Dual battery? At what point?

Please bare with me, this is mostly academic.

At what point is a dual battery set up needed vs maximizing the space the original battery is (shoving the largest battery that can fit in the oem spot)

I figure with stuff as simple as auxiliary lights, even a large light bar and auxiliary back up and dust lights etc etc, a ham, even OBA, one would not overwhelm the abilities of a single battery and the alternator set up.

it would seem to me that when a winch is introduced or a fridge (or both) that is when a second battery would be a needed option let alone a necessity.

but has anyone put together a document listing the power usage of certain things and how it effects the battery and alternator and as such, when the added gear requires an add on to the electrics equipment?

 

It’s not always necessarily about raw power capacity.
You typically just want to split your uses between the two, so you can keep one strictly for cranking the engine.
You might be out in the wilderness and need to run a fridge, some camp lights, keep the phone charged, and maybe run a fan if it’s hot. You certainly don’t want to rely on your cranking battery for these things. Then you risk being stranded out in the woods.
You may want to hook up your air compressor to it so you can inflate the tires without the engine running and fumes blowing all around the truck. Or you may need to use the winch for an extended period of time, so you link the batteries together to provide more capacity (then immediately let the truck charge the batteries back up afterwards, of course)

Ultimately, there aren’t too many common scenarios where someone will be overworking the stock charging system. Winches obviously draw a lot of power, and some air compressors can pull quite a bit as well. But other than that, the 2nd battery is more for preserving the first battery, rather than being combined with it.

 

I run a winch just have one Northstar 27F battery. Listed @ ~975 CCA. The shop tests it when I go in for front end alignment. Their report always comes back over 1000 CCA.

 

For the prerunners, or the luxury runners, I’m seeing so many of them with dual batteries in the bed. I can’t imagine it’s just in case one separates inside, that you have the second as a back up.
They are almost always mounted together...
hmmm..

 

I think many times it is really keep up with the Big Boys .I got sucked into this back in the Seventies with my Camaro.

When you think you need another battery it is your choice .

Maybe go camping run down the truck battery without giving it a thought when the truck just starts decide a second battery is a good project.

 

I kind of like the idea of having a second battery to put in its own fuse box for anything extra you want to add to your truck. I’m thinking about adding one at some point for my audio build but I’m going to upgrade the alternator and battery first then go from there.

 

I just installed a dual battery system 6 months ago. I decided to add a second battery because i was adding more and more electronics to the truck and run many of them with the truck turned off.

As of right now, the house battery has my compressor, fridge, audio system (2 amps), switch-pros system, aux fuse panel under the hood, aux fuse panel in the bed cubby, and soon to be hooked up 2000w power inverter. The rear aux fuse panel is used to power the fridge, usb/cigarette plug, and scene and bed lights.

My starting battery will just have the winch connected to it.

I will also be installing a 100w solar panel to help keep the batteries topped off.

 

I am looking into a 2nd battery option as well for my 2016 tacoma, its my DD, but I also like to go camping deep into the North Maine woods, and with soon to be added items diesel heater (for winter/cold months), a 12v fridge, added lights for campsite ( I am night-blind, so a little bit of light to direct me is good, nothing major, just a few small LED light strings, maybe a small work light at my tailgate for cooking meals in the dark/dusk), AND A 120V INVERTER FOR SMALL ITEMS
my fear of draining a battery and being alone in the NMW for a few days is not a good feeling.. I do have comms (garmin inreach mini, which typically lasts 5 days or so.)..I was thinking of a dual battery in my 2016 tacoma with the offgrid engineering battery tray (with redarc 40A dc to dc charger)



straight from them it looks to be about $800.. and I do plan to add the cascadia4x4 VSS solar panel @85 watts. which will maintain my auxilliary battery, and I plan to install a switchbox, so if I need to the solar can charge my main battery & disconnects the auxilliary (no fear of activating the dc to dc charger and draining my main battery at 50A)...

 

A winch doesn't warrant a 2nd battery, unless you plan to be winching all day but then I would question if you need to be where you are offroad..

