Hello folks,
I don't have any specific problem or issue (but I am sure they will come up lol.) Just wanted to get people's opinions and comments before I start this project. I have a decent subscriber base on YouTube & am happy to include anyone's name and URL / link who wants to help out. (Going to make a short vid of this install.)

I want to set up a multiple battery system in my 2007 RX 350. It will be primarily to power a trailer and the electronics inside it. (Computers, cameras, chargers, ect.) I was also thinking of adding a small fridge, however all the portable ones are in the $600 range? Don't understand why. I have a little office fridge I got for 75 bucks and it works perfect, but perhaps there's something about keeping the compressor stable / immobilized that adds the extra cost. Or maybe it's something to do with slowly starting the compressor motor..

Anyway. I have all Optima yellow top batteries. I have got a D35 starter battery already installed, and two D25/D75 batteries loose. Going to hook up a Battery Isolator and then finally tandem inverters.

So, I guess to get the project started, I need to run a cable from the starter battery's hot terminal (+). There is existing wiring for the trailer's lighting & power, but I think the wiring is not sufficient gauge to carry the load my I need it to. I checked up on my vehicle’s capabilities, being that this version has the “towing package” and I’m never going to be hauling anything really heavy (Except maybe a LED Disco ball for parties!!) I should be fine on the weight.

So anyway, has anyone ever run such a thick cable through a 2007 RX’s firewall? There is also a lead that runs under the plastic on the driver’s side of the vehicle for the trailer, I am thinking of trying to follow that as far as I can. I got a repair manual on eBay, but it’s not exactly step-by-step, it’s very cryptic. I will need to really study it to understand things.

Lastly, my hope for the future is to put a solar panel on top of the trailer’s roof, that way if the whole vehicle is left idle there is something to keep the batteries from going dry. I guess I would use a charge controller and connect the panel to one of my batteries. Or use a grid tie inverter, I wonder if that’s ever been done before!

Anyway, I have a full selection of tools, meters, equipment, supplies, ect. I probably have every gauge wire possible lying around my garage, so parts won’t be a problem. Would be awesome to get anyone’s feedback, if I am making some huge mistake catch it now before I implement it. Thanks in advance.

 

Personally, I would try to avoid modifying your RX in any way. Allows you to move the trailer to a different vehicle in the future without worries. Try to keep the trailer as self contained as possible. Consider going to a solar setup on the roof of the trailer to provide a charge while on the road along with a 120V connection to the outside of the trailer to hookup when possible to provide a more immediate charge. Put in a switch so you can move from one charging system to the other.

Solar kits, for example, can be obtained from a number of sources such as Harbor Freight and others:

http://www.harborfreight.com/Solar-P...att-68751.html

http://www.batterystuff.com/solar-chargers/BSP60WK.html

Next, you can wire in a couple of AGM battery tenders to charge the batteries when you connect an extension cord to the 120V exterior outlet. Be careful of battery outgassing. You will need to be mindful of proper ventilation for these batteries and to make sure the chargers will not damage any batteries you might install.

http://batterytender.com/power-tende...12v-at-5a.html

These products are just for example and are meant only to give you an idea of what I am talking about and get you moving in the right direction. Take a look around and do some searching before getting too far ahead of yourself on this project. You may very well find many a product better suited for what you have in mind.

BTW, this type of thing is very common in the RV world. Would be one source of information I would look at in your research. Many new RVs have multiple AGM batteries to run appliances while off the grid and use solar charging. Have also seen a few rigs along the way which had their own wind power setup. Perhaps you might pull some useful information off the following:


Just one man's thoughts.

 

Thank you very much for your reply and suggestions, I hear you about keeping the equip inside the trailer.. here's the thing, I may want to use some of the high-power capability with the trailer detached.. I guess I could afford to give that up though.

The other thing is that in the trunk, where you'd think the spare tire would be, are huge empty plastic trays / compartments! I mean like *perfect* places to put some of this stuff. I will take a photo and some measurements tomorrow.

 

Another thought, my instructions explicitly state that I need to run a positive hot lead from the battery and a negative return lead from the chassis. The chassis has no areas to connect lead wires too, so I would have to randomly solder a wire in an inconspicuous space. How important is this? Why can't the negative lead simply be the negative terminal on the battery? Makes no sense to me since they are directly connected.

 

I would suggest running a heavy duty wire UNDER the RX back to the trailer hitch, 30 amp CB right at the battery connection. Put the spare batteryin the trailer anmd keep it charged using a 400 watt inverter (HF <$40)/10 Amp battery charger combination.

Simply wiring the trailer battery to the main battery will not work well due to the to/from voltage drop.

Your office frig may not work with an MSW inverter and PSW inverter are no cheap. So determine the starting current for the frig's compressor motor and buy a PSW inverter to meat that requirement. Power the PSW inverter through ta relay via the frig's thermostatic switch.