I am in the process of making a dual battery setup in my 2000 4Runner, and can't decide if I should go all-out and get an "intelligent solenoid" like the National Luna or IBS, or just use a solid-state isolator like a Sure-Power. The first option is MUCH more expensive, especially if I opt for the in-cab monitor with "link" capability.

Most (if not all) of the write-ups I've seen have used solenoids, not isolators, so I am leaning that way...just not sure if the extra cost is really worth it, or necessary.

Anyone running an isolator out there that wants to share their experiences? Did you have to run the "excite" wire to the alternator wiring?

Or, if you have the Luna or IBS system...any buyer's remorse? Worth the extra cash?

Thanks in advance!

Also, I am going to use two Optima batteries, but haven't decided if I should go red (starting) & yellow (deep cycle), or two yellows.

Hmmmmmm......

I have been thinking the same things, and would also like to hear others personal experiences and views on this.

I found this it has some good informationg Multi-battery isolator or constant duty solenoid? - Off-Road Forums & Discussion Groups and the second post says an isolator is MORE EXPENSIVE...?

Well, I think the difference is that he is running a continuous duty solenoid vs. one of these "intelligent" solenoid "systems" that I was referring to. I couldn't see his pic of his setup (link didn't work), so I'm not sure exactly what his looks like, so can't really comment.

So, I guess there's a 3rd choice...constant duty solenoid!

Any and all comments welcome...thanks for the link TheRealFeeny.

I have an isolator and a solenoid. The isolator is hooked up to the alternator and will split the charge between the 2 batteries when the alternator is running. The solenoid is just to link the batteries together if you ever need to self jump and is hooked up to a switch in the cab.

Thanks for the info, ironhippy. I see you've got the same truck I do, I believe (2000 SR5 4WD). So, what isolator did you go with? I have been looking at these

Sure Power 13023A Battery Isolator

&

Sure Power 16023A Battery Isolator

My situation is a little more complicated, too, as I've got a CS-144 alternator in my truck now, too, so I wanted a few more amps supported on the isolator. Oh, and what about the "excite" terminal...do we need to worry about this? I know we've got internal regulated alternators, but I'm no electrician (makes my head hurt!).

So, you've got the continuous duty solenoid, something like this?

Solenoid Relay Switch Continuous HD Duty 300 Amp | eBay

I really like the idea of being able to bridge them with the solenoid. So, you just wired up a relay and a switch to turn on the solenoid?

Thanks in advance!

I used to have a former NYC EMS ambulance (Chevy C30) as a work truck, and I completely re-wired everything from batteries to emergency lighting and here is what I did with the batteries...

The ambulance came with worn out dual batteries along with dual 300amp constant duty solenoids, and a dual output battery isolator...

I purchased a 900 cold cranking amp battery for starting the truck, and an Optima yellow top deep cycle for the vast lighting and existing external PA system (awesome for venting road rage by the way...) I chose to add a third battery, (this time a LARGE one that they put in semi rigs) and place that within one of the bays of the ambulance body - This one was to power the extensive A/V system that I had planned for back there... I then swapped the dual output isolator for a three output model to accommodate the extra battery.

The starter battery was wired directly to the starter and nothing else, save for the isolator for charging it (I figured I could manually use jumper cables to one of the other batteries in the rare occurrence that my starting battery was dead - that never happened).

The lighting deep cycle battery was wired to one of the solenoids so that I had a remote switch in the center control console to kill all lighting power when I parked somewhere (there was a TON of lights on this thing and wanted to make sure that everything was off with one switch). I even ran a bunch of relays to a trigger switch so that with a single flip I could change the lights from my custom use controls (extra flood lights, extra tail lights, grill guard mounted flood and spot lights) back to the original emergency flashing controls within the center console.

The semi battery was wired through the second solenoid so I could kill the A/V system juice when I wanted to make sure that it was off as well.

About the time I got all these modifications done, gas jumped over $2 a gallon, so I stopped driving it, and got rid of it a few years later...it got 8 miles to the gallon...yes, 8 (at $2 a gallon it cost me $40 to drive it 100 miles)...and that was double what it got before I upgraded to a header/dual exhaust system with AeroTurbine mufflers with 3" pipes...LOUD!!!

I do not think this was useful to you at all, but felt the need to share the story of my shrine to automotive wiring overkill...did I mention all this battery wiring was done with 2/0 welding wire...?

