What’s the Best Dual Battery Setup - VF Commodore?

[vsiicalais]

I’m looking to put in a dual battery setup in my VF Sedan. I want to run my dash cam and the fridge off the second battery 24/7. I’ve tried to research the different setups but can’t work out which is best for my needs.

I drive 5 mins to and from work each day, do a couple of 20-30 min trips a week and a 2-3 hour trip every fortnight so the charging time isn’t the best, but I want to be able to keep the fridge/dash cam running as long as possible without affecting the main battery.

Both don’t draw a lot of power (can run them for a day or so on the main battery after a long trip) so it’s more for when I don’t make the longer trips. I think I need a dc-dc charger and a battery but not sure what ones. Any suggestions or examples you have fitted would be greatly appreciated.

 

[axemurderer101]

For the dcdc charger i'd stick to either Redarc or Ctek. Ctek is easier to wire as it has posts you connect ring terminals to so all you need is a crimp terminal tool. Battery depends on your budget but any deep cycle will be fine, a standard lead acid battery will need proper venting to the outside of the car though. Size wise look for around 100ah or more.

 

[vsiicalais]

For the dcdc charger i'd stick to either Redarc or Ctek. Ctek is easier to wire as it has posts you connect ring terminals to so all you need is a crimp terminal tool. Battery depends on your budget but any deep cycle will be fine, a standard lead acid battery will need proper venting to the outside of the car though. Size wise look for around 100ah or more.

Ok awesome, just been browsing the dcdc chargers, now I’m even more confused haha. There are soo many to choose from. Which one do you recommend in either brand. Looking to pay up to about $300 maybe a little more if needed for a decent one.

 

[axemurderer101]

For redarc go the BCDC1220IGN, Ctek go D250SA. Both are 20amp chargers and you will need to run an ignition trigger to them.

 

[losh1971]

CTEK will be the cheapest. Where do you plan on installing the aux battery? If it's going in the boot or inside the cab you will need an AGM. There are other options for charging the battery like having a solenoid that charges the aux battery once the voltage in the main battery hits 13.8v. Even with the CTEK you will still probably need a dual battery isolator to set it up properly. I guess you could have it switched through the ignition but that will require a relay as the CTEK will draw a lot more current than the thin cables can handle in most of the car. I used to run a Weaco and had a dual battery isolator with 250a override switch to jump the battery if I ever had a battery failure. There is a lot to consider and if your total budget is 300 bucks you will need to at least double that. How big is your fridge? A 40L Waeco draws about 5amps while running and about 10amps for the first min each time it cuts in. Idle they draw about 2amps. So not sure how you can run it for 24hrs and not drop the volts right down on your main battery??

 

[axemurderer101]

CTEK will be the cheapest. Where do you plan on installing the aux battery? If it's going in the boot or inside the cab you will need an AGM. There are other options for charging the battery like having a solenoid that charges the aux battery once the voltage in the main battery hits 13.8v. Even with the CTEK you will still probably need a dual battery isolator to set it up properly. I guess you could have it switched through the ignition but that will require a relay as the CTEK will draw a lot more current than the thin cables can handle in most of the car. I used to run a Weaco and had a dual battery isolator with 250a override switch to jump the battery if I ever had a battery failure. There is a lot to consider and if your total budget is 300 bucks you will need to at least double that. How big is your fridge? A 40L Waeco draws about 5amps while running and about 10amps for the first min each time it cuts in. Idle they draw about 2amps. So not sure how you can run it for 24hrs and not drop the volts right down on your main battery??

A standard voltage sensitive isolator like the redarc Sbi12 are not recommended for most new cars due to voltage variable alternators controlled by the ecu, if the ecu drops the alternator voltage the relay may cut out or you might not get a good charge voltage into your aux battery. Both dcdc charges i listed above (only black ctek though) both have a small ignition input into the charger so it will always charge above 14v when the car is running.

 

[vsiicalais]

I have just ordered the ctek d250sa, I’m looking at getting a agm deep cycle battery which will be installed in the boot near the existing battery. The fridge I have is a Waeco CF50.

 

[losh1971]

A standard voltage sensitive isolator like the redarc Sbi12 are not recommended for most new cars due to voltage variable alternators controlled by the ecu, if the ecu drops the alternator voltage the relay may cut out or you might not get a good charge voltage into your aux battery. Both dcdc charges i listed above (only black ctek though) both have a small ignition input into the charger so it will always charge above 14v when the car is running.

True but the DC charger switched through the ignition only will only charge while the engine is running pretty much. I agree that a solenoid in isolation is not the best option as it does take some work to set them up to give decent charge. I had to run thick battery cable and circuit breakers to ensure the charge rate was sufficient. I also had to trick the alt into charging at a higher rate by modifying the battery temp sensor. Not sure if this can be done on a VF, probably not and may not even be needed. The problem with the cheaper DC chargers is they are only about 20A and short trips won't charge up a deeply discharged battery. Where as having an isolator and DC charger you get the best of both worlds. IIRC some of the Redarc's incorporate both into there 40a DC charger, but last time I looked they were well over $500 to buy I'm pretty sure. Also where would the OP draw power from for the CTEK? If it's not from the battery surely the current draw will overload the aux port in the boot if the boot has one. Yet if you connect to the main battery as it should be then it will require relays connected through a switch that only works when the ignition is on, with 6BS cable connected to the CTEK.

 

[axemurderer101]

Dont really wanna argue with you lol but the ctek will not draw power from the battery when the car is not running. Ive been an autosparky for 10 years and have fitted all sorts of dual battery systems from dcdc chargers to the old cole hersee manual switches.

 

[losh1971]

Dont really wanna argue with you lol but the ctek will not draw power from the battery when the car is not running. Ive been an autosparky for 10 years and have fitted all sorts of dual battery systems from dcdc chargers to the old cole hersee manual switches.

OK that makes sense then. So what you're saying is the CTEK more or less acts as solenoid, in that once the voltage drops to a certain level in the main it automatically cuts the feed to the fridge from the main, meaning that it won't flatten the cranking battery because the fridge is drawing down on the aux alone?