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Electrical help please! Dual Battery setup

Fancy

Fancy

1/2 ton status
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So I have installed an Aux. battery in my blazer and it will be isolated by an ACR like in the link below.

https://www.westmarine.com/buy/blue-sea-systems--ml-acr-automatic-charging-relay-with-manual-control-24v-dc-500a--16934135

As of right now I have all my aftermarket accessories connected to the Aux. battery and the stock system to the Main battery. Both batteries are yellow top Optima’s.

What I want to accomplish is transferring the power to the stock wiring system to the Aux. battery and isolating only the starting system to the main.

After researching it looks like it is as simple as tracing the leads highlighted green in my photo and switching them to the Aux. battery and running a new lead from the Main battery to the Batt1 terminal on the ignition switch. However im not know to be an electrical wizard so was looking for some input.

Thanks

K5 Wiring Diagram.jpg
 

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What are you trying to gain by only having the starter be linked to the main battery and everything else on the aux? I'm missing something here I'm sure.

I set mine up so all the accessories will be drawing from the aux battery. Winch, air compressor and eventually the fridge once I get one will pull only from the aux, this way the starting battery won't have the load on it.
 
Well at this point if I leave the truck in Acc. Mode I will still be drawing power from the Main battery. What I want to accomplish is no matter how I use the truck I can only drain one battery while the truck is off, in Acc, or even Run. This would insure the second battery always has power to start the truck. My concern here is if I connect it the way I am anticipating, I will provide power to start the car but the second the key gets back to Run it will have no power depending on how drained the Aux. Battery is. Im thinking I may have to install a switch that allows me to toggle the green leads back and forth from Aux Battery to Main Battery.
 
Look at the 12volt Guy dual battery kit. I think it will accomplish what you are trying to do. It is a solenoid type switch that can automatically connect your batteries with your ignition on (yes, I believe that it Acc position will join them), or you can manually switch it off so that they don't join.
http://12voltguy.com/dual-battery-kits_1.html
 
Keitha - Thanks for the link! that's a lot nicer version of what my old system was basically!

I guess i'm not explaining myself very well though. I currently have a really nice working dual battery system. However my interior lights, stereo, CB, seats controls, seat heaters and some small accessories all work of the stock harness. I really do not wish to run new wiring for these features when all the original is still there and in great shape.

So I know it would take along time before I drain a battery using any of these components with the truck off or in Acc., but I wouldn't be worried about it if I could say I have never had it happen :/ So even though my batteries are isolated at this point I still draw from both batteries. My goal is to only ever draw from one battery.

With my current system the battery that has the starting system on it will them receives a charge from the alternator while the truck is running, this in turn will activate the ACR and start a charge on the second.

I guess I will play with it and give it a shot if I get a chance in the next week or so.... I try to post back.
 
Reverse your thinking a bit - Your house battery can still do the same thing as if it were a 1 battery truck. Your second battery becomes a back-up. It charges when the motor is running, then is isolated when you shut the motor off or open the manual switch. If you kill your house battery, you still have your auxiliary batter to basically self-jump start your vehicle.
It's a lot of brain damage the way your thinking about it.

While you are on the West Marine site, look up the Blue Seas "Add-a-Battery" kit and how it is wired and what it does.
 
Years ago in the back of the Standard Ignition catalog,they showed how to use a SS-584 starter solenoid relay as a auxillary battery isolator ,that allowed both batteries to charge while the engine was running,and isolate one battery when the key is off,so you'll always have one fully charged battery...

It was a simple hook up--two battery cables to each positive battery terminal to the solenoid ,and a 12V hot wire from the ignition to activate it in the "on" position..

Basically that part number is just a metal cased constant duty solenoid,similar to the ones many Fords used,but those had a plastic case...
 
If you can swap the yellow top starter side battery with a red top at some point..the extra cold cranking amps is better than the deep cycle on the starter battery..deep cycle yellow top is great for the aux side tho
 
Keitha said:
Reverse your thinking a bit - Your house battery can still do the same thing as if it were a 1 battery truck. Your second battery becomes a back-up. It charges when the motor is running, then is isolated when you shut the motor off or open the manual switch. If you kill your house battery, you still have your auxiliary batter to basically self-jump start your vehicle.
It's a lot of brain damage the way your thinking about it.

While you are on the West Marine site, look up the Blue Seas "Add-a-Battery" kit and how it is wired and what it does.
Click to expand...

