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

[IdaSHO]

With a dual bank/output alternator, yes.

But the ground still need tied.

 

[dwh]

Is this possible? The two batteries are NOT connected, but must be charged by the alternator. i.e. can the alternator isolate the two?

View attachment 280522

In that diagram, the batteries ARE connected - permanently - at the alternator.

 

[Dust999]

Thanks. Will explore this option.

 

[Phoenix]

After 51 pages of reading and finally acquiring the appropriate budget, I believe I will need the following to put power in my trailer. Expected uses for now include LEDs on trailer for trailer/campsite visibility at night, and a cpap machine so I don't scare away all the other campers. Future use includes a water pump and maybe someday a fridge. My JKU is approximately 18 feet from battery, down the frame to the rear. My trailer has a 5 foot tongue. The battery will be mounted in a battery box against the front wall (close to the tongue) of the trailer. I'm running a 7 Pin connector but will not be hooking up the 10 gauge power wire. This may not qualify as an under $50 dual-battery setup, but I've already seen one Jeep go up in flames, so I'm going to trade cash for peace-of-mind.

Shopping list.
1. Starting / Truck Battery (stock battery is 2 years old)
2. Aux / Trailer Battery
3. 50 feet of #2 Ground Wire (yes I know this is twice the length I need, but only if I do things right the first time)
4. 50 feet of #2 Power Wire
5. 6 - 10 Eye Connectors for #2 Wire
6. Solenoid 200A / TMax 160A / Samlex ACR-160 160A (Knowledgeable opinions are welcome, see above about having my first Jeep burst into flames)
7. 2 Appropriate size fuses (So what didn't stick from 51 pages of reading is how I determine the appropriate fuse)
a. One between Truck battery and Solenoid / TMax / Samlex ACR-160 (160A or 200A?)
b. One near Trailer battery (160A or 200A?)
8. 175 A Power pole plugs (2) for disconnecting from Truck and Trailer (Options include 120, 175, 350)
9. Appropriate disconnects for voltage meter on Aux / Trailer Battery if I choose TMax (TBD)
10. Battery Box (I have a few plastic tool boxes that may do the trick)
11. Blue Sea Systems ST Blade Fuse Block - 12 Circuits with Negative Bus & Cover
12. Inverter (to charge various do-dads that will make my children and friends happy)
a. USB
b. Standard Plugs

Anyone see anything missing? Anyone think this is over or under engineering it?

 

[dwh]

I'm liking the looks of that Samlex. It can be forced on and forced off, and IIRC can have an indicator LED hooked up as well. Haven't checked the price though.

Size the fuse to protect the wire. Whatever the wire that you buy is rated at, there's the size fuse you use.

You're missing a fuse between the aux battery and the aux fuse block to protect the wire that feeds the fuse block.

Otherwise, offhand it looks good.

 

[dlichterman]

After 51 pages of reading and finally acquiring the appropriate budget, I believe I will need the following to put power in my trailer. Expected uses for now include LEDs on trailer for trailer/campsite visibility at night, and a cpap machine so I don't scare away all the other campers. Future use includes a water pump and maybe someday a fridge. My JKU is approximately 18 feet from battery, down the frame to the rear. My trailer has a 5 foot tongue. The battery will be mounted in a battery box against the front wall (close to the tongue) of the trailer. I'm running a 7 Pin connector but will not be hooking up the 10 gauge power wire. This may not qualify as an under $50 dual-battery setup, but I've already seen one Jeep go up in flames, so I'm going to trade cash for peace-of-mind.

Shopping list.
1. Starting / Truck Battery (stock battery is 2 years old)
2. Aux / Trailer Battery
3. 50 feet of #2 Ground Wire (yes I know this is twice the length I need, but only if I do things right the first time)
4. 50 feet of #2 Power Wire
5. 6 - 10 Eye Connectors for #2 Wire
6. Solenoid 200A / TMax 160A / Samlex ACR-160 160A (Knowledgeable opinions are welcome, see above about having my first Jeep burst into flames)
7. 2 Appropriate size fuses (So what didn't stick from 51 pages of reading is how I determine the appropriate fuse)
a. One between Truck battery and Solenoid / TMax / Samlex ACR-160 (160A or 200A?)
b. One near Trailer battery (160A or 200A?)
8. 175 A Power pole plugs (2) for disconnecting from Truck and Trailer (Options include 120, 175, 350)
9. Appropriate disconnects for voltage meter on Aux / Trailer Battery if I choose TMax (TBD)
10. Battery Box (I have a few plastic tool boxes that may do the trick)
11. Blue Sea Systems ST Blade Fuse Block - 12 Circuits with Negative Bus & Cover
12. Inverter (to charge various do-dads that will make my children and friends happy)
a. USB
b. Standard Plugs

Anyone see anything missing? Anyone think this is over or under engineering it?

The crimper I posted a few posts back might really come in handy compared to the hammer style ones for those large lugs: http://www.harborfreight.com/hydraulic-wire-crimping-tool-66150.html

For the fuses - think of max draw you think you'll ever have. I did 200A as that is enough to let me self jump when I have a low starting battery, and is the max rating for the solenoid I picked: http://amzn.com/B000CEBXRS

 

[dwh]

Also, depending on which inverter, you might need a fuse to protect the feed to that as well.

 

[Phoenix]

Also, depending on which inverter, you might need a fuse to protect the feed to that as well.

Very much appreciate all the info you have shared. Hope to see you on the trail some day so you can see the finished product.

Any chance you will be in North Carolina this fall?

 

[Phoenix]

The crimper I posted a few posts back might really come in handy compared to the hammer style ones for those large lugs: http://www.harborfreight.com/hydraulic-wire-crimping-tool-66150.html

For the fuses - think of max draw you think you'll ever have. I did 200A as that is enough to let me self jump when I have a low starting battery, and is the max rating for the solenoid I picked: http://amzn.com/B000CEBXRS

Should have had that on my list. Thank you.

 

[dlichterman]

Should have had that on my list. Thank you.

This appears to be just about the same thing, and a little cheaper: http://amzn.com/B00KHY7SOA

Though with a 20% off coupon it's about the same.

 

[Phoenix]

Also, depending on which inverter, you might need a fuse to protect the feed to that as well.

Any suggestions on inverter?

 

[dwh]

Very much appreciate all the info you have shared. Hope to see you on the trail some day so you can see the finished product.

Any chance you will be in North Carolina this fall?

Unlikely. I'll probably be here in the southwest, poking around in the desert as the U.S. Military "volunteers" the local citizenry to serve as "designated hostiles" for their upcoming martial law rehearsal. Either that or possibly hiding out in the mountains as ISIS storms north across the Mexican border.

Or maybe just sipping Pina Coladas on the beach channeling the ghost of George Carlin and ogling bikini babes. But no, no plans to head east at this point in time.

 

[dwh]

Or maybe I'll be tinkering. I like to tinker. I want one of these, but to get one, I'd probably have to build it myself:

http://dataviz.com.au/robot_guitar.html

 

[dwh]

Any suggestions on inverter?

Not really. I have a 400w el cheapo, and a 1000w el cheapo. Both work so I don't spend any time worrying about it. Both modified square wave, but that doesn't bother me.

The good stuff? Morningstar SureSine is the shiznitz.

 

[Phoenix]

So a friend of mine that owns a boat, and a Jeep, and about everything else you could imagine, asked why no alternator regulator. As I have no idea, all I can do is post the link to the product and hope those more knowledgeable will chime in. His quote follows, "Right now your alternator puts out a one-stage charge suitable for a flooded battery. If you use AGM or Optima batteries, especially on that is to serve as a house battery, you ideally want a three-stage charge. You batteries will charge at least twice as fast and will live much longer lives. Speed of charge, particularly from a deep discharge, is something that would appeal to me in an overlanding scenario."

http://www.xantrex.com/power-products/power-accessories/alternator-regulator.aspx

Thoughts?