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

What head unit is that? Is it android auto?

 

Alpine iLX-207 i got it for Apple CarPlay. I just checked online and it has android auto

 

@CalTacoma09 in case you haven't seen this yet

 

I’m finally looking to do a dual battery system and I’m more of the simpler is better mindset. If I just wire the batteries in series (with breakers), do I avoid the issue with our smart alternator and need for a DC-DC charger? I realize that I would be giving up some functionality and protection that a ML ACR provides, but mostly I just want greater capacity and to keep it simple. Looking for some advice on things I might not be thinking of. Thanks in advance!

 

Well first off if you wire then in series you we fry your truck. You need to do them in parallel.

The simplest wound wire them together without any breakers. The breaker Shound be as close to the battery as possible. If you add breakers you are not able to self jump since they Shound be ~80 amp breakers. If you go 200+ amp breakers you may as well not add them.

Dc-dc controller is for 2 miss matching batteries. If you get 2 battery’s dates the same with the same make up they are vine being connected together.
Another option is a continues duty relay and only connect the batteries when the truck is running

 

I thought you wanted a breaker at whatever the alternator put out?

Finally thinking i want to add a dual battery and looking at this (link) and a 140a breaker. Itll be going in the passenger fender spot.

Also just wanting to buy another ots battery from oreilly (should be fine for my purposes)

$115 Dual Battery Isolator Kit 12V - 140 Amp Voltage Sensitive Relay (VSR) for Dual Battery Setup

https://smile.amazon.com/gp/aw/d/B00WTAFR5W/ref=ox_sc_act_image_4?smid=A2QEJ1BGOVPAGN&psc=1

 

If you go with a automatic disconnect like that then yes, you should use a breaker. Either way you will not be able to self jump with that controller because it does not have enough amp capacity.

You should size the breaker to the wire or power draw that your intending. For 140amp draw, you’d wanna use 4 or 6 gauge wire. For instance wile the alt can only generate a max of 140 amps you wound not put a 140 amp breaker to a winch. Winches can draw over 300 amps as then get maxed out.

 

Correct. Im not worried about the self jumping aspect. Itd be easy enough to throw jumper cables between the two.

You reccommend 6 gauge? Cant imagine it being more than 5-6ft connecting the two batteries. Only going to be running my fridge on the house

 

While you can get away with 8 gauge and probably be fine, I wound not go lower than 6 gauge. Better to be safe than have the wire heat up and melt.

While the fridge only draws 5ish amps an hr give it 24 hrs and that can add upwards of 100 amps out of the battery.

Also the longer the run the more voltage drop occurs. Hence why going up 1-2 wire gauges helps so there is not as much resistance in the wire.

 

“Parallel”, thanks, that is what I meant.

So no need for breakers or fuses in between the batteries when in parallel? I don’t care about self jumping because if there is no auto disconnect, both will be dead at the same time anyway. In that case I would use a jump pack.

Also, I thought the DC DC controller helped since house vs starter batteries discharge at different rates, but our alternator only reads the starter battery and puts out voltage based on its need which could leave the house battery not getting fully charged. Did I go wrong somewhere?

Thanks for helping me sort this stuff out.

 

Always use breakers or fuses. Breakers are easy to reset, fuses are cheap. You'll want 2, one at each end of the POS lead connecting the two batteries. Closer to the battery is better. The point is to prevent fires if the wire was the chafe through and contact metal. In that case you would basically have an unstoppable stick welder in the engine bay.. As far as the rating, that would probably need some more research but Id make a guess at 200A.

If you wired them in parallel with no disconnects, then they would share the same voltage, charge, and discharge rates at all times (assuming the same group size). Only need to worry about different charge / discharge rates when there is a disconnect or when one is significantly smaller than the other. So the need for a DC-DC charger in this application you described kind of depends on what type of batteries you get. If you get standard wet lead-acid batteries, no problems. Just pick 2 similar sizes (group 27F and 35 are common in these trucks), wire them in and go, the truck will essentially just 'see' one really big battery. It doesnt care beyond that and will charge normally like I said. If you go for something like an AGM battery, then theres some debate on that. The short version: AGM batteries like to charge at a slightly higher voltage than regular batteries. Some people do DC-DC chargers designed for this, some do the alternator voltage booster upgrade thing (dont recall its exact name), and some dont do anything in the truck. Im in that last category. I run dual Northstar (AGM) batteries. Didnt want to mess with boosting the charge voltage, so I run it normally. What I do is put a good float charger designed for AGM chemistry on about once a month and bring them both to 100%. This method has worked fine for me so far, and to your original point this keeps it very simple.

 

Well to set it up properly you wound need a breaker at each battery.

Agree with ^ to a point.

When I ran my duals I used the ml-acr and did not use a breaker. But I did use an extra abrasive coverage on the wiring.

 

Thank you very much! That’s just the info I needed.

I’d like to do a split system in the engine bay on my second gen with a pair of group 35s. Anyone know what size breakers and gauge wire I should use?

 

I’d say 140-150amp breakers. And that puts ya at 4 or 6 gauge wire.

 

So im good with these right?

$60 EWCS 6 Gauge Premium Extra Flexible Welding Cable 600 Volt - Combo Pack - 10 Feet Each Black+Red - Made in The USA

https://smile.amazon.com/gp/aw/d/B01BK0NE0G/ref=ox_sc_act_image_1?smid=AQM8XQPCVFUN3&psc=1

$5 4 Pack - 6 Gauge - 3/8" Ring - Tinned Copper Marine Battery Welding Lug Terminal Connectors - Dual Wall Adhesive Heat Shrink Included

https://smile.amazon.com/gp/aw/d/B06XF683YF/ref=ox_sc_act_image_2?smid=A8FBWALW1QSDH&psc=1

$9 Shoreline Marine SL52071 Battery Marine Terminal Kit

https://smile.amazon.com/gp/aw/d/B004LR5K30/ref=ox_sc_act_image_3?smid=ATVPDKIKX0DER&psc=1

$80 Dual Battery Isolator Kit 12V - 140 Amp Voltage Sensitive Relay (VSR) for Dual Battery Setup - Automatic Disconnect Switch for Car, Truck, RV, UTV, ATV, Marine

https://smile.amazon.com/gp/aw/d/B00WTAFR84/ref=ox_sc_act_image_4?smid=A2QEJ1BGOVPAGN&psc=1

 

I’d change out the marine terminal for a military version.
Look like these, but these are pricy Fastronix Top Post Military Spec Battery Terminal and Cover Kit

$25 Fastronix Top Post Military Spec Battery Terminal and Cover Kit

https://www.amazon.com/dp/B01LLWKXV6/ref=cm_sw_r_cp_api_i_uzzcDb343AWT6

 

Thanks for the help

 

To keep from having to go through 123 pages, has anyone found a way to mount a 2nd battery on the passenger side of a SR5? I saw Flyingwill(sp?) did, but I couldn't really tell how to relocate the ABS on the passenger side.

 

Push it out of the way. I did. In build thread. And just did on a friend’s truck.
https://www.tacomaworld.com/threads/red-baron-slow-build-w-pics-n-bs.417162/page-65#post-20869243

 

Thanks

I don't suppose it matters I have that secondary pump thing?

Also saw your poll. I assume you have the Wilfred Brimley? I've been a diabetic since I was 6(40 now)