Simple Dual Battery System

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Greg B

Greg B

Joined
Jan 13, 2005
Threads
36
Messages
1,112
Location
Louisville, KY
I have searched the 80's, 100's, and Outfitting forums and have found tons of info on dual batteries. The problem that I am finding is that they all seem too complicated.

Is there anything wrong with a more simple design? My wants are very simple. I want to run a fridge and a winch off a second battery while not touching my main battery that runs my 100 now. Currently, I have an Odyssey PC1700MJT as my main battery. It works well for the day-to-day driving and a couple of accessories (cb radio, small power inverter).

I would like to add a Slee 2nd battery tray and add a deep cycle battery to run a winch and fridge. I don't really want the winch and fridge connected to my main battery. What is the most simple way of doing this? Also, I don't care about the jump starting feature either. I can always use jumper cables from one battery to the other, correct? Basically, I'm looking for the most simple way to charge a second battery to run my fridge and battery without affecting the main battery.

Thanks in advance for any advice.
 
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Darwood said:
I'm going to go with one of these (actually I have one waiting to be installed) for my dual battery install:

http://www.surepower.com/separator.html

It installs like these instructions:

http://www.surepower.com/separator.html

For me it was a toss up between the Hellroaring isolator and the SurePower seperator. I decided to go with the seperator just to be different ;)
Click to expand...
That's what I was going to recommend, they are only about $80 when I searched online.
 
I want simple AND reliable. If you want stupid simple? Carry that 2nd battery and some jumper cables. Use a trickle charger to recharge on a regular basis (you decide how often) or after you've jumped the main.


My simple and reliable -- meaning once it's set up you no longer need to think about it -- is the Hell Roaring BIC. I'm following Cruiserdrew's write up for mine. I ordered and received my Hell Roaring unit last week. Now I just need to find some time and get the cables ready for the install.

Sure it's more work initially, but it's something that I won't need to worry about going forward.


As for what to hook up, it might be safest to run everything off your main battery and keep the other battery just for starting the car (or jumping) as needed.
 
I have the surepower setup and it is extremely simple, the seperator does the switching for your so there is little driver input on the setup which some may dislike.
So far, after 2 months i haven't touched anything with the setup and it runs alot of eletrical without even knowing it.
 
Simple...

I run two identical batteries. I have a starter solenoid wired so that I can run the batteries in parallel. I run all my accessories off the number two battery. I have a switch that is energised from the "key on" circuit that energises the solenoid and I am able to run 2 batteries in parallel for winching and all my other stuff runs off the number 2 battery. The solenoid cost 12 dollars and has zero current draw when off.

JB

Greg B said:
I have searched the 80's, 100's, and Outfitting forums and have found tons of info on dual batteries. The problem that I am finding is that they all seem too complicated.

Is there anything wrong with a more simple design? My wants are very simple. I want to run a fridge and a winch off a second battery while not touching my main battery that runs my 100 now. Currently, I have an Odyssey PC1700MJT as my main battery. It works well for the day-to-day driving and a couple of accessories (cb radio, small power inverter).

I would like to add a Slee 2nd battery tray and add a deep cycle battery to run a winch and fridge. I don't really want the winch and fridge connected to my main battery. What is the most simple way of doing this? Also, I don't care about the jump starting feature either. I can always use jumper cables from one battery to the other, correct? Basically, I'm looking for the most simple way to charge a second battery to run my fridge and battery without affecting the main battery.

Thanks in advance for any advice.
Click to expand...
 
FJ40_owner said:
I run two identical batteries. I have a starter solenoid wired so that I can run the batteries in parallel. I run all my accessories off the number two battery. I have a switch that is energised from the "key on" circuit that energises the solenoid and I am able to run 2 batteries in parallel for winching and all my other stuff runs off the number 2 battery. The solenoid cost 12 dollars and has zero current draw when off.

JB
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Add an isolator to that and your set.
 
Simple and reliable = Powergate.














Here we go again :crybaby:
 
the system that is described on George's sight is real simple. Two small relays, one large relay (200 amp constant duty) and some new battery cables. even the wiring diagram is easy to follow. This system is only on when it getts the charge good signal. otherwise I never even think about it.

The battery switch is extra and does not need to be added I don't think. I added it for a future winch and also for the self jump feature. I live in the Arctic and it is no fun playing with jumper cables at 35 below 0 .

I got the 200 amp relay for like 50 from a local Napa. The small relays are available everywere for like 6 bucks. The only spendy part was the battery switch and the new battery cables.

On my truck everthing tucks nicely between the battery box and the air cleaner, really neat and orderly.

