Dual Battery questions

[hawairish]

Ideally I'd like to add a small battery (primary) for starting, and use the existing battery (secondary) for all other electronics.

 

From what I can tell from other installs, the main battery is for normal OE duties (starting and accessories), and the 2nd for other other accessories (lights, winches, fridges, RigRunner, etc.)

 

I plan to add a fused power distribution panel at the rear of the vehicle for camp-related items. But if the vehicle is off, I might want cabin or exterior lighting and the radio on...wouldn't I want those on the 2nd battery, too?

 

My positive terminal has a main lead and two smaller leads. I haven't followed the wiring yet, but I'm presuming that the main wire goes to the alternator and starter, one smaller goes to the fuse/relay panel under the hood, and the other smaller goes to the interior fuse panel. Is it as simple as putting the larger on the primary battery, and one or both smaller on the secondary battery?

 

If this is the case, I'd then probably want the heavier duty OE items like A/C and headlights on the primary battery, and all the all the interior electronics and future stuff on the secondary?

 

I also like the idea of using a marine battery switch for linking the battery, should I need to jump the battery. I know this is what the T-Max does with the Link button, but for some reason I think I'd prefer a hard switch in the engine compartment and one less set of wires to run into the cabin. Any thoughts here?

[Motofish]

I have been planning nearly the same thing. It seems like this should be about ideal as far as a switch goes: http://www.amazon.com/Blue-Sea-Systems-Selector-Battery/dp/B000K2MCR2/ref=sr_1_1?ie=UTF8&qid=1438047183&sr=8-1&keywords=Marine+battery+switch Im a fan of the k.i.s.s. principle.

 

Are you currently running a deep cycle battery? That would be the best choice for frequent current drain applications with the engine off, as far as i know... Something like this:

http://www.amazon.com/Optima-Batteries-8014-045-YellowTop-Purpose/dp/B000MSBUA4/ref=sr_1_1?s=automotive&ie=UTF8&qid=1438047506&vehicle=1993-67-893-49--9-12-8-5591-1727-4-2-1873-18-3-0&sr=1-1&ymm=1993%3Anissan%3Apathfinder&keywords=optima+yellow+top

Im planning on this being the second battery and then getting another to be the main battery when my current standard die hard, dies...

 

Finally, you would need a way to moniter each system... Thats where im hanging up a bit... How to monitor the actual battery level while it is charging. A voltage readout will only be accurate while the battery is not charging, otherwise if its tied to the alternator it would read system voltage correct? Maybe that is where the T-max actually saves time and money?

Edited July 28, 2015 by Motofish

[Rebelord]

Look up ThExbrit. He has a dual battery setup. Also on Expeditionportal.com there are a ton of dual setups.

 

Sent from fat fingers on S6

[hawairish]

Yep, I was looking at the Blue Sea stuff specifically. Just seems like a really good, well-documented product line. I got a chuckle out of the T-Max instruction where it shows a pic of the "Batter" monitor (the pic looks a little lumpy, too).

 

I didn't see this kit earlier when searching, but it seems to be what I'd go with. The included switch (5511e) is the one I want because I couldn't think of a scenario when I'd need a 2-only position. Price seems right, too: http://www.amazon.com/Blue-Sea-Systems-120A-Add-A-Battery/dp/B000RZNP5K.

 

I was thinking about the lack of a meter, too. It'd be nice to see the status, but I wouldn't think putting some inline voltmeters would be any different than what the T-Max can display, and when (running, off). I've got a voltmeter under my radio now, and that seems to be sufficient enough for me`to determine charge and voltage. A second one on the other system would probably be fine (and inexpensive).

 

However, one feature I did like about the T-Max, is that its Link mode is on a timer. Prevents accidentally leaving the system in a linked mode for an extended period and draining both batteries. But since I'd only be using the manual switch for specific reason (jumping the battery) and it'd be installed under the hood, seems like having the hood open would be a good reminder.

 

Ironman also has a kit, but seems pretty pricey ($300 through a Toyota parts dealer in TX is all I've found for a source): http://www.ironman4x4.com/products/dual-battery-systems/dual-battery-kit-140-amp-includes-monitor

[hawairish]

Look up ThExbrit. He has a dual battery setup. Also on Expeditionportal.com there are a ton of dual setups.

