Installed Dual Battery Set Up (update) picture added

[1-ton]

I installed a dual battery set up in my square body crew cab. Even though my truck is a 1-ton it did not come factory with a dual battery set up. I got ahold of a left handed battery tray and a couple of group 34 / 800 CCA batteries. It is a basic set up with no fancy isolators or anything. This set up will just run both batteries all the time. Sometime later I will get an isolator. I built this set up myself with raw battery cable, cable lugs, and some studded top post battery terminals.

 

[rampage]

What’s the thinner positive wire for?

 

[1-ton]

What’s the thinner positive wire for?

Alternator charge wire. I have an Alt charge wire going from the Alt hot terminal to the positive right side battery terminal, and another charge wire lead from the right side battery terminal to the left side battery terminal.

 

[Desert_K5]

Looks good. If you can while you're doing it, I'd suggest the Painless Wiring switch kit. It's a neat kit and not too expensive.

 

[rampage]

Alternator charge wire. I have an Alt charge wire going from the Alt hot terminal to the positive right side battery terminal, and another charge wire lead from the right side battery terminal to the left side battery terminal.

If I understand what you’re saying correctly, you have the alt charge wire and the positive cable both going from the right battery terminal to the left battery terminal. If so then I believe it’s safe to remove the alt charge wire running from battery to battery.

 

[Truckman4life]

I put dual batteries in my old '79 half ton with a small block. It cranked over so much faster and started way easier. And yes you only need a single positive and single ground connecting the two batteries or you can run a single positive cable and connect ground back to the engine.

 

[88Silverado]

Heres how I did mine, with an isolator, to give you some ideas. Alt charge to the main Batt. Main and Aux connected via Isolator. On Aux batt a short negative cable is tied to both the engine block and body. The two cables from Aux run to the Winch.

 

[1-ton]

Heres how I did mine, with an isolator, to give you some ideas. Alt charge to the main Batt. Main and Aux connected via Isolator. On Aux batt a short negative cable is tied to both the engine block and body. The two cables from Aux run to the Winch.
View attachment 428326 View attachment 428327

I will change the left side battery ground to engine and frame instead of that negative all the way across from battery to battery.

 

[1-ton]

If I understand what you’re saying correctly, you have the alt charge wire and the positive cable both going from the right battery terminal to the left battery terminal. If so then I believe it’s safe to remove the alt charge wire running from battery to battery.

I will take that out too. I am sure the positive cable run across the batteries will move the charge from one side to the other.

 

[rampage]

I will take that out too. I am sure the positive cable run across the batteries will move the charge from one side to the other.

That extra wire also makes the positive wire appear larger than the negative wire. I like making my ground wire at least the same gauge as the positive if not larger (lower AWG number).

 

[88Silverado]

I have both negative cables from the batts connected to the engine and body. Make sure you clean the mating surfaces of the ground connections or use good star washers to make the connections.

 

[1-ton]

I have both negative cables from the batts connected to the engine and body. Make sure you clean the mating surfaces of the ground connections or use good star washers to make the connections.

I would like to connect the left side negative battery cable to the block because that does make more sense, but the A/C compressor and steering pump takes up every accessory mounting hole in the block and head on the left side of the engine. I will have to figure something out. I did connect an 8-gauge pig tail to the frame on the left side battery.

 

[88Silverado]

I would like to connect the left side negative battery cable to the block because that does make more sense, but the A/C compressor and steering pump takes up every accessory mounting hole in the block and head on the left side of the engine. I will have to figure something out. I did connect an 8-gauge pig tail to the frame on the left side battery.

I pulled one of the long bolt outs of either the power steering or A/C (cant remember and cover is on so cant easily look) and placed the lug under the bolt head. Once things were adjusted up, that bolt is tightened and it makes a satisfactory ground. If you zoom in on the picture above and follow the black cable you can probably figure out which bolt it was.

