Aux Power Proposal

Hi Allan,

Not too sure about anything else, but I just love the idea of a
bottle chiller;))))



Michael

Hi Allan


Not a guru at this stuff but my set up is similar. I found the HF better wired to the start battery. If i was camped in one spot for a few days and the aux batteries were getting a little low I liked the idea of a fully charged battery to operate the HF.

Whilst I understand you can start the car , as you would to use the compressor,
I just liked the thought of that charged battery and emergency communications together.

I too am looking fondly at your bottle chiller.


Cheers Teza

A well thought out set-up Allan. I know you use appropriate cabling and connectors so won't even mention those.

Only thing you may consider is a battery monitor along the lines of a Nasa BM1 instead of V/A. I used to use just V and A meters, but the info the BM1 in my camper shows has me sold. Just something to consider as you have the circuit down pat - but it would add considerable expense and would be very hard to justify the $$$. But remember, "he who has the most toys wins" :)

Cheers mate

Captain

I have just discovered that Waeco does produce a Single Bottle Cooler here.
Image Could Not Be Found
But before you get too excited Michael and Tezza, it does not appear to be marketed in Australia. Sorry.

Hi Allan,
Nice setup, only change I would make is to have individual fuses or breakers for each device. This make fault finding a lot easier if someting fails and if one device fails it does not interfere with the others.

from Marty.

Allan,

Our setup doesn't include an AUX1 battery, so all loads go to the main 200Ah AUX2, and we don't have the bottle chiller.

Just a few thoughts -

1. I run our fridge through a changeover relay (headlight type) so it draws from the INPUT side of the dc-dc charger when voltage is available there, or the output side ( = your AUX2 battery) when no charging voltage is available. (The relay coil is driven by the input side voltage in our setup, so your situation differs because of the AUX1 battery.) This allows the dc-dc charger to deliver rated current to the battery regardless of the fridge cycling and ensure this cycling doesn't interfere with the charger's smarts. Suggest this might work well for you too, though the relay would need to be activated by the ignition rather than the charging voltage because of the presence of AUX1.

2. Not too happy with the fact that your AUX1 will continue to charge AUX2 when the alternator is not running.

3. I've had one occasion when the alternator died and it would have been great to be able to charge the cranking battery (and run the vehicle electrics) from the 200 Ah house battery and its 200W solar system. To allow this, I intend installing Anderson plugs each side of the dc-dc charger so that it can easily be reversed. Probably not an issue in your case as you can fall back on the AUX1 in an emergency, but a couple of Anderson plugs might add flexibility. In my case too, I have a 50A x 12-15V mains power supply that can be plugged into the input side of the dc-dc charger once those plugs are installed. Again - flexibility.

(When the alternator died, the cranking battery had enough grunt to start the (petrol) engine and I established a temporary connection so that the house system then ran the ignition and vehicle electrics - I have tenuous grounds for claiming to have had a solar powered Troopy!)

Cheers

John

Well it is all connected and working just as I expected. I'm pleased.


As anticipated, the BCDC continues to charge Aux2 from Aux1 for a short time after engine shutdown but drops out as the surface charge voltage on Aux1 drops below the threshold of the BCDC. I have not connected an ignition enable function to the BCDC as I could not be bothered running the wire. Seems unnecessary but can always be added later.

I connect a 15A Ctek charger to the cranking battery if the vehicle is to be idle for a while. This has worked fine as the Redarc SBI isolator closed with the elevated terminal voltage of the cranker and simultaneously float charged the two auxiliary batteries connected in parallel. This continues to work with the new arrangement as the SBI still closes and the terminal voltage of Aux1 battery rises above the 13.2 volt cut in of the BCDC and charges the Aux2 battery in 3-stage mode. All is good.

It has occurred to me that the scheme that I have concocted, although installed within a single vehicle, is no different from installations where a caravan or camper-trailer is involved. So nothing is really new.

Thanks again for your appraisals.

UPDATE 17 Dec.

After installing the system as proposed I observed its operation and decided to upgrade it.
Aux Battery 1 is not looking in the best of health probably due to being too deeply discharged then not being sufficiently charged. I will probably replace it. To protect it in future I decided to remove the Redarc SBI isolator and add a second Redarc BCDC1220 to service Aux Battery 1. This battery is in the engine bay but I have located the BCDC behind the glovebox yet close to the battery in order to not subject it to engine heat. The cranking battery remains directly connected to the alternator. The image below shows the new setup.

In operation, it was rewarding to see Aux Batt 1 being charged at a full 20 Amps whilst Aux batt 2 sat at 12.75 Volts and drawing no Amps as the fridge had not been on and it was now in float mode.

I may reinstall the solenoid from the SBI as shown dotted to enable the Crank and Aux1 batteries to be paralleled for emergency starting. However, if these batteries are paralleled for jump-starting it will be necessary to open CB1 first to avoid placing a short between the input and output of the BCDC Charger1.

Image Could Not Be Found

If all this does not provide the goods I may have to consider steam power. LOL