Dual Battery: Soleniod vs Isolator

[kert0307]

I've been thinking about going to dual batteries for awhile and after doing some searching I'm still not sure if I want to use a soleniod or an isolator, So I thought it might be good to start a kind of comprehensive thread about the pros and cons of each setup, and which is better for certain cases. Like for the audio people running an extra battery for their system, or for off road acessories.

I am somewhere in between these to because I use my stereo to provide music for tailgating and camping, run aux. lights, and occasionally use a power inverter. I have decided that I will be using a deep cycle battery as the 2nd battery and use the red top I currently have as the main starting battery. The 2nd battery will most likely be in the rear in the cargo pocket area with 4 or 5 guage wire running to it. So this breaing me to my questions...

Choices:
Setup one - Battery Isolator
Setup two - Soleniod set up to close when engine running, and open when off.


How much power is lost from heat in an Isolator? (estimated percent?)

If the 2nd battery is run down and I sart my engine with the soleniod setup will the primary battery suffer any "temporary rundown" since both batteries will be connected?

Lifetime of a soleniod in a daily driven vehical?



I'd like to keep this as simple as possible, and yes it will be fused in all necessary locations. Thanks for your help.

[BrooklynBay]

I have a dual set up on my 88 with an isolator, and a solenoid. The solenoid engages only when I'm cranking the engine, then disengages. The isolator is connected to both batteries. If I want to manually connect both batteries, I have a high current key switch which connects (+) to (+). An isolator usually has a .7 volt drop which isn't so noticeable.

[BrooklynBay]

This link has a couple of wiring schematics: http://www.explorerforum.com/forums/...0&postcount=14

[kert0307]

thats good information, but I already know how to wire it up (I gave the two options I was concidering), I was asking about the lifetime of a solenoid, or how much power is lost by the heat dissipating off of the isolator. Sorry for the confusion.

[BrooklynBay]

In comparison, the isolator should last longer than the solenoid providing that the isolator is not constantly overheated, or under rated for the amount of current it is handling.

[Bill Kemp]

The battery on my car is under the back seat and vented through the floor.
When I asked about using a Ultima they said it shouldent be used in the inside of a car as there was no vent.
Just a thought.....

[RV Wrench]

Originally Posted by Bill Kemp

The battery on my car is under the back seat and vented through the floor.
When I asked about using a Ultima they said it shouldent be used in the inside of a car as there was no vent.
Just a thought.....

I believe gell cell batteries do not require venting. Is this Ultima battery a gell-cell? Or were you referring to Optima batteries? (yes, Optima's are gell-cells).

kert0307,
dependability if either of your choices would be most dependant on the quality of the hardware (solenoid/isolater). If it were me, I would copy BrooklynBay's layout, which gives you more options than either a solenoid or isolater alone.

[kert0307]

Thanks for all the info. Yes, I am planning to use an Optima Yellow Top battery so I'm not too concerned about venting. Looks like I've got a little more to think about. Whatever I choose I will definetly get an isolator or soleniod that is rated for higher then I will need. Thanks again for your input.

[little x]

I am planning on wireing a dual system with a solenoid. Where can I find a solenoid that will handle the power (I have a 200 apm alt)?

[BrooklynBay]

They make one type which looks like a big starter solenoid. The place I got mine from is not in business anymore, but I'm sure that you could find one on Summit Racing, or JC Whitney.

[Alan in AZ]

Originally Posted by BrooklynBay

I have a dual set up on my 88 with an isolator, and a solenoid. The solenoid engages only when I'm cranking the engine, then disengages. The isolator is connected to both batteries. If I want to manually connect both batteries, I have a high current key switch which connects (+) to (+). An isolator usually has a .7 volt drop which isn't so noticeable.

If your secondary battery fails how will you know in this configuration? If it does fail and you don't know it then you'd be fully exposed to failures of the primary battery. Do you have any other monitoring for the secondary battery (perhaps via the isolator?).

I was under the impression that a more reliable method is to have an isolator for charging and a manual battery changeover/combine switch for starting duty only as needed (or for testing). Keeping the secondary battery fully charged but not stressed by the partial starting loads should lead to longer life I think. What I described is what I have on my Expedition today.

