Quote:
Originally Posted by JamesLaugesen
That sounds like a good plan 
I just ran two 6mm cables through the existing cable grommet on the passenger side of the firewall (accessible behind the ABS pump and behind/above the interior trim around the bonnet release lever, along the floor under the sill trim, up behind the rear quarter-panel trim and into the void where the battery is. I used two thinner cables only because they'd feed through better than a slighter thicker single cable.
I considered drilling a hole through the floor, but already have the AUX tank in and couldn't find a good spot to feed the cable through conduit and know that it's safe from rubbing.
But in my case it's only feeding a 30A DC-DC charger, so only really need to handle ~60A peak. Then I just have a relay triggered from a momentary switch on the dash to bypass the charger, so I can 'boost' a flat crank battery off the lithium. That's a manual thing though so I just have a slow-burn fuse after the relay.
Charging a large lifepo4 directly off the alternator (via a VSR or whatever.) is a bad idea, a low battery will easily pull 100% load from an auto alternator for hours on-end. Need something to limit the current and an off-the-shelf DC-DC charger is the most cost effective way I found.
This is pretty-much where's it's at now;
A cable drag (the black thing from the fridge.) is a good way to get power to the sliding floor, since it stops the cable from falling down into the void space and getting pinched or whatever. I planned to run it on the underside of the floor but I ran out of space once the charger and inverter were in, so it ended up on the top looking a bit clunky. |
Cool - it looks like it is coming along nicely! I have never seen that cable drag thing, does it coil up automatically as your drawer/slide gets pushed back in? I definitely want to install a switch to give the cranking battery a boost if needed too.
I was just planning to run an 120Ah AGM deep cycle battery that I can swap in from my camper trailer (I have 2). I also want to interconnect the other battery in the camper trailer whilst towing as well (it is set up with 6 B&S cable, Anderson plug and circuit breakers already). A lithium battery would be nice of course, but at this stage I will stick with what I have got.
I must say that 12V electrics is not my area of expertise, however I did do a lot of research prior to wiring my camper trailer a few years ago and there was always heated arguments between the Pro DC-DC charger brigade and those that believe they were a waste of money in most applications.
From my understanding, you only NEED a DC-DC charger if you have a situation where you have a large voltage drop from the alternator to the battery you want charged (i.e. undersized cable) OR your vehicle alternator does not put put 14.4V consistently - for instance modern Toyota 4WD's either have temperature-sensitive or time limited maximum outputs that drop alternator output to 13.2V when triggered.
So if you have an alternator that consistently puts out 14.4V (I believe that the CRD alternator does?) and the appropriate cabling (6 B&S) then I understand that I don't need a DC-DC charger? The other point that I read is people say you need to be driving for a long period of time before a DC-DC charger can actually bring a deep cycle battery back up to a high state of charge - longer than for the equivalent direct charge from the alternator.
Have I got this right? I would rather keep things simple, but I also want to make sure I get it right the first time!!
BTW - where did you source your anchor track from? I need ~4 x 950mm lengths and struggling to find a decent option for supply of this requirement on eBay. Most that have 610mm lengths going cheap, don't also have the 305mm lengths as well. I suppose I could always cut it to suit?
