[Grench]

OK, I don't know if this will work/show up right, but what the heck. The whole thing started with a sketch on the back of a napkin and I've never built a formal schematic for it. Its pretty basic though. For the off chance of making it legible, I'll keep this as simple as possible.


Here's the basic idea.

[fj40ec]

Can't you put the two batts on parallel? I thought that you could! if not, why?

[Beowulf]

Yes, you can parallel 2 batteries. That is what the above diagram illustrates.

-B-

[fj40ec]

Originally Posted by Beowulf

Yes, you can parallel 2 batteries. That is what the above diagram illustrates.

-B-

Ah!! now I understand the diagram!! thanks!

[Grench]

Yes. The marine switches (scroll back to the picture) have 4 settings. Up is off, turn it to the left and it is battery 1 which is the DS battery. Right is battery 2 which is the PS battery. Yeah, the left/right feels backwards when looking in the hood. Turn left to get the right battery, etc... I wired it considering 1 as primary and I wanted to keep the logical primary one in the stock location.

There is a 4th position on the switches that doesn't come into the phot because of my very tight install. Straight down is 'both' and puts the system into parallel.

If either switch is set to parallel and the other switch is not off, then the whole system is in effect in a parallel mode.

[samis]

Newbie Question for you guys

Yes I have searched this forum for my answer and haven't found it.

Why do you guys mainly run an isolator or selonoid for your dual battery setups. Why don't you run dual alternators???

What are the benifits other than costs ???

Thanks

[Beowulf]

Sami,
A battery stores energy; an alternator produces energy "real time." The objective for a dual battery system is to enable you to run down one battery without running down the other. A dual alternator with a single battery wouldn't help with this objective.

A dual alternator; each with it's own battery to keep charged up is another solution, and probably what you are suggesting. The main reason that I wouldn't do this on an 80 is that you would have to fab up alternator mounting, pulleys, belts, tensioning device, and acquire a 2nd alternator. This is spendy. The stock 80 alternator has enough capacity to keep 2 batteries fully charged and the stock alternator is reliable. If you are going on an extended expedition then a spare alternator would be something to consider.

A friend of mine with an FJ60 had dual batteries charged by dual alternators. This was an easy project on his 2F engine because he simply replaced an air pump with an alternator. Brackets, belts, tensioner, and all that stuff was already there so all he had to do was wire up the 2nd battery and run some accessories off of it. I don't recall how he would handle jump starting unless he wired the starter to both batteries. Maybe he had a marine switch for this purpose?

-B-

[tech_dog]

One other reason is that with dual batteries, dual alternators, but no solenoid you would have two completely isolated systems. You'd lose the ability to start off of either or both batteries, winch off of either or both, etc.

There are definitely advantages to having a second alternator for charging, but there are just as many advantages to being able to combine the batteries when you need to.

I think the best solution would be to have dual alternators and dual batteries, while maintaining the switching to combine or select the batteries you want to use.

You'd also want to be able to disable the 2nd alternator if you haven't been using your 2nd battery. I've found that I go weeks without charging my 2nd battery, because I'm trying to avoid cooking it if I haven't been draining it.

[Grench]

Originally Posted by samis

Newbie Question for you guys

Yes I have searched this forum for my answer and haven't found it.

Why do you guys mainly run an isolator or selonoid for your dual battery setups. Why don't you run dual alternators???

What are the benifits other than costs ???

Thanks

Actually I don't. I'm the weird one in this though. I have full OO cables running through and dual switches. If I had to do it over again I'd lighten up on the cables to 2ga instead of the OOga. Those were expensive and a PITA to work with.

I've since put 300amp marine fuses right off the + post on each battery. I have spares in case the winch blows one and can bypass them if I feel a need.

I've also solved my horn delima with a powder coated stainless steel Oringo marine horn mounted on the ARB support bracket. I'll see if I can get a picture of the fuses and one of the horn placement onto this sometime this weekend.