Alan

[Tbars4]

..There are a few isolators to choose from in the 200 amp range..Just for general purposes here are couple different kinds/styles of various amperage...

..One is electrical and keeps the starting battery online at all times and only adds the second battery online after the vehicle has started...This isolates the second battery from starting duty and the primary batter from auxiliary duty while allowing both to be charged while the vehicle is running..

Stinger 200 Amp Battery Relay Isolator
http://www.amazon.com/Stinger-200-Ba.../dp/B001HBYXVS



..The other is totally manual and serves the same purpose as above but also can directly isolate either the primary or the secondary for starting duty at the flip of a knob..(shown with key lock)
http://www.westmarine.com/webapp/wcs...splayErrorView



..This one is like above with a combiner, but 120 Amp..This also has a video on it's page to better explain it but it's geared for boat owners but many use this for their vehicles..
http://www.westmarine.com/webapp/wcs...classNum=50547



and the video from their page just for visual aid....

YouTube Video

[BrooklynBay]

Accessories are connected to the dual battery. If the accessories lack sufficient power or if the vehicle feels weak starting because the secondary battery is draining the primary battery, then I know that the secondary battery failed. There is also a voltmeter for monitoring the charge. It could also be used to check the battery after the vehicle is sitting for a while with everything off. The primary & secondary batteries have circuit breakers, so the accessories might cause them to trip if there is insufficient current from both batteries working simultaneously.

[Tbars4]

..These were top item at SEMA a year or two ago..

The IBS won a Global Media Award as one of the best new products at the 2009 SEMA Show.

http://www.sierraexpeditions.com/ind..._detail&p=2074

[Alan in AZ]

Originally Posted by BrooklynBay

Accessories are connected to the dual battery. If the accessories lack sufficient power or if the vehicle feels weak starting because the secondary battery is draining the primary battery, then I know that the secondary battery failed. There is also a voltmeter for monitoring the charge. It could also be used to check the battery after the vehicle is sitting for a while with everything off. The primary & secondary batteries have circuit breakers, so the accessories might cause them to trip if there is insufficient current from both batteries working simultaneously.

OK that makes sense.

My usage has nothing connected to the secondary battery - its truly just a starting battery backup so staying off line during starting is better. I do use a Blue Seas HD switch - a 2 circuit one a bit like the one shown - its a real work of art - just so well made - specs are fantastic too...

I also use this in the 100A version: http://order.waytekwire.com/products...nt%20Products/

I have also ordered some neat little battery monitors from a guy in Scotland - single multi-color LED (Green Yellow Red). Has different voltage maps for discharge (e.g. ignition on engine not running) and charging (alternator generating). I think this will be simple & helpful for in cabin monitoring on both batteries... I have 2 dual battery sysems and will try these out on the system not due for transplantation.

Check out "LED voltage monitor" by sparkbright on ebay for an idea of how these work - though the one I am talking about doesn't show up there yet - has dual maps.

[kert0307]

Originally Posted by Tbars4

..These were top item at SEMA a year or two ago..



http://www.sierraexpeditions.com/ind..._detail&p=2074

Look at the original thread date... 2007

FYI, I went with a 140amp isolator. It worked fine when taken off a couple months ago when I sold the truck.

[Tbars4]

So I thought it might be good to start a kind of comprehensive thread about the pros and cons of each setup, and which is better for certain cases.

..Since the thread was brought up again yesterday, I thought it would benefit the thread to add some more current information that I was sitting on for those who are still looking for this information...

..You never did say what all items you ran on your secondary battery...

[krbeave1]

As a retired marine mechanic having some experience with these systems,here are a couple of thoughts.An isolator/selector switch system has more flexibility than a solenoid . Make sure your selector switch is a "make before break"unit. If you want the option of using the secondary battery as a starting back-up ,your cables should be larger (Google I squared R losses). Finally ,ensure that you don't leave the switch in the "off " position as your ECM could lose it's presets.

[Rick]

Been running the same solenoid on mine since the mid '90s with zero issues and 100% reliability. With the three position switch mounted on the dash I can charge both batteries, isolate the auxiliary battery, or jump start myself.

[Tbars4]

..Rick...Would you happen to have a link or picture to your solenoid and 3 position switch in the cab? You got me curious..