Dual Battery Setup

javelinadave

javelinadave

Administrator
Staff member
I have researched this till it all ran together. I have learned that:
National Luna is troublesome and people regret installing it
People are frustrated with IBS systems
Lots of happy people who built the $50 system posted here:
http://forum.expeditionportal.com/t...-dual-battery-setup-for-50?highlight=isolator
Blue Sea Systems sounds like the new up and coming system
I'm curious what systems you are running and if you are happy?
I am currently running in my Defender 110 2 separate systems. One battery is 100% dedicated to a 100 amp alternator and the other (home) battery is attached to a 100 watt solar panel. The home battery runs an ARB fridge, a few LED lights and intermittently a 400 watt inverter to charge my camera gear and electric toothbrush.
 
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The_Vermonster

The_Vermonster

Well-known member
There is also the Blue Sea system that I have heard some very good things about.
https://www.amazon.com/dp/B001VIXLRO/ref=twister_B01LEHLINK?_encoding=UTF8&th=1


The advantage of the NL, IBS, or BSS is that it prioritizes charging the main battery, then switches to charging both. They also allow you to link the batteries for a "self jump start." Plus, fancy LEDs to show you how charged the batteries are (not on the BSS)

I think a lot of people are happy with the National Luna, but not happy with the price. You pay quite a premium for the name. Plus a lot of people install it when they don't really need it.
 
javelinadave

javelinadave

Administrator
Staff member
I was looking at the BSS last night and am considering it too. I'm hoping for some solid posts of peoples experiences.
 
jymmiejamz

jymmiejamz

Founding Member
Callsign: KN4JHI
Do you even need two batteries for that? The only draw on my truck when it isn't running is the fridge and interior lights. I have a couple USB ports for charging whenever I'm driving. I also keep a Brunton portable battery charger for phones and iPad. I have a micro jump box if I were to kill my battery.
 
RDavisinVA

RDavisinVA

Technical Excellence Contributor
This is the most versatile, in my opinion.
I run a deep cycle battery bank in our 110 using the XS Power D5100, 12-volt AGM batteries.
https://www.crutchfield.com/p_122D51...c&awug=9008492

2 will fit nicely in the battery box along with the "car battery".
The next step will be to install 2 more under the right seat as soon as I can modify the tool box.

The deep cycle battery bank powers everything we use while stationary when camping or anything plugged in to the deep cycle battery bank outlets while driving.

We have a series of relays that can switch the alternator output from the "car battery" to the deep cycle battery bank.
While camping you can run the deep cycle battery bank flat, then start the engine on the "car battery", charge the "car battery", then switch over and charge the deep cycle battery bank.
While driving you can switch back and forth to keep both the deep cycle battery bank and the "car battery" charged.

We are going to make a proper series of cables for the deep cycle battery bank, but all works for now even though it looks jack legged.
Note the series of relays on the bulkhead triggered by a single switch to switch the alternator output.

We have a 145 Watt - 12V 12AMP solar panel to add while stationary.
Sometime when I get a chance, will post pictures of the swivel mounts for the solar panel that will let you position the panel in a variety of positions.

The plan is to refine this and use it in out Dormobile camper project retirement ride.
 

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The_Vermonster

The_Vermonster

Well-known member
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
What is the purpose of going with the set of relays to manage the batteries?

I'm just going to use a 100% manual switch that 100% isolates them, or charges one or the other or both. I will have have a voltmeter on both batteries, but I want to keep it as simple as that.

I will also use a deep cell for the camping battery and have a standard car battery for start-ups.
 
rocky

rocky

NAS-ROW Addict
A twin battery is one potential avenue I'm likely to go down for the winch and I guess fridge. Thanks for starting the thread. I'm liking the BS systems I've got.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I've never been able to make an isolator or relay actually keep one battery from draining anothe. The only thing that has worked for me is a solenoid. This time I'm just using a Blue Sea switch. Simple as possible.
 
RDavisinVA

RDavisinVA

Technical Excellence Contributor
RBBailey said:
What is the purpose of going with the set of relays to manage the batteries?

I'm just going to use a 100% manual switch that 100% isolates them, or charges one or the other or both. I will have have a voltmeter on both batteries, but I want to keep it as simple as that.

I will also use a deep cell for the camping battery and have a standard car battery for start-ups.
Click to expand...

How do you wire the alternator output to charge your batteries separately using a master battery selection switch?

The setup you describe requires you to switch battery connections through a central manual switch.
It may work fine for your 1 battery, but not a choice for a battery bank.

This manual switch connects all the batteries together and shares 1 charging source from your alternator that runs to all the batteries concurrently.
Bad idea for a variety of reasons.
You can leave all the batteries switched together and run them all flat, then you are unable to start your vehicle.
You can also burn out the manual switch if you are drawing current for an inverter.
Different batteries maintain a different voltage and they charge and discharge at different rates.
A car battery will charge faster than a deep cycle battery bank and if left connected without anything hooked up can form a circuit that will discharge the deep cycle batteries into the car battery.
Your volt meter will likely show the alternator output and when the car battery is charged will show a full charge even though your deep cycle batter is not fully charged.
Likewise if you discharge your deep cycle battery and hook it to your car battery.
The car battery will form a circuit and discharge into the deep cycle battery.

Being able to switch alternator current lets you maintain your car battery fully charged, and start up under any conditions, charge up the car battery after the start-up and switch over to charge the deep cycle battery bank separately.
This allows you to have all your auxiliary items directly wired without having to run them through a master selection switch and to see a volt meter reading based on what is being charged only.