 

Sent from fat fingers on S6

 

Yep, I read Theexbrit's, 96Pathfinder4x4's, KiwiPete's, and some info from XPLORx4 and his components (not sure about his setup) and a few other outside of here including one particular gem on ExPo before posting. I've seen numerous diagrams, and have read up on several configs, including some provided by Blue Sea and other marine applications.

 

But none really answer my questions, just explain the typical setup of just adding a battery, and adding new stuff to that battery. The one question in particular interest is divorcing the starting system from the other electronics (how easy, and if worthwhile). The few diagrams I've seen just show the starter/alternator on battery 1, and everything else on battery 2...but it's not clear to me how everything is just simply separated like that.

Edited July 28, 2015 by hawairish

[hawairish]

Are you currently running a deep cycle battery? That would be the best choice for frequent current drain applications with the engine off, as far as i know... Something like this:

http://www.amazon.com/Optima-Batteries-8014-045-YellowTop-Purpose/dp/B000MSBUA4/ref=sr_1_1?s=automotive&ie=UTF8&qid=1438047506&vehicle=1993-67-893-49--9-12-8-5591-1727-4-2-1873-18-3-0&sr=1-1&ymm=1993%3Anissan%3Apathfinder&keywords=optima+yellow+top

Im planning on this being the second battery and then getting another to be the main battery when my current standard die hard, dies...

 

I'm not currently running a deep cycle, but I think it's on its last leg anyway. The heat and age has been taking its toll and if it sits for a couple days, it takes a little extra to turn over. I was thinking something small for the starting system, maybe a Group 25 size, and then a basic battery. I don't currently have anything that warrants an Optima, but eventually I will.

[Motofish]

 

I'm not currently running a deep cycle, but I think it's on its last leg anyway. The heat and age has been taking its toll and if it sits for a couple days, it takes a little extra to turn over. I was thinking something small for the starting system, maybe a Group 25 size, and then a basic battery. I don't currently have anything that warrants an Optima, but eventually I will.

So if you will be running everything but the starter off of your secondary (larger) battery, and only using the smaller for starting, that would neccesitate having battery 2 connected to the alternator most of the time and battery 1 only long enough to replenish cranking losses? So in your setup maybe a standard battery would be better?

 

I guess the reason i was planning on a deep cycle for my secondary battery is because ive heard that frequently draining to low level and recharging a normal lead acid battery will result in an early death for the standard battery. (Im thinking fridge, lights, etc while camping, engine off) I figure with the light duty it would perform in the backup role, a deep cycle should last a very long time... If thats the case, i would think it would be well worth the initial investment for a potential 10-15 year battery (2-3x lead acid lifespan).

 

Im still doing research, though, and have a lot to learn about batteries, and things. But maybe someone who is more knowledgeable can jump in and drop some knowledge?

[hawairish]

I think I see what you're saying...since the smaller battery would only be for starting, it probably doesn't need to be on the alternator-side of the isolator or ACR.

 

But, the more I think about it, though the less I think it really matters as long as:

 

1. The batteries charge together

2. The batteries discharge separately

3. Whatever electronics to be used for prolonged periods between starts are connected to the deep(er) cycle battery.

 

I probably will plan for a setup with a deep cycle when the current battery croaks. This power project will eventually support an inverter, air compressor, water pump (for an onboard water supply), and maybe even a fridge. But I also want the radio and cabin lights on that circuit, and redundancy for starting. I think that Blue Sea kit is the "essential" items.

 

...but if I'm not mistaken, all that's really essential is an isolator, which is just a big relay: + from battery 1 to one side, + from battery 2 to the other side, and a latching signal across two other terminals (12V when the ignition is ON to ground). A selector switch is useful for selecting which battery(ies) to use for a function (like starting), or combing the two for jump starting. The T-Max is useful if you want meter readings, and both the T-Max and ACRs manage the charge (when both batteries are charged, it opens the circuit to prevent over-charging, then senses when the secondary battery has discharged enough and closes the circuit...kind of like a trickle charger).

 

Is that it in a nutshell?

[Motofish]

I think I see what you're saying...since the smaller battery would only be for starting, it probably doesn't need to be on the alternator-side of the isolator or ACR.

