Dual Battery in a 72 K20?

[72longbed]

Looking to add a battery that will be used for winching when needed. I would like to ask you guys that have done this to share ideas on location, wiring, safety, etc., please.

I would like the 'secondary' battery to be available for the winch only, but also being charged by the 100amp alternator that is in there now. I am very mechanical, but not very 'electrical', so wiring expalinations would be very helpful. I'm thinking to have the + and - leads from the new battery go to a quick connect block end, and leave it disconnected to the winch leads block end until needed?

Can a battery get over-charged if it is hooked up to the alternator and not used for long periods of time? This second battery would not be hooked into the starter ... or should I? I figure if I have two batteries under the hood, and the primary battery goes dead, I can always put the other battery in it's place. Right?

Thanks for your input 4 wheelers and winchers.

72longbed

[andrewmp6]

You might like this kit http://www.12voltguy.com/product.php...cat=258&page=1 its a kit that lets you have a extra battery as a back up just flip a switch when needed.

[Billhilly]

I plan on using one of these - http://redarc.com.au/products/produc...-sbi_12v_100a/ Pretty basic unit, but has the ability of adding a switch to combine both batteries (for example if the start battery was low). I'm sure you would find something similar built in the US.

[bilfman]

My 71 came factory with 2 batteries, here is a pic, might want to just mimick that. They are joined to each other with a battery cable on each + post. First battery grounded to the block, second battery to the frame. If you want both to charge and also have the ability to isolate one you can use a solenoid, such as a ford (cough cough) in between them on the battery cable connecting them. Then run a switch so when the solenoid switch is on = second battery balances and charges with the first one. Switch off = second battey is solo and gets nothing. This is a cheap way to isolate a battery, mostly used in camping applications, when the truck is not on/running there is no power to the solenoid, so both batteries are isolated from each other. So you can drain one with your accessories, but the other is fully charged when you want to start. There are expensive battery isolaters but this is one way to do it on the cheap.

Though for you winching, I would just have them both together all the time, just join them with the 1 cable and be done, as in the pic below, see the cable on the fan shroud connects the + posts. As mentioned earlier, one is grounded to the block and the other to the frame. This way both batteries get used all the time and are charged all the time, there are no issues electrically other the the benefit of 2 charging and usable batteries. You just have that much more reserve capacity to pull from. This is great for winching and cold weather starting.

[72longbed]

Thanks bilfman ... nice truck too! So let me see if I understand: I can leave the wiring to my starter just the way it is now, add a battery on the other side of the rad., ground it to my frame somewhere below, and run a single maybe #2 cable from the new Positve post to the old Positive post, and I'm good to go? How will the new battery get it's charge? There is a wire from my alternator (with internal regulator) to the original battery ... will charging for both batteries take place through that? Am I at risk of running too much amperage/voltage to my starter with this setup?

If I use a second battery with top and side posts, can the winch be directly attached to one set of posts on the new battery ... maybe with a quick connect plug?

thanks.

[72longbed]

I was searching online last night and found this Thread about Dual Batteries. Tell me what you guys think, and the option that might be simplest for just wanting to have reserve winch power. I like the simplicity of bilfman's idea the best so far. From what I am reading, the more 'components' you build in, the more chances of system failure and amperage blocking through those components? I need to be able to handle up to 500 amp draw with my new winch. Seems that putting a 200 amp rated 'switch, solenoid, gizmo', etc. will defeat the amperage need?

Again, I'm 'electrically challenged' so I have to ask for knowledgable people to help out please.

Check out this Thread and let me know what you guys think: http://www.jeepforum.com/forum/f8/du...lding-1231432/
It is a very long thread, but if look at the very first couple of diagrams and then you scroll down to "Winch Install", you can see some his ideas.

Thanks.

[86c20]

best thing to do is look at a truck with a diesel as it is the same way as above. one pos wire to the pass side batt. with that it gives you better cranking abilty and more reserve to run other things. and if you do a top and side post batt you can run the winch off the top or side for dericet power. i have a wrecker and this is what i do for a jump box. i really dont see a need for a isolation switch but i am not out in the woods hunting and the like.

[72longbed]

Still need to understand the 'charging' of both batteries. Will the one wire that is currently going from alternator to my original battery be enough to charge a second battery? I have to assume that this happens by way of charging current flowing through the Positive cables that link the two batteries? Is that correct?

If yes, do you guys beef up the size of that Alternator wire?

Thanks.

[bilfman]

Just the one wire from the alternator charges the batteries, it is only needed on one of the batteries. Only the one, in your case as you said, the #2 wire is needed. Having them set up exactly as you said in your post keeps both batteries equally charged. The batteries automatically equalize their voltage. When you hook 2 batteries in this fasion it is called a parallel connection and both will have the same voltage.

Think of it this way, when you boost a vehicle with another vehicle you are hooking up their batteries in parallel, if you left them hooked up long enough both batteries would eventually have equal voltage. The same will happen in your case both your batteries will be charged and equalize just by being hooked up as stated.

Here is another example, for understanding parallel, that I use year round. I have several 'summer use' vehicles bikes, quads, tractors, mower, boats etc. In winter I end up with 7 batteries that need to be maintained, I hook all the batteries up in parallel and keep them charged with 1 small battery maintainer. So 1 charger/alternator charges them all even if just hooked up to the first battery.

[72longbed]

Thanks guys ... all good stuff!

72

[odog]

Subscribing

[OregonFXSTC]

Some really good info here in the dual Battery section.
www.junkyardgenius.com

[cabcorner]

A friend helped me put a dual battery set up in an old plow truck I had . We used a constant duty solenoid from napa to isolate the positive terminals on the batteries . He ran a wire from the ignition through a single pole double throw switch to the solenoid . The solenoid would pull in before the starter engaged so both batteries would would start the truck . The starter never bogged down having plenty of available current from both batteries, which I believe will lengthen the life of the starter. Because the batteries are connected in parallel the voltage is still 12v and the alternator will charge both batteries ( It's like having one larger battery) . If you used two 650 cca batteries you would have the equivalent of a 1300 cca battery . Make sure the solenoid is rated for the current it will see . My friend also ran a wire from the positive of the isolated battery through a momentary push button switch through the other side of the single pole double throw switch ( the common on the single pole double throw switch pulls in the solenoid ) so that if the primary battery dies you can pull in the solenoid with the isolated battery and jump start your truck without getting out and popping the hood .

[72longbed]

All good ideas ... I'm going to try and keep it simple by just connecting the two batteries with a single Positive + cable. I'll use the extra set of top terminals on the Aux. battery to connect to the winch leads. Ground the Aux. battery to the frame. Primary battery is already grounded to engine block.

From what I have read here, the two batteries should charge from the one wire from alternator to primary battery.

I figure if I keep the truck running while winching, I should be good with this very simple setup.

I appreciate all the info shared here .... thanks folks!

[jhiggy94]

I really like the info that you found in http://www.jeepforum.com/forum/f8/du...lding-1231432/. I like the idea of being able to take one battery out and using it for other purposes and the face that if i accidentally leave the lights on in my truck i will still have one battery to use to start the truck. I think that this is the setup i will use in my truck when i get to that point

[72longbed]

Fabbed up the cables from #2 welding cable today. Going to run them to a quick connect block, then fab up a couple on the top of the Aux. Battery to the other end of quick connect. This way I can have the leads from the aux. battery sitting there ready for the winch (not connected until needed), it will have the other end of qicky connect on winch leads, or for jumpers with a quick connect on one end. If anbody has a nice aux. batt. box for a 72 they want to sell, I'm paying good money for one depending on the shape of it. Pictures are necessary because of acid and rust damage to these things.

Thanks.

[72longbed]

ttt

[wilkin250r]

I'm a bit confused. My father's old 72 had a dual-battery setup with just a simple battery isolator, does nobody do that anymore? I'm not a fan of parallel battery connections because if you ever disconnect them to use just one, you can end up with HUGE loop currents when you reconnect.

Granted, you can't use both batteries for starting or for winching, but that's exactly what a battery isolator is designed for, multiple batteries that are both charged from the alternator, but otherwise electrically separated. I like simple.

[72longbed]

I like simple also .... that's why I'm not using an isolator. I am no 'electrical genious' by any means, but I have read that the problem with isolators and winching is the amperage blocking? I have to be able to provide my winch with up to 500 amps when needed ... if the isolator isn't rated high enough it can only allow so much amperage to pass through.

Is this correct, or did I read it wrong?

Thanks.

[willett]

ed.

damn, I typed a whole speil out before reading the other posts... I pretty much said what has already been explained :|

[72longbed]

I would be willing to do that .... but am I only drawing from one (1) battery when I run the winch?

72

[wilkin250r]

Yes, I think you're reading it wrong.

The amperage rating on the isolator only applies to the charging current going IN to your second battery from your trucks alternator. It has absolutely nothing to do with any amount you can pull OUT of the battery.


Imagine this scenario. Imagine you put a second battery in your truck, not connected to your current electrical system at all. Nothing. Then you hook your winch up directly to that second battery so it becomes it's own separate little system, just the winch and the battery. That's all well and fine until that battery goes dead. What you need is a way for your truck to charge that second battery, but otherwise keep it "isolated" from the rest of your truck's electrical system. That's exactly how the isolator works.

Yes, at that point, you are only pulling from the one battery when you winch, which can be both bad and good. It does decrease your winch time, true. But it also protects your starting battery so that you can never drain your starting battery with your winch and possibly leave yourself unable to start.

[bilfman]

There is not really a need for an isolator for winching. Isolators are designed for mostly camping/vehicle not running use. So if you happen to drain that battery while, lets say, running lights and having a few too many bubblies to realize the potential downside. When you wake up hung over in the morning you still have one charged battery.

With his description of use, vehicle running or a temporary winch, there really is not a need for an isolator. Less is more in some cases.

[MTCK]

I've got a painless wiring isolator that works great. Three position switch for constant connect, connect with ignition on and off. I leave it so it comes on with the ignition. It has saved me many times when I've left my lights on. The starter draws more current the. A winch. I got the all weather version and have had no problems with it in over 3 years.

Google dueling batteries for the reason for an isolater. I had a 6.2 with factory dual batteries. Had one to bad and it took the other with it...
Posted via Mobile Device

[72longbed]

bilfman is correct on the intended use. As I stated in the very first Post ... I am looking for a proper, powerful, dependable dual battery setup for winching out in the woods, and/or winching to recover from 'stuck'.

There's a tendency on this website for all of us to 'justify' what we did personally by recommending it to others ... even if the APPLICATION is not the same. That's Ok ... I appreciate the different opinions, as long as we can come back to the APPLICATION specific need.

1. First of all, I will be running the winch with the engine running. If the winch is being used, the truck engine will be running.

2. MY winch can draw as much as 500 amps, therefore, (VERY IMPORTANT) I NEED the amperage of both batteries when called for. That is why I upgraded all cables, terminals, connections to handle the conduction of at least 500 amps.

3. I WANT both batteries to power the winch when the truck is running and the winch is running.

4. There will NOT be any refrigerators, snow-cone machines, 'in-da-hood' sound systems, Port-A-Potty's, or concert lighting running on my truck ... ever.

So .... that's about it. If I can simply accomodate MY specific need with two batteries ... that's what I'm looking to do.

I hope this clears up any confusion.

Thanks.
72longbed