This is a Upgrade to that first, Simple diagram that allows you to remove one battery at any time for field service, camp site chores, to 'Lend' power to someone that needs it so you don't have to stay and wait to jump start them when they are done 'Fiddling' around, ect.
This is the next step up in dual batteries with 'Isolated' second battery.
The second battery is ISOLATED, so if something runs your primary battery down when the engine isn't running, you will be able to 'Self Jump Start'.
This system also DOUBLES the current to your starer, making for much faster starts and allowing you to use the starter to get yourself out of situations where the engine won't run...
The LAST Graphic for this series of simple Dual Battery arrangements is a Dual Battery ISOLATED with 'Lend Power'.
By making a quick release battery mount (Fabrication) you can pull a battery for use anywhere you can carry a battery. Great for jump starting another vehicle when your Jumper Cables won't reach or use in the camp...
This installment covers SIMPLE WINCH with Dual Batteries.
Winches will draw 500 to 700 Amps (Amperes) of DIRECT CURRENT when in 'Full Pull'.
There is no generator/alternator out there that would produce that much DC energy to power the winch directly.
It would take a separate V-8 engine and a DC generator the side of that V-8 to produce that 500 to 700 Amps directly.
Not very practical to tow around an 800 pound engine and 2,000 pound generator everywhere you go!
Enter a second battery...
The idea behind a second battery is four fold.
1. Batteries store a tremendous amount of energy that is fairly quickly released, more than any automotive charging system can produce.
A second battery will increase your 'Winch' time by supply the current needed by the winch motor,
2. A second battery will keep the first (Primary) battery from discharging to the point it gets damaged.
Batteries heat up during discharge, and if you 'Pull' on one too hard, the plates will heat up and warp, touch each other, and run the battery.
3. Batteries CHARGE SLOWLY, they don't like 'Fast' or high amperage charging, so the output from the vehicle factory charging system is PLENTY to charge both batteries over time after you discharge them while winching.
4. A second battery will leave you with enough energy to start the vehicle when you are 'Un-Stuck'.
Batteries recover very quickly, and a second battery DOUBLES your starting reserve as they recover.
('RECOVER', continue to convert chemical energy stored in the battery to electrical energy after you stop winching or welding, ect.)
The one thing to remember here is BATTERY CABLE SIZE TO THE WINCH!
The winch will REQUIRE more current than the starter motor,
So you MUST use larger cables to any connection to the winch.
Starters will normally run just fine in 4 AWG (American Wire Gauge) cables,
While most winches will draw upwards of 500 Amps in full pull,
So that cable size should be no less than 2 AWG in size.
I normally OVERSIZE the cables to the winch. 'Small' cables OVERHEAT when used hard, so oversizing the cable size is cheap insurance.
"Full On", Dual Battery, Dual Starter, Dual Winch Solenoids with ISOLATION of the second battery when the engine IS NOT running is a little difficult to do...
The Dual Starter Solenoid, Isolated battery part is pretty easy, and covered above.
But Going full on with Dual Isolated Batteries and getting the winch to work on demand, even when the engine IS NOT running is more difficult.
This particular Graphic allows me to 'LEND POWER', WELD, ISOLATES BATTEREIS, WINCHES WITH ENGINE NOT RUNNING and does it all quite well!
THIS IS BY ALL RIGHTS OVERKILL! The chances of your winch relays quitting are slim, but this DOES supply full current to the winch from BOTH batteries since there are direct leads from both,
And the winch solenoids are backed up by a second set,
So one battery and one set of winch solenoids will work even if the second is broken or removed.
It addresses the primary problems I run into once in a while.
With welding 'Yoke' below, jumper cables with Anderson Connector, and some welding rods or spool gun MIG welder I'm off to the races with about anything I face.
This may SEEM like a lot of wiring, but it's actually not compared to what your vehicles have right now, and not nearly as much as modern vehicles have!
Using High Amperage transfer connectors, like the Anderson connectors I use (Dirt cheap all over E-bay) You can modify your system to 'Lend Power', Have quick disconnect Jumper Cables,
Use your dual batteries for welding, both 'Stick' and 'MIG' welding,
Take a battery out to use in camp, personally, I run fans and lights in my tent with my extra battery.
An 'Anderson' connector on the simple version lets you drop a battery out VERY EASILY,
I use mine to jump start the lawn mower,
Jump Start vehicles that are beyond the reach of my Jumper Cables,
Pull one battery for use in other vehicles I don't use very much (with Anderson connector installed),
Use the extra battery in my camp site, the 'Little Woman' likes having a fan, lights, cell phone charger, ect. in camp, and the extra battery works very well for those things.
Another version is Dual Battery with ISOLATION of the second battery.,
A single battery with Anderson connector makes for a safe (Can't be hooked up backwards on your end),
Solid Jumper Cable connection (no 'wobbling' jumper clamps for connection),
And it keeps the connection at your battery away from the explosive gasses!
But a second Anderson connector mounted on the front of the vehicle makes for a quicker connection and you don't have to raise the hood!