[TCH2FLY]

Hmmmm interesting discussion.
Frankly in my eyes the biggest and ONLY disadvantage is the cost of fabrication/second alternator. For someone with extensive loads on their second battery this would be an ideal arrangement with no downside except perhaps the ability to combine batteries easily (note I did not say it isn’t possible you would be amazed what can be done in the rare cases where you might need to).

No offense but I am really curious about all you guys that have built complex systems with the ability to self-jump…how often do you need to do that??? Frankly if this is an issue for you; your energy would be better spent figuring out why your primary battery keeps going dead.
Seems kinda like preparing for hurricanes when you live in Nebraska.

My simple isolator set-up provides no built-in means to combine my batteries. Does this mean I’m out of luck if my starting battery is dead….no. Let me share some information about some fantastic technology….. a set of jumper cables. (BTW in 22 yrs of dual battery systems I’ve never had to self jump…but I can )

[Beowulf]

Originally Posted by TCH2FLY

... in 22 yrs of dual battery systems I’ve never had to self jump

Rather than answer YOUR question, I'll ask one of you. If you have never had a battery go dead in 22 years then why do you keep building dual battery systems in your vehicles?

-B-

[TCH2FLY]

[

Originally Posted by Beowulf

Rather than answer YOUR question, I'll ask one of you. If you have never had a battery go dead in 22 years then why do you keep building dual battery systems in your vehicles?
-B-

First I'll be clear that I've had car batteries go dead (many times) BUT oddly enough never in one of my dual battery offroad rigs. (perhaps that is reason enough)

However to answer your question ....capacity. I maintain the starting battery for starting and engine systems while running all accessories (radios, supplemental lighting, etc) off the secondary. Most importantly I prefer to have my winch attached to a secondary power supply...so yes....I will always have a good charged battery for starting my truck. I can see how running parallel for winching is an advantage.... until they are both dead, so I have always managed with one to do the job.

Re-read my post I never said 2 batteries is a bad idea
I wondered why everyone is building expensive/complex systems for what is (at least in my case) an extremely rare occurrence.

Now I'll answer my question myself...because most gearhead types (not derogatory ) want to appear to have the coolest most high-tech solution to every situation even if that situation may never occur.....or am I wrong??

I'm also not saying that I will never have a dead battery but I have a quick easy solution if I do.

[Beowulf]

Originally Posted by TCH2FLY

I'm also not saying that I will never have a dead battery but I have a quick easy solution if I do.

Exactly. The doubled battery capacity is the reason the rest of us build dual battery systems. The capability to self-jump is just an added bonus.

-B-

[Cube Dweller]

Originally Posted by Grench

Actually I don't. I'm the weird one in this though. I have full OO cables running through and dual switches. If I had to do it over again I'd lighten up on the cables to 2ga instead of the OOga. Those were expensive and a PITA to work with.

I've since put 300amp marine fuses right off the + post on each battery. I have spares in case the winch blows one and can bypass them if I feel a need.

I've also solved my horn delima with a powder coated stainless steel Oringo marine horn mounted on the ARB support bracket. I'll see if I can get a picture of the fuses and one of the horn placement onto this sometime this weekend.

Where did you find 300a marine fuses and 00 cable? West Marine?

[TCH2FLY]

Originally Posted by Beowulf

Exactly. The doubled battery capacity is the reason the rest of us build dual battery systems. The capability to self-jump is just an added bonus.

-B-

I don't think we ever had a disasgreement about why we have dual batteries (did we??).

My original question still stands.
Your "added bonus" is considerably more expensive then my solution to the same rare problem with no real difference in performance for normal use. I see the additional potential for error in a misplaced switch as enough reason to avoid that set-up, the cost would be next.

I am glad it works for those that have it. I do think that due to the wide variety of abilites and budgets of the board users any discussion of upgrades or modifications should involve the K.I.S.S principle in at least one solution.

[Beowulf]

Originally Posted by TCH2FLY

Your "added bonus" is considerably more expensive then my solution to the same rare problem with no real difference in performance for normal use.

This is a FAQ on dual battery systems, not an open discussion thread. Post up pictures, schematics, and costs on your solution so we can decide for ourselves on the merits of your setup.

