Multi Battery Isolator

roving

Observer
Anyone every used one of these. I'm planning on using this on my Rover. Its rated to 160 Amps. My alternator is rated to a max of 150 amps. so i shouldn't be able to overload it.

Think it'll be reliable enough. I thing they are mostly used in Diesel pickups with dual batteries.

https://fbcdn-sphotos-a.akamaihd.ne...59897215028_599460027_9508467_922268891_n.jpg

I already installed the Isolator next to the factory battery location. I'm going to keep the other battery in the Rear cargo area of the vehicle. Just need to get some battery or welding cable and a battery still. I have not decided which battery I want to use yet. Its going to be a minimum of 900 CCA or 100Ah

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Jeff@QuadShop

Explorer
Yep, I'm using one in my rig. You can see it behind the passenger side battery.

attachment.php
 

dwh

Tail-End Charlie
That's a diode type isolator.

The only problem with them, is that there is usually a drop in voltage through the diode. Usually around a half a volt. Which means that the aux battery is always half a volt low, which doesn't seem like a lot, but when you consider a fully charged battery is around 12.8v and a dead battery is around 10.5v - it means that the aux battery is always going to be undercharged by around 15% or 20%.

Having the battery at less than full charge helps to accelerate sulfation, which ends up shortening its life.
 

Jeff@QuadShop

Explorer
That's a diode type isolator.

The only problem with them, is that there is usually a drop in voltage through the diode. Usually around a half a volt. Which means that the aux battery is always half a volt low, which doesn't seem like a lot, but when you consider a fully charged battery is around 12.8v and a dead battery is around 10.5v - it means that the aux battery is always going to be undercharged by around 15% or 20%.

Having the battery at less than full charge helps to accelerate sulfation, which ends up shortening its life.

Not in my case, my aux battery is always exactly the same after charging as my main battery as shown on my National Luna battery monitor and checking it with my multimeter.
 

roving

Observer
Find a different source and I may believe it. I always take someone else's sales brochure with a grain of salt. especially when they are in competition with another idea or product.
 

762X39

Explorer
I have one of the diode type isolators (it is about 20 years old) and yes, the batteries will always be 1/2 a volt low (it's how diodes work, no rocket science involved). The solution is to set your alternator regulator 1/2 a volt higher and all will be well. Of course, a lot of regulators are not adjustable, oh well, it's only a couple of $200 batteries.:coffee:
 

dwh

Tail-End Charlie
At least the guy from SmartGauge backs it up with math instead of just rhetoric.

And - if solenoids were such bad news (as the people who want you to buy their diode isolator would have you believe), then why do the isolators from companies like National Luna and Blue Sea use solenoids instead of diodes?

http://www.nationalluna.com/intelsol.htm

http://bluesea.com/category/78/79


Sterling Power Products does make a split-charge diode, but they also state the voltage drop figures right up front:

http://www.sterling-power.com/products-diodes.htm


Victron makes an FET type isolator, which has less voltage drop than a diode type:

http://www.victronenergy.com/battery-isolators-and-combiners/argo-fet-battery-isolators/

AND they also make diode types:

http://www.victronenergy.com/battery-isolators-and-combiners/argo-diode-battery-isolators/

According to the datasheet on the Victron diode unit:

"The Argo battery isolators feature a low voltage drop thanks to the use of Schottky diodes: at low current the
voltage drop is approximately 0,3 V and at the rated output approximately 0,45 V.
All models are fitted with a compensation diode that can be used to slightly increase the output voltage of the
alternator. This compensates for the voltage drop over the diodes in the isolator."

http://www.victronenergy.com/upload...rgo Diode Battery Isolators - rev 08 - EN.pdf



So...if the people who are SELLING the diode units are saying they have voltage drop...wouldn't that be considered a "reliable source"? Pretty much unimpeachable if you ask me.

Thus, the guys who are selling solenoids aren't lying about the voltage drop of diodes just to make a sale.
 

zoblo

Observer
I bought a Hellroaring isolater last year for the aux battery in my popup camper. It is a little spendy but seems to solve the diode issue while still being completely solid state. I use to use a solenoid but one time when the starting battery was low and with the solenoid open it use power from the aux battery and burned up the wires as the aux battery was wired with only 10ga wire.
 

brian90744

American Trekker
Try to keep the battery cables as short as possible, see my set-up. tx brian
 

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chilliwak

Expedition Leader
I read about a cheap solution on another thread in the domestic and full size area where the person just used a battery disconnect switch on the positive terminal of the main battery. If you disconnect the aux battery from the main starter battery when your vehicle is not running then you are effectively doing the same thing as the isolator are you not? If you keep an eye on the voltage of your aux battery and turn things off before the voltage gets too low, then you should be ok, right? As far as I see it as long as you dont reconnect the isolator switch before you have fired your vehicle up on your main battery, then everything should be ok. Please feel free to give your 2 cents worth everyone.....:)
 

toymaster

Explorer
^^^^^ Yes you are exactly right. However, people try to design a system that is automatic for convenience reasons. Also, as humans we often forget; hate to get stuck at the camp site from a dead battery because it was forgotten. The simplest way is to wire a heavy duty solenoid between the positive of both batteries that closes from a keyed source while having all of your aux circuits feed from the aux battery. This way when you are parked you only run off of the aux battery and with the key on you have both batteries being used and charging.

As automation is my career and I'm a master electrician you would think I'd have a fancy set-up but alas I do similar to the way you described. (My aux battery is on my trailer and I just unplug the trailer from the jeep). I do thing the simplest way that it will work and when it does not I just fix it.
 

762X39

Explorer
Not in my case, my aux battery is always exactly the same after charging as my main battery as shown on my National Luna battery monitor and checking it with my multimeter.
This makes sense. I tested my Cole Hersee 48120 battery isolator and found the voltage drop to be .451 vdc to batt 1 and .464 vdc to batt 2. The isolator consists of 2 140 amp diodes encapsulated on a large heat-sink. The heat is generated by the voltage drop through the diodes. If your charging system has a high enough charge voltage to make up the 1/2 volt loss there will be no problems but if your charging system is marginal, the batteries will be consistently undercharged.:coffee:
 

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