Survivalist Forum banner
  • Are you passionate about survivalism? Would you like to write about topics that interest you and get paid for it? Read all about it here!
1 - 20 of 53 Posts

·
Padre in the woods
Joined
·
2,806 Posts
Discussion Starter · #1 ·
(Note: I tried posting this 10 min ago, but I was knocked off line. Apologies if it's duplicated.)

I'm preparing for leaving the metro and moving up north to a property I have. It's very rural, so I would like to add a second battery to my Chevy Silverado 1500 CC. At the time I purchased the truck I wanted the second battery, but didn't see the immediate need. Since that time the dealer has changed, and the new people seem oblivious to how it's done.

As an engineer in electronics, I feel I can do it myself. I found this web site, with a diagram of how to install the batteries and the device to interconnect them.

I'm probably over-thinking this, but I assumed there also needs to be a path for the batteries to charge. Or do you only charge the battery which is selected at the time? Is there a different method to interconnect two batteries? Is there other equipment I should use, or perhaps upgrade the alternator?

Reason I'm wanting two batteries is I will have a winch, work lights, plus a radio in the truck. I've noticed that this has taken down my single battery to nearly 11.5vdc even with the truck running. I don't want to be stranded in the woods. TIA

I would appreciate dialog with someone who, (excuse the pun), has been down this road before.
 

·
Greyman with a Mohawk
Joined
·
912 Posts
Nope that's about it- really is that simple for that style of isolator unless you have a newer vehicle that requires the extra ignition wire.
I used the Noco 200 amp, to run run my stereo, lights, compressor etc off the 2nd battery in my 88 r20 suburban.
 

·
Ephemerally here
Joined
·
6,875 Posts
My 1994 Diesel Blazer has Two batteries. Connected in the "Dangerous" directly parallel configuration. No isolator. Has worked fairly well for 22 Years. I do suspect that the batteries' lifes ARE reduced by circulating currents, as they don't last as long together as the single batteries in either my 1993 Silverado or my 2002 Tahoe Z71.

Remember, if you use an isolator, the "main" battery will always be more fully charged, as the isolated battery has a diode drop between it and the alternator.

If you use a either/or switch regime, they are nearly always at different states of charge, but it won't matter. If you use a #1 or #2, OR Both setup, you could run into HUGE circulating currents (Fire/Explosion?) Risk if one Shorts out or is dead, and you select "Both"...

If it can happen,.........

That said, my Blazer has never had an alarming problem, yet!

Ya pays Yer money, an takes Yer Chances!
 

·
Ephemerally here
Joined
·
6,875 Posts
Re the question about the alternator: I have seen a new Diode pack in a refurb'd alternator release the magic smoke when trying to charge a pair of Zero Charge, larger than OEM batteries in direct Parallel. Sometime in my many Years of Motoring, I ran across an explication of "Good Practice" when dealing with big battery banks in vehicles: charge the batteries before installation, and that keeps the alternator Diode pack from danger, especially in High temp ambient start-up.

I have also seen a small battery Boiling Vigorously when being charged by a big alternator - I stopped the evolution before we Exploded the battery. Safest system configuration is probably one that leans toward a slower charging rate, not one capable of Very high rate....

Have you ever been around a Lead/Acid Explosion? Not a Place I EVER want to be after witnessing one!!!
 

·
Wile E Coyote, Genius.
Joined
·
34,576 Posts
On sailboats 2 batteries are hooked up all the time. Usually designated as a starting battery and a house battery. Lots of ways to do it.
1) Simply connect them both in parallel which is what I did. Simple, nothing to screw up. Both batteries should be similar in type, size and age. Downside is if you leave the lights on for 12 hours both batts go dead.

2) Isolation diode that allows both to charge, but only 1 to discharge. Then you need a switch to use the standby battery in an emergency, or move the terminals manually. Downside, is the float battery charges to a lower voltage. Also adds to complexity and cost. You can run this with 2 load centers. 1 for the vehicle starting etc, and 1 for extra stuff like winch and maybe a stereo and lights you want to play and still be able to start on the other battery if it gets too low.

3) You can just put in a Perko Off/Both/A/B switch and manually decide when to charge or use each battery. Seems everyone has a war story of failure when they tried a complicated method and did something to screw it up. In this case, if the engine is running and you rotate the switch you can blow your alternator.

jeese this spell checker sucks.
 

·
Padre in the woods
Joined
·
2,806 Posts
Discussion Starter · #6 ·
Nope that's about it- really is that simple for that style of isolator unless you have a newer vehicle that requires the extra ignition wire.
I used the Noco 200 amp, to run run my stereo, lights, compressor etc off the 2nd battery in my 88 r20 suburban.
I've seen the diode packs, which supposedly allow for one battery to be charging while the other one is running the truck. I imagine this arrangement could also be DIY with some heavy duty relays and some thought on how to switch things.


