Do I really need a dual battery system?

[wreckdiver1321]

So I've been doing some thinking lately, and I had always planned to install a dual battery system in my 2005 Frontier, but now I'm not so sure. I know it's ExPo cool, but is it really necessary fo what I do?

My truck is a daily driver, but also sees plenty of time camping and running trails in the spring, summer, and fall. Extra electrical goodies will include 4 LED lights: two on the bumper, a roof bar, and a reverse light; a Dometic fridge; CB radio; ARB air compressor; ScanGauge/UltraGauge; and a winch. The winch will probably not see a whole ton of use to be honest, but the fridge will be used during the camping trips. I may unplug it during the night, since out here the temps get fairly chilly at night, even in the summer. Maybe I won't. If I left it plugged in, I would probably use something to turn off the battery power once it drops below a certain point. Most of my trips at this point are weekend getaways, but I do occasionally do the 7-10 trips.

So, given this setup and this usage, do I really need dual batteries? The peace of mind is great, but considering the added cost, complexity, work to make it all fit, and the extra weight, it sound like a dual system might be overdoing it for me. If I kept it to one battery, I would just get a high quality Odyssey or DieHard group 34 or 35 battery, install a voltage monitor to keep an eye on it, and carry a jump start pack with me just in case. This setup would also allow me to keep the ARB compressor under the hood, which probably wouldn't be possible with two batteries.

Thoughts from ExPo? Am I crazy? Or logical?

 

[bat]

NO

plus 2

If I kept it to one battery, I would just get a high quality Odyssey or DieHard group 34 or 35 battery

jump start pack with me just in case.

 

[wreckdiver1321]

NO

plus 2

Not sure what this means...

 

[DiploStrat]

Short Answer = No

You may need a larger battery(s) and the only way to accomplish that may be to add additional batteries to your truck. If you do so, you must decide whether you want to be able to separate the additional battery(s) from the starter battery(s).

Depending on your load; that is, how much you will draw before you recharge (typically by starting the engine), the steps are:

-- Replace your starter battery with the biggest battery that will physically fit.

-- Add an additional battery(s) permanently connected in parallel with your starter battery(s).

If your load is light enough, you can stop here. If your load is large enough, then you probably want to be sure that the second battery is a deep cycle battery so that it can stand repeated deep discharges. If you do this, then:

-- You could add a manual disconnect switch so that you cannot discharge your starter battery, no matter how much you discharge your second battery.

-- You could replace the manual disconnect switch with an automatic switch, controlled by either the ignition switch or by an intelligent controller.

If you want to stick with one battery and you have reasonable sunlight, you could add a solar kit of some sort.

Bottom line, you are asking a good question and the most important issue is the danger of discharging your battery so much that you cannot start.

If I had a clean sheet of paper, I would actually design my charging system to meet the needs of my camper battery bank and simply add an automatic switch to charge the starter battery. Consider, in my case, I have 600Ah of camper batteries and only 150Ah of starter batteries. Thus even with my camper batteries discharged to 50%, they are still twice the size of my starter batteries. And yes, I do have an automatic disconnect.

 

[dwh]

Pretty much everything you listed is going to running only when the engine is running, except the fridge and maybe the radios.

I'd say no, you don't need it.

Low-voltage disconnect (adjustable is preferable) plus a jump pack just in case should do you fine.

 

[wreckdiver1321]

Pretty much everything you listed is going to running only when the engine is running, except the fridge and maybe the radios.

I'd say no, you don't need it.

Low-voltage disconnect (adjustable is preferable) plus a jump pack just in case should do you fine.

This was sort of my line of thinking. Thanks for the to-the-point response!

Thanks everyone for the help!

 

[schulz11]

Pretty much everything you listed is going to running only when the engine is running, except the fridge and maybe the radios.

I'd say no, you don't need it.

Low-voltage disconnect (adjustable is preferable) plus a jump pack just in case should do you fine.

Agree totally here and your dometic doesn't take that much power. I know the Dometic (as I have one of the 50q) has setting for low voltage shut down and it works great for me. I run mine on med and always am able to start my truck.