This is a smart way to do it. Your system with all of the accessories on it is as you said on the main cranking battery, but done well. If you don't want to change the existing wiring for those items, put a continuous duty solenoid that the others have listed on with a 3 position switch. Switch in one position joins the batteries with it on and the key on. In the middle (off) position, the two batteries are divorced with the key on. Position 2 powers the solenoid up from the second battery to join for self jump starting. By doing this you can leave the accessories as you already have them. Throw the switch to the "off" position and the load while using the accessories and the 2nd battery is still is in reserve to allow for a self jump with the switch put into the 2nd position.
 
Some of the systems they have out now, as mentioned here, are probably a lot better than the way I ran dual batteries on my '79 F150. But, you might be able to use some of the ideas.
I used a dual diode isolator.
I cut the power out wire coming out of my alternator, ran the output of the alt to the center pin of the isolator. Then hooked the other cut end to one of the outputs.
On that model Ford the rest was simple. All the hookups to the battery connect at the battery terminal on the starter solenoid. I removed all those wires, spliced them together and connected them to the second battery.
I left the cranking battery hooked to the starter solenoid, and ran a wire from the second terminal of the isolator to it.

For the cranking battery, I used a high current many cranking amps model. For the second battery, I used a high capacity model that was still rated to crank the truck.
This worked great. I could leave my headlights on, radio playing, whatever, and still have a hot battery to crank the truck.
The hidden problem with this showed up one day when I got home from driving in the rain. I had had my headlights on, and forgot to turn them off. The truck sat for several days. When I went to start it, nothing happened.
The second battery was too dead to fire the starter.
Since they were both hooked to ground with heavy cables, I simply got out my jumper cables and jumped just the positive terminal from one battery to the other and jumped myself off.

Later that day, I went to town and bought a Ford starter solenoid and some heavy battery cable. Ran the heavy cable from each positive post to the terminals on the starter solenoid.
Since I'm an electronics engineer, I had some heavy diodes laying around. Hooked one to each of the solenoid battery posts, ran the output to a pushbutton on the dash and back to the control post on the solenoid.

That way, if either battery was dead, the other one would supply power to fire the solenoid when I pushed the button, and I could jump myself off without getting out of the truck.
Used a momentary pushbutton so I would not forget and leave the two batteries tied together.

I have heard all the arguments about how the diode isolator is not the best way, due to the voltage drop, but in 10 years of use, I never had a problem. Batteries were always good and hot, and seemed to have a normal life span.
In fact, I don't remember ever replacing the second one.

I don't remember what brand of isolator I used, but it was one like this one.

https://www.amazon.com/Cole-Hersee-...=1486053169&sr=1-1&keywords=Cole+Hersee+48160

If your GM alternator needs B+ to start charging, they recommend this one.

https://www.amazon.com/Cole-Hersee-...rd_wg=JyFH2&psc=1&refRID=CT5M2CSMDB6F00HQQB9W

Having said all that, the relay types are probably better than the diode types since they eliminate the .7 of a volt drop in charging voltage. But like I said, my batteries never seemed to notice.
 
Im really interested in this because i want a second battery. the tray is 60 bucks the battery is 200 to mach the red top i have. and the kit from painless is 250 for the weather proof one 191 for the none weather proof one.
 
The Blue Water "Add-a-Battery" kit and the 12volt Guy kit work on the solenoid principle. I have the 12volt guy kit in my Suburban and it is flawless. You can probably assemble all the parts yourself cheaper, but his kit comes with the solenoid, switch panel, all the high quality wiring you need, and is labeled and easy to install. It's money well spent.
http://12voltguy.com/dual-battery-kits_1.html
 
Kain said:
are the instructions good with 12volt guys kit?
Click to expand...

I recall them being clear. It really is an easy install - you tap into a switched 12v source to energize the solenoid and wire the auxiliary battery in with the supplied cable. I mounted my switch panel behind the driver side auxiliary battery under the hood, but others prefer to mount it in the cab. All the wires are labeled. In "normal" mode, the switched 12v source energizes the solenoid and joins the batteries together. If you house battery is dead, the 12v source won't be able to energize the solenoid, so you switch to "Emergency" which manually joins the batteries for a "self-jump". If you want to isolate the starter battery while you have your key in the auxiliary position, then switch to "Off" to manually keep the batteries separated.
 
Kain, here is the schematic for my self-jump setup. The two diodes were just a perk. If I had not had them available, I would have just hooked the switch to the cranking battery side, since it should not be dead under normal circumstancesDual battery.png .
 
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