Caveman Dual Battery

[Bluetribal]

OK, so I want my dual battery system and first off wire diagram to be sooo simple a CAVEMAN could do it! But I have very little idea as to how to wire stuff, where to put fuses, when to add relays, etc....

So currently I have been collecting all of my items according to Boston Manglers dual battery set-up. But I don't understand the purpose of his positive distribution bus and I don't want to split up my OEM harness containing the starter & alternator wires.

I have already:

• Installed my starter battery a year ago: Sears Die Hard Platinum P-2 Group 65 in DS tray.
• Installed OEM PS Battery Tray
• Installed Slee Washer Bottle Relocation Bracket
• Temporarily Installed CB Radio
• Purchased Blue Sea 4 Position Battery Switch
• Purchased Blue Sea 6 Circuit Fuse Block
• Purchased 2 Sets of Military Terminal Connectors from Sierra Expeditions
• Purchased 2 AWG Welding Wire To Connect Batteries
• Purchased used HAM Radio
• Purchased Spal Electric Fan

So the only things I need to do now is purchase the second battery and figure out how to wire it all up.

Here is round 1 of my diagram; What is wrong with it and what do I need to add to it?

Diagram 1

 

[superjuice]

Looks good to me, just don't ever flip the switch with the engine running. From what i have read you could melt the alternator/rectifier. This happens when the alternator senses low (in this case zero) voltage and tries to ramp up the output to bring the voltage back up. I would also fuse the ground on the second battery as well to be safe.
Maybe something like this:


Just my two cents

 

[Salue]

I copied the same setup and have a positive distribution post. The only reason is because my fusible links wouldn't reach where I mounted the 4 position switch on the firewall.
As for not turning the switch while the engine is on, that is partially correct. You are ok to turn from 1 to 2, 2 to 1 or to the combine dial, as long as you don't turn it past the off switch. I was curious about this and I emailed Blue Seas and that's what they told me. I tried switching from 1 to 2 (with fingers crossed) and it was fine.

Cheers,
Salue

 

[greentruck]

The positive distribution bus is simply where you tap power for your various circuits. For instance, you could plug the entire factory harness into it. Personally, I'd leave the factory harness alone.

Are you certain you want a manual switch to control charging for the batteries? This means that you need to get under the hood each time you want the other battery to charge. Plus, unless you rig up a voltmeter to read the battery voltage on the battery that's not in use, you'll just be guessing when and for how long to charge before switching to the other battery, etc, etc.

Now, if you just want to save the approx. $200 or more that a decent automatic isolator will cost, I suppose I can see this. But I suggest considering that option for both convenience and relaiability.

In my own install, I used the Blue Sea switch, but only to control the power from the batteries to my winch (although you could also use it to feed other accessories), not the charging circuit itself.

To help in thinking through my design, I considered the charging circuit and the distribution circuits separately. It's just a whole lot less confusing and helps you understand what's happening better. I went with auto control of charging, but manual control of use of power from the second battery.

Your second diagram looks a little like the distribution side, but is so, then you need two Blue Sea switches, one to control which battery is being charged and then another to control the distribution of power according to what battery you want to feed your loads. In that case, you'd be manually controlling both the charging and the distribution of power and you can't do both with just one Blue Sea switch.

 

[Bluetribal]

Yeah, I don't care to spend an additional $200 bucks. I'm a poor man in a rich mans sport! HA!! It took my 4 years 7 months & 10 days to get my lift finally last week! Not that I was keeping track.

Your second diagram looks a little like the distribution side, but is so, then you need two Blue Sea switches, one to control which battery is being charged and then another to control the distribution of power according to what battery you want to feed your loads. In that case, you'd be manually controlling both the charging and the distribution of power and you can't do both with just one Blue Sea switch.

OK I only have one diagram the first one is Boston Manglers which I am trying to simplify /or modify.

I don't understand why when I have the dial on "1+2" it wouldn't charge both batteries? How would an additional switch to the same wires change distribution and charge?

 

[Salue]

Yeah, I don't care to spend an additional $200 bucks. I'm a poor man in a rich mans sport! HA!! It took my 4 years 7 months & 10 days to get my lift finally last week! Not that I was keeping track.



OK I only have one diagram the first one is Boston Manglers which I am trying to simplify /or modify.

I don't understand why when I have the dial on "1+2" it wouldn't charge both batteries? How would an additional switch to the same wires change distribution and charge?

Based on your diagram, you would only be charging the 6 circuit fuse block if your dial was on 1+2 or 2, assuming 2 is your aux battery. If you were running on just 1, you'd be pulling power to the fuse block from the aux battery and it wouldn't be charging.
A simple way to fix that is to move that wire from the fuse going to your + aux battery over to the common on the dial switch.

Hope that makes sense.

 

[Bluetribal]

Charging the 6 circuit fuse block? No I do not understand. Is it not possible for 1&2 to be charged simotaniously?

And yes I realize I would be pulling off the Aux. battery if I was switched to 1. I only need the Ham, CB & rear 12v for off-road trips. So I am thinking of adding a cut off switch to the 6 circuit fuse block to eliminate excess drain on the Aux. battery.