 

But, the more I think about it, though the less I think it really matters as long as:

 

1. The batteries charge together

2. The batteries discharge separately

3. Whatever electronics to be used for prolonged periods between starts are connected to the deep(er) cycle battery.

 

Agreed, since in this case the ACR should be isolating the "full" battery anyway during charging. I think other systems would only add levels of automation and perhaps some type of convenience features. But you have boiled it down to the essential elements, as i see it, as well.

 

I probably will plan for a setup with a deep cycle when the current battery croaks. This power project will eventually support an inverter, air compressor, water pump (for an onboard water supply), and maybe even a fridge. But I also want the radio and cabin lights on that circuit, and redundancy for starting. I think that Blue Sea kit is the "essential" items.

 

...but if I'm not mistaken, all that's really essential is an isolator, which is just a big relay: + from battery 1 to one side, + from battery 2 to the other side, and a latching signal across two other terminals (12V when the ignition is ON to ground). A selector switch is useful for selecting which battery(ies) to use for a function (like starting), or combing the two for jump starting. The T-Max is useful if you want meter readings, and both the T-Max and ACRs manage the charge (when both batteries are charged, it opens the circuit to prevent over-charging, then senses when the secondary battery has discharged enough and closes the circuit...kind of like a trickle charger).

 

Yes, i think that would cover the necessities, other than adding your own voltage readouts, which i think you said you already have (at least for your current setup). I like the idea of the blue sea systems rotary knob vs tmax's style of buttons from a durability standpoint. Also, a quality electrical component designed for marine environments should be ideal for our purposes due to superior corrosion resistance, i would think. What do you think about vibration? Would that be more of a concern for 4wd than it would be for marine? Maybe that answer would depend more on what type of wheeling one does with their rig... Also is dust a concern? Im still vacuuming dust out of my pathfinder and i havent wheeled in the desert for over a year! Lol. (Used to live in SoCal)

 

 

Is that it in a nutshell?

I think you have a good plan for your system, its protected from overcharging, your starting battery is protected from excessive draining and recharging (isolated), your selector is simple and easy to manipulate, as well as durable from a corrosion resistance standpoint...

Are you planning to put them both under the hood?

[hawairish]

Yes, i think that would cover the necessities, other than adding your own voltage readouts, which i think you said you already have (at least for your current setup). I like the idea of the blue sea systems rotary knob vs tmax's style of buttons from a durability standpoint. Also, a quality electrical component designed for marine environments should be ideal for our purposes due to superior corrosion resistance, i would think. What do you think about vibration? Would that be more of a concern for 4wd than it would be for marine? Maybe that answer would depend more on what type of wheeling one does with their rig... Also is dust a concern? Im still vacuuming dust out of my pathfinder and i havent wheeled in the desert for over a year! Lol. (Used to live in SoCal)

 

Are you planning to put them both under the hood?

 

I prefer a physical switch, too. There are a couple other little nuances about the T-Max that have me hung up...one, it doesn't appear that there's any integrated way to mount it (I'm not using Velcro, and it's not going to get tucked away somewhere), and two, if the Link button should fail for any reason (integrated circuit, melted tactical button), I'd have to cut wires to bypass it (which I don't want to do). I'm a big stickler for clean installs.

 

The Blue Sea modules are IP66 and IP67 rated, meaning they're both dust proof (the first "6") and resist either powerful jets of water (the second "6") or full immersion (the "7") for a minimum period of time. And of course the superior corrosion. If it can withstand of the neck-jarring impacts of a boat going through crests at speed, I have no doubt it'll withstand vibrations from on/off-road. Even then, it would be pretty easy to put those units on rubber feet, but probably not necessary.

 

I'd mount them under the hood, probably somewhere near the passenger strut tower or firewall. I tend to use ABS plastic sheets (1/4") for mounting things...rigid, insulating, easy to work with. I think it'd be pretty easy to make a one-piece module that holds a switch, ACR, and pair of breakers.

[ferrariowner123]

http://pcoa.org.au/forum/viewtopic.php?f=19&t=6415

 

Don't know how useful it may be but here is how some of the aussies went dual battery. I remember Andy (exbrit) going dual using some fancy auto switching device. Might be worth looking into.

 

-Kyle

[hawairish]

Yep, seen it. It just talked about battery and mounting options, which I have no concerns over. I plan to buy a pair of plastic battery trays in the sizes I need, rivet them side-by-side, and fasten to the chassis. Ones like this have integrated straps...no point in re-inventing the wheel.