-B-

[Grench]

As I stated earlier, I have made a modification to my dual battery setup. I realized that in my configuration I still had a fusible link from my main + terminal to the truck, but I didn't have anything between the batteries and the marine switches or in line with the winch/accessory/etc... switchi and the 12' of OO cables running about. I figure if one of those shorts out and welds itself to the body or radiator and isn't fused I'm .

So, I went to www.defender.com and got a bunch of stuff. For this project:
2 mega fuse blocks 100-300a
4 300 amp fuses (2 for the project, 2 for spares)

I had some left over OO cable and 5/16" lug ends to make the little jumpers from my battery install.

I have a bit of peace of mind knowing that my odds of running a dead short and going up in a blaze of glory are somewhat reduced.

[Grench]

I solved my horn issues mentioned above. The marine switches are installed where the factory horns were.
http://forum.ih8mud.com/80-series-tech/109434-ongaro-marine-horn-installation.html

[samis]

Ok

Thanks for the answers.

I see another bonus about running dual alternators is that you will have a spare alternator if the primary alternator dies on the road.

[sandcruiser]

where are you folks getting your mil spec battery lugs?

[CoveredInRedMud]

West Marine has them in the store on Dixie Hwy here in Miami...

[robmir]

Originally Posted by Grench

OK, I don't know if this will work/show up right, but what the heck. The whole thing started with a sketch on the back of a napkin and I've never built a formal schematic for it. Its pretty basic though. For the off chance of making it legible, I'll keep this as simple as possible.


Here's the basic idea.

My only main concern should be the winch powered through a marine switch.

A stalled winch could go way up to more than 400 amp, something than ever the biggest heavy duty marine switch can´t provide.

I have seen many fried marine switchs, be Perko or other brands.

[robmir]

Originally Posted by Beowulf

Sami,

A dual alternator; each with it's own battery to keep charged up is another solution, and probably what you are suggesting. The main reason that I wouldn't do this on an 80 is that you would have to fab up alternator mounting, pulleys, belts, tensioning device, and acquire a 2nd alternator. This is spendy. The stock 80 alternator has enough capacity to keep 2 batteries fully charged and the stock alternator is reliable. If you are going on an extended expedition then a spare alternator would be something to consider.

-B-

3 guys in my country set some years ago a very succesfull company to manufacture 80´s accesories including aux gas tanks.

They designed, produced and sold many kits to add a second alternator and it was very easy to install.
No tensioning device needed because the aux alternator was the only item to adjust since it pivoted on the alternator mounting. Kit included one belt, one alternator mounting base with it´s bolts, one crankshaft main pulley with longer bolts and one brace (not showed in the enclosed photo) to avoid alternator vibrations. By the way you could get a fine Nippon Denso used 60 Amp or up alternator on ebay for less thatn $ 50.

Unfortunately the limited availability of the Isuzu Trooper (2.6 ltr motor) crankshaft main pulley (which was a perfect bolt on) ended this project .

[Grench]

Originally Posted by robmir

My only main concern should be the winch powered through a marine switch.

A stalled winch could go way up to more than 400 amp, something than ever the biggest heavy duty marine switch can´t provide.

I have seen many fried marine switchs, be Perko or other brands.

I considered that. Its one of the reasons there are two switches and fully isolated house & winch circuits with both batteries protected by 300 amp slow blow fuses.

If I do manage to stall out the winch it -should- blow the fuse on the circuit it's running on first before it takes out the switch. If it doesn't, thats what the fire extinguisher is for.

So far it works fine for me. I haven't had the opportunity to stall out the M12K winch yet though. It does make an entertaining twist on gathering firewood at the end of the day.

[robmir]

Originally Posted by Grench

If I do manage to stall out the winch it -should- blow the fuse on the circuit it's running on first before it takes out the switch. If it doesn't, thats what the fire extinguisher is for.

So far it works fine for me. I haven't had the opportunity to stall out the M12K winch yet though. It does make an entertaining twist on gathering firewood at the end of the day.