I ran across an explication of "Good Practice" when dealing with big battery banks in vehicles: charge the batteries before installation, and that keeps the alternator Diode pack from danger, especially in High temp ambient start-up.
Just curious, should they be changed to a higher quality, more "Ah" output? Any thought about Diehard over generic brands like Interstate.


Have you ever been around a Lead/Acid Explosion? Not a Place I EVER want to be after witnessing one!!!
No, I haven't. But while working on a broadcast tower we had a serious RF arc within a transmission line causing mouton copper to drop on us. Luckily nobody got hurt, but one vehicle's cap was damaged. I've also seen the effects of lightning hitting towers and ingressing into buildings and equipment. And had a transformer carrying 20kv @ 5.8A decide to have a hissy fit and blow out a side and catch fire.
 

·
Wile E Coyote, Genius.
Joined
·
34,576 Posts
If it was me I would just hook them up in parallel.

Maybe put a simple disconnect on the 2nd battery in case you want to use a bunch of power while parked.

 

·
Ephemerally here
Joined
·
6,875 Posts
I'll see your RF arc, and raise a Ball Lightning Flashover from an open Locomotive motor commutator driven to destruction by a Drive Controller directing a much too fast dV/dT !! The lightning melted several pounds of Commutator Copper, Steel brush rigging, and then meandered across the Machinery House of the Container Crane, spitting sparks. Done by GE's Innermost Guru of the (then) new digital controllers.

Lots of energy available from 500VDC, 2500Amp system!!!

The things Folks do to make a living!!!

We Survived! Sometimes Skill, Sometimes Luck!

Glad to be completely retarded! You?
 

·
Wile E Coyote, Genius.
Joined
·
34,576 Posts
OK, I'll raise you 13,000 volts.

A 13.8 kV switchgear room flashover. vaporized about 10 lbs of copper which condensed on most of the room contents making it look like a bronzed baby shoe inside. Luckily nobody was in the room when it flashed or they would likely have been killed.

I'm not a EE, but I was impressed.
 

·
Ephemerally here
Joined
·
6,875 Posts
The batteries? As a personal rule, I always carefully measure the available space (careful eye towards tool space around terminals, and clearance from battery terminals' contact underhood or elsewhere!), then cruise available sizes. I then put in largest volume/highest capacity battery that can be fit. Bigger battery can then support higher ampacity Alternator. Brand names?? I am not convinced that there is much difference between labels. Many different brands are built by only a very few factories. Best storage amount/dollar wins, IMHO:D:
 

·
Registered
Joined
·
2,788 Posts
The link in the first post is how I did mine. I had to add in the battery tray but then I added a smart relay separator.

Now most people mistake isolator and separator like in that article. The relay type are a separator, once the relay is closed the batteries are in parallel and not isolated. A true diode isolator does still isolate while charging since its two diodes it doesn't pass drops or noise spikes etc from loads on one to the other. A decade ago before you could play mp3's on most any car radio I want with a true isolator to keep noise out of the computer I had in mine but a relay separator like the one in the article works fine and is what I run now.
Mine is a 2004 and the main battery went into the underhood electrical center where it went through the square J case fuses into larger branch circuits then individual loads were fused off of those by the smaller mini fuses. One of those larger J case fuses was dedicated to the trailer charging so when I added my second battery I moved the lead from that to a dual J case fuse block from the second battery. Now whatever I have at the trailer hitch stays on the second battery. The second fuse from that block runs into the cab then to a small fuse/relay block where individual circuits are then split off with mini fuses matching the rest.
 

·
Ephemerally here
Joined
·
6,875 Posts
One more "I Wuz There" sidetrack, because you'll appreciate it:

Labor Day Weekend, all the mucky mucks were outta town. Had been raining pretty hard for Southern CaCaLand. I got a call - roof drains on Container Yard Substation had been plugged, flat roof gave way, right over 22KV Switchgear, 1200 Amp service. Two main branches, and a Spare, to serve Container Yard of refrigerated cargo...Lobster containers, Automotive adhesive Resins, Fruit, and so on...maybe 3500 30-Ton Reefer Containers, Our Office Building, and the Crane Shop all needed power!

I was Crane Department head. Three Ships alongside, Seven Longshore crews all Idled at Holiday pay, Demurrage, Wharfage, Dockage, and City of Long Beach tax Meters all running!!! I was later told it was running $6700/minute. Nobody at Facility maintenance mgmt answered the phone. So, on my say-so, I hired a Huge generator, hooked up the building. Then went into the wet Switchgear, faked some limit switches, cross-connected both outgoing service legs, and wound up the big contactor spring mechanism. The facility's Maint crew wouldn't even come inside with me! They stood about twenty yards away, looking in the door as I tripped the" engage". It worked! Only lost about Fifteen hours'production.

I got a nice framed "Attaboy"... No performance award, no Story in Company paper. Not even My Department, or Responsibility! Saved them MILLIONS!
 

