Off-Grid Engineering Dual Battery System Q&A

It shuts off when there is a power draw. For me, if I turn on anything connected to the six battery, it disconnects immediately, otherwise status connected for a little while

 

Did a bit more investigating after some driving around as these are brand new batteries to me. Upon shutting the truck down, voltages at both batteries is roughly 13.2. It takes a pretty good amount of time (couple hours) for the voltage to come down to 12.8 before the system isolates the batteries. Not saying this is a bad thing, just a lot longer than I thought it would. I don't have anything drawing on the system at this point - my ARB fridge will be connected to the house battery soon and I expect the system to isolate in a shorter amount of time. So far I'm extremely happy with the setup: how it functions, how clean it looks, and how expandable it will be in the future.

 

The ACR is a voltage sensing relay. It has several algorithms for when it connects but only one for when it isolates. When either battery reaches 12.7 volts, the ACR will open the circuit (yellow button pops up). This means it has effectively isolated the load from the other battery.

So... The ACR will CONNECT when it sees charging voltage of 13.5 or greater for 30 seconds or 13.0 or greater for 2 minutes. It will DISCONNECT only after one of the batteries reaches 12.7 volts. This can be caused by introducing a load or by natural settling. Depending on the overall health of your batteries, the ambient temperature and some other factors, the ACR can remain engaged for 1 minute or several hours.

I hope that clears things up. Im really excited to hear all the positive feedback. Thank you all for your support and please don't hesitate to call or email me with any questions you may have. I don't get to check TW as often as Id like anymore... mostly because Im building cool power systems for you all!

 

Annnnd final install picks of with my homemade (no drill) fridge slide. Keeping some brew chilled and will be getting a nice workout at the end of this week as we go on our 9 day camping trip around Lake Superior. Dual battery system for the win as it keeps me sane knowing the truck will always start up in the morning.

 

Looks great! Is it just a bracket attached to the bed bolts? I see you have the Total Chaos (I think) bed stiffeners as well.

 

Slide is made from 3/16" aluminum utilizing 2 bed bolts to hold it down. The bolt closest to the tailgate is almost too short and I'll most likely replace it at some point. Absolutely does not budge and maintains what I wanted from a slide - zero new holes in the bed. Bed stiffeners were my first addition to the truck as I knew I would be adding the shell/RTT and wanted to head off the bedside separation early.

 

I'll probably do something similar. I was thinking about using the bed bolts to mount a mount, if that makes sense. Then bolt the slide to the mount to make it easier to remove it when I need the truck as a truck, but I haven't figured out how yet. Still waiting for my fridge to arrive. Pretty sweet setup you have there.

 

@kakwvu look at the first post to see the side-by-side dual battery set up. I believe you were asking about this the other day.

 

I might want to know how you made the slide if you mind sharing!

 

Made the design in Solidworks and took it to a local fab shop for them to do up in aluminum. Slides are 22" lock in / lock out and rated at 500lb that I bought online. Assembled it all together with some machine screws and GR8 hardware. Might have been a bit overkill but I can rock the entire truck by the fridge and it doesn't move an inch.

 

Nice work! Question, how is it attached to the bed? The two bed bolts along that side? Or your TC bed stiffeners (or combination of the two)?

I've been dreaming up some ideas of doing something similar to this and wanted it to be somewhat removable (undo a few bolts without too much hassle) for storage during the off-season.

 

The 2 bed bolts are the only thing holding the slide in place. The bed bolt closest to the tailgate is also used for the total chaos support and is almost a hair too short. I eventually want to replace that bolt with something longer so I have more thread engagement. As you have pointed out, the idea was to be able to remove the system completely without leaving unsightly holes behind. My dual battery system was installed the same way and I hope to keep doing the same with all future additions to the truck.

 

Do you just cut back the rubber coating to expose the wire, slide the heat shrink over one of the cables, then slide both ends in the butt connector and then crimp it and heat shrink it? Hoping its that easy, looking to install today/tomorrow.

 

yep! I just did one side at a time though, pretty hard to hold both in the butt connector at the same time while crimping it. Just make sure to remember to slide the heat shrink on!!!!

 

Awesome thanks, wish me luck!

 

Like the dual battery setup but I with all the research I've been doing I'm pretty concerned about the core support with putting two heavy batteries in a location where only one is supposed to fit.

@HeliMedic

I would do the split system but I have non movable crap on the passenger side firewall.

 

Have you considered doing a battery box then? You wire a quick connect under the hood, then it connects to your battery box in the truck bed or wherever while you are driving about to charge it. The bonus is your second battery is now portable.

Edit: The quick connect would be wherever you plan to carry your second battery. It's wired under the hood, though.

 

How do you use your truck?

Is it your daily driver too?

 

Mild off roading and camping rig (building up to it)

Yes, it is my DD for right now and will be for another couple of years.

 

If it were a dedicated expedition rig, locating the 2nd battery to the bed is a reasonable option. But not really for a DD.

I've seen a few builds put the house battery in the cubby behind the rear seat. Is that an option for you?

Edit: Here is an example of mounting a group 31 behind the rear seat.

https://www.tacomaworld.com/threads...e-batteries-thread.295653/page-5#post-7693288