Dual Battery System

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DiscoveredLC

DiscoveredLC

Joined
Jun 30, 2010
Threads
85
Messages
1,119
Location
in the NV desert
After returning from the Rubicon, I finally got sick of the usual cooler annoyances. Having to deal with the size, weight, ice, etc.... and all the other problems a cooler brings. Everyone has been there! So I went back to my old stomping grounds at Sportsmans and had a friend special order the Engel 45qt fridge Ive been wanting for over 10 years now.

Right now Im running a Sears DieHard Platinum for the main battery. My Plan was to buy another Platinum, run the fridge, lights, and other future accessories off that battery. Ill leave the winch off the main battery and Alt since I never run it without the engine running/revved up.

So, what about the dual battery system? What have you guys used and heard of? Ive done some research and it seems like they can be simple to a total pain in the a$$. Ive seen threads of the home built setups, and also the high dollar ones you can buy.

The two Ive been looking at are Slee's IBS...
http://www.sleeoffroad.com/products/products_battery.htm

and the National Luna setup from EQUIPT....
http://www.equipt1.com/companies/Battery Systems/product-nl/118188-dual-battery-kit

Opinions? The National Luna setup looks really nice and a friend of mine has had great luck with his.
 
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I'm using the Powergate dual rectifier/isolator. Small form factor...and it works.
 
^This I've been using the exact same system for 30 years on travel trailers.

I am baffled by the expensive systems that cost much more. The only advantage I can see is the ability to flip a switch and jumper start your truck. On the few occasions I have needed to do this it really wasn't that big a deal to bust out the jumper cables ( you'll probably carry them anyway right?) and jump from the aux battery.

It's not like I don't understand solid state relays, been working with them since the 80's. Solid state relays are great for AC circuits, they allow what is called a zero state crossing switch. Basically they can be made to switch when the AC supply is at the zero voltage crossing in the sine wave. This can prolong the life of stuff like light bulbs. Absolutely no advantage for a DC application.

Mechanical relays have a huge advantage in DC circuits because they have an on resistance of milli-ohms, which means they have a low voltage drop, which equates to low power dissipation and a higher voltage to the load. Look at the solid state systems, they typically have a huge heat sink to dissipate they power created by the voltage drop across the FET (fancy word for an electric switch). Would you rather heat your engine compartment or charge your battery?

I'll go toe to toe with anybody who thinks a silicon relay is more reliable than a mechanical relay. I've done the math.
 
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FWIW there's no heat sink with the PG. Runs cool and occupies slightly more space than a pack of cigarettes...which, given all the crap I intended to pack in my engine bay, was high on my priority list.

Now if I can just figure out where to mount a second alternator :D
 
Stay away from the isolators. While normally fine, the refrig will hate the voltage drop and you will not get as much time before the auto-shutoff cooks your beer.

Either of the systems you specify are fine but for the cost. I am somewhat suspect of all the electronic gadgetry as well. I am currently just using two batteries directly connected on one truck, an isolator setup on another and was using an isolator in my expedition vehicle- but now switching to the mechanical solenoid configured similarly to Jack's post (however I don't understand why the need for 2 fuses). It is also the method preferred by Power Products who made my last alternator.

Plus, I will be able to find replacement parts in Eureka, or in most ranch junkyards to boot, so the cost is almost negligible. For the fuses, I use Skosche (WalMart) stereo maxi-fuses, but I think there are circuit breakers available in appropriate sizes.
 
I use a single thermal breaker on the input side of the relay.
The guys at Kro Built have all the parts and will give good advise.


@Spresso, The Power Gate is a nice product, however I still do not see the cost benefit balancing out for me. Just the price of the optional combine battery feature is about the same as a mechanical relay. Over $300 is a lot to pay for something that can be accomplished for around [strike]$50[/strike]* with identical results. Unless there is something I am completely missing?

*Just called Kro Built
Solenoid $31.95
Breaker $4.95
Breaker terminal cover $2.95
So closer to $40
 
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I've been planning on putting in a dual battery setup for a while... I concur the solenoid approach is best. I'd personally use a "battery isolation" solenoid, one rated for at least 200 AMPs.

I also note that one can wire the solenoid "on" with a switch to have "on when engine is started", "off", and "on" for very little extra cost (mostly the switch).

dual_battery_setup.jpg


-- Kurt
 
If you are planning a dual battery set up and are using a solenoid or relay make sure it is a mechanical latching type. Non latching solenoid and relays have a coil draw and will drain your batteries when the vehicle is off or when using a solar charger. Blue Sea is a good choice for mechanical latching relays.
 
I talked to Wil at Sierra Expeditions since he sells both kits. He said that over the years he has used many different systems on his personal vehicles, but now has the IBS on his 80. It seems like a straight forward install and many people have been happy with the system. He explained to me why he likes it and so I decided to go with that.


I appreciate all the posts and advice, but when it comes down to it I have no idea of what most of you even said. I've never taken a single class on anything electrical. The most I dive into stuff like this is with a detailed diagram that I can follow and feel safe with.

Yeah, I did spend more money, but I'll feel better with this than guessing if what parts I tossed together were correct. I don't feel like having an electrical problem out in the desert due to my ignorance.

Hopefully I'll get the fridge up and running soon. Antelope scouting trips are in order before the season starts in August!
 
LandCruiserPhil said:
If you are planning a dual battery set up and are using a solenoid or relay make sure it is a mechanical latching type. Non latching solenoid and relays have a coil draw and will drain your batteries when the vehicle is off or when using a solar charger. Blue Sea is a good choice for mechanical latching relays.
Click to expand...

Phil,

I am new to this and I think that you have brought up a valid point. Do you know of any specific Blue Sea part numbers that would coincide with your recommendation?

Btw...that was me that met you in a parking lot in Moab the week of CruiseMoab and discussed the Campteq product. I am the one that was able to figure out your screen name based on the mountain pass at 65mph video.
Smitty
 
smittycrusher said:
Phil,

I am new to this and I think that you have brought up a valid point. Do you know of any specific Blue Sea part numbers that would coincide with your recommendation?

Btw...that was me that met you in a parking lot in Moab the week of CruiseMoab and discussed the Campteq product. I am the one that was able to figure out your screen name based on the mountain pass at 65mph video.
Smitty
Click to expand...

:o

http://www.bluesea.com/products/category/Solenoids/ML-Solenoids

http://www.bluesea.com/products/category/Automatic_Charging_Relays/ML-ACRs

I link 2 Blue Sea one is a charging and the other is for switching.
Blue Sea makes some of the finest products
 
LandCruiserPhil said:
If you are planning a dual battery set up and are using a solenoid or relay make sure it is a mechanical latching type. Non latching solenoid and relays have a coil draw and will drain your batteries when the vehicle is off or when using a solar charger. Blue Sea is a good choice for mechanical latching relays.
Click to expand...

Agreed, Blue Sea all the way, used the add a battery kit, simple and has worked in the marine world for years without breaking the bank. I also used their safety hub as an aux into the cab for DC outlets, amps, inverters, and what not.
 
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