 

[1973Guppie]

just get a switch with a 1, 2 and both setting. Keep in mind that when you switch to "both" the 2 batteries will be connected and will balance each other out, meaning there will be a surge of energy between them if one is very low and the other is very high, I may be wrong here but somebody will let me know if I am.

I have run a manual system in my fj40 for years and I like it. I can positively choose which battery I am pulling from. FWIW, I rarely use the both switch and if I do it is usually when I need to charge both up. I have never had an issue with this manual setup, it takes a bit more attention to the maintenance of the batteries. I have had the best of luck using deep cycle batt's as they can be discharged with no problems.

Noah

 

[Bluetribal]

That's what I was thinking, I would just put it on 2 or 1&2 a day or so before an off-road trip. And during the summer when I don't wheel as much I would just swap from 1 to 2 every other week to keep both charged.

 

[sandcruiser]

the only thing I would add is that in my opinion it is a bad idea to fuse the ground

put fuses close to the battery on hot wires so that if I device does short to ground, the fuse can stop the flow of power.

 

[Bluetribal]

OK so if I added a disconnect switch between the Aux. battery and the 6 circ. fuse block should I put that fuse between the battery and disconnect switch or the fuse block and discoonect switch?

 

[Grench]

I put a set of big 400A fuses directly on the batteries. I'm running a brute force system very similar to that. The primary difference is that I have a 2nd switch dedicated to the winch.

I'm sure you've read through the dual battery FAQ?

YMMV

 

[1973Guppie]

with the setup I am going to do, I am putting 200amp fuses at the pos battery terminals, then from the source post of the switch will be a pos post terminal, from there I plan to run to the winch, inverter, and aux fuse panel. All the major devices like winch, lights and inverter will have an inline fuse of 100-150, then all the accessories will run off the aux marine fuse panel (as well as future aux add ons). This way everything is fused properly.

I don't understand why you would fuse the neg side of the battery? don't get that , but maybe I am not getting something. I would make sure the batteries are both grounded well to the frame and the body to the engine and the engine to the frame, etc.

Noah

 

[Wheelingnoob]

with the setup I am going to do, I am putting 200amp fuses at the pos battery terminals, then from the source post of the switch will be a pos post terminal, from there I plan to run to the winch, inverter, and aux fuse panel. All the major devices like winch, lights and inverter will have an inline fuse of 100-150, then all the accessories will run off the aux marine fuse panel (as well as future aux add ons). This way everything is fused properly.

I don't understand why you would fuse the neg side of the battery? don't get that , but maybe I am not getting something. I would make sure the batteries are both grounded well to the frame and the body to the engine and the engine to the frame, etc.

Noah

You may want a bigger fuse on the winch than a 100-150, under a hard pull you will be well into the 300-400amp range.

 

[Grench]

You may want a bigger fuse on the winch than a 100-150, under a hard pull you will be well into the 300-400amp range.

The load the starter motor can draw is up in that range as well.

 

[619TOY]

Using the switch you have, I'd do a pretty simple setup. Just keep all of the stock system as is and use the switch as a simple on-off switch for the 2nd battery. I see no reason to ever charge the 2nd battery without charging the main battery. The circuit breaker for the fuse block serves as protection and as an on-off switch. This is a slightly different overall design than Kevin's.

This is basically the system I do all of time, except I use a solenoid instead of the manual switch.

 

[1973Guppie]

You may want a bigger fuse on the winch than a 100-150, under a hard pull you will be well into the 300-400amp range.

Good point, I may not use a fuse at all on the winch going to the pos acc terminal, it would be protected anyhow from the fuse inline at the battery + post. Plus I remember now the warn instructions did not call for a fuse, it does have a breaker in the winch I believe anyhow. The nice thing about the fuses, is that they can be replaced with larger ones if need be if I start blowing them.

as far as the stock wiring goes, you should not have to go into that at all, just wire what is now going to your pos battery terminal into the post post for all your accessories.

Noah

 

[Bluetribal]

Using the switch you have, I'd do a pretty simple setup. Just keep all of the stock system as is and use the switch as a simple on-off switch for the 2nd battery. I see no reason to ever charge the 2nd battery without charging the main battery. The circuit breaker for the fuse block serves as protection and as an on-off switch. This is a slightly different overall design than Kevin's.

This is basically the system I do all of time, except I use a solenoid instead of the manual switch.

So for this layout I don't even need the three way switch I have, a basic breaker switch would work. But if I did use the 3-way switch what would I switch the dial to and how would I wire stuff up?

 

[Bluetribal]

The load the starter motor can draw is up in that range as well.

So even without a winch I should use at least 300Amp fuses?

 

[619TOY]

So for this layout I don't even need the three way switch I have, a basic breaker switch would work. But if I did use the 3-way switch what would I switch the dial to and how would I wire stuff up?

You would wire the system just like my diagram. The stock/main battery would connect to the common terminal of the switch and the auxiliary battery would connect to the battery 2 terminal.

When you want the Aux. battery to charge you select position 2 on the switch. Just don't forget to turn the switch back to position 1 or off when you park while camping, etc. or you could drain down your stock/main battery.

With this configuration the main battery will always be connected to the alternator and always charge when the engine is running.