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-   -   The MY14 2nd Battery and DC Thread (http://www.jeepgarage.org/f190/the-my14-2nd-battery-and-dc-thread-63061.html)

coreys 07-19-2013 10:59 PM

The MY14 2nd Battery and DC Thread
 
This thread allows us to talk about wiring up high-current DC into the MY14 GC.

coreys 07-19-2013 11:14 PM

Re: The MY14 2nd Battery and DC Thread
 
Quote:

Originally Posted by lt4vette (Post 861424)
When I get my Overland CRD (its actually been allocated to a ship!), then one of the first things to do is fit a second battery. From my reading so far, it seems the options are in the wheel well - small battery - or in a separate tied down box on the floor in the back. It also seems to be highly recommended to use a DC-DC converter, partly to ensure the charging system doesn't get confused, and partly to ensure the right voltage for,say, a fridge. I have yet to determine whether a separate battery isolator is required. Any further suggestions would be greatly appreciated.

I use a DC-DC converter in my Camper Trailer, It's a CTEK D250S-dual. Works very well, though it did die just before warranty was up so it got replaced.

Most DC-DC chargers should shut-off when the input voltage drops below a certain value. This provides battery isolation and should be sufficient unless you want the threshold voltage to be higher. For the D250S-dual it is:

Quote:

The charger starts charging the target battery when the supply voltage exceeds 13.1V for 5 sec (engine on).
The charger stops charging the target battery when the supply voltage drops below 12.8V for 10 sec (engine off).
Of course, my second battery, along with the D250S-dual are in the trailer(you want the DC-DC charger as close to the battery as possible) but electrically, it's the same, except my cable run is longer hence there is an even greater need for a DC-DC charger.

I did see one site talking about the D250S-dual needing a relay when used with a variable alternator. Might need to do some more research. I don't have my car yet so I have not tested it.

lt4vette 07-19-2013 11:44 PM

Re: The MY14 2nd Battery and DC Thread
 
Quote:

Originally Posted by coreys (Post 861513)
I use a DC-DC converter in my Camper Trailer, It's a CTEK D250S-dual. Works very well, though it did die just before warranty was up so it got replaced.

Most DC-DC chargers should shut-off when the input voltage drops below a certain value. This provides battery isolation and should be sufficient unless you want the threshold voltage to be higher. For the D250S-dual it is:



Of course, my second battery, along with the D250S-dual are in the trailer(you want the DC-DC charger as close to the battery as possible) but electrically, it's the same, except my cable run is longer hence there is an even greater need for a DC-DC charger.

I did see one site talking about the D250S-dual needing a relay when used with a variable alternator. Might need to do some more research. I don't have my car yet so I have not tested it.

I too have a camper trailer (new - haven't tried it out yet except in the paddock!), but I was thinking I'd like the option of having the fridge in the car when not towing. Or maybe even when towing. Maybe the ideal would be a self contained (battery plus DC - DC charger) battery box which could be moved from car to trailer at will. I haven't decided what to do about lights in the trailer yet, and that could determine whether the battery needs to be there. Otherwise the fridge could stay in the car.

Pharmaboy 07-20-2013 12:10 AM

Re: The MY14 2nd Battery and DC Thread
 
Gee, is it all that high tech ? Can't you just wire in a second battery into the wheel space, and then onto the rear 12 v power supply for occasional 24hr use?

dunkit 02-10-2014 07:41 AM

Re: The MY14 2nd Battery and DC Thread
 
After reading many threads on the matter I finally put together a 2nd battery system where the battery box can be removed from the car for camping or 240v charging and the cabling can be removed when not being used.

I'd look at isolators and the like, but the Ctek D250S offers full charging of AGM batteries upto 14.6v and can be used with solar panels at camp sites.

I run a 40lt Waeco fridge in the boot, that leaves just enough room for the battery box and Ctek D250S charger to sit in front of it.

There is a Britax RC-1260R 60/80A 12v relay connected to the 12v cigarette socket in front of the gearshift (this is live with ignition - the centre bin is live all the time - I've swapped the fuse to enabled constant 12v for rear cargo). 12v 30A circuit breaker attached to the side of the relay box.

https://lh5.googleusercontent.com/-9...h809-no/10.jpg

What I didn't understand with this setup was the use of the relay and the diagram provided by Ctek didn't help. Looking at the diagram you're led to believe it switches between solar and alternator, thinking that if you don't have solar you don't need the relay - WRONG. Due to varying output of the Jeep's alternator, you need to use the SOLAR input on the Ctek. This will continue to charge/drain from your source even as your source voltage drops. The relay ensures you're only charging when the car is running...ahhh.
https://lh6.googleusercontent.com/-o...taltenator.jpg

Here are the parts I used
- Repco/SuperCheap large battery box
- Ritar RA12 120SD AGM
- CTek D250S
- Britax RC-1260R relay with connector
- Anderson plugs, cabling, connectors from Jaycar

https://lh6.googleusercontent.com/-1...-h809-no/9.jpg

LINK

INSTALLED PHOTOS TO COME....

adamt 02-10-2014 04:38 PM

Re: The MY14 2nd Battery and DC Thread
 
I use one of these ArkPak. Ark Corporation, powers the fridge in the car when travelling then gets transfered to the camper when set up.

Cheers

BobT 02-13-2014 01:17 AM

Re: The MY14 2nd Battery and DC Thread
 
I installed a Projecta 150A electronic isolator trailer kit. It charges the lithium battery bank in the Kimberley camper trailer in no time without a DC-DC converter and while the fridge is running. The isolator slots in neatly next to the battery in the car.

allypally 02-13-2014 05:50 AM

Re: The MY14 2nd Battery and DC Thread
 
Bob,

I can't get my isolator to supply power to my caravan battery, and to power my caravan fridge. I know the isolator is working correctly, and suspect the problem lies in the voltage drop in my wiring. The car has 6B&S and the caravan 10mm.
I measured the car supplied voltage at the caravan fridge and is showed 12.08V, which I suspect is so low that the isolator can't sense the caravan battery.
I plan to swap the caravan 10mm wiring for 4B&S cable to see if that fixes the issue.
If that fails, I will probably have to install a DC/DC charger.

coreys 02-13-2014 06:12 AM

I'm pretty sure that you will need a dcdc converter. The variable alternator just can't be guaranteed to provide a high enough voltage. As I understand a standard alternator is only ever designed to keep a battery charged to 70-80% anyway. This is due to the limitations of fixed voltage charging. If they made the charge voltage higher, the battery would overcharge.

Bob has an unusual situation as his kk had lithium batteries. Lithium batteries always need complex electronics to charge, else they tend to explode. These electronics are probably designed to cope with lower voltages in fact they likely already have a dcdc converter built in.

allypally 02-13-2014 06:46 AM

Re: The MY14 2nd Battery and DC Thread
 
Forgot to add, my caravan uses 2 x 110AH Lithiums.

dunkit 02-13-2014 07:17 AM

Re: The MY14 2nd Battery and DC Thread
 
Here is a pic of the relay box in place next the battery, showing 30a circuit breaker on top and the activation lead running off to the cigarette lighter socket. All photos here.

If your building your own battery box have a look at this volt amp ah gauge - ebay link

https://lh3.googleusercontent.com/-X...211_172943.jpg

pug303 02-13-2014 05:02 PM

Re: The MY14 2nd Battery and DC Thread
 
Dunkit, I've been trying to work out where to run the wires from the main battery. Your pics show your wires coming straight out onto the cabin floor. Did you do anything else to run them back please.


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