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

I saw that while I was building mine as well.

One thing that I read but don't see very often is that a huge alternator is great but one thing to consider is the idle output since, most of the time, your truck will be idling while parked or stuck.

 

That guy is tacoazrd I believe. I looked at that page recently because of planning to do the sensor wire relocate.

 

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Okay, I have a question or two -
Going to install an aux battery in the engine bay to power some work lights, power inverter and to be able to jump myself if need be. I plan on following this guide on Expedition Portal instead of buying a fancy kit with more automation and monitoring. My logic is, A) I don't have a winch and am content to jump myself with jumper cables if need be, and B) I don't have a huge amount of money for this project.

I was thinking of purchasing this battery from Home Depot - Nautilus 27 Dual Purpose Marine Battery. It's cheap and seems to have enough amperage to start my engine: I think that this should be a fine choice, but what do y'all think?

Next I was wondering the effect of always having this battery charging and rarely discharging it all the way? Since it's always going to be hooked to my alternator (via the starting battery) and I probably wont be running much off of it most of the time I am worried I will somehow damage it. Thoughts?

Here is a link to my parts list so far.

 

Here's my new set-up using the National Luna components. A friend and I fabricated the second battery mount.

 

@andrewprime1 Why not just connect the work lights etc. to the second battery so you don't have to jump your primary?

 

I want to see someone get a cross-bed tool box and slap a Prius battery in it lol.

 

It sounds like that is his plan, but he'd like to be able to jump with the aux battery if needed

 

Should work. I don't have any experience with any of those components but if the guy on expedition portal is happy with the setup then it might work for you too.

As for the battery, keep in mind that wet cell batteries don't like to be discharged lower than about 50%, so that will cut down on your potential power time. I read that it advertised 8 hours of 10 amp draw, but with a brand-new 100 amp hour battery that would take you down to about 20% and probably too deep for repeated cycles on a wet cell battery. You need to figure out what kind of work lights and inverter you're going to use. 10 amp 12v draw is 120 watts and figure you can get that for 4-5 hours before youd want to charge it. Work lights can be 50-100 watts each and I'm sure the inverter you're wanting is in the 400-1500 watt range. Again, you could take it down to the advertised level if you absolutely needed to, but you'd be severely limiting the life of your battery. You can do some math to see if that's enough power for you. If you're just working on your car/house and need to see for a couple hours you're probably fine, but if you're trying to run lights out camping for a weekend, power tools, or something then I'm not so sure. I don't know your exact end goal.

Finally, you should have no problems with it charging on the alternator and not discharging it often.

Oh and get a multimeter if you don't have one already. It'll help with diagnosing any potential issues and can help you keep an eye on your batteries

 

I guess I read that wrong. I guess I am confused because, typically, there isn't a huge need to jump if there are no accessories. If the primary is dead, the secondary would more then likely be dead as well.

 

Thanks @abarber11! Super insightful. I should have clarified that the "work lights" i want to run would be a 3w led lamp or two in the bed for reading and the power inverter would probably be used for charging headlamps and cell phones. My power needs will be pretty low I would think.

As for jumping myself, I just thought that was a cool feature to have. I haven't needed a jump in years, but having written that just now, I am sure I will kill my battery within the week. Glad that this setup will work. If my needs change in the future I can invest in a nicer, non-wet cell battery.

 

It sounds like that battery should work for you then. LEDs draw basically nothing. Honestly, you might not even need an inverter if you're just planning on charging cell phones and headlamps. In fact, I would recommend against the use of an inverter if that's all you require. Inverters are rather inefficient for that purpose and I think should be avoided unless you truly require 120V AC power. Think about it this way... To charge a cell phone with an inverter you'd start with a 12V battery, convert it to 120V AC power with the inverter, and then the cell phone charger converts that to 5V in order to charge the phone. Just add a hard-wired 12V socket to the auxillary battery using 10 or 12 gauge wire and a 10 or 15amp in-line fuse and plug a car charger into that. Thats how I charge my phone when Im camping, and I have a 400watt and 1500 watt inverter in the truck. Of course, if youre going to be blowing up an air mattress and it only has a 120V plug on it, then you might need the inverter.

You could also probably get a set of rechargable batteries and a 12v adapter for the headlamps, or just get a new 12V chargable headlamp for cheaper than you could get an inverter. Just a thought, obviously ultimately up to you on that.

Jumping yourself is definitely a cool feature for emergencies. Although, odds are once you start down this dual battery path you'll be much more in tune with your system and battery voltages. I am anyway.

 

This is how mine is set up too - all my big draws on the auxillary - but you never know. It sounds like andrew is not going to transfer all the big draws to his auxillary tho so it might be more useful for that setup. Or if the starting battery just flat out fails then its a nice feature to have.

 

For anyone that was looking for confirmation - the stock battery harness is 4 AWG wire. Crimped my new terminals on today.

 

What size of your aux battery?

 

It looks like a smaller 34.

 

Thanks

 

Looking to start a dual battery kit group buy:

https://www.tacomaworld.com/threads/national-luna-or-ibs-group-buy.414553/#post-11744107

I would like you guys to chime in on your experience: National Luna or IBS?

 

I think the automatic kits are cool, but pricey and not necessary. I said screw it and went with a manual battery bank switch (40 bucks)

 

So I'm sure this question has been answered somewhere in here... But what amp rating are y'all using for fuses between the batteries and the solenoid/relay?

I'm planning to use the Blue Sea ML-ACR that's rated at 500 amps.