A manual master switch may work great until it has issues.
They are also generally bulky and require cutting holes in the panels and running a variety of cables to and from this single point of failure.
 
RDavisinVA

RDavisinVA

Technical Excellence Contributor
RBBailey said:
I've never been able to make an isolator or relay actually keep one battery from draining anothe. The only thing that has worked for me is a solenoid. This time I'm just using a Blue Sea switch. Simple as possible.
Click to expand...

The relay(s) are not wired to isolate the batteries.
The car battery is not connected to the auxiliary batteries.
The relays only switch the alternator output.
Also you can have a solar charge regulator wired directly to the deep cycle battery bank.
 
RDavisinVA

RDavisinVA

Technical Excellence Contributor
Forgot to mention.
The only reason that a master mechanical battery selection switch is used is in the first place is to connect an auxiliary battery to the "car battery", so it can be charged by the single vehicle alternator that is wired up to charge the "car battery.

With my setup, you never need to have the auxiliary battery bank of deep cell batteries connected to the "car battery", it is wired up completely independent.
The car battery powers the vehicle, while the auxiliary battery bank is wired to the 12V connections to power the fridge, LED lights, other 12V accessories (like a cell charger - or a 12V air compressor - a 12V AC System - a Webasto air top - 12V hot water heater), and a 120V power inverter to power a hand winch or whatever 120V appliances you bring along (my wife's hair dryer - hotplate for that quick cup of morning coffee without having to fiddle around with propane).

It is also nice to plug in the george foreman grill and cook something when it's too windy for propane.

We also have a solar charger connected directly to the auxiliary battery bank of deep cell batteries that operates when the solar panel is providing 12 volts.

Again when the auxiliary battery bank needs a charge or some extra power for the inverter, we can switch the alternator over to provide a charge up independent of the car battery.
 
chris snell

chris snell

Administrator
Callsign: NW5W
Staff member
I don't understand why so many people think they need a dual-battery setup. Unless you've basically built a RV on the back of your truck or your truck is staying stationary in camp for multiple days without running, you'll be fine on a single battery. So many people build these complicated switch-over systems and then cheap out on the batteries with crappy Optimas or some store brand and skimp on the battery cables.

I've run a single Odyssey PC2150 for 10 years now (two trucks, two batteries) and never had a problem with it. I've never even come close to draining it. I run a fridge, USB chargers, Hella 550s, and a number of other accessories off mine. The fridge can run for days and the battery will still start the truck.

I think most people would be served well by skipping the complicated power setups and running a high-end single battery with high-quality marine grade cables that are appropriately sized.
 
rovercolorado

rovercolorado

Well-known member
I ran a single Yellow top Optima for almost 16 years in my Disco and ran a fridge, inverter and USB ports and never had an issue. Of course I didn't use it year round on a global trip but I had zero issues when I was camping and needed battery power. Many years I made 6 plus long trips and the battery was used heavily for weeks on end. It's a nice to have IMHO but not a must have. Spending $500 for a dual battery setup doesn't make sense when you can get a good fridge for that kind of money. Cool discussion for sure and I love cheap solutions so if I was going to set something up I would spend the $60 instead of $500.
 
RDavisinVA

RDavisinVA

Technical Excellence Contributor
chris snell said:
I don't understand why so many people think they need a dual-battery setup. Unless you've basically built a RV on the back of your truck or your truck is staying stationary in camp for multiple days without running, you'll be fine on a single battery. So many people build these complicated switch-over systems and then cheap out on the batteries with crappy Optimas or some store brand and skimp on the battery cables.

I've run a single Odyssey PC2150 for 10 years now (two trucks, two batteries) and never had a problem with it. I've never even come close to draining it. I run a fridge, USB chargers, Hella 550s, and a number of other accessories off mine. The fridge can run for days and the battery will still start the truck.

I think most people would be served well by skipping the complicated power setups and running a high-end single battery with high-quality marine grade cables that are appropriately sized.
Click to expand...

Some of the stuff that I run while camping would drain your battery setup in no time.
For example when it's windy, I cook on a 120V george foreman grill and hotplate that would drain any single or dual battery flat very quickly.
We have on-board 12V heated hot water for washing and showering.

If you don't need a battery bank, then no need to install it.
The 12V fridges are very very efficient these days and use very little power.
The same is true of USB setups.
Am not saying my setup is so much better, it just has more capacity, is versatile to recharge, and doesn't use a manual change-over switch.
 
rovercolorado

rovercolorado

Well-known member
RDavisinVA said:
Some of the stuff that I run while camping would drain your battery setup in no time.
For example when it's windy, I cook on a 120V george foreman grill and hotplate that would drain any single or dual battery flat very quickly.
We have on-board 12V heated hot water for washing and showering.

If you don't need a battery bank, then no need to install it.
The 12V fridges are very very efficient these days and use very little power.
The same is true of USB setups.
Am not saying my setup is so much better, it just has more capacity, is versatile to recharge, and doesn't use a manual change-over switch.
Click to expand...

Now you're talking! When you have heated showers and use power hungry appliances I see the need for a dual setup. Solar panels in this case would be a great add on and if I wanted use more than a gas stove.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
When I was using campers, I had two deep cell batteries hooked up to run the lights, the water pump, and to charge cell phones, etc... I ran out from time to time. I ran low on a deep cell with the Disco just running the interior lights for the evening.

Chris has the only option to a dual set up. A $375 battery made for a semi-truck. But this won't fit in all vehicles.
 
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