Off-Grid Engineering Dual Battery System Q&A

Yep! Not a problem at all. That is called the "fuel resistor" and it simply gets mounted to the new tray. I think I just replied to your email as well.

 

With the batteries right next to each other it shouldn't matter that much. With the batteries across the engine bay I might start to be concerned about long term and how much over or under charging one of the batteries gets. It will help to do periodic maintenance charges to reduce that concern.

I would only be worried enough to do something about undercharging parallel batteries placed a long distance away from each other. Perhaps a remote battery placed in the bed that is parallel with one under the hood. In that scenario I would take time to route cables to make sure there's not a lot of current imbalance. Or use a proper controller that prioritizes charging or is an actual battery-to-battery multi-stage charger.

I got a pair of Odyssey PC1400 group 25/35 from Matt when I bought the tray. It's a lot of weight but the original battery wasn't light either. I figure it's about 25 to 30 lbs more over the original 60 to 70 lbs that was there. As of right now it's all solid but I'm also sketching up (so far only in concept in my head) a brace that will fit under the fender to support the weight. I'm really only worried about eventual fatigue and cracking seams and stuff.

I should mention that I did replace my radiator core support bushings with Energy Bushing poly. My OEM rubber ones were starting to break down anyway but they are definitely an improvement over even new ones as far as support.

 

Part of the reason that you can be sure is by using an ML-ACR or other semi-intelligent combiner. The problem of parallel batteries and doing proper wiring is when they are always wired together for both charging and discharging. Since the relay opens when the voltage dips below 12.7V and only connects after it raises above 13.0V for long enough you aren't actually running a full time bank.

One battery will be the primary one getting charged and if it's run way down the alternator will take some time to charge it enough for the voltage to rise. When that does happen it's OK to let the 2nd battery connect and as long as the loop impedance isn't super high the alternator should charge it.

Since we have the voltage-based solenoid in there it's less critical as far as damaging anything. It's worthwhile trying to follow good practices but there's more leeway. The only thing to watch is undercharging the remote battery.

 

all these big words make my brain hurt... Look!!... shiny...

 

Oh boy... I've been looking into dual systems as I plan out my build... and a GREAT solution is mere miles away!! @ramonortiz55 's deals and the group buys have accelerated and drained my budget too! What to do???

This is awesome... and when combined with a solar charger and inverter, will be perfect!!

Hmmmm...

 

Yes it is!

 

Look what we have here!

 

Does anyone know who makes or sells the tray the switch-pro module is mounted to in post #124. I'm interested in buying the kit with the Switch-pro module but would also like to buy the mounting bracket. Also should I be thinking about fuses between the battery and switch-pro module or the switch-pro module and the devices being powered?

 

@ROK-NJA

 

That is a Pelfreybilt fuse box tray that we modified.

The Switch-Pro unit comes with a 100 amp inline fuse built in to the cable that powers it. When you order a Switch-Pro through me, in conjunction with a dual battery system, I build a longer cable with the same 100 amp fuse built in.

The Switch-Pro has built in circuit protection for the devices its powering. 18 amps per circuit, except circuit 8, which can run up to 30 amps if wired properly. The directions walk you through how to do it.

 

I used the same fuse box tray for mounting mine similar set up.

 

Last question, do you offer the witch-pro module with blue led backlighting vs the green?

 

Yes. But they're not always on the shelf.

 

How much for the Swtichpro mounting plate? or where did you get it?

 

Its a @pelfretbilt

I just drilled new holes where i needed to mount my SP. you need M8 flange bolts once you get it!

Here http://www.pelfreybilt.com/product/fuse-panel-automatic/

 

Very effin clean.
Love it

 

Matt,

From the photo I took, can you see if the longer switch pro cable with the proper 100 amp in line fuse was included in my kit?

Edit: I ask because I don't think I identified it.

 

It does not appear so. It doesn't appear I ever invoiced you for it either. Im very sorry, I can get one of those out to you tomorrow.

 

Could you just let me know the length and gauge I will need?

I may have to buy or make one because I plan to complete the install this weekend.

 

4 AWG. The length is determined by you. To reach from the aux batt to the location that most people mount the Switch-Pro (near the brake booster) is about 4 feet with a nice easy bends in it. You'll need a 100 amp fuse in there as well.

Your Switch-Pro should have come with a 2 foot cable with a 100 amp fuse built in. You should reuse the fuse and lengthen one side of the cable