to be 2A. How would one ever be measuring 6A. The current draw can only be either 4A or 2A.

So, using your approximation, 4A when the compressor runs for 8 hours (over 24-hours) = 32Ah total and not 48Ah total.

cheers
Mike

 

[Axl]

Hi @Axl,
ok, thanks for the explanation. Now I understand how you arrived at the conclusion.

One further question. Why have you added 4A to 2A to get 6A? That bit confuses me.
If you measure total current with the compressor running to be 4A and without the compressor running to be 2A. How would one ever be measuring 6A. The current draw can only be either 4A or 2A.

So, using your approximation, 4A when the compressor runs for 8 hours (over 24-hours) = 32Ah total and not 48Ah total.

cheers
Mike

Yep, to be honest as I have said I have no idea what the 2amp draw that has been spoken about is for but as it was mentioned I simply added it to the total.....so as you have said 4ampX8hr=32amp/24hr:encouragement:

 

[mikerezny]

@mikerezny I didn't really look at @Les321 figures to be honest, I simply wanted to let him know that his calculation of "6 a/ h X 24 hours = 144 a/ h" is not correct as the compressor wont be running for 24 hours straight. A lot of people use the rule of thumb and have done for many years that over a 24 hour period your compressor will be running for 8 of those hours.

It is not exact science mate its just a rule of thumb that is used but it is pretty accurate. As I've said there a lot of variables that can play on this and your fridge may pull more power or it may pull less.

So if the said fridge uses 4amp whilst the compressor is running and 2amp whilst it isn't this equals 6amp, 6ampX8hours=48amp. As I said mate its not exact but it is a bloody good guide.

Still cant work out 2amp usage whilst fridge is sitting idle though, if it was a light doing this I would be disconnecting it quick smart. I don't believe anyone was starting Waeco V's Engel debate as mention above but there is no way id own a fridge that pulls 2amp whilst doing nothing regardless of who makes it.

That watt meter you have pictured is one of the handiest gadgets you can have when measuring either power in or power out of a battery. Put an Anderson plug on each end and place it inline to or from the battery and you can see whats happening.

You can just see mine in this pic showing me the amps flowing into the battery.
View attachment 58387

Hi @Axl,
I have one and it is used exactly as you do: inline from the output of the solar controller to the battery. Wouldn't be without it. I understand that the much fancier solar controllers can provide the same, if not more, information (and they do cost more). But I could not go past a $6 solar controller and a $12 wattmeter to go with my $30, 40W portable solar panel.

cheers
Mike

 

[Drover]

Hi drover
I think I might poo poo the whole idea of portable unless I want too carry a spare trailer to power the dam thing
And might get rid of the waeco.

Nah, don't chuck the fridge, you will regret it later your just filling your head with too much mumbo jumbo.....to keep it simple back in the analogue days when we went bush we just put a normal truck battery (from work) in the back and plugged in the Engel (same one I have now, except it was only 5 yrs old) now this battery kept the beers cold for about 3 days before it was knackered but we had drunk the beer anyway..........so a modern AGM 100ah with a 100w panel will keep the fridge cold so long as you have sun, if plugging into your van it is easy to add another battery to van to make sure you have a heap of storage................It is possible to over spend on gadgets and whiz bang stuff but a plain old plastic battery box, some cable and a 100ah battery is enough to keep it all happy......@mikerezny gizmo is a handy item to have though......an Anderson plug fitted in your tug will allow you to run your fridge while your driving with no problems, you only need an aux battery and DC charger if your going to leave it in there when parked up....................I have an extension I made up so I can plug the Engel, which lives in the ute, into the van if the aux croaks it...

 

[Bellbirdweb]

Hi guys
Sorry for miss information the 2 amp should 0.13 when the wifi is on
Sorry to all next time I will have my glasses on.
@mikerezny i love the idea of the amp mater great idea .
What I'm trying to do is two things
1 when I go off grid how long will my 100/ah last with this beast , planing to go off-road for 7 days but if 3 of those day are cloudy I could be in a spot of trouble.
2 as I have new van should I get a new battery put into it to help ? , as I can just plug the beast into the cig port
Add the extra 250 watt solar panels and mppt to the battery's (as per solar forum ) job done .
Or go portable with the above set up (in case I get a new run just swap over ).

As per the test being a newbie I thought when I heard the fan turn on the compresser was working
So evertime they turned on I started the stop watch so In 1hr the motor and fans come on I timed them , off and on 3x times Just over 15min each time so 3.6 round it off 4 x24 hrs = 88 .

I did hook it up to the new van it went ok while the sun was out all fine .
But soon as the sun went down that when it changes.
After 3.5 hrs later my battery check ( bmpro ) went off on my phone .I was down to 50% which was suprising . Plug it into 240 v in 1.5 hrs the battery was all charge up and full .
The fridge was empty .(not Good)
May be something is wrong with battery .?.
Thanks for the advice and information.
Thanks
@Drover
@mikerezny
@Axl
@bigcol

Your battery may not be at peak capacity or perhaps not being fully charged.

I have an older mode Engel which uses around the same amount of power as your Waeco.

I run a 100AH deep cycle battery in the Landcruiser and no solar. In hot weather I’m lucky to get 24 hours out of it when it’s operating as a fridge only. If I try and use it as a freezer, I can only get around 8hrs.

If you have solar, and you also charge from your alternator and have something like a CTEK D250S which can aggregate between th solar and alternator supply with 2 batteries in parallel then you should have enough power to keep the fridge running.

Now with the van, I have 2 batteries in the van, and still the 1 in the tug, so when I connect the Anderson plug I get all 3 batteries in parallel, 240w of solar and we have oodles of 12v Power to keep the Engel running as well as everything else on the van.

 

[Les321]

Hi guys
Sorry for miss information the 2 amp should 0.13 when the wifi is on
Sorry to all next time I will have my glasses on.
@mikerezny i love the idea of the amp mater great idea .
What I'm trying to do is two things
1 when I go off grid how long will my 100/ah last with this beast , planing to go off-road for 7 days but if 3 of those day are cloudy I could be in a spot of trouble.
2 as I have new van should I get a new battery put into it to help ? , as I can just plug the beast into the cig port
Add the extra 250 watt solar panels and mppt to the battery's (as per solar forum ) job done .
Or go portable with the above set up (in case I get a new run just swap over ).

As per the test being a newbie I thought when I heard the fan turn on the compresser was working
So evertime they turned on I started the stop watch so In 1hr the motor and fans come on I timed them , off and on 3x times Just over 15min each time so *Try posting a bit more so your post isn't boring* = 45min Round of to 4a/h , 3.6 round it off 4 x24 hrs = 88 .
Still a bit confused. The compresser on come for half the time ? Even if the manual Says average time is around 4a/h (3.6)

I did hook it up to the new van it went ok while the sun was out all fine .standard 120 watt solar panels and 100 a/h battery. Bmpro j 35 b management system.

But soon as the sun went down that when it changes.
After 3.5 hrs later my battery check went off I was down to 50% which was suprising .
The fridge was empty .
May be something is wrong with battery .?.