Dual Battery Setups! Let's see them! Multiple Batteries Thread!

Sub'd

 

I like how your system is weight balanced. I was thinking putting one in the truck bed on the passenger side. But if there is room under the hood, I would prefer it there.

 

what is te best way to isolate the second battery? a solenoid or isolator?

 

You are referring to a diode relay vs a solenoid relay; both are isolators, but vendors will not always use the term. Each has it's cons/pros.

Diode relays are solid state and will last the longest. Thy tend to be easier to wire. They are more expensive and get so hot they come in a heat sink - high heat areas will kill them. Unless you get a high end model, expect about a .5 voltage drop.

Solenoid relays are mechanical and will wear down in time. They are more affordable and can withstand high heat areas much better than SS relays. Solenoid relays experience virtually no voltage drop but consume about an amp per 100 rated amps when activated. Solenoid relays come in many more shapes/sizes and variations. The one you need is one rated for continuous duty.

Both types of relays should be rated at or above the max output of the alternator. There are hybrid models; essentially, they are smart solenoid relays - they use SS circuitry to monitor voltage levels and control when they activate.

I may have overlooked some features, but I believe these are the basic differences.

Edit. A big disadvantage of the solid state relay, for off-roaders at least, is that the ss relay cannot be used to help start your vehicle if the primary battery dies. The ss relay connects to the alternator and all the relay can do is split the charging power between the two batteries. That being said, if the primary battery is too drained, you don't want to use the 2nd battery to try and start the car through the relay circuitry because too much current will be drawn through and can pop fuses and fry the relay. To overcome both shortcomings, you can easily run a jumper cable from 2nd battery directly to the starter and break the cable with a manual on/off high amp switch.

 

Well I fixed my power issues over the weekend with some help from Mj.

Solar



Dual batteries

 

I am thinking to do the same thing before I damage mine. Do you have any pics of your battery relocation?

 

I would say the key is to distribute the weight as evenly as possible when installing the battery over the inside fender. I have four points on mine with fender washers at one end; a thick mending brace down the middle (with two mounting points on the fender); and a thick L bracket at the front end, bolted off the fender. That being said, I have yet to install the battery and carry the weight around, but I was cognizant of the weight on the fender when I installed the battery tray, a metal WirthCo model.

If you do go with batteries in the bed, definitely consider going with solenoid relays over diode, unless you get the $300+ models. Diode relays will take about .5 volts off your system; add up voltage lost over long wire lines and you'll be looking at long alt-battery charge times.

 

I have a couple of question for those that have installed a Peak DBI voltage monitor with a Bluesea ML-ACR. Where did you connect the red and yellow wires on your setup? Did you go all the way to the positive post of the respective batteries? Or perhaps to the posts on the ML-ACR?

If I connect to the ML-ACR, do you think there will there be a significant voltage drop? Significant enough to not want to do it?



@abarber11 @docloco

 

I connected mine to the two terminals on the ML-ACR. They were easily accessible rather than running wires to my fuse panels or battery terminals.

I don't see a voltage drop. We are running 1/0 cable to the ML-ACR so it's probably insignificant

 

I've been thinking about adding a small spst switch to the ground wire from the monitor so that I can switch it off if I want to, but haven't gotten around to it yet.

 

For now, they are connected directly to the battery terminal of my stock battery. I haven't installed both batteries yet. When I do (in the next month or so) connecting them to the two terminals of the ML-ACR would be an option too.

 

Thanks for the response. Good to hear. The shortest, simplest run for me is to the ML-ACR. I will likely go that route

I would be interested in hearing what you end up doing and what results you get. Thanks for the feedback.

Why is that? Is it because the lights are bright/distracting?

 

The ML-ACR is a smart solenoid relay; that coupled with the large 1/0 cables, and you got yourself a solid system. Comparatively speaking, 10 ft of 2AWG results in about .40 voltage drop; 1/0 is about .25 drop.
http://www.calculator.net/voltage-drop-calculator.html

 

They aren't too bright or distracting. I sometimes don't drive the truck for days at a time, so I just don't feel like I need the monitor all the time. It's a very low draw, but adding a little toggle switch to the ground just seems like an easy way to allow me to have control depending on my actual need to monitor. I haven't decided if it's necessary yet, tho.

 

Thanks. Good to hear that over brightness is not a big issue. I was thinking about where I want to place it. It would be great to make it visible during normal driving and also be readily visible in camp, by looking thru the window. Guess I will have to play around with placement.

 

Thanks for putting some numbers to it. I just knew that I wanted as much efficiency out of my system as I could get and 1/0 was one of the cheaper ways to achieve that.

@Digiratus based on the website that Chuy copied, for the 50ma draw of the monitor it looks like the drop is around 0.001v with 1/0 to the ACR terminals. That monitor isn't that sensitive anyway with LEDs about every 0.3 or 0.4 volts. Its got to be better to run 4ish ft of 22ga(?) from the monitor to the ACR rather than run smaller gauge wire all the way to the batteries (one of mine is behind the rear seat in a DC). If your batteries are closer to the monitor it might not make as much/any difference

 

It's visible in the location that I put it and is located right by the switch so it satisfies my OCD need to keep things together. You might not have open switch blanks in the right most location depending on your accessories. I drilled a very small hole in the trim to the right of the last switch blank and fed the wires thru then added the 3M mounting tape to the back and it's been holding fine.

It's mostly visible from the driver's seat if I tilt my head 2 inches to the left and it's very visible thru the driver's side window. No complaints.



Couple more for shits n gigs
Thru window


Thru window in dark

 

Outstanding info gentleman. Helps a lot.

One batt is in the stock location (~18" run), the other one is in the bed. I will likely start by going directly to the ML-ACR for both and not worrying too much about the v-drop from the house batt in the bed. Using 1/0.

 

I really appreciate the feedback but my '02 is quite a bit different so this part is interesting but probably not that applicable to my situation.
I'm actually thinking about placing it next to the winch plug on the center console.

 

Ah didn't realize you were in a first gen. Lol. Then my location will not help!