Dual Batteries on the Cheap

[Titanpat57]

Hi guys,

Been following this thread over on ExPo, and have looked into hooking up two batteries, and have a house battery and a starting battery, both living under the hood, with my Aussie Battery Tray (thanks Philly). The starting battery is a Diehard AGM Group 31 and the house battery is a Diehard AGM Group 34.

Here's the thread...and I like this guy for two reasons.

How to make a cheap isolated dual-battery setup for $50 - Expedition Portal

1. He likes beer
2. He likes beer

But seriously, he writes his descriptions on a second grade level, which actually works for me, and he is in reality, is a pretty knowledgable guy.

In a perfect world Id love to spend umpteen dollars on fancy LED light bars that display all kinds of pertinent info, and be able to switch between batteries, but this will offer me isolation, and the ability to start the car in the event something happens. That is all I'm looking for, and as the the thread progresses, I'll supply prices, and places, to purchase the items needed to do it. He also list the same thing, and is pretty close.

Plus, the more money I save is the more money I can give Ducameister for a lift when the time comes....and Rigids, and Gobi, and...

I better start rinsing out toilet paper!!:boink:

I'll be back to post progress throughout the day...I only have about 12 Yuenglings and a few Sams in the Engel, so obviously it needs to be finished in 4-5 hours.

In the illustration he shows hooking a 12# wire into "on with key" fuse...if anyone has location to find said fuse it would be appreciated!

 

[Gerdo]

I have done this on three vehicles now. Works great.

 

[jca21]

looking forward to the results.


take lots of pics bud!

 

[phillyd2]

Been watching that thread too. Very interesting and smart. But here is the thing for me: I would rather have cheaper lights than save money on the battery set up. Hell, I would almost have cheap anything else than save money on the battery set up.

Not saying this does not work but all considering it should carefully read all the posts to fully understand its limitations.

 

[Titanpat57]

Been watching that thread too. Very interesting and smart. But here is the thing for me: I would rather have cheaper lights than save money on the battery set up. Hell, I would almost have cheap anything else than save money on the battery set up.

Not saying this does not work but all considering it should carefully read all the posts to fully understand its limitations.

Well if you're talking about being able to use one battery, or the other battery, or both...it won't do that (I think I stated that though earlier). In my case I have a Blue Sea 6 circuit box hooked up to the Starting Battery (the bigger of the two) so I already have a big thumper to start with.

The goods..

I'm using 2# by the way for future winch use down the road.

I borrowed a "crimping tool" for the big lugs from my electrical supplier, it comes with jaw sets you change out to match the lug size. They get a coat of applicable color shrink wrap.

God, I'm exhausted...I need a beer..

 

[jca21]

just out of curiosity, couldnt you use a relay switch to control power to the solenoid?

so... 12v from acc fuse panel to relay. relay is control by a rocker switch.?

that way you would be able to control power to the second battery vs the solenoid simply being switched on when the key turns in the ignition.

 

[GrantK]

I would recommend upgrading the wire, relay and fuses to handle at least the output of the alternator, if not the maximum draw. That means at least 2ga wire and 150amp relay and fuses. The alternator is 140amp IIRC. for the heat shrink tubing the best is double wall, adhesive. It hermetically seals the connection. Don't forget to put insulator caps on the wire at the relay.

The last time I did a setup like this I used a PAC500 500amp marine grade relay and fuses with 1/0 wire. Worked great and lasted for years before the truck went crunch.

jca21,
Yes, that's the way I've always done it. I used a SPDT, center off switch. One side went to the ignition, the other to the 2nd battery, common to the relay. This way when the switch is off (center) the batteries are always separated, when set to the 2nd battery they are always connected, when to the ignition they are connected when the ignition switch is on. I also put a indicator light on the common (to ground) so that it would light up whenever the batteries were connected.

 

[Titanpat57]

just out of curiosity, couldnt you use a relay switch to control power to the solenoid?

so... 12v from acc fuse panel to relay. relay is control by a rocker switch.?

that way you would be able to control power to the second battery vs the solenoid simply being switched on when the key turns in the ignition.

and you're asking ME that?!?...silly boy...I'm playing "monkey see, monkey do"

I would recommend upgrading the wire, relay and fuses to handle at least the output of the alternator, if not the maximum draw. That means at least 2ga wire and 150amp relay and fuses. The alternator is 140amp IIRC. for the heat shrink tubing the best is double wall, adhesive. It hermetically seals the connection. Don't forget to put insulator caps on the wire at the relay.

The last time I did a setup like this I used a PAC500 500amp marine grade relay and fuses with 1/0 wire. Worked great and lasted for years before the truck went crunch.

jca21,
Yes, that's the way I've always done it. I used a SPDT, center off switch. One side went to the ignition, the other to the 2nd battery, common to the relay. This way when the switch is off (center) the batteries are always separated, when set to the 2nd battery they are always connected, when to the ignition they are connected when the ignition switch is on. I also put a indicator light on the common (to ground) so that it would light up whenever the batteries were connected.

Thanks Grant, good stuff there!.....as stated above I am using #2 but with 80 amp fuses. I did use the PAC500 btw....found it on fleabay for like 70 smackeroos!

Ok..pic time..

Here's the way it right now...Starting battery..

House battery (or spare)

The PAC 500 mounted(there were two 6mm threaded holes there that fit perfect..I know, I know... I'm a lazy bas****, Antman..you can call me Cantman..hows that?!