If you have BOTH batteries on Anderson Connectors,
It's VERY EASY to adapt them for welding. All you need is three more Anderson connectors and some cable.
By disconnecting the batteries from the vehicle, and connecting them to a 'Yoke' that produces 24 volts, you can do simple stick welding, or if you have a spool gun, you can do MIG welding right off the batteries.
Since the batteries are disconnected from the vehicle, there is no worries about cooking your sensitive electronic components, alternator, MSD module, stereo are all safe since you have the batteries unhooked from the vehicle.
This arrangements also lets you weld with 'STRAIGHT' welding polarity (Work POSITIVE, Electrode NEGATIVE) which would kill your changing system and batteries if you tried it with batteries/alternator hooked up.
I use my jumper cables, since they are 4 AWG (American Wire Gauge) welding cable anyway, for the 'Ground' and 'Stinger' when 'Stick' welding.
This 'Yoke' makes for 24 volts output at around 200 Amps (restricted by cable size) and will do 'Rescue' welding quite well.
I use smaller diameter rods for 'Digging', Deep welds, and larger rods or reverse welding polarity (Work 'Negative' & 'Stinger' Positive) for lighter duty welding that doesn't require deep penetration.
Batteries come in all Shapes, Sizes, Terminal Configurations and Types.
For the purpose of this article,
I'm sticking with Basic Type Automotive Batteries because they are the least expensive,
I'm sticking with Basic Type Automotive Batteries because they are the easiest to find,
I'm sticking with Basic Type Automotive Batteries because they are the most reliable 'Common' batteries,
Top Terminals because the larger top terminals have more contact surface area to transmit Amperage, Top Terminals because they have the terminals above the electrolyte level, so they don't leak as much acid out where the terminals pass through the case, Top Terminals because they are the LEAST LIKELY to get shorted out in a Jeep Application,
Lead/Liquid Electrolyte type because they are more reliable than 'Gel' cells or 'AGM' batteries (and MUCH less expensive!)
'Rough Service' or 'Industrial/Farm' use batteries because they are just plain built tougher...
(and I'm HARD on stuff! )
I also don't care for 'Maintenance Free' batteries because you can't service them, if they get low on electrolyte because of hard use (Discharging) or fast charging they loose moisture you can't replace.
"Rough Service", "Industrial" & "Farm Use" batteries also have Thicker Cases,
Heavier bridges between cells and posts,
'Caged' plates so the plates can't bounce out of the separators and short the cells out,
They have a 'Mud' tray at the bottom to catch debris off the plates so it doesn't short the cells out.
You can use what ever you want, but those are my recommendations.
TYPES OF BATTERIES,
Common 'Starting' Batteries convert the CHEMICAL ENERGY into Electrical Energy faster than DCM or "Deep Cycle/Marine" batteries do.
Deep cycle batteires are designed to discharge much further and recover when charged, but they do it SLOWLY.
When winching, you need A LOT of current very quickly and DCM batteries are often damaged by the process of draining them so rapidly.
Common Staring Batteries will convert Chemical Energy into Electrical Energy you can use much quicker, and in most cases, you WILL NOT discharge them so deeply you will harm them.
To me, it's not worth the extra expense of DCM batteries when Starting Batteries will do.
Gell Cell and AGM have two very fatal flaws for this application,
One is EXPENSE! They are STUPID EXPENSIVE and have little or no warranty.
The second is the gel electrolyte can't 'Off Gas' the hydrogen gass produced during rapid/deep discharging, so the bubbles of gas stay trapped against the plates, causing 'Dead' spots on the plates that will never transfer energy again.
This effect is cumulative, so the more you quickly Charge/Discharge, the more damage is done.
Several Vehicles used an oil pressure switch to activate the electric choke and/or the 'Idiot Light' on the dash.
These are VERY easy to find, cheap to buy and make for 'Automatic' safety switches for electric fuel pumps,
They are also very good at turning your electrical appliances 'On' and 'Off' with the engine without having to flip switches, like the above isolated battery systems, or things like electric fans, ect.
This particular one is from an '80s Chevy Truck...
If you shop around for different makers, different years, ect. you will find one, two and three terminal switches, long stems, short stems, 1/8", 1/4" threads, ect.
Relays come in an astounding number of shapes, sizes, Amp loads and do the switching when you don't want to handle the current loads yourself!
How A Relay Works, LINK:
The Smaller current circuit creates a magnetic field. That's all it does.
The magnetic field pulls in the larger contacts of the primary load device.
Switching is VERY quick, so you get less sparking/burning of terminal material,
And a very low current circuit can activate a much larger current load without having a bunch of current running all around the vehicle via wiring that might be pinched, burned, rubbed through, ect.
This is a rundown of small relays, most are 20/30 Amp relays, but some go up to 70 Amps without problems.
These are what is known as 'Continuous Duty' relays, which means they can be activated every minute your vehicle is running with no issues.
This will give you an idea of what is available, how to wire it and where to use it.
Larger Relays are often called 'Solenoids'. This is a misnomer.