·
Registered
Joined
·
1,300 Posts
I have a Yukon XL (1500)--which happens to have two battery trays in the engine compartment--convenient. I have auxiliary loads which I run 24/7 off 12 volts, and it would deplete the start battery overnight!.

There are several problems with the systems diagramed and outlined above. Diodes have about 1/2 volt drop--and thus you do not fully charge the auxiliary battery.
Switches of any sort, are troublesome--you don't want to leave the loads connected all of the time.

The solenoid relay, consumes power, on whenever the ignition key is "on"--again old technology.

You have to have adequate sized alternator, for your loads. Assure that.

Your two batteries should be of the same type (flooded lead acid, AGM, etc) age, and size. If not there will be some misequilibium of the battery banks. This can early decay of one or both of the batteries.

The simple way, is to connect the second battery to the main start battery with a "Voltage Sensitive relay" or "Automatic Charing Relay" These combine the two batteries when the engine start battery is over 13.7 volts (well on its way to be charged), it keeps the batteries combined--and charging or discharging until the voltage drops to below 12.7 volts. This occurs when the engine is shut down, and is the fully charged resting voltage of the second battery. Thus you isolate you start battery, there is no current drainage, at rest, or voltage drop (less charging) due to diodes.

The wiring is simple. You attach an adequate ground, equal in side to the positive cable,--able to carry the current output from the alternator. The VSR is installed by the new battery. There is a fuse (adequate to protect the wire and rated the the amount of current it will carry, right by the take off point from the start battery. There is another fuse on the input to the secondary battery. The VSR is placed by the new battery. I put a simple 12 volt switch to shut off the VSR if I was not using the auxiliary system. This does not have to be a heavy duty switch.
 

·
Registered
Joined
·
27 Posts
Your best best is to call a local car audio retailer (NOT Best Buy, an independent shop will be better). A lot of cars have stereo systems installed that require extra batteries to be installed in the vehicle. These guys know how to do it safely and efficiently to accommodate your needs.
 

·
Registered
Joined
·
3,286 Posts
Sorry to burst anybody's bubbles here, but every Dodge equipped with a Cummins has had 2 batteries hooked in parallel since 1994 without any fancy isolaters or switches. Pretty sure Chevy does the same thing when they are ordered with a dual battery setup, though I haven't seen one since my 1986 6.2 truck ( It was hooked up just like the Dodge).

The only real issues are 1.) as has been pointed out, replace them in pairs of the same size, and obviously age, and 2.) Make sure the terminals are corrosion free, as on occasion if you happen to get corrosion on one the other can cause an overcharging condition and boil one dry.
 

·
Registered
Joined
·
1,550 Posts
my duramax has 2 batteries stock. I have hooked up dual batteries many times on boats and cars in parallel with no issues whatsoever. usually on boats I just use a standard isolator. run stereo on one, starter on the other. no need to overthink it...
 

·
Free-ish Man
Joined
·
1,877 Posts
Sorry to burst anybody's bubbles here, but every Dodge equipped with a Cummins has had 2 batteries hooked in parallel since 1994 without any fancy isolaters or switches. Pretty sure Chevy does the same thing when they are ordered with a dual battery setup, though I haven't seen one since my 1986 6.2 truck ( It was hooked up just like the Dodge).
Yup, Ford Powerstrokes too. Just hook them up in parallel. Very easy, very simple.
 

·
Premium Member
Joined
·
2,563 Posts
Wow - with all the there I was stories, you guys sound like pilots!

I don't have any good blowup battery stories, but I HAVE been zapped anywhere possible on an aircraft and by however many types of power on board (3 phase AC, single phase AC, and 28 VDC). Oh yeah, I did have an engine kablammo and several electrical fires in flight.

WW
 

·
Greyman with a Mohawk
Joined
·
912 Posts
Sorry to burst anybody's bubbles here, but every Dodge equipped with a Cummins has had 2 batteries hooked in parallel since 1994 without any fancy isolaters or switches. Pretty sure Chevy does the same thing when they are ordered with a dual battery setup, though I haven't seen one since my 1986 6.2 truck ( It was hooked up just like the Dodge).

The only real issues are 1.) as has been pointed out, replace them in pairs of the same size, and obviously age, and 2.) Make sure the terminals are corrosion free, as on occasion if you happen to get corrosion on one the other can cause an overcharging condition and boil one dry.
My suburban was ordered from the factory with 2 batteries wired like that, but I eventually ran into problems with my stereo, lights, pumps etc. causing a slow drain. After replacing the alternator and adding the Noco iso, I haven't had any issues even after leaving it parked for a month.
If you have a bunch of aftermarket electronics and equipment then I highly reccomend one. Btw I used the Knu konceptz 0/2 gauge wiring kit and it's by far some of the nicest power cable I have ever found.
 
1 - 20 of 53 Posts
Top