Where I'd like to mount the fuse holders..what say the Collective?? Everything can be disconnected very easily and quickly in the event I have to get into the air cleaner or fuse box..thoughts (please hurry though)

The air cleaner side...

Fuse box side (screwed from underneath and siliconed...coz that's just how I friggin' role..

 

[GrantK]

Looks good!!!

Suggestion, run the positive cable in split-loom or at least on top of the negative wire where it goes over the battery hold-down clamp. That will reduce the chance of the positive wire chaffing and shorting out.

 

[Titanpat57]

You think it's allright to mount the fuse holders in those positions?

Thanks!

 

[GrantK]

You think it's allright to mount the fuse holders in those positions?

Thanks!

Several of us (me included) have made custom brackets for fuse panels in that same location and haven't had any problems.

 

[jca21]

what kinda battery tray is that for the house battery?

also, moar info on the blue sea fuse block.

 

[Gerdo]

The one down side is when using heavy draw while running like winching. That load will want to pull from both batteries. Is is conceivable that you drain both batteries if doing a lot of continuous winching. This also means that you have a larger reserve of power for winching. This usually is not an issue unless you are doing a lot of continuous winching (like 6+ pulls in a row). Also if your wiring and/or fuses are not large enough, you can have issues.

More expensive electronic isolators will only allow power to flow toward each battery and not back toward a load being drawn on one.

The draw on the control wire is very low and 12awg is a lot bigger than is needed. I run off my DRLs and have it fused with a 2amp fuse. I would recommend fusing the control wire too.

Since you have power flowing down the line to/from the second battery, fuse both ends close to the ends.

 

[Antman]

Lookin good Pat! Couple of things.

I wouldn't mount the fuse holders there simply because they are both access panels, and well, that limits the access. Out in the boonies the KISS method is best. Why make it harder to get to a fusebox if you don't have to? I would mount them to the fender wall, but your spot is OK.

There is some 12ga? red wires on your firewall. Please split-loom them. Naked power wires aren't sexy.

Crossing 2ga battery cables over the battery isn't a great idea. Try to sort the wires out so they run parallel off the battery so they can't touch.

Cantman? Funny stuff! I will be doing something like this in the future. Hmmmmmm.


PS- I don't remember taking those pictures, but uh they are aweful. Welcome to the club bro!

 

[janefennell147]

Works great.

 

[Titanpat57]

Lookin good Pat! Couple of things.

I wouldn't mount the fuse holders there simply because they are both access panels, and well, that limits the access. Out in the boonies the KISS method is best. Why make it harder to get to a fusebox if you don't have to? I would mount them to the fender wall, but your spot is OK.

There is some 12ga? red wires on your firewall. Please split-loom them. Naked power wires aren't sexy.

Crossing 2ga battery cables over the battery isn't a great idea. Try to sort the wires out so they run parallel off the battery so they can't touch.

Cantman? Funny stuff! I will be doing something like this in the future. Hmmmmmm.


PS- I don't remember taking those pictures, but uh they are aweful. Welcome to the club bro!

I took your advice, and did everything you told me not to do, with the exception of wire looming the back wires, that was a $hitshow.. so thanks for nothing...and you can straighten this f'in birdsnest out next Friday....I'll buy you a beer, because that's the kind of big hearted bas**** I am.

The pictures rock don't they...it's like your glasses are really, really dirty ...lol.

I saw that and decided to leave them, for posterities sake...


Here's the finished product, the ground wire runs under the front radiator fascia, and is secured under it (with two rubber bands). The only thing I didn't have was an add a fuse, so it's hot all the time in the fuse box, which I think translates to "both batteries are connected, and can both be run down" ...but I could be wrong. I honestly don't get a lot of electric, and have no idea why it works sometimes.:thumb3:

 

[phillyd2]

I too am a big fan of KISS and know from personal experience that not only does Mr. Murphy live but he also a evil SOB with a wicked sense of humor.

I have the exact same batteries but when all is said and done I will not be using the secondary terminals because if I'm who knows where and must replace (buy or steal) it there is a good chance I will not find the same type with extra terminals. The last thing I'm going to want to do is start rewiring everything to fit on just two terminals.

Each of us has different comfort levels - nothing wrong with that. But still a interesting set up. Please do keep us updated on how it works long term. :thumb3:

 

[Antman]

I took your advice, and did everything you told me not to do, with the exception of wire looming the back wires......

You're funny!

Most of what you did looks great- and yes, I will fix the crossed wires on the main battery, and the positive cable on the aux battery that's sitting on the metal battery hold down for you. I don't want your username to change to DeepfriedPat57, or BlowndafukupPat57 now do I? (actually you are fused anyway so it's not that bad).

I laughed at this picture when I saw you wire loomed the ground wire. Are you afraid it may get chafed and ground itself? :hello: Sorry- you can punch me later.


Anyhoo...


FWIW, when I got home from work today I saw your post and tested every freakin fuse in that underhood fuse box and they are all hot all the time. To get an "ignition-on" powersource without tapping into underhood wires you are probably going to have to run a wire into the driver's footwell fusbox ( the P/Outlet fuse for instance). That's easy.

Hope I have room for my electrical box and junk after I load up...

Overall I like it!:thumb3::thumb3::thumb3::thumb3:

 

[jca21]

any updates?

btw is this the battery tray from ABR-Sidewinder?

 

[SVBIED]

Hi guys,


I better start rinsing out toilet paper!!:boink:

Wow....

:wtf: