Aux battery charging from 12V cig socket

I've recently bought a 100AH deep cycle battery in a standalone battery box, mainly to power a little Evakool camp fridge.

The battery will be hooked up to a 240V smart charger while at home and I have a couple of solar panels to keep it going once camp has been set up, but looking for the best way to keep it charged enough to run the fridge while on the go.

I bought the battery, battery box and solar panels on sale at RTM and was going to get a DC-DC charger but the guy at RTM said I should "just plug it into the 12V cig socket" in the cargo area of my Forester. He even made up a lead with a 12V cig plug on one end and an Anderson plug on the other and gave me that for nothing (think he was bored).

I'm not thinking that's actually going to work too well, and that I will need a DC-DC charger to get the voltage I need to charge it properly. So thinking something like a CTek dual DC-DC charger, and assume I will need to run some heavy cables to an Anderson plug in the cargo area, and plug the charger into that.

Any thoughts on this setup?

Cheers,
John

Gday Bundyjd

Have a look at the very informative post about bush power from Condor22

https://www.prospectingaustralia.com/forum/viewtopic.php?id=9156&p=1

You should be able to find what you are looking for .

Have a look around Post 34 it starting to deal with chargers for deep cycle batteries

Cheers

Bob

Balmain Bob said:

Gday Bundyjd

Have a look at the very informative post about bush power from Condor22

https://www.prospectingaustralia.com/forum/viewtopic.php?id=9156&p=1

You should be able to find what you are looking for .

Have a look around Post 34 it starting to deal with chargers for deep cycle batteries

Cheers

Bob

Click to expand...

Thanks Bob, I did read condor22's thread and a few others until my brain hurt prior to asking the question. I'm pretty sure the guy at RTM gave me a bum steer about charging an aux battery from a 12v cig socket, but it would be good if someone with a bit more auto electrical knowledge could confirm that before I shell out some more cash on a DC-DC charger etc.

After a bit more research into what's relatively new on the market I'm leaning towards the Projecta IDC25 charger which I think could be mounted on top of the battery box. It seems to get better reviews than the Ctek 250S and is way cheaper than the Redarc units.

Gday Bundyjd

Condor22 is very good with electrical, its worth taking the time to understand.

I run 120ah deep cycle from solar or the alternator hardwired in the car using a Ctek 250s which has worked for about 4 years, it runs a fridge. Recently the Redarc has had better reviews. My system runs 16mm sq twin core cable from the car battery to the Ctek which is in the boot area to charge the house battery. It needs to be capable of supplying 20 amps to the Ctek with minimum coltage drop.

Whatever you choose, buy correctly sized cable or you degrade the entire system. Fit fuses.

The 12v cig socket will charge the battery at a slow rate but not to the correct voltage for AGM, nor will it provide a maintenance charge. Your Battery will suffer.

Best of luck.
Barry

Un Needed

Bundy,

The guy gave you a bum steer, I'm assuming the 100AH you have is an AGM, if so, it needs 14.5VDC to charge properly, your alternator typically puts out 13.8V which is not enough.

Many years ago, I got a 40AH Thumper included in the deal with my caravan, I tried charging it from the cig socket to run my Engel in the rear of the car. It didn't run my fridge properly and it stopped holding charge in less than a year. 2 reasons, first 40AH aint enough, it draws to deep and secondly the Thumper wasn't getting enough charge. I tried taking the cheap way out and had I have paid for it the Thumper was worth over $700.

I replaced it with a DCDC charger and a 100AH AGM. I still have the Redarc BCDC1220 DC to DC and the battery lasted 10 years (I replaced it earlier this year.)

Invariably, taking the cheap way out, ends up costing a whole lot more. Not withstanding things usually fail when you need them most !!

Get a DC to DC and get a good one. If you go the Redarc BCDC1225, it is also a solar regulator and can be wired to auto switch between solar and engine charging.
If you already have a decent regulator, the BCDC1220 is all you need.

Thanks Barry, I think I'll just grab some cable and a charger and be done with it.....

The Projecta can be had for around $279 on ebay and supports "Smart Alternator" vehicles out of the box, not that my 2007 Forester is likely to have that but if I upgrade to a more modern vehicle later at least I know I can reuse it.

The manual for the Projecta says to use 8 B&S cable with 50A fuses from the starter battery to the charger for cable length up to 12m, so not sure I need the 16mm sq cable you mentioned.

Cheers,
John

condor22 said:

Bundy,

The guy gave you a bum steer, I'm assuming the 100AH you have is an AGM, if so, it needs 14.5VDC to charge properly, your alternator typically puts out 13.8V which is not enough.

Many years ago, I got a 40AH Thumper included in the deal with my caravan, I tried charging it from the cig socket to run my Engel in the rear of the car. It didn't run my fridge properly and it stopped holding charge in less than a year. 2 reasons, first 40AH aint enough, it draws to deep and secondly the Thumper wasn't getting enough charge. I tried taking the cheap way out and had I have paid for it the Thumper was worth over $700.

I replaced it with a DCDC charger and a 100AH AGM. I still have the Redarc BCDC1220 DC to DC and the battery lasted 10 years (I replaced it earlier this year.)

Invariably, taking the cheap way out, ends up costing a whole lot more. Not withstanding things usually fail when you need them most !!

Get a DC to DC and get a good one. If you go the Redarc BCDC1225, it is also a solar regulator and can be wired to auto switch between solar and engine charging.
If you already have a decent regulator, the BCDC1220 is all you need.

Click to expand...

Thanks, I think it's actually a 100AH Gel battery if that makes a difference? The folding solar panels do have a built in regulator, so I guess while in camp I could hook that directly to the battery or add some extra plugs to bypass it and run it through the DC-DC instead if that's a better solution.

Any thoughts on this unit as opposed to the Redarc? http://www.ebay.com.au/itm/PROJECTA...048074?hash=item5d659257ca:g:UgMAAOSwo4pYWBHU

Cheers,
John

Reminder, put the DC to DC as close to the battery as possible re cable length.

The reasons I go Redarc are;

1. Australian made
2. The Redarc BCDC series run from 9VDC to 32VDC input, so voltage drop is of less concern and suitable for 24V vehicles. Also some solar panels can output over 20V. The C-TEK range upper limit is 23VDC which is close to what some panels output and they don't specify a minimum voltage.

http://www.autoelec.com.au/ is where I buy from, good pricing and free post.

I have no affiliation with Redarc or Autoelecau other than as a satisfied customer

Given you already have as stated The battery will be hooked up to a 240V smart charger while at home and I have a couple of solar panels to keep it going once camp has been set up
Not sure why your looking at $300 to $400 dollar units when a Redarc SB12 will do all you require all day long without complication for $100 :|
Another advantage keeping it separate is that if one unit fails then you don't lose all charging ability whilst away. Things do fail and usually the first day when your away

Second AutoElec Au for both prices and service

Bogger said:

Given you already have as stated The battery will be hooked up to a 240V smart charger while at home and I have a couple of solar panels to keep it going once camp has been set up
Not sure why your looking at $300 to $400 dollar units when a Redarc SB12 will do all you require all day long without complication for $100 :|
Another advantage keeping it separate is that if one unit fails then you don't lose all charging ability whilst away. Things do fail and usually the first day when your away

Second AutoElec Au for both prices and service

Click to expand...

G'day Bogger,

I'm not a fan of spending money for no reason, but as condor22 says:

"I'm assuming the 100AH you have is an AGM, if so, it needs 14.5VDC to charge properly, your alternator typically puts out 13.8V which is not enough."

So I'm thinking an isolator isn't going to solve that problem?

BTW - the unit I linked to above is from AutoElecAU

Fair call 13.8 being enough for float charge but not quick charge. I found another cost effective way was to run a solar panel on roof that I could demount and also use at camp site. Comes in handy to keep fridges going whilst out from camp. But I run an 80 and 40 litre and the 80 sucks power. If the 80 packs up I'll get a 60 to replace it but the 80 is about the only waeco low enough to fit under a hard cover on ute. Problem is when you open it the whole paddock falls in the lids that big.
Main thing there is a genuine MPPT and not the dodgy ebay one's that arn't
They should be called PFFFT :|
As Condor has mentioned as long as it's quality set up you won't have issues.