 

Seen the Theexbrit's setup, too...same as 96Pathfinder4x4. Both use the T-Max and have a RigRunner for accessories.

Edited July 28, 2015 by hawairish

[Motofish]

 

I prefer a physical switch, too. There are a couple other little nuances about the T-Max that have me hung up...one, it doesn't appear that there's any integrated way to mount it (I'm not using Velcro, and it's not going to get tucked away somewhere), and two, if the Link button should fail for any reason (integrated circuit, melted tactical button), I'd have to cut wires to bypass it (which I don't want to do). I'm a big stickler for clean installs.

 

The Blue Sea modules are IP66 and IP67 rated, meaning they're both dust proof (the first "6") and resist either powerful jets of water (the second "6") or full immersion (the "7") for a minimum period of time. And of course the superior corrosion. If it can withstand of the neck-jarring impacts of a boat going through crests at speed, I have no doubt it'll withstand vibrations from on/off-road. Even then, it would be pretty easy to put those units on rubber feet, but probably not necessary.

I have had too many of those types of electronics (T-max) fail on me. The buttons get old and crack/corrode and its just not worth it for me either. Thats great info on the Blue Sea switch, sounds pretty capable! I think that is the direction id like to go as well (as if i need another project right now...lol).

 

 

I'd mount them under the hood, probably somewhere near the passenger strut tower or firewall. I tend to use ABS plastic sheets (1/4") for mounting things...rigid, insulating, easy to work with. I think it'd be pretty easy to make a one-piece module that holds a switch, ACR, and pair of breakers.

If you dont mind me asking, where do you source that kind of plastic from? It seems like there would be tons of uses for something like that.

 

Overall, sounds like a good plan! Im looking forward to seeing the install (if you decide to post it up). I would tackle this one soon... But i think it would work better with an engine in the truck... Lol. (Partway through an unnecessarily lengthy vg33 swap). But i hope to see yours soon!

[hawairish]

I have had too many of those types of electronics (T-max) fail on me. The buttons get old and crack/corrode and its just not worth it for me either. Thats great info on the Blue Sea switch, sounds pretty capable! I think that is the direction id like to go as well (as if i need another project right now...lol).

 

If you dont mind me asking, where do you source that kind of plastic from? It seems like there would be tons of uses for something like that.

 

Overall, sounds like a good plan! Im looking forward to seeing the install (if you decide to post it up). I would tackle this one soon... But i think it would work better with an engine in the truck... Lol. (Partway through an unnecessarily lengthy vg33 swap). But i hope to see yours soon!

 

Yeah, I'm not sure how well the label on the meter will hold up in the heat tucked away in a glovebox. Surely the heat can't be good for it.

 

Tappplastics.com. I've use them for a couple years for various computer projects and materials. They do custom cuts to precise sizes, or you can buy standard sizes/pieces. All sorts of neat materials. I've also found that if you decide you want a specific size cut (especially small sizes), that you can get multiple pieces for the same price as 1 piece. So I just have them make as many as I can get for that price. Maybe if I need a custom size, I'll pick up extras and send a drilled-out one your way since it sounds like we'll use the same components.

 

The ABS is particularly nice because it can be tapped easily, and resists cracking (especially where drilled), and can be heat molded. http://www.tapplastics.com/product/plastics/cut_to_size_plastic/abs_sheets/524. I have some leftover sheets for a project I did on my Jeep...mounted a small power inverter, small OE sub amp, and fused power block to a sheet mounted to the rails of the passenger seat...having it move with the seat saved it from being stepped on by people climbing into the back if I had mounted it to the floor. But because it's plastic, also makes for a great electrical insulator.

 

They also sell HDPE sheets (the stuff Fleurys uses for spacers), and various acrylic sheets.

 

I bumped this project to my "on deck" circle, once I'm done with this tire carrier retrofit. Thinking I might be drilling some mounting holes for it tomorrow... Thinking this project might come alive in a month or two.

[hawairish]

Stumbled across this gem when looking for advice on what breaker rating to put on the batteries:

 

http://www.outbackcrossing.com.au/FourWheelDrive/Basic_Dual_Battery_System.shtml

[Motofish]

Wow! Bookmarked! That was a great article! Good find! It seems like that site has good info on other topics as well, Thanks for the link!

 

I like the wiring diagram they threw up there. Very simple!