Household items for camping is where a dual battery shines. If you plan to be camping a lot even if you are driving around during the day, it's a piece of mind thing. You know you can have you're perfectly chilled beer and steak dinners out of your fridge with your perfect ambient mood lighting every night without fear of your truck not starting and your date night being spoiled.

 

dont need it for the winch..

Primary battery- starting and running the truck, any driving lights, and winch power duties, a battery monitor will tell when battery is full for shutdown at camp. a cool down after trail riding is a good idea anyways. check for leaks, noises...

2nd battery will have duties such as scene lights (non driving), fridge, 12v accessories, diesel heater, rtt lighting/power for devices such as cell phone or charger when the vehicle is not running. as well as a 120v converter for running a laptop, or slow cooker (maybe)

 

I just received Off-Grid Engineering's dual battery system (not the DC to DC version) for my TRD OR.

My experience with having a dual battery setup is in a Jeep TJ to power a Snomaster 42L fridge for long road trips, which the fridge is mostly moving to my Tacoma. In my Jeep, it has a National Luna system that I've been mostly happy with. The National Luna system does draw on the the starter battery, which my Jeep sits more often then not so a trickle charger is usually required. I've read that the Blue Sea relay in this new system also draws on the starter, but my Tacoma is a daily driver.

One could power a fridge off of the starter, which in my Jeep on trips with the fridge running, I mostly drove it daily, but on occasion I'd not start the Jeep and the Group 34 auxiliary battery would easily power the fridge for two days (depending on outside temperatures). I felt better not using the starter battery for the fridge. Plus, the auxiliary battery would quickly charge when driving.

As far as my Tacoma, I now have land that I'm going to be camping/ workoing on and I may not be starting the Tacoma each day so I just wanted a dual battery setup as not to worry about, and I may also use the auxiliary battery for other things besides the fridge.

Anyway, Off-Grid Engineering's setup looks really nice and is complete. I like that it puts the auxiliary battery in the opposite back corner under the hood. I need to next order batteries, which I'll probably go with the Full Throttle Group 35s.

 

I always ran two batteries but only hooked up at a time. Swapped every couple of trips. Switches can fail and dual battery circuits can also fail and draw power. When you kill your battery trying to winch out of a river or mud hole and then can just swap the terminal and drive out of there - that is nice....

 

Do you have anything written up how you did this or could you provide me with a little insight in a PM? I have a lot going on with a switch pro off the main battery. I want to run a second battery but not a separate system if possible. ie: When I get to camp, I don't want to run separate accessories off a separate battery. Ideally, I'd like for the truck to be off or in an accessory and just switch over to the second battery. I'm thinking I just need an isolator etc but I'm looking at DC to DC for a lithium battery and future solar etc.

 

I know this is a late reply, but since the thread is still going I'll jump in.

The reason for dual batteries is that a starting battery can be easily damaged if it's run down past a certain point. A second battery is usually a deep cycle battery that can be drawn down much further than a starting battery and not be damaged.

Boats are set up the same way. You have a cranking battery to start the engine and then a separate large bank of deep cycle batteries to run the house electrical needs. The bigger the house bank, then the more power it will require to charge to 100%, which is where you want to get it after every discharge if possible. I use a single deep cycle 80ah battery as a house battery. This runs two fridges, lights, stereo, charging various devices and whatever else needs to be done. I have never run it past 50% charge and I am able to charge it back to 100% quickly using a solar panel.

 

I'm quoting myself as an update that I did install Off-Grid Engineering's dual battery setup with two Full Throttle Group 35s.

Final install here:
https://www.tacomaworld.com/threads...ttery-system-q-a.468553/page-35#post-25334780

I recently ran a test here:
https://www.tacomaworld.com/threads...ttery-system-q-a.468553/page-36#post-26260762
To summarize it, the Group 35 during the summer which includes high daytime temps inside the cab with no air circulation, runs my 42L fridge for about 30 hours. Once the fridge shuts off at 11.2v, I'd estimate that it takes upwards of 45 minutes of driving to recharge the battery.