Anyway just another system I have not seen mentioned in your thread.
 
I used the BlueSea marine battery combiner. A solid state device that runs the batteries combined unitl one drops below satndard voltage. It can be overridden from the dash switch.

My research indicated that it is best to have both batteries the same type and age. I used Optima group 31 YellowTops in Noel's Stainless Battery trays - highly recommended product.

Been running this system for over a year with zero troubles.

Mike
 
can't get much simplier than this.

just hook one of these from you existing battery to the switch disconnect when you want it separate connect it once the vehicle is running to charge.


or you can use one of these, cheaper and looks fancy ;)


"fancy"
 
Cant get any simpler then my setup:

No solenoids, no isolators, very very simple to build and works like a champ!

http://www.yankeetoys.org/mangler/dualbats.htm

Here is a pic of my wiring:

batdiagramnew.jpg
 
Kevin,

With all due respect... you also have no fuses or circuit breakers shown in that simple diagram and installing that much 2 gauge wiring without fusing is asking for a melt-down. If someone is saying "show me how to do this" and you post up an official-looking diagram, then there are people that will duplicate the above wiring on their trucks.

-B-
 
Boston Mangler said:
Cant get any simpler then my setup:

No solenoids, no isolators, very very simple to build and works like a champ!
Click to expand...

Actually, I believe there is a simpler setup: Two identical batteries wired in parallel with a Battery Brain hooked up. You always have the use of dual batteries but never run them down so far as to not be able to start your engine. I think this works especially well with Odyssey or similar type batts, since they are sort of a combinatino beween a starting and deep cycle battery. I have this low-tech set up and so far it has been foolproof.

Tim
88 fj62 TLCA
 
Is there any reason why you couldn't hook up a large relay to the second battery triggered off the ignition switch? So when you start the engine, both batteries are connected for charging, but when you turn off the car, the relay turns off and isolates the batteries. It's pretty much the same thing as using a mechanical switch, but it would automatically connect and disconnect for you. It seems with a stock alternator, you could even get by with a standard 40 amp relay for $5, although I wouldn't recommend it.

In it's simplest form, all you have to do is run one positive wire to the second battery, and put a relay on that wire. I've actually used this method to recharge a bank of 3 batteries sitting in the back of my car, but I tapped the power off the rear cigarette lighter outlet rather than the alternator. Even though that circuit was fused at 20 amps, I never blew a fuse, I think mostly because I would never let the batteries run down enough to draw much current. If the battery is fully charged, there's very little current flowing through the cable, it's just trickle charging it
 
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ducktapeguy said:
Is there any reason why you couldn't hook up a large relay to the second battery triggered off the ignition switch?
Click to expand...

I have no comment on your approach other than to say on the 80 Series, most people use the "Alt good" signal rather than the ignition switch. The reason for using this wire rather than one switched via the ignition is explained in George's write-up (links are in earlier posts.)

-B-
 
Greg B said:
Is there anything wrong with a more simple design? My wants are very simple.
Click to expand...

[BeoRant]
Nothing wrong with a simple design and everyone is posting their ideas and stating that each solution works great for them. Always keep in mind that these solutions will work up to the point that they don't work.

A case in point might illustrate: NASA flew dozens of Space Shuttle flights and the O-rings worked every single time.... up to the point in time when they didn't work. I believe they fixed that and then NASA flew dozens of missions and the tile insulation worked every single time.... up to the point in time when it didn't work.

I strongly feel that you must plan for the worst case scenario when you are hooking two high amperage batteries together and you should wait until you can spend the $$$ to do it right.

[/BeoRant]

-B-
 
That's true to a degree. Any solution will work as long as you know the limitations of your system. A lot of commercially built items are way, way overbuilt, to the point of being foolproof. Sometimes it's a good thing, to prevent unwanted accidents, and other times it's just overengineering in order to cater to the lowest denominator (meaning you gotta CYA so stupid people won't sue you). If you're comfortable with wiring up your own system, and you know exactly what you're doing, then you can get by with a less robust design. It all depends with what you're comfortable with.

Slightly off topic. The failure of the space shuttle Challenger was not a problem in the O-rings, or a problem in the design. The problem was a human error. The space shuttle was meant to operate in a very specific temperature range. Because of cost and management pressures, NASA couldn't afford to delay the launch because of the cold weather, so they were forced to proceed with the launch even though the scientist/engineers recommend against it. So even though there were no flaws in the actual space shuttle, the system was operated outside of it's original design parameters, leading to the disasters. In fact, a lot of the major disasters in history can be traced back to a chain of human errors, rather than a single component or system failure.
 
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