 

[con kso]

I had this exact same thought about 4 months ago. I ended up installing a group 31 size diehard platinum with 100 amp hour capacity in my 2007 Tundra (it fits). I power an ARB 50L refrigerator and a water pump for taking freshwater showers. I bought a 100watt Zamp portable solar panel and a lithium jump pack (antigravity brand- it's tiny and almost unbelievably it works- I jumped some guys car with it). I figured the solar panel would more than keep up with the my battery useage. I tested this by running the ARB as cold as possible for a four day trip, I ran the ARB 24 hours a day. I deployed the solar panel when possible. The system worked fine- I'm going to install a volt meter to get an idea of where I'm at battery-wise. I think for my uses, a single battery system that takes advantage of the alternator while driving and the solar panel while stopped works just fine- I'll do an extended test in a week when I take off for southern Baja for a three week trip. Good luck.

 

[v_man]

Get a voltmeter for sure ...

 

[BigSwede]

Like con kso,I also went single battery. If you are going to base camp for an extended period a dual battery system may be a good idea, but for overnight camping like I do the single battery has been perfectly fine. I run a fridge and a CPAP overnight, and have a group 31 Sears Platinum.

I will recommend you get something bigger than a 34 or 35, those will only be around 50-55ah or so. A group 28 or 31 is the way to go if you can fit it, they have nearly twice the capacity of the 34 or 35. And a LiFePO4 jump pack is cheap insurance.

 

[ober27]

BigSwede,
Do you power your CPAP through an inverter, or plug into 12 volt?

 

[dnellans]

I have a dual battery setup (wire in parallel, no disconnect) in my 2004 tacoma. Back when I had a single battery, using the engel + 8watt solar (best at time) to recharge I definitely was able to run that battery to dead on my annual week long dirtbiking trip into the desert. So I bought a dual battery setup that fit in the stock location from columbia overland. Basically just a new holder. The group 34's give me 120AH combined from the batteries, which is great, but since they're in parallel I still carry a jump pack just in case. Fast forward 8 years and my energy draw needs are still identical - fridge + laptop charging + misc bull****. However I can top them off with a 100Watt panel (250bucks on amazon from renogy including decent charge controller) which is 10x better than the old solution. I've never drawn them down so much the truck won't start.

We're in the position of needing to buy a new truck (which one tbd) soon (for 4 doors due to kids) and my plan for that one will be to just buy a group 31 battery as the main battery (assuming it fits) since that is will be nearly the same AH rating as dual group 34's without the hassle of extra wiring and whatnot. continue using the same solar panel setup (which in 8 more years will probably be upgraded to a 200watt or something as solar keeps getting better) and then just get a lithium jump pack for the emergencies.

IMO solar top off + a lithium jump pack has changed the game such that basically no one needs true dual batteries anymore, hell I might not even bother with the group 31... I was given a goalzero yeti 400 (34AH battery) and topping it up with 100watts of solar every day, that can run laptop and fridge indefinitely if its sunny, but if it was cloudy for 2+ days it would be dicey so having some extra capacity (say 60ah) would be pretty good for my use.

 

[BigSwede]

BigSwede,
Do you power your CPAP through an inverter, or plug into 12 volt?

My CPAP does 12V as well as AC. It is a Devilbiss IntelliPap. They tell me it uses about 1.3 amps/hour (I don't run a humidifier, which would take considerably more juice). So between 8 hours of CPAP use and the fridge (averages about 1 ah) for maybe 16 hours at most before breaking camp, I figure I am using around 26 ah overnight. That is why I want bigger battery than a group 34 because that is uncomfortably close to the 50% max you want to draw down your lead-acid battery between charges. With the 100 ah group 31 I have more of a cushion.

 

[brushogger]

I power my 2m, charge phones, and power an Edgestar fridge off a group 31 Diehard platinum without starting the truck for 3 days in 100 degree heat and have no issues. That doesn't include much transmitting with the radio though. I do have a 100w solar to top things off if I needed it.