How to make a cheap isolated dual-battery setup for $50
- Thread starter evldave
- Start date
continuecrushing
Member
Hmm, I'm now thinking it may be best for me to get 2 smaller deep cycle, and run them in parallel? I don't have the room for a full size second battery under the hood, and I don't want a full size mounted lower/in possible damage area under the truck.
If I did go this route, I'd have two smaller batteries (30-40ah each?) under the hood with the blue sea 7622, and 2/4 gauge wiring etc. This way I could self jump if needed/run anything I want off them. I know this sounds weird, but I've got room to put a few smaller batteries, but not a full size starter+full size deep cycle (80+ah).
If I did go this route, I'd have two smaller batteries (30-40ah each?) under the hood with the blue sea 7622, and 2/4 gauge wiring etc. This way I could self jump if needed/run anything I want off them. I know this sounds weird, but I've got room to put a few smaller batteries, but not a full size starter+full size deep cycle (80+ah).
aqasprt
New member
Looking at diagram is the solenoid on a red continues power if so I really would have a fire extinguisher on hand. But what do I know worked on things from fuel-powered MAXXIS to Mack semi's 1.5 hp outboards to ships with 300-ton crankshafts for over 30 years.So there are a lot of kits you can buy to have truly isolated dual-battery setups. Those are VERY NICE kits. They are also very expensive. I try and replicate those kits without spending as much money, while still having a similar level of quality and/or reliability. There are constantly posts on this forums about 'How to do dual-battery setups' and most are from people who don't want to spend the $$ on the kits. I didn't want to spend the money either, so came up with a simple list people need to buy to get a reliable and safe dual-battery setup.
Step #1 - Get a beer, this will take awhile
Step #2 - Look at the diagram - study it in detail as this is an incredibly complicated setup that will take years to learn properly. Plus, there will be a test at the end.
Step #3 - Have another beer, that was a rough diagram and you deserve a reward
Step #4 - Source your parts!
Get your own batteries - I won't go into batteries, which are best, etc. I have 2 DieHard Platinum batteries in my truck and a cheap Wal-mart battery in my trailer. Some like Odyssey, some like Optima, some like Trojans
Get your cables ($14)...for a simple setup you can go w/8 or 6 gauge, but I've found that 4 gauge battery cables with the ends cut off work well, because they are cheap and carry a decent amount of current.
http://www.handhelditems.com/20$$-guage-booster-cable-p-47794.html
You'll also need some 12 gauge wire. If you don't have 12 gauge wire laying around, you probably shouldn't be wiring your own dual-battery setup. Or borrow some from a friend. If you don't have any friends, turn off your computer and get a life! :sombrero:
Get your connectors ($7)...you know, to connect your cables to your batteries and stuff
http://www.amazon.com/IMPERIAL-71861-STUD-BATTERY-LUG/dp/B001E5A3UC/ref=pd_cp_hi_3
Get your fuses!!!! ($13) ... you need one fuse for each battery, trust me on this one
Go here are order part number ANB740N0N02, they are 80A ANL fuses + the fuse blocks
https://www.vtewarehouse.com/content/electromech/fuse/html/anl/anlfuse.php
Note: If you are wondering why 2 fuses, it's because each battery has power and could blow up your truck, so it's best to fuse both batteries. Put the fuses as close to the battery as is practical.
Get your solenoid ($16) ... this is what keeps one battery from draining the other battery, or something similar to that (mostly it keeps them 'isolated' from each other so you can still start your truck to make a beer run)
Cheap -->http://www.amazon.com/Continuous-Duty-Solenoid-80AMP-12V/dp/B0050I94XG/ref=pd_sim_sbs_auto_1
Good -->http://www.amazon.com/Cole-Hersee-24106-Continuous-Solenoid/dp/B001FQL43U
Way good -->http://www.amazon.com/gp/product/B001YIPXR2/ref=oh_details_o00_s00_i00
Step #5 - While you're online, order some good beer from the great Pacific Northwest (they ship everywhere!)
http://www.northwestliquidgold.com/
Step #6 - Wiring everything up
Follow the picture above
- Find somewhere to put everything in your engine compartment (or truck bed, or wherever your 2nd battery might end up...unless it's one of those fancy sealed-up battery things, don't put it inside your rig or it might leak hydrogen gas and Hindenburg your *****, so just don't do that, okay?