 

[1-ton]

Got a problem with the dual batt install. When I turned my key on for the first time the interior right turn signal arrow was lit up. I knew then that there was an electrical problem. I started my truck, and it started normally. When I took it around the block the ignition would not go above 3000 to 4000 RPM. After I parked my truck I touched both positive terminals to see if they where excessively hot. They where not. The problem has to be at the starter, which has an ignition wire. Something with an ignition wire or battery wire is having a problem.

I will get to it later because NASCAR is in town for the races at Las Vegas Motor Speedway (LVMS) this weekend, and since my wife works for the company that is the sponsor for the race I get free general admission tickets.

 

[Blue85]

OK, two batteries in parallel is normal for the diesel trucks, but what problem are you trying to solve here? For two batteries in parallel, they should be the same battery, of about the same age, or there will always be misbalance problems. Just ground both to the frame (or both they frame and body) for the negative. For positive, you will need about the same wiring from both batteries to the truck and alternator, as an alternative approach, make the wire between them giant. There's no point having a 2nd battery off to the side just tied in with a dozen feet of 10AWG without some 2nd electrical load to service.

 

[88Silverado]

Just adding a aux battery and connecting a new hot and ground lead would not mess up the ignition or turn signal. A lit turn signal indicator usually means a bulb is out but this will also happen if a ground wire is disconnected. Probably a coincidence.

I dont understand the RPM comment. My stock 88 TBI floored will not surpass ~4000 RPM on a good day going downhill.

As Blue85 noted above, both batts should be approx the same. Looks like you are good with that. I had dual blue tops originally until the main one died after 3 years. I decided to go back to a standard replacement for as I do not see the cost benefit to these custom batts. Wasnt long after that photo my aux (winch) blue top died (4 years). I now have identical Costco batts for reason listed above (load/charge voltage balance) and I replace them as a pair.

 

[max 02]

I put dual batteries in my old '79 half ton with a small block. It cranked over so much faster and started way easier. And yes you only need a single positive and single ground connecting the two batteries or you can run a single positive cable and connect ground back to the engine.

That is how I did mine on my 77.

 

[ZooMad75]

I've been running my homebrew dual battery setup for a while now. I've been using a 150amp continuous-duty solenoid between the two batteries. Mainly to run the camper and winch off of the aux battery and take any load of those items away from the main cranking battery when the truck isn't running. Single 0 gauge with the ground cable off of the second battery to the block. I can monitor individual battery voltage and the aux battery does run a couple of tenths of a volt under the main battery. I'm suspecting a slight amount of voltage drop over the run and the solenoid.

I set it up on a 3-position rocker switch (on-off-on). When the switch is down, the solenoid is triggered on by power from the ignition switch. When the switch is up the power to trigger the relay is from the aux battery (self jump). In the off position the two batteries are divorced all the time, engine running or not.

I leave the switch down, so that both batteries charge while the engine is running, but are isolated when the key is off. I have had to use the self jump feature in the past and it's proven to be quite nice when the truck was nosed into a parking spot next to the garage where I couldn't reach with a set of cables.

I do have an ASR type relay from Cyrix to replace the solenoid with that will automatically connect or isolate the batteries depending on input voltage. When I have solar onboard, this will be quite slick. The ASR relay will connect the two batteries automatically if one battery is at or above 13.5v. So if the solar is putting power in, both batteries can get charged, same goes if the engine is running. Once voltage drops below the threshold the ASR will open and isolate the two batteries from both being discharged. The relay does have a self-jump feature that will still allow that to occur from my rocker switch.

 

[Wes Harden]

I have asr and a tiny solar panel in windshield, the relay continually opens and closes because the solar panel can get 1 battery over 13.5 but not both.

 

[ZooMad75]

I have asr and a tiny solar panel in windshield, the relay continually opens and closes because the solar panel can get 1 battery over 13.5 but not both.

I'll end up putting 200-300 watts worth of solar on the roof of the camper. I see it keeping both batteries charged pretty well.