I would say that you should definitely plan on using a battery isolator if you are planning on dual batteries. If you think you will be draining one more than the other for some reason (big sound system or power inverter while the engine is turned off), choose one battery for that purpose, and leave the other dedicated for starting the truck, and every other OEM power need. As long as you buy quality batteries designed for each purpose you should never have a need to tie both batteries together.

If you require additional "run time" for the system that draws a bunch of power while the engine is off, then plan on buying an additional battery(s), and wire them in parallel to the battery designated for this purpose. Your isolator will still work the same - independently charging both the starting battery, and the "accessory" battery bank...

I feel that the only time a solenoid would be a good idea is if you required a remotely controlled "kill" switch for either of these applications. I liked the peace of mind of "killing" juice to all of those 2/0, high-amp, long length cables when I was not around. Plus, I was worried that the gear reduction starter for the 454 big block would pull than 300amps (what the solenoid was rated for) when I tried to start the ambulance in the winter - so I did not run this short power run through a solenoid.

I guess you could use a solenoid to remotely tie two batteries in parallel, but it seems like a significant expense over what a good high amp starting battery would cost - just keep all of your high-power draw accessories wired to the other battery.

Also, keep in mind that if you tie both isolated batteries together, you are defeating the purpose of the isolator, and I am unsure how the isolator (or the alternator for that matter) would react to this output connection once the engine starts.

Hope this helps in some way...

Just remember you will lose about 1 volt running an isolator. They have served their purpose but smart solenoids or switched solenoids (if you remember what the switches are for) are the way to go. Besides that, the alternator cannot see the isolated battery as far as charge goes, so you will notice the isolated battery will go dead over time. You can alleviate this by swapping batteries every so often. Just my .02.

My thoughts on a dual-battery setup ...

I went with the SurePower battery separator, basically a moderately intelligent solenoid system. I really like how simple (reliable) it is; I think for 90% of dual battery setups its all you really need. It disconnects the aux and main battery when the main battery discharges below a certain voltage and doesn't connect the aux battery back to the charging sytem until the main battery is above a certain voltage. It also allows for manual or automatic start assist; if the main battery is weak, 200amps of help from the aux battery comes to the rescue. Again, very simple and very inexpensive. I got super lucky with my battery find as well. Craigslist scavenged a brand new Trojan 24AGM for $40. If I was buying new, yellow top optima or diehard platinum would be where my money went.

I have a scanguage and I'm a bit paranoid about my battery levels.

On my LX450, before I added the isolator, I just had a solenoid hooked up to a switch. My voltage was consistently between 13.5 - 14.5 when charging.
After adding the isolator, my voltage is still consistently between 13.5 - 14.5 when charging. I have a slee LED dual battery indicator and so far (running the isolator for 2 months) the 2 batteries both charge and keep the charge as expected.

In my experience I did not lose anywhere close to 1 volt and my isolated battery has always been charged with an isolator. (but I ensure my truck runs long enough to charge both batteries after they've been discharged)

So if you shut down the truck, you are only taking your aux power from one battery? Are you using a diode type isolator? Maybe its the fact that I am used to seeing large isolators?

Here is the isolator I am using NOCO 140 Amp High-Performance Battery Isolator: BatteryMart.com it is a diode type isolator.

I'm reading that apparently there is a voltage drop with these isolators, however I am seeing 14.5 (and as high as 14.7) on my scangauge whenever I am in the 2 - 3000 RPM range so my voltage lost can't be huge. (any higher rpms and I'm not watching my scangauge ;))
I will start checking the (exact) voltage on my 2nd battery and compare it to my scangauge because maybe I am missing a voltage drop, but my led indicator has given me no reason to worry about the state of my 2nd battery. Hopefully I'll remember to report back.

My caveat is my build is starting so my draw is still low. I have my aux fuse panel wired to my 2nd battery, and only my stereo, outlets, leds and a couple other things wired to my fuse panel. Before I add too much, I will need to refresh my alternator as my voltage drops at idle.

Turns out I am losing voltage to my 2nd battery, I just didn't realize it.

On my drive to work today, my scangauge (which is connected to my main battery) would read 14.2 - 14.5 volts while my aux battery (hooked up to a digital voltage gauge through an outlet) never got above 13.6 volts. Also when I idled, my scanguage dropped to 13.1 volts and my aux battery dropped to 12.9 volts.

I do not think this is a huge issue (isolators are standard equipment in dual battery setups) but it is something to keep in mind.