).
- Make a short 4GA wire from your main starting battery POS (short for positive, not for piece of $hit)to your fuse block.
- Make another 4GA wire from your fuse block to the isolator
- Make another 4GA wire from the other side of your isolator to the other fuse block
- Make a short 4GA wire from the other fuse block to your other battery POS
- Make a single 4GA wire from the NEG on your starting battery to the NEG on your other battery
- Connect a 12GA wire from pin on the isolator to a fuse in your fuse box that is only 'hot' when the key is in the 'ON' position (aka the truck is running)
Note: You can use fancy heat shrink on your wire connections, and that will work very well. Or you can take a roll of electrical tape (UL Listed, please) and wrap each connector-wire connection in electrical tape. It's about 80% as effective at about 10% of the cost or effort.
TOTAL COST - $50 (cheap) $59 (good)
- Cables - $14
- Connectors - $7
- Fuses - $13
- Solenoid - $16/$25
Note: Cole-Hersee solenoid will be much more reliable, so spend $9 less on beer and upgrade to the nice solenoid
Note #2: Don't try and jump-start your truck using your other battery using just this setup (ie through the solenoid). Instead, pull out your jumper cables (you DO have jumper cables, right? you didn't just cut up the pair you keep IN THE EVENT OF EMERGENCIES, right? right?) and jump from your backup to your starting battery using the jumper cables
Note #3: The big difference between this and the fancy setups (other than the cool battery gauge things) is those will usually use a voltage-sensing time-delayed-opening solenoid-type dohickey that allows your starting battery to charge first, before charging up your other battery. If that means anything to you, it might be worth spending the $200 more to get one of those sets. If you have no idea what that means, get in line, I don't really understand it either, but apparently it's worth $200
Final Step - Have a beer, enjoy how cool you are, and now go build a cheap $100 awning with the money you just saved.
another_mike
Adventurer
Joined yesterday.... welcome to the forum... what is a “red continues power”? Are you asking a question? Question marks help clarify that.
patoz
Expedition Leader
Mike, that post made no sense to me either.
Of course what he's saying is that a solenoid presents a fire risk. Of course it might- anything added to the system presents a new possible source of failure, from a poor quality part to a poor installation. And even the factory system carries a risk of fire (Ford cruise controls, anything made by Ferrari, etc.) But the real questions for this expert are 1) Why would a continuous duty solenoid rated at 500 amps present an unacceptable or unusual risk of fire? and 2) How to improve the parts or design? (And don't cop out by saying "leave it stock.")
another_mike
Adventurer
He might have also been assuming the power to switch the solenoid was on constant hot? Who knows except for him, and it was a drive by posting by someone who only joined hours earlier and from we will probably never hear from again.
dwh
Tail-End Charlie
No, it's on an ignition hot. Clarified in later diagrams after Dave partially sobered up.
Yes, I've done it for years. I have a deep cycle battery in a box that I move from vehicle to vehicle, where ever the fridge is going. I've wired a 7-pin trailer plug to the charge circuit only (2 wires). The plug goes into the trailer socket next to the hitch, and through the back hatch. When the engine is running, the battery charges. When off, it doesn't. I've also installed a volt meter into the box to keep track of the battery charge, a bunch of accessory ports, and a 800w 110v inverter on the lid. It's a bit ghetto what with the wire pinched in the door, but it works just fine. If I really had my act together, I'd wire a permanent socket off of the same trailer battery charge circuit into an access panel inside the vehicle.
Some will say that the 8-10 gauge wire and 40 amp fuse won't allow full charging or fast charging, and they may be right. But like I said, I've used it on and off for years and it works.