DC to DC Charger vs Battery Isolator

[johndavis125262]

this is were i put my DCDC CHARGER and in the back regards john

[reciprovac]

DC to DC Charger

I have a 2013 NW Pajero and I am in the process of wiring up an auxillary battery for my Waeco 40L fridge in the rear of the wagon.
I read somewhere that most 4WD's built after 2010 have cut back on the output from their alternators and that a DC to DC charger was needed to bring the second battery up to full charge. Is this the case?
I was about to hand over some coin for a Projecta 25A DC to DC charger but if the alternator pumps out enough for both batteries to fully charge, then I can purchase a Projector 150 dual battery isolator for less than half the cost of the DC to DC charger. Will the isolator do the job?
Thoughts?

I installed a Projector Isolator and could only ever get 11 Volts to the rear Aux supply.Finally gave up and installed a DC to DC charger,result a full 13 Volts to Aux and no more problems.
It is all caused by the Smart or not so Smart Alternator.
Regards.

[Sparky3975]

One of the benefits of a DC-DC charger is that it can compensate for the voltage drop on long cable runs - which you're foregoing if you mount the charger under the bonnet and the battery in the rear.

Mount the charger as close to the aux battery as you can.

I was watching a YouTube video last night and they suggested installing a Redarc BCDC charger within a metre of the auxiliary battery to get full effectiveness. That was on the JTS (Jamie's touring solutions) site.

[Dicko1]

I have the redarc 1220bcdc-ign in the rear tub of paj with 2 agms. Last week I installed a projector icd25 in the camper trailer to feed 2 x fullriver agm,s. Fed from anderson plugs on rear bar. Fuses at both batteries. Straight away I got 14.4 on the gauge. Happy knowing that all 4 auxillaries will be getting 100% charge and will be maintained well. Definately put the dcdc as close as you can next to auxillary batteries. I have expensive seperate MPPT solar charger that I have connected solar with on the trailer.

[sharkcaver]

I have the redarc 1220bcdc-ign in the rear tub of paj with 2 agms. Last week I installed a projector icd25 in the camper trailer to feed 2 x fullriver agm,s. Fed from anderson plugs on rear bar. Fuses at both batteries. Straight away I got 14.4 on the gauge. Happy knowing that all 4 auxillaries will be getting 100% charge and will be maintained well. Definately put the dcdc as close as you can next to auxillary batteries. I have expensive seperate MPPT solar charger that I have connected solar with on the trailer.

You would be better off with a 40 Amper DC/DC for 2 batteries. However, with 4 batteries on the go, you wouldn't get away with 2 x 40 ampers I would think. I have the idc25 supplying a single battery in the tub and a BCDC40 in the camper feeding 2 batteries. There is nearly 90A consumed (at full load) from a 130A peak alternator. Somehow I reckon I will never get full current output on both the DCDC chargers as the alternator wont supply their needs. Voltage will be fine, but amperage wont.

[Dicko1]

You would be better off with a 40 Amper DC/DC for 2 batteries. However, with 4 batteries on the go, you wouldn't get away with 2 x 40 ampers I would think. I have the idc25 supplying a single battery in the tub and a BCDC40 in the camper feeding 2 batteries. There is nearly 90A consumed (at full load) from a 130A peak alternator. Somehow I reckon I will never get full current output on both the DCDC chargers as the alternator wont supply their needs. Voltage will be fine, but amperage wont.

Happy with 20 amp going to the aux batteries in tub as they are also fed by a constant source of solar (5 amps). They only runa 45 litre engel when camping and do it easily. The 25 amp dcdc in camper feed a 47 litre evakool and also camp leds, laptop and fan. These also have solar on when camping (160 watts..10 amps roughly). As you said I wouldnt get any benefit from a 40 amp set up for both sets. You cant get 25 litres into a 20 litre bucket. The solar panels are a huge bonus when camping and if all else fails...crank up the 2 kva honda!!!..

cheers

[denmonkey]

have had a projector dcdc in a previous vehicle with a 120w solar panel on top for about a year.
It's now coming over the the paj when time permits.
It has worked faultlessly and I have had a 45l fridge running 24/7 for that year.
Even when the car has not been run for 3 days it is still topped up and I have no worries in that area.
So if you're camping long term a dcdc charger with solar input is very handy, so you don't have to run the car to top it up.

As said the charger has to be mounter as close to the Aux battery as possible otherwise you're defeating the purpose of having it there with voltage drop between them.
After all this is why you fit it in the first place.

[rosmbr]

I run a Redarc Bcdc1225 mounted in front of the radiator, with 120w Project Panel mounted to roof rack connected to the BCDC. Running a 65l Waeco CFX, camp lights and used for charging all your peripherals such as phones, torches etc... Rarely under 100% charge during daytime hours, even on overcast and days of rain.

The Battery can also make a significant difference. I installed my deep cycle in the Aux tray. Went with the Optima Yellow Top (75AH). I have been away for multiple weeks at a time and have never been concerned about running out of power. Been away with with friends using 100AH+ eBay specials who run a similar setup and seem to run their batteries down long before I do.

[KPJero]

If I get a DCDC charger (i will get one that can handle solar for future solar panels) so I also need an isolator or is that it?

[2bad4u]

If I get a DCDC charger (i will get one that can handle solar for future solar panels) so I also need an isolator or is that it?

Just the DC-DC as they have an inbuilt isolation function.

[KPJero]

Just the DC-DC as they have an inbuilt isolation function.

Thanks mate

[MikeL]

You may still want to have an isolator like the Redarc Voltage Sensing Relay which has the ability for an in-vehicle battery bridge switch which may get you out of trouble if your starter flattens and you still have juice in your secondary battery.

[2bad4u]

You may still want to have an isolator like the Redarc Voltage Sensing Relay which has the ability for an in-vehicle battery bridge switch which may get you out of trouble if your starter flattens and you still have juice in your secondary battery.

Or just use a $10 set of jumper leads rather than an expensive isolator for "just in case".

[KPJero]

I'm hoping someone can help me.
I fitted a projecta idc25 today using the instructions supplied and am having issues.
Basically, the DCDC charger only blinks blue (AGM LED) every 8 seconds, that's it. The mounted LED indicator i fitted to the dash doesn't light up nor does the Input (solar / alternator / charging). The only way I can get the alternator led and the mounted LED indicator to light up, is to hold the Mode button for 4 seconds. Then both those light up for a few seconds while the device thinks and then it goes back to the AGM flashing blue every 8 seconds.
Here is how I wired it, as per the instructions:
From starter battery + I used 8b&s to 50amp maxi fuse to Anderson plug (just used one half of Anderson, and yes the positive end, and connected to Anderson plug that was leftover from another installation (of my VSR that wouldn't work because of the stupid smart alternator). This then runs 8b&s the length of the pajero to the red cable of the DCDC charger.
I used twin core power cable 15amp and attached one cable to the LED and the other to the ignition switch at the DCDC charger. Then I ran those to the front near the steering wheel where I took the LED cable to the mounted LED indicator. Then grounded the LED indicator. The other cable of the twin core power cable is connected via a fuse tap to the fuse panel. I think I used ABS braking or something. I tested with a 12v test light. It only comes on when the key is switched to ON.
Solar and temperature sensing wires are taped up.
The brown cable of the DCDC charger is connected to the + of my aux battery box via a 50amp maxi fuse and 8b&s cable.
The black cable of the DCDC charger is connected to the - of my aux battery box.

If i disconnect my start battery from the DCDC charger (by unplugging Anderson plugs) the AMG blue light will still flash every 8 seconds, goes for with car off or on.
It will also flash if my ignition is off. If I turn my battery box off, it will not flash.
I am very very confused. Shouldn't the DCDC charger show 'alternator' when my car is on? Shouldn't the LED indicator light also be onewhen my car is on? And shouldn't the DCDC charger not flash AGM if it has no power / ignition turned off?!

[Tis]

I am very very confused. Shouldn't the DCDC charger show 'alternator' when my car is on? Shouldn't the LED indicator light also be onewhen my car is on? And shouldn't the DCDC charger not flash AGM if it has no power / ignition turned off?!

These can take up to 2 minutes to start charging