I like very much your concept and again agree with you is better to be safe than sorry but just put you in my shoes: I am crossing, on my heavy 80, a river with some current, water up to my door handle, the wire rope is the only thing holding me to the anchor point on other side and bam, a 300 amp fuse just blow then the only use for the fire extinguisher will be to point and discharge it on my mouth just to freeze my brain before I start to shout out your ancestors because I followed your idea, and forget about gathering firewood because the matches would be probably soaked

[Grench]

Originally Posted by robmir

I like very much your concept and again agree with you is better to be safe than sorry but just put you in my shoes: I am crossing, on my heavy 80, a river with some current, water up to my door handle, the wire rope is the only thing holding me to the anchor point on other side and bam, a 300 amp fuse just blow then the only use for the fire extinguisher will be to point and discharge it on my mouth just to freeze my brain before I start to shout out your ancestors because I followed your idea, and forget about gathering firewood because the matches would be probably soaked

Sorry if I failed to emphasize this enough in the previous write ups. I am neither an engineer nor a mechanic. The things I try may not work well for others.

If you're doing something as dangerous as the water crossing you described, then the fuses in my example may be more dangerous than beneficial and would need to be bypassed as would the switches. There are still penty of places for potential failure in your example. Solenoid packs frying, winch line bunching up, battery or alternator, the plug for the remote dangling over the hood into the solenoid pack... At some point this comes to using a giant blade switch on a 4/O cable setup directly into the winch. Not elegant, but it removes the complexities.

I have never had to make that kind of life/death water crossing and at this point I do not plan to need to.

As always, YMMV.

[dfmorse]

Here is a link to my dual batt system.

http://homepage.mac.com/dfmorse/BattProj2/index.html

The system uses small flashlight batteries to run every thing.

Hellroaring Tech is here:
http://www.hellroaring.com/bic75300.htm

Terminals are here:
http://www.quickcable.com/

This is some great cable:
http://www.partsexpress.com/pe/pshow...=100-194&DID=7

Batteries:
http://www.enersysreservepower.com/o...ID=5?brandID=5

JCWhitney - terminals & switches:
http://www.jcwhitney.com/autoparts/B...000909/c-10101

Switch [ZX747827P] is US made an will handle at least 500 amps. I use one to isolate the winch.

[robmir]

Originally Posted by Grench

Sorry if I failed to emphasize this enough in the previous write ups. I am neither an engineer nor a mechanic. The things I try may not work well for others.

If you're doing something as dangerous as the water crossing you described, then the fuses in my example may be more dangerous than beneficial and would need to be bypassed as would the switches. There are still penty of places for potential failure in your example. Solenoid packs frying, winch line bunching up, battery or alternator, the plug for the remote dangling over the hood into the solenoid pack... At some point this comes to using a giant blade switch on a 4/O cable setup directly into the winch. Not elegant, but it removes the complexities.

I have never had to make that kind of life/death water crossing and at this point I do not plan to need to.

As always, YMMV.

Don´t worry LOL , pleeeeease no hard feelings because I like your tips a lot.

This kind of water crossing is quite common in rain season when we do fun trips to our rain forest border with Brasil

Of course I try to avoid them as much as possible. We are a bunch of old timers with a lot of off-road experience, we travel with our families and stay away of the other nuts who enjoy to see how deep they can go inside before topping their air intake extensions with the water

By the way my solenoid remote control box is installed inside the motor compartment close to the battery and as high as possible, just in case

[Romer]

Here is another setup and is discussed in detail in this thread

quote=450 DUDE;2979084]Here is another dual battery install.......


This is a little different due to the cramming them both in one tray.
I went this way because I didnt think I needed a full size # 2 battery.
I was just looking for something to start with if I managed to kill the main.

Main players:

Optima D31M
Odyssey 680 MJ
Hellroaring BIC
Custom mount for the Odyssey.

So far so good , I do need to tidy up a bit and secure some of the wire.

ken[/quote]

[Romer]

Here is the link to SF80's Hellroaring Setup