If it's just to charge while driving to camp spot, the cig socket should be fine.on the understanding the 100ah will only charge to approx 85%. Don't leave hooked up while camping. Connect to solar while camping. DC DC charging set up is best but not needed if not being used continually.

I have a ark power Pak and 110 amp battery have been using cig socket for yds,only on 5 hr drive to Clermont-Ferrand. Most times plug fridge to cig socket and use power Pak and solar for camp set up. I have a 60ltr Engel off.

Polly.

A quick drive to camp? Fair point.

In the winter my Engel uses about 1 amp per hour, so if that's the drive and it's then connected to solar I can't see a problem. In summer my Engel uses nearer 3amps/hr and again a 1 hour drive would be no problem. However,

Towing my van from S.A. to VIC can take me most of the day and when I arrive and then setup, the sun is probably going down, so solar won't do any good till the next day and the fridge still needs power overnight. So for longer trips the only way to give the battery what it needs is a DC-DC. That way I know the battery is full when I arrive and its overnight use is acceptable re depth of cycle.

Ok found it .................

Condor a question wondering if you could shed some light ? Running a Projecta dc/solar charger 25 amp unit and until recently all was good. Have lately been getting an error showing as solar panel input over voltage ? Found a loose connection in Anderson plug connector on output from charger and was wondering if that could or would trigger this ?
Thanks in advance
Cheers
ps VOC is marked 21.6 on panel ....................... getting 21.3 VOC from panel Projecta max solar input 23Vdc so unless panel is spiking has me beat as VOC is under max input and so shouldn't be showing solar input over voltage?? Is this simply the case where you turf the Projecta and go and buy a redarc ?

A loose connector, on the output, should only do one of two things, 1. reduce the available charge (in simple terms) or, 2. get hot, again in simple terms.

It shouldn't increase the voltage especially to that extent as the output V max (for an AGM is 14.4v)

A panels VOC is generally noted as Max but is variable depending on sun conditions. Yours noted at 21.6 and measured at 21.3 is ok (keep in mind that over time a solar panels output does reduce.

Assuming you have this; http://www.projecta.com.au/Products/DualBattery/DCSolarChargers.aspx#!prettyPhoto

The max input is 32VDC so your panel should never get close. However, you haven't mentioned what panel or panels you have, or how connected. How old is the Projecta?

If you can try someone else's panels on your Projecta, and their controller on your panel, that would be the easy way to isolate the problem. (panel/s or controller)

If the controller is at fault, they are generally made such that it would cost as much to fix as replace. However, contact your supplier and find out if it's worth sending it for investigation or not.

Before you spend any money, it would pay to try getting your kit checked, panels and charger.

Cheers for reply

I agree with you on the effect of loose input / bad connection in that it should not effect solar input. Techo at Brown and Watson said it may be that when unit saw the bad connection the only fault code it had available to throw due to getting incorrect readings was the solar input and hence it just threw it to show something was amiss.
It is an IDC 25 unit and only a month old . Panel info is as shown below

Just for info ....................... spoke with auto elec au and they said they had a few redarc units back under warranty but no Projecta units as yet. Again as always they are super helpful
Thanks for your time regards this

In this day and age returns happen. I have 2 Redarc BCDC1220s and have had no problem with either, over 4 years old...

Correct wiring and use are also essential, lol.

I guess the first thing to do is disconnect the circuit, reconnect and retry. Keep in mind that a solar controller or indeed a Dc to DC won't charge if the battery is full.
So run the fridge for a few hours without charging, then connect the solar and see what happens.

My van has 2 x 100W multi spectrum panels. At my last use, I had used 42AH overnight (checked at about 8.30 am) When I returned at 1pm same day, the battery was full.

My portable 110W multi will replace my overnight Engel use by lunchtime in the 4x4 (not driving).

Both on an average partially overcast cool day.

My solar panel regulator failed, waiting on a new reg to arrive. Talking to a supplier, he said he had never had a panel fail but regulators do fail usually with no output.

I have ctek 5 years old, the auto elect says they fail 'all the time' but he has never seen redarc fail. Maybe has something to do with what he sells.

My clone fridge draws about 2.4 amps, 200w panel keeps the battery charged under average conditions if it is under 30c, above 30 run the car every 2nd day. The panels Condor used are better quality than mine, hence better performance.

Good luck with yours.