Dual Battery Setups! Let's see them! Multiple Batteries Thread!

Awesome thanks for the reply!

 

In parallel the batteries will not jump to 24v, connecting them in series will.

If both batteries are the same and you connect them in parallel it is essentially like creating one large battery. There is no isolation but it will not run down as fast as a single one. They will also take longer to charge and I would still put a switch or fuse to manually disconnect them.

 

Yes, sorry, that is correct. Parallel ups the amp hours, keeps the volts, series doubles the volts. What you do need to be careful about is if you connect them in parallel without an isolator/solenoid then the batteries must be exactly the same to avoid them drawing from each other and discharging.

I think a preferred method is to use either the isolator or the solenoid method. In this manner the aux battery can be a smaller unit, like a deep cycle marine type, which could fit better under the hood. I am starting to plan out a system like this for my Gen1 Taco.

 

I have a couple of questions for the Blue Sea ML-ACR (which I just bought), can anyone help me out?

My idea is to have an independent battery for all accesories and the other battery for engine start and I understand that in case of draining the secondary battery the solenoid will protect my main battery from draining so I can start my truck, my question is: What happens if my main battery dies (from it being old)? I will put the switch in the ON position, but won't this make the other battery to start feeding the main battery and then I won't be able to start my truck?


Also, from what I'm understanding in the before sketch, B terminal is for the main battery, correct? I saw a couple of drawings and comments here putting it the other way around... (I think the logic behind this is that the solenoid is basically checking voltage on the main battery, once it's charged it switches and starts charging the secondary battery).

 

You can override the switch by manually connecting the batteries and you can start the car, similar to a jump. I've had to do this recently when my main battery died. Make sure you have large enough cables if you do this, the ML-ACR does not like to jump the car, but once it's on the alternator takes over.

I would not connect them in reverse, the ML-ACR protects the start battery. It's really a nice system, you simply connect it and forget it.

 

Did you disconnect the ML-ACR to jump start the truck or did you just connect the positive terminal from one battery to another? Or did you actually un-hooked the engine wire from the main battery and connected it to the secondary?

 

I simply pressed the button down on the yellow top switch to connect the batteries and then started the truck. I had to do it a few times until i got a new battery the same day and on occasions the button kept reseting (disconnecting).

 

If you refer to the installation instructions of the manual, you will see the following note:

FWIW I wired my setup differently than many, and how boats are: one battery's sole duty is to provide cranking amps. The other battery is connected to the rest of the stock system, and multitude of accessories I have. And, can even start the truck without the starting battery, technically. In other words, there is a redundant part to all aspects of my electrical system, which is not the case with most.

To follow up on my issue above - I had a defective unit. Blue sea finally sent me a replacement and the auto functionality works wonderfully now. So happy to not have to manually switch all of the time.

 

I am planning a dual battery setup in my 2015. After reading through this thread and product reviews, this is what I am going with. I also have an attached diagram that I put together specific for the product i've listed. Electrical is not my strong point so I'd appreciate feedback if I drew it up correctly.

$257 Blue Sea Systems 7622 ML-ACR 12V DC 500A Automatic Charging Relay with Manual Control, Gray

Blue Sea Systems ML-ACR

$31 Blue Sea Systems 5026 ST Blade Fuse Block 12 Circuit with Ground and Cover, 100 Amps

Blue Sea Systems ST Blade Fuse Block
12v LED Double Battery Voltage Monitor
Trail Gear Back To Back Battery Box

 

Getting closer to finishing my Dual/Triple battery set up. I am mostly just waiting for the RFRM fuse panel now. I still need to clean up the wires. Does anyone know why my ML-ACR switch LED wouldn't be working though?

 

Would this help you? From the looks of your picture, your ML-ACR looks like its connected to one positive wire and one negative, which is not what the wiring diagram shows. Your voltmeter should only be connected to the intended battery. I can't tell where you have your connections for that, but hope this helps anyway.

 

Nice and clean. I like it.

 

What are you using to secure those batteries?

 

Hopefully this helps explain whats going on here:

Thank you. It will look much better once I have everything back together but that wont be until I get my RFRM.

I will have nylon strap going through a D-ring with velcro holding these down. I left just enough room below and behind to run that.

 

I'm assuming because I can't see it, that your voltmeter #1 is hooked up to your start battery. If it's not showing a reading, maybe check ground?

 

Subd for future project

 

I'm new to wiring stuff, learning here.
My question is the two wire from ML-ACR green/orange that mark X. You don't have to connect it right? But what is it for?

 

I don't know what they really do to "Isolate" but those wires are typically used in cases like this where there are multiple engines. My guess would be that it provides a signal to the battery switch for different system connections.

 

I'm learning myself. After a little help, this is the final drawing I've come up with. The wires that have an "X" at the end are not required to be connected at all. They would be used in a different setup utilizing multiple engines on marine boats.

 

Thanks guys! I was looking at my engine bay and looking where to put the aux battery. I can't figure out where the sweet spot. Any recommendation where to put it? I don't want to relocate to much just to make space.