A 'Relay' is an electromagnetic switch that uses small current to control a much larger current.
A 'Solenoid' is an electromagnet that works a mechanical device, like an air valve or hydraulic valve or moves a mechanical arm...
This is the 'Brown & Sharp' scale, the industry standard for over 100 years,
And this scale will tell you what size wire you need for any amp load device.
The sizes listed for Amp load rating are for CONTINUOUS DUTY use without the conductor (wire) heating up.
Since most battery/winch cables will NOT be used long enough to get them extremely hot, I Under-Sized a little bit rather than Over-Size wires like I do with things like Head Lights that will be used for hours on end.
If you take a close look at this scale, it would take a HUGE wire (or combined wires) to feed a winch drawing 500+ amps at 'Full Pull'...
Most of the time somewhere between 2 AWG and 2/0 Gauge wire will feed a winch just fine, but if you are in a long, hard pull, you WILL notice the cables heating up!
This is your basic battery/winch cable fabrication materials and tools.
Something Between 2 AWG (American Wire Gauge) and 2/0 (00 or 'Double Ought') Cable to start with,
Some Solid Copper, Lead Cadmium Plated Battery Terminals with Stainless Steel bolts and correct 'Terminal' nuts,
Some solid copper 'Lug' terminals,
Some 'Silver Bearing' Electrical Solder,
Some Heat Shrink Tubing with internal 'Glue' to seal up the connection,
Cable Cutter that will do double duty as a stripper,
And a Terminal Crimper.
That glue seals up the connection and keeps that cable from rotting out for a LONG TIME...
If you don't have 'Red' cable, A couple of inches of heat shrink can be used to label 'Positive' cables even when the wire insulation is 'Black'...
One battery, two batteries, doesn't matter to the factory charging system...
It only 'Sees' one large battery when wired this way.
Now, if you have two different size or types of batteries (Starting with DCM) you need to do things a little differently because different sizes or types use different charge rates, but a 'Matched Set' of batteries will charge as one large battery, and your factory alternator is more than capable of doing the job.
The same Delco-Remy 10 SI alternator, or 12 SI alternator was installed on MANY vehicles with dual batteries from the factory, and it's amp capacity is more than enough to overcharge the batteries if it goes unregulated, so there aren't any issues with charging other than most of use 'Off Roaders' do our thing at low RPM...
And the 10 SI & 12 SI doesn't charge at low RPM very well...
But then again, the dual batteries will carry us through until we get the RPM back up, so it's a 'Win/Win' with dual batteries...
No alternator that would fit under your hood would keep up with a winch drawing 500 to 700 amps in 'Full Pull' trying to get out of a 'Bad Stuck' situation...
It would take a V-8 engine and generator nearly as large as the V-8 to make that much DC amperage directly!
It's AMAZING how much power a battery stores!
That's why a SECOND BATTERY is so important when you winch!
It's capable of keeping up with the winch for a short period,
Then the alternator takes over and recharges the battery SLOWLY like batteries like to be charged...
Second battery keep you from discharging the first battery too far so it's not damaged, and gives you more winch time.
With that second battery, you can do all sorts of other 'Tricky' things!
If it's there, why not use it for something other than occasional winching...
Anyway, charging system upgrade is coming...
My alternator keeps getting packed full of mud, so an upgrade is coming when I pull this engine. Probably a CS series alternator, since they are cheap, available, simple to switch to, and work really well at lower RPMs.
The idea was to give EVERYONE something, from 'Simple' to extravagant with all the 'Whistles & Bells'...
Show the full range of what you can do with a second battery...
And how to make cables that won't starve your winch, connect the winch so it works 'Best', and to use what you have more efficiently.
Just curious, I am setting up dual batteries in my CJ but I am using a voltage sensitive relay on mine and completely isolating the starter battery and using the other battery for all accessories. The VSR basically has both positive leads connected to it and switches from one to the other based on voltage. Once one battery is charged the relay pole gets thrown to the other battery for it to get charged so that it is charging them separately and the two batteries are never hooked to each other. Sorry this diagram is so "busy" I just use it as a reference for all of my wiring. I will break these out individually eventually but you can see the voltage sensitive relay as "VSR".
Just wondering though if there's an issue keeping one battery only hooked up to the starting system and one hooked up to the accessories without having the two connected together. I want the system to stay redundent even if it's not benefiting from the higher amperage rating as your system due to the fact that in your system the batteries leach off of each other. In other words in your system if one battery fails they both fail. I want mine to stay reliable and I think that since mine is setup to have one battery starting and one battery powering accessories it should be plenty of power for everything. See any potential powers?
I have recently bought a new "starting" battery and have a friend who has another good "starting" battery he is willing to give me. Will the fact that they have different CCA be a problem or the fact that one is brand new and the other is used but still testing ok?
"Anyway, anyone have any suggestions on stuff I forgot to cover?" You were joking, right? Thank you Jeephammer for yet another overkill awesome write-up. Some of the stuff I have never even seen